Igcse Revision Guide Questions (bio)
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a document by the cie with sylabus,questions and answers...
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Scheme of work – Cambridge IGCSE® Biology (0610) Overview The aim of this scheme of work is to set out a progression through the syllabus content, and to give ideas for activities, together with references to relevant internet sites. The scheme of work follows the 0610 syllabus, but has been sub-divided into ten units, each covering a theme. The scheme of work is intended to give ideas to teachers upon which they can build. It is certainly not intended that teachers undertake all of the activities shown in the various units but rather to offer choices which could depend on local conditions. The progression through these themes has been designed to build on students’ own experiences, and to ensure that students have sufficient basic knowledge and understanding to tackle the more challenging issues. Outline The units within this scheme of work are: Unit 1: Unit 2: Unit 3: Unit 4: Unit 5: Unit 6: Unit 7: Unit 8: Unit 9: Unit 10:
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Cells and cell processes Animal nutrition Plant nutrition and transport Respiration and the human transport system Coordination, response and homeostasis Reproduction in plants Human reproduction Inheritance and evolution Organisms and environment Human influences on the environment
Cambridge IGCSE Biology (0610)
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Details of unit structure Unit 1: Cells and cell processes 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11
Characteristics of living organisms Concept and use of a classificatory system Adaptations of organisms to their environment Simple keys Cell structure and organisation Levels of organisation Size of specimens Diffusion Active Transport Osmosis Enzymes
Syllabus reference – Section I: 1, 2, 3 Section II: 1, 2, 3, 4, 5 Unit 2: Animal nutrition 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9
Nutrition Nutrients Diet Food supply Human alimentary canal Mechanical and physical digestion Chemical digestion Absorption Assimilation
Syllabus reference – Section II: 6.1, 6.3 Unit 3: Plant nutrition and transport 3.1 3.2 3.3 3.4 3.5 v1 2Y05
Photosynthesis Leaf structure Mineral requirements Transport in plants Water uptake Cambridge IGCSE Biology (0610)
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3.6 3.7
Transpiration Translocation
Syllabus reference – Section II: 6.2, 7.1 Unit 4: Respiration and the human transport system 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8
Respiration Aerobic respiration Anaerobic respiration Gas exchange Transport in humans Heart Arteries, veins and capillaries Blood
Syllabus reference – Section II: 7.2, 8 Unit 5: Coordination, response and homeostasis 5.1 5.2 5.3 5.4 5.5 5.6
Nervous control in humans Hormones Tropic responses Homeostasis Drugs Excretion in humans
Syllabus reference – Section II: 10, 9 Unit 6: Reproduction in plants 6.1 6.2 6.3 6.4 6.5 6.6
Asexual reproduction Mitosis Sexual reproduction Meiosis Sexual reproduction in plants Growth and development
Syllabus reference – Section III: 1.1, 1.2, 2, 3.2, 3.3
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Unit 7: Human reproduction 7.1 7.2 7.3 7.4
Sexual reproduction in humans Sex hormones Methods of birth control Sexually transmissible diseases
Syllabus reference – Section III: 1.2.2, 1.3, 1.4, 1.5 Unit 8: Inheritance and evolution 8.1 8.2 8.3 8.4 8.5 8.6
Inheritance Chromosomes Monohybrid inheritance Variation Selection Genetic Engineering
Syllabus reference – Section III: 3.1, 3.4, 3.5, 3.6, 3.7 Unit 9: Organisms and environment 9.1 9.2 9.3
Energy flow Food chains and food webs Nutrient cycles
Syllabus reference – Section IV: 1, 2, 3 Unit 10: Human influences on the environment 10.1 10.2 10.3 10.4 10.5
Population size Human influences on the ecosystem Agriculture Pollution Conservation
Syllabus reference – Section IV: 4, 5
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Teacher support The up-to-date resource list for this syllabus can be found on the University of Cambridge International Examinations website www.cie.org.uk. In addition, the password-protected Teacher Support website at http://teachers.cie.org.uk provides access to specimen and past question papers, mark schemes and other support materials. We offer online and face-to-face training; details of forthcoming training opportunities are posted on the website. Resources Cambridge IGCSE Biology webpage www.cie.org.uk/qualifications/academic/middlesec/igcse/subject?assdef_id=837 Cambridge Students – University of Cambridge International Examinations www.cambridgestudents.org.uk/subjectpages/biology/ Biology for IGCSE, Williams, G., Fosbery, R. and Adams, J. Nelson Thornes 2009. ISBN: 9781408500170 An Atlas of Histology, Freeman and Bracegirdle. Heinemann Educational. ISBN: 9780435603113 Cambridge IGCSE Biology Coursebook with CD-ROM, Jones, M. and Jones, G. Cambridge University Press, 2009. ISBN: 9780521147798 Cambridge IGCSE Biology Teacher's Resource CD-ROM, Jones, M. and Jones, G. Cambridge University Press, 2010. CD-ROM ISBN: 9780521176170 Cambridge IGCSE Biology Workbook, Jones, M. and Jones, G. Cambridge University Press, 2010. ISBN: 9780521124430 Complete Biology for Cambridge IGCSE, Ron Pickering. Oxford University Press, 2011. ISBN: 9780199138760 Complete Biology for Cambridge IGCSE Teacher's Resource Kit (with CD-ROM), Ron Pickering. Oxford University Press, 2011. ISBN: 9780199138791 Experiment Simulator CD-ROM: Experiments for IGCSE, GCSE and A Level. Cambridge Assessment. Cambridge Hitachi, 2005. ISBN: 9781845651404 IGCSE Biology, Mackean, D G. Hodder Education, 2009. ISBN: 9780340981863 IGCSE Biology, Jones, M. Heinemann, 2009. v1 2Y05
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ISBN: 9780435966805 IGCSE Biology for CIE, Clegg, J. and Smith, M. Collins Educational, 2006. ISBN: 9780007755424 IGCSE Biology Revision Guide, Pickering, R. Oxford University Press, 2009. ISBN: 978019915265-0 IGCSE Biology Study Guide, Hayward, Dave. Hodder Education, 2005. ISBN: 9780719579042 IGCSE Bitesize Biology – BBC www.bbc.co.uk/schools/gcsebitesize/biology/ SAPS (Science and Plants for Schools) www.saps.org.uk/ Practical Biology www.practicalbiology.org/ Society of Biology www.societyofbiology.org/home ® IGCSE is the registered trademark of University of Cambridge International Examinations. © University of Cambridge International Examinations 2012
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Scheme of work – Cambridge IGCSE® Biology (0610) Unit 1: Cells and cell processes Recommended prior knowledge Students can come to this unit with very little prior knowledge. In order to understand diffusion and osmosis, they will need some understanding of particle theory. Some knowledge of catalysts will also be helpful, and they should know a little about simple chemical reactions and how to represent these by word equations. The concept of pH should also be understood at a simple level. Context This unit covers some fundamental topics that will be drawn on in all the units that follow, and therefore the majority of it is covered by both Core and Supplement (Extended). Outline The unit first considers the special features that make living things different from non-living objects, and then looks at the structure and functions of animal and plant cells, which leads into the organisation of cells into tissues. Some particular examples of specialised cells are considered, which introduces the idea of structural adaptations for particular functions. Movement of substances within living organisms by diffusion, osmosis and active transport (the latter for the supplement only) is considered. A simple treatment of enzyme function and some applications completes the unit. Note that Unit 1.2, 1.3 and 1.4 (dealing with classification and keys) are included in this unit, but some teachers may prefer to cover these topics at the beginning of Unit 9 Organisms and environment. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref I1
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Learning objectives 1.1 Characteristics of living organisms • List and describe the characteristics of living organisms • Define the terms: - nutrition as taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them - excretion as removal from
Suggested teaching activities Section 1 of this unit can provide an introduction to the Biology course. The seven characteristics of living things form a basis from which the themes underlying many biological concepts can be developed. Activities can include: 1. The comparison of the characteristics of living organisms with those of non-living things – for example, what are the characteristic of life shown by a petrol engine. The comparison is clear when written in a table. 2. The mnemonic, MRS GREN is useful to remember the seven characteristics. Cambridge IGCSE Biology (0610)
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p2–3 Student activity – Characteristics of Living things: www.exploratorium.edu/imaging_s tation/activities/classroom/charact eristics/ca_characteristics.php Including video clips and student 1
Syllabus ref
Learning objectives
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-
organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements respiration as the chemical reactions that break down nutrient molecules in living cells to release energy sensitivity as the ability to detect or sense changes in the environment (stimuli) and to make responses reproduction as the processes that make more of the same kind of organism growth as a permanent increase in size and dry mass by an increase in cell number or cell size or both movement as an action by an organism or part of an organism causing a change of position or place
Suggested teaching activities 3. Students should understand that single-celled organisms, plants and animals all have these characteristics. 4. The characteristic of nutrition could be extended to include autotrophic and heterotrophic nutrition and the terms parasite and saprophyte. 5. If models or specimens are available, students could discuss the importance of having a large surface area in relation to volume for diffusion. The importance of diffusion of gases in respiration will be understood more easily when Unit 4 is studied. 6. Growth could also be explained as an increase in size due to cell division. There might be a change in shape with growth. 7. Examples to explain the need for energy to carry out each of the characteristics should be discussed. Students will appreciate that energy is required for movement and this can be extended to show that energy is needed for growth, nutrition and sensitivity.
Learning resources worksheet. Revision – Cells and Life Processes: www.lgfl.skoool.co.uk/content/key stage4/biology/pc/lessons/uk_ks4 _cells_life_processes/h-frameie.htm Revision – Characteristics of Life: www.scool.co.uk/gcse/biology/cells/revis e-it/characteristics-of-life
Extension – students could perform a search of the characteristics of life. Do all scientists use the same list? How do we classify viruses? Student progress could be assessed using: May/June 2011 Paper 0610/22 question 1 May/June 2008 Paper 0610/02 question 1
I 2.1
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1.2 Concept and use of a classificatory system • Define and describe the binomial system of naming species in which the scientific name of an organism is made up of two parts showing the genus and species
Students may know some binomials, such as Homo sapiens. Use this as an introduction of the Latin names for classification of all organisms. Carl Linnaeus can be mentioned and his work discussed. Emphasise the format of binomial names: Genus with a capital letter and species with a lower case letter and the possible use of italics or underlining.
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p4–13 Students can visit a variety of living organisms to appreciate the variety amongst living things: Local zoo Game park Natural history museum Online specimen collections www.nhm.ac.uk/index.html
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Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
• List the main features of the following vertebrates: - bony fish - amphibians - reptiles - birds - mammals
The use of the internet, photographs or specimens of the five groups of vertebrates can be used to draw up a table or produce a poster to include the main characteristics of each class.
The four species of crow can serve to explain the importance of classification. Corvus coroner: carrion Corvus corax: raven Corvus frugilus: rook Corvus monedula: jackdaw www.rspb.org.uk/wildlife/birdguide /name/c/carrioncrow/index.aspx
Students should understand the specific features that differentiate each class: e.g. Birds have feathers, beaks, front limbs modified into wings and lay hard-shelled eggs.
Student progress could be assessed using: May/June 2010 Paper 0610/21 question 2 May/June 2009 Paper 0610/31 question 1 Oct/Nov 2010 Paper 0610/21 question 1 Oct/Nov 2010 Paper 0610/22 question 2 Oct/Nov 2008 Paper 0610/02 question 1 I 2.1 (S)
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1.2 • Know that there are other classification systems e.g. cladistics (based on RNA/DNA sequencing data) • List the main features used in the classification of the following groups: - viruses - bacteria - fungi and their adaptation to the environment, as appropriate
Bird images: www.allaboutbirds.org/Page.aspx ?pid=1189 Species diversity: www.seaworld.org/animalinfo/info-books/biodiversity/index.htm An exploration of Biodiversity
Viruses and bacteria should be studied from photomicrographs or diagrams but their relevance can be mentioned in nutrition and disease ref: Unit 2 and Unit 7.1.
Cladistics: www.evolution.berkeley.edu/evolib rary/article/phylogenetics_01
Mucor as a fungus can be grown and the gross structure studied under a light microscope. Emphasise the role of spores in dispersal.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p10–11
Positive applications of viruses and bacteria can be mentioned in Unit 2.2 and 8.6.
The virtual virus experience: www.library.thinkquest.org/13373/i ntro/intro.htm
Student progress could be assessed using: Oct/Nov 2009 Paper 0610/31 question 1.
Cambridge IGCSE Biology (0610)
Infectious diseases – Pathogens: www.abpischools.org.uk/page/mo dules/infectiousdiseases_pathoge ns/index.cfm
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Syllabus ref I 2.2
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Learning objectives
Suggested teaching activities
Learning resources
1.3 Adaptations of organisms to their environment (to be illustrated by examples wherever possible) • List the main features used in the classification of the following groups: - flowering plants: monocotyledons and eudicotyledons (dicotyledons) - arthropods: insects crustaceans arachnids myriapods - annelids - nematodes - molluscs
This section focuses on the adaptations of animals and plants to their environment. Specimens from each group can be viewed under the microscope and the main features noted. Emphasis should be given to drawing clear diagrams in pencil.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p4–13 & p94–95
1.4 Simple keys • Use simple dichotomous keys based on easily identifiable features
Students can draw a chart to list and then compare the distinguishing features of each group. Reference should be made to the organism's habitat and reference later in Units 3.6, 9.2 and 10.5.
A comparison of monocots and dicots: www.csdl.tamu.edu/FLORA/201M anhart/mono.vs.di/monosvsdi.html Preserved specimens if available, are excellent for explaining external features.
Extension – students could be asked to search the ARKive database and compile a presentation of the listed groups of organisms. Many students have difficulty in constructing dichotomous keys. The concept can be introduced with coins or nails/ screws with different shaped heads or even with postage stamps.
An excellent source for images and video clips of animals and plants is ARKive: www.arkive.org/ Biology for IGCSE, Williams et al. Nelson Thornes 2009 p14–15
The students can then classify a selection of leaves from the school grounds or from a selection of small pictures of different arthropods. Extension – more complex keys could be used to identify local flora or fauna. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 1 May/June 2010 Paper 0610/22 question 1 May/June 2009 Paper 0610/02 question 1 Oct/Nov 2010 Paper 0610/33 question 1a
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Syllabus ref II 1
Learning objectives 1.5 Cell structure and organisation • State that living organisms are made of cells • Identify and describe the structure of a plant cell (palisade cell) and an animal cell (liver cell) as seen under a light microscope • Describe the differences in structure between typical animal and plant cells
Suggested teaching activities Palisade cells can be seen using prepared slides or transparencies of leaf sections. Students can make their own slides of freshwater filamentous algae, Elodea or moss that can be mounted in a drop of water on a slide and viewed with a microscope. Liver cells are difficult to observe, but it may be possible to make temporary mounts of wrist cells. Wash the inside of the wrist and place a piece of scotch tape onto this part of the wrist. Pull off the scotch tape and view the cells under the microscope. Extension – Students can also make models of a plant cell and / or an animal cell to gain an idea of the orientation of the main structures of each type of cell. Show video clip – cell structure: www.bbc.co.uk/learningzone/clips/parts-of-plant-and-animalcells/10602.html Student progress could be assessed using: May/June 2010 Paper 0610/21 question 1 Oct/Nov 2009 Paper 0610/02 question 2
II 1 (S)
1.5 • Relate the structures seen under the light microscope in the plant cell and the animal cell to their functions
Candidates studying the supplement should consider functions of features that are common to plant and animal cells, and those that are found in plant cells only. They should understand how the differences between animal and plant cells relate to their different methods of obtaining nutrients. Examine a temporary mount of epidermal tissue peeled from the inner surface of an onion bulb.
Learning resources PowerPoint presentation – Cells and Tissues: www.biologyresources.com/biology-CD.html Illustrations of cells: www.cellsalive.com/ An Atlas of Histology, Freeman and Bracegirdle. An excellent reference book for teachers. Cell structure: www.exploratorium.edu/imaging_s tation/activities/classroom/elodea_ explorations/ca_elodea_exploratio ns.php Revision – Cell structure: www.scool.co.uk/gcse/biology/cells/revis e-it/plant-and-animal-cells Biology for IGCSE, Williams et al. Nelson Thornes 2009 p19 Inside animal and plant cells: learn.genetics.utah.edu/content/be gin/cells/insideacell/ Video clip – Cell structure: www.bbc.co.uk/learningzone/clips/ plant-and-animal-cellstructures/4188.html
Students could review cell structure (“cell structure and function” or “organelles”): www.exploratorium.edu/imaging_station/gallery.php v1 2Y05
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Syllabus ref II 2
II 3
Learning objectives
Suggested teaching activities
Learning resources
1.6 Levels of organisation • Relate the structure of the following to their functions: - ciliated cells – in respiratory tract - root hair cells – absorption - xylem vessels – conduction and support - muscle cells – contraction - red blood cells – transport • Define: - tissue as a group of cells with similar structures, working together to perform a shared function - organ as a structure made up of a group of tissues, working together to perform specific functions - organ system as a group of organs with related functions, working together to perform body functions using examples covered in Sections II and III
The coverage of these examples of cells and of organs and organ systems could come later when they can be dealt with in context but it may help to introduce the students to cells with different functions at this stage using an overhead or on a PowerPoint presentation. Students can select their own specialised cell, draw and label it on A3 paper. Flash cards are an interactive way of learning about specialised cells.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p20–23
1.7 Size of specimens • Calculate the magnification and size of biological specimens using millimetres as units
Examples of differentiated cells: www.rothamsted.ac.uk/notebook/o rgan.htm
Students can draw a flow diagram from cells to the particular organ system to begin to understand the complexity of the human body. An outline of the human body can be used to draw in the main organ systems of the body. Extension – students could research a greater range of specialised cells. This could link to stem cells and their uses. Student progress could be assessed using May/June 2009 Paper 0610/02 question 5.
Use the temporary mount of epidermal tissue peeled from the inner surface of an onion bulb or rhubarb stem and to use an appropriate scale to determine the size of cells. Students can magnify a piece of hair to understand that magnification is size of image size of object Student progress could be assessed using: May/June 2009 Paper 0610/31 question 2b
Microscope magnification specifications & field of view: www.microscopemicroscope.org/advanced/magnifi cation-1.htm
Student activity – Specimen size: www.exploratorium.edu/imaging_s tation/activities/classroom/size/ca_ size.php Relative sizes of cells: www.cellsalive.com/howbig.htm
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Syllabus ref
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Suggested teaching activities
Learning resources Scale: learn.genetics.utah.edu/content/be gin/cells/scale/
II 4.1
1.8 Diffusion • Define diffusion as the net movement of molecules from a region of their higher concentration to a region of their lower concentration down a concentration gradient as a result of their random movement • Describe the importance of gaseous and solute diffusion and of water as a solvent
Use a simple demonstration of diffusion, for example a potassium manganate VII crystal in a gas jar of water or a drop of methylene dye on gelatine solidified in a test tube (diffusion of a solute), or ammonia and hydrochloric acid placed at opposite ends of a long glass tube, or simply a perfume container opened in one corner of the room. Bromine in a gas jar (carried out in a fume cupboard) can quickly show diffusion (gaseous diffusion). Teachers should be aware that these experiments are often carried out by the Chemists at the beginning of the Cambridge IGCSE course and collaboration is important. Emphasise the random motion of particles. Variables of temperature, pressure, distance moved, concentration and size of particles. Consider the relevance of diffusion to living organisms – for example, the diffusion of oxygen and carbon dioxide into and out of a plant leaf or across the surface of the alveoli in the human lungs. Emphasise that water is an important solvent and most cells contain about 75% water. Water transports substances and allows many chemical reactions to take place.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p26–27 PowerPoint presentation – Diffusion: www.biologyresources.com/biology-CD.html Experiments in biology – Diffusion: www.biologyresources.com/biologyexperiments2.html Practical Biology – Diffusion: www.nuffieldfoundation.org/practic al-biology/diffusion Diffusion and animation and text: www.bbc.co.uk/schools/gcsebitesi ze/science/add_gateway/living/diff usionrev1.shtml
Extension – students could investigate the effects of surface area/volume ratio on rates of diffusion. Student progress could be assessed using: May/June 2011 Paper 0610/22 question 6 Oct/Nov 2009 Paper 0610/02 question 9
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Syllabus ref II 4.2 (S)
II 4.3
Learning objectives 1.9 Active Transport • Define active transport as movement of ions in or out of a cell through a cell membrane, from a region of their lower concentration to a region of their higher concentration against their concentration gradient, using energy released during respiration • Discuss the importance of active transport as an energy-consuming process by which substances are transported against a concentration gradient e.g. ion uptake by root hair cells and the uptake of glucose by epithelial cells of villi 1.10 Osmosis • Define osmosis as the diffusion of water molecules from a region of their higher concentration to a region of their lower concentration, through a partially permeable membrane • Describe the importance of osmosis in the uptake of water by plants and its effects on plant and animal tissues
Suggested teaching activities A simple explanation is climbing uphill. No detail of the molecular mechanism of active transport needs to be considered. Students should understand that energy for this process is provided by respiration. Students will understand the importance of the movement of particles by active transport after having studied Units 2, 3 and 5.
Osmosis should be treated as a special case of diffusion, in which only water molecules are able to move from one side of a partially permeable membrane to another. Ensure that students understand what a solution is in terms of particles, so that they are able to imagine the water molecules and solute particles behaving independently of each other. Use visking tubing to demonstrate osmosis. Investigation of changes in mass or length of potato chips or of dried raisins placed in a range of different concentrations of sugar solution provides good opportunity for quantitative treatment of results, as well as enhancing understanding of osmosis. Discuss differences in the effects of water uptake and loss on animal cells that lack a cellulose cell wall and plant cells that have a cellulose cell wall. Turgor as an important mechanism of support in plants could be discussed (Unit 3.4 & 3.5).
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Learning resources Biology for IGCSE, Williams et al. Nelson Thornes 2009 p32–33 Practical Biology – Active uptake: www.nuffieldfoundation.org/practic al-biology/active-uptake
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p28–31 PowerPoint presentation – Osmosis: www.biologyresources.com/biology-CD.html Experiments in biology – Osmosis: www.biologyresources.com/biologyexperiments2.html Practical Biology – Osmosis: www.nuffieldfoundation.org/practic al-biology/osmosis Osmosis animation and text: www.bbc.co.uk/schools/gcsebitesi ze/science/add_gateway/greenwo 8
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Suggested teaching activities Relate water uptake by osmosis to the structure of root hair cells covered earlier in this unit. Student progress could be assessed using: Oct/Nov 2008 Paper 0610/02 question 9
Learning resources rld/waterrev1.shtml Interactive osmosis (advanced for IGCSE): www.physioweb.uvm.edu/bodyflui ds/osmosis.htm Revision – Osmosis: www.scool.co.uk/gcse/biology/cells/revis e-it/moving-molecules
II 4.3 (S)
II 5
1.10 • Describe and explain the importance of a water potential gradient in the uptake of water by plants
1.11 Enzymes • Define the term catalyst as a substance that speeds up a chemical reaction and is not changed by the reaction • Define enzymes as proteins which function as biological catalysts • Investigate and describe the effect of changes in temperature and pH on enzyme activity
Explain water potential as the tendency for water to leave a solution. The more water (that is then a more dilute the solution) the higher the water potential. Water moves from a high water potential to a low water potential – that is, down a water potential gradient. Do not introduce the idea of negative water potentials at this level. Relate to intake of water by root hairs. Simple experiments with catalase are an excellent introduction to enzymes.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p36–39
Revise the meaning of the term ‘catalyst’. Ensure that students understand that enzymes are simple (protein) molecules, not living organisms. They cannot, therefore, be ‘killed’. Investigate the effect of temperature on the effect of enzyme activity, for example using starch and amylase, or pepsin and milk powder. Explain the rise in activity with temperature, in terms of kinetic theory, and the fall as temperature rises above the optimum in terms of denaturation of the enzyme molecules. Consider the different optimum temperatures of different enzymes, not only those in humans.
Experiments in biology – Enzymes: www.biologyresources.com/biologyexperiments2.html
Extension – students could investigate the effectiveness of enzyme based washing powders.
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Practical Biology – Enzymes: www.nuffieldfoundation.org/practic al-biology/investigating-enzymesused-laundry-detergents Simple account of how enzymes work: www.abpischools.org.uk/page/mo dules/enzymes/enzymes1.cfm
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Suggested teaching activities Use the kscience animation on an interactive whiteboard to demonstrate enzyme actions. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/22 question 1 May/June 2008 Paper 0610/02 question 3
Learning resources Interactive model of enzyme action: www.kscience.co.uk/aanimations/ model.swf Revision – Enzyme experiments: http://lgfl.skoool.co.uk/content/key stage4/biology/pc/modules/digesti on/digestion_experiments/index.ht ml Revision – Enzymes: www.lgfl.skoool.co.uk/content/key stage4/biology/pc/modules/digesti on/digestion_part_3/index.html Revision – Enzymes: www.scool.co.uk/gcse/biology/enzymes/r evise-it/enzymes
II 5 (S)
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1.11 • Explain enzyme action in terms of the 'lock and key' model • Explain the effect of changes in temperature and pH on enzyme activity • Describe the role of enzymes in the germination of seeds and their uses in biological washing products and in the food industry (including pectinase and fruit juice) • Outline the use of microorganisms and fermenters to manufacture the antibiotic penicillin and enzymes for use in biological washing products • Describe the role of the fungus
Power point demonstrations and graphs to show the trends of increasing temperature and of different pH solutions provide useful means of interpreting data. The role of amylase in the breakdown of starch to maltose in seeds provides an example of enzymes in plants. Germinating barley seeds, dipped into a sterilising solution to destroy any micro-organisms on their surfaces, can be placed on sterile starch agar in a Petri dish, which can later be tested for starch with iodine solution. Extension: proteases, lipases and amylases, often with high optimum temperatures, are all used in biological washing products. Investigations can be carried out into the effectiveness of these in removing different types of stains. Simple experiments on the effect of pectinase on the yield of juice from crushed apples or tinned apple purée can be carried out. Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes 2009, p36–41
Downloadable booklets with practical investigations using a variety of enzymes: www.ncbe.reading.ac.uk/NCBE/P ROTOCOLS/pracbiotech.html www.ncbe.reading.ac.uk/NCBE/P ROTOCOLS/juice.html
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Syllabus ref
Learning objectives Penicillium in the production of antibiotic penicillin
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Suggested teaching activities
Learning resources
Student progress could be assessed using: May/June 2009 Paper 0610/31 question 3 Oct/Nov 2010 Paper 0610/33 question 3 May/June 2008 Paper 0610/31 question 3
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Core 1
[Total: 4]
Cells & Cell Processes
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Core 2
Cells & Cell Processes
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Core 3 Fig. 1
Fig. 1
Cells & Cell Processes
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Core 3
Cells & Cell Processes
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Alternative to Practical 1
2
2
2 Table 2
Cells & Cell Processes
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Alternative to Practical 1
2
Cells & Cell Processes
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Extension 1
[Total: 15]
Extension 2
[Total: 15]
Cells & Cell Processes
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Core 1 a(i)
any three of these growth (or alternative wording) movement (or alternative wording) irritability / sensitivity (or alternative wording) excretion (or alternative wording) reproduction (or alternative wording)
(ii)
photosynthesis
Cells & Cell Processes
page 1
Core 2 In order in the table Respiration Reproduction Excretion Nutrition / feeding
Cells & Cell Processes
page 2
Core 3 a(i)
B – cell membrane C – cytoplasm
(ii)
chloroplasts
b
red blood cell any one of these functions with its relevant adaptation carries / combines with oxygen haemoglobin present more space for haemoglobin lack of nucleus oxygen uptake / release biconcave shape / increased surface area root hair cell uptake of water / minerals increased surface area / cell extension reject anchorage as a function
Cells & Cell Processes
page 3
Alternative to Practical 1 a(i)
in order in the table + 3.0 mm + 1.5 mm - 1.0 mm - 3.0 mm - 4.0 mm - 5.5 mm
(ii)
points plotted accurately neat clear line passing through each point
b(i)
potato strips in sucrose solutions lost or decreased in length potato strips in water or dilute sucrose solutions increased in length point noted of no change in length
(ii)
osmosis
Cells & Cell Processes
page 4
Extension 1 a
any six of these points with a maximum of 3 for the diagram (third point) suitable named plant cell function described diagram recognisable with main features drawn, at least 3 accurate labels cell wall cytoplasm / reference to lack of cytoplasm (sap) vacuole nucleus chloroplast (or other named feature appropriate to named cell)
b
nine points from the following provided cell is named red blood cell or corpuscle / erythrocyte reference to lack of nucleus description of shape provides large surface area (or alternative wording) reference to presence of haemoglobin carries / transports oxygen phagocyte / granulocyte / monocyte / neutrophil has lobed nucleus can change shape / pass out of capillaries engulfs bacteria (or alternative wording) digests bacteria / foreign material (or alternative wording) lymphocyte / B cells / T cells has large nucleus (or alternative wording) produces antibodies makes bacteria clump (or alternative wording) / ref. to long term immunity produces antitoxins neutralises toxins (or alternative wording)
Cells & Cell Processes
page 5
Extension 2 a
any three of these biological / present in living organisms catalyst / speeds up reaction rate / lowers activation energy reference to protein nature reference to specificity
b
any three of these reference to optimum temperature / specified temperature eg 25 – 40 0C reference to optimum pH (or specified pH for named enzyme) only work in liquid medium (or alternative wording) reference to lack of limiting factors for example concentration of substrate
c(i)
any three from amylase breaks down to starch reference to sugar / named sugar reject glucose / sucrose use, for example for energy / growth / respiration reference to sugar being soluble for transport
(ii)
any three of these protease / named protein enzyme, for example pepsin, trypsin breaks down / digests protein to amino acids / peptides reference to solubility
(iii)
any three of these lipase breaks down / digests protein reference to fatty acids and glycerol reference to molecules small enough to pass through gut wall / into lymph or lacteal reference to site of action, for example small intestine / duodenum / ileum
Cells & Cell Processes
page 6
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 2: Animal nutrition Recommended prior knowledge Students can come into this unit with very little biological knowledge. However, they do need to understand some basic chemistry such as atoms, elements and compounds. An understanding of bonding and the role of ions in simple chemical reactions is an advantage. Context The molecules that make up the bodies of living things are introduced here, and will be referred to in all of the subsequent units. Outline This unit considers the molecules from which living organisms are made, and then looks in detail at how animals acquire the materials that they need to form the structure of their bodies, and also to supply energy. The way in which small molecules can be used to make larger ones is briefly considered, before thinking about how such large molecules need to be broken down again before they can be absorbed through the wall of the alimentary canal. The functions of the main digestive enzymes are considered, linking back to the work on enzymes in Unit 1. The use of food to supply energy will be covered in more detail in Unit 4, and the functions of the liver in glucose and amino acid metabolism, touched on very briefly here, will be treated in more depth in Unit 5. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref II 6
Learning objectives 2.1 Nutrition • Define nutrition as taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them
Suggested teaching activities Discuss the need for materials for growth and repair and for energy to maintain their activities such as movement and sensitivity. A simple definition of an organic substance is one whose molecules contain carbon and hydrogen. Cross link with plant nutrition in Unit 3.1.
Learning resources Biology for IGCSE, Williams et al. 2009. p44–45 Unit revision: www.scool.co.uk/gcse/biology/nutrition/r evise-it/nutrition Unit revision: www.lgfl.skoool.co.uk/content/key stage4/biology/pc/lessons/uk_ks4 _digestion/h-frame-ie.htm
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Cambridge IGCSE Biology (0610)
1
Syllabus ref II 6.1
Learning objectives 2.2 Nutrients • List the chemical elements which make up: - carbohydrates - fats - proteins • Describe the synthesis of large molecules from smaller basic units: - simple sugars to starch and glycogen - amino acids to proteins - fatty acids and glycerol to fats and oils
Suggested teaching activities Ensure that students have some understanding of the terms: element, atom, molecule. Beads that string together, or simple chemical modelling kits, can be used to illustrate the idea of small molecules joining together to make larger ones. A table or flash cards can identify the classes of foods. Headings: class of food; source of food; uses of food in body; Once Unit 1.11 is completed, the enzymes and products of digestion could also be added to the summary table.
Learning resources For detail on carbohydrates, fats and proteins: www.nutrition.gov/nal_display/ind ex.php?info_center=11&tax_level =2&tax_subject=388&topic_id=16 65&placement_default=0 PowerPoint presentation – The Chemicals of Living Things: www.biologyresources.com/biology-CD.html
Students should understand that starch is the carbohydrate stored only in plants. Animals store carbohydrate as glycogen. II 6.1
• Describe tests for: - starch (iodine solution) - reducing sugars (Benedict's solution) - protein (biuret test) - fats (ethanol) • List the principal sources of, and describe the importance of: - carbohydrates - fats - proteins - vitamins (C and D only) - mineral salts (calcium and iron only), fibre (roughage) - water • Describe the deficiency symptoms for: - vitamins (C and D only) - mineral salts (calcium and iron only)
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Students should have the opportunity to carry out each of these tests on a range of foods. It is a good practical lab in which students should realize the importance of safety when using a water bath. As an extension exercise, students can be given a solution containing a mixture of unknowns such as a reducing sugar and a protein. This can also give useful practice in recording qualitative results in a clearly presented results chart. Conclusions can also be written from the observed results. Food tests also enhance the students' understanding of the main classes of foods.
Biology for IGCSE, Williams et al. 2009. p46–47 Food tests: www.biologyresources.com/biologyexperiments2.html Revision – Food tests: lgfl.skoool.co.uk/content/keystage 4/biology/pc/modules/digestion/fo od_tests/index.html
The information on multivitamin tablet packets lists the vitamin contents and their requirements in the human body. Extension – students could carry out research into food composition using the site Nutrition.gov
Cambridge IGCSE Biology (0610)
Nutrition.gov: What’s in food: www.nutrition.gov/nal_display/ind ex.php?info_center=11&tax_level =1&tax_subject=388 2
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
A summary table could be produced with vitamins and minerals, their source, function in the body and details of deficiencies. Student progress could be assessed using: May/June 2011 Paper 0610/22 question 6b Oct/Nov 2009 Paper 0610/02 question 3 II 6.1 (S)
2.2 • Describe the use of microorganisms in the food industry, with reference to yoghurt and single cell protein
Students can make yoghurt in the lab and should discuss the importance of sterile apparatus and of the constant temperature necessary for the process. The use of yeast for bread making can be linked to anaerobic respiration: Unit 4.3 Students can vary the mass of yeast in a given volume of water that is added to a constant mass of flour to measure the increase in height of flour in a large test tube or plastic cup over time. Temperature or sugar can also be used as a variable. A good source of ideas for this is the booklet 'Practical Biotechnology'. Student progress could be assessed using: May/June 2010 Paper 0610/31 question 5 Oct/Nov 2008 Paper 0610/32 question 3
•
Describe uses, benefits and health hazards associated with food additives, including colourings
The health benefits of preservatives, in terms of greatly reduced risk of food poisoning, should be emphasised. Antioxidants also increase storage times for many foods. Flavourings and flavour enhancers increase palatability. A few artificial colourings, such as tartrazine, have been associated with problems such as hyperactivity.
This website has some suggestions on fermentation: www.ncbe.reading.ac.uk/ncbe/pro tocols/pracbiotech.html and www.ncbe.reading.ac.uk/ncbe/pro tocols/juice.html Revision – Fermentation: www.lgfl.skoool.co.uk/content/key stage4/biology/pc/modules/breathi ng_respiration/fermentation/index. html Practical Biology – Preserving food: www.practicalbiology.org/areas/int roductory/health-anddisease/preservingfood/preserving-food,96,EXP.html Biology for IGCSE, Williams et al. Nelson Thornes 2009 p50–51
Student progress could be assessed using: Oct/Nov 2009 Paper 0610/31 question 2c II 6.3.1
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2.3 Diet • State what is meant by the term balanced diet and describe a balanced diet related to:
Diets in most countries depend on a staple food such as bread, potatoes or rice, which is usually the main source of carbohydrate. Students should be aware of the main sources of each type of nutrient in their own country, but also be Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p72–73
3
Syllabus ref
Learning objectives - age - sex - activity of an individual
Suggested teaching activities prepared to consider how diets differ in other parts of the world. Extension – the Association for Science Education has a project called Science Across the World, which includes a unit on diet, and encourages schools in different parts of the world to share information. Students can keep a record of the food that they eat during a short period of time and then consider whether they are obtaining the nutrients that they need. Their diet could be analysed using standard food tables or by accessing the nutrient data laboratory. Alternatively students could use the interactive Balanced Diet activity. Show video clips – Balanced diet: www.bbc.co.uk/learningzone/clips/a-well-balanceddiet/102.html www.bbc.co.uk/learningzone/clips/a-balanced-diet/10609.html
• Describe the effects of malnutrition in relation to: - starvation - coronary heart disease - constipation - obesity
Malnutrition should be considered as the result of eating an unbalanced diet, not just the lack of a particular type of nutrient. Controlled discussion on malnutrition can be useful and the problems associated with starvation can be linked to Unit 10.1 The long term problems associated with obesity like onset diabetes should be discussed. Students could take part in the Science Across the World – Keeping Healthy. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 2 May/June 2011 Paper 0610/22 question 2 Oct/Nov 2008 Paper 0610/32 question 2
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Cambridge IGCSE Biology (0610)
Learning resources Science Across the World – Talking about food: www.nationalstemcentre.org.uk/eli brary/resource/1727/talkingabout-food-food-nutrition-andhealth Revision: lgfl.skoool.co.uk/content/keystage 4/biology/pc/modules/digestion/ba lanced_diet/index.html National nutrient database: www.nal.usda.gov/fnic/foodcomp/ search/ Interactive Balanced diet: www.abpischools.org.uk/page/mo dules/balanceddiet/index.cfm Practical Biology – Energy in food: www.practicalbiology.org/areas/int roductory/energy/energy-infood/how-much-energy-is-therein-food,42,EXP.html Biology for IGCSE, Williams et al. Nelson Thornes 2009 p76–77 Science Across the World – Keeping Healthy: www.nationalstemcentre.org.uk/eli brary/resource/1741/keepinghealthy Revision – Malnutrition: lgfl.skoool.co.uk/content/keystage 4/biology/pc/modules/digestion/m 4
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources alnutrition/index.html
II 6.3.2
II 6.3.2 (S)
II 6.3.3
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2.4 Food supply • Discuss the ways in which the use of modern technology has resulted in increased food production to include: - modern agriculture machinery - chemical fertilisers - pesticides - herbicides - artificial selection
Material to illustrate this topic, and to form the basis of discussion, can be collected from newspaper and television reports. Students may like to consider whether new technologies, such as the development of genetically modified varieties of crops, are likely to improve the situation or exacerbate it. Extension – students could consider “food miles”. Student progress could be assessed using: May/June 2009 Paper 0610/02 question 9
2.4 • Discuss the problems of world food supplies • Discuss the problems which contribute to famine: - unequal distribution of food - drought - flooding - increasing population
Drought and flooding can be linked to Unit 10.1.
2.5 Human alimentary canal • Define ingestion as taking substances e.g. food and drink into the body through the mouth • Define egestion as passing out of food that has not been digested as faeces, through the anus • Identify the main regions of the alimentary canal and associated organs including: - mouth - salivary glands - oesophagus - stomach
Students often do not understand that the alimentary canal is a long tube - albeit a coiled one - through which food passes. A long flexible rubber tube can demonstrate the idea. A schematic diagram on A3 paper can clarify the main events that take place from ingestion by the mouth to egestion from the anus. Arrows in different colours can show which enzymes are involved along the canal. Students should understand that food cannot be considered to have entered the body until it crosses the wall of the canal.
Student progress could be assessed using: May/June 2010 Paper 0610/31 question 6 Oct/Nov 2008 Paper 0610/31 question 2
Science Across the World – How Plants Grow: www.nationalstemcentre.org.uk/eli brary/resource/1725/how-plantsgrow Food miles: www.saps.org.uk/secondary/teach ing-resources/138--how-scienceworks-food-miles-and-changinglevels-of-co2 Links with Unit 10 – Human influences on the environment Technology to Feed the World: www.nationalacademies.org/webe xtra/crops/ A discussion of the problems of feeding the world's growing population, with excellent links to many other websites.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p78–83 Digestion: www.abpischools.org.uk/res/coRe sourceImport/resources04/digesti on/index.cfm
The need for digestion to take place before absorption occurs is shown by using Visking tubing (to represent the alimentary Cambridge IGCSE Biology (0610)
5
Syllabus ref
II 6.3.4
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Learning objectives
Suggested teaching activities
- small intestine: duodenum and ileum - pancreas - liver - gall bladder - large intestine: colon and rectum - anus • Describe the functions of the regions of the alimentary canal listed above, in relation to: - ingestion - digestion - absorption - assimilation - egestion of food Cross reference 6.3.4 to 6.3.7 inclusive.
canal) containing a mixture of glucose, starch and water. The visking tubing is placed in a beaker or a large test tube of water (to represent the blood), and left for several hours to allow the glucose to diffuse across the tubing. The contents of the tubing and of the beaker can be tested for starch and for glucose.
2.6 Mechanical and physical digestion • Define digestion as the breakdown of large, insoluble food molecules into small, water soluble molecules using mechanical and chemical processes • Identify the types of human teeth and describe their structure and functions • State the causes of dental decay and describe the proper care of teeth • Describe the process of chewing • Describe the role of longitudinal and circular muscles in peristalsis Outline the role of bile in emulsifying fats, to increase the surface area for the action of enzymes
Learning resources
Extension – the importance of active uptake could be considered. This is particularly important for students studying Supplement.
Student progress could be assessed using: May/June 2010 Paper 0610/21 question 7 Extension – different types of teeth could be studied and related to different diets.
Revision: lgfl.skoool.co.uk/content/keystage 4/biology/pc/modules/digestion/di gestion_part_1/index.html Video clips – Digestion: www.bbc.co.uk/learningzone/clips /the-digestive-system/4180.html www.bbc.co.uk/learningzone/clips /the-human-alimentarycanal/103.html
Cambridge IGCSE Biology (0610)
6
Syllabus ref II 6.3.4 (S)
II 6.3.5
II 6.3.6
II 6.3.6 (S)
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Learning objectives
Suggested teaching activities
2.6 • Describe how fluoride reduces tooth decay and explain arguments for and against the addition of fluoride to public water supplies
Although most health professionals strongly support the addition of fluoride to water supplies, there are also some arguments against this.
2.7 Chemical Digestion • State the significance of chemical digestion in the alimentary canal, in producing small, soluble molecules that can be absorbed • State where, in the alimentary canal: - amylase - protease - lipase enzymes are secreted • State the functions of a typical: - amylase - protease - lipase listing the substrate and end products
This topic should be linked with earlier work on enzymes, in Unit 1.11.
2.8 Absorption • Define absorption as the movement of digested food molecules through the wall of the intestine into the blood or lymph • Identify the small intestine as the region for absorption of digested food • Describe the significance of villi in increasing the internal surface area of the small intestine
Core students do not need any detail of the villus structure but they need to understand that the dissolved substances, glucose and amino acids, are transported in the blood to the liver before they can be assimilated into the body.
2.8 • Describe the structure of the villus, including the role of
The absorption of glucose should be linked with earlier work on active transport, in Unit 1.9.
Student progress could be assessed using: May/June 2011 Paper 0610/32 question 5
Students could draw a spider diagram of the alimentary canal. This can help them visualise from where the enzymes are secreted and where they act on specific substrates. The importance of optimum pH and temperature should be emphasized, as well as the importance of enzymes in the whole process of digestion.
Learning resources Fluorides and fluoridation: www.ada.org/fluoride.aspx The American Dental Association's site dealing with the fluoride issue.
Revision – Digestion and absorption: lgfl.skoool.co.uk/content/keystage 4/biology/pc/modules/digestion/di gestion_part_2/index.html Video clip – Digestion: www.bbc.co.uk/learningzone/clips /digestion-of-carbohydrates-fatsand-proteins/105.html
Student progress could be assessed using: May/June 2011 Paper 0610/22 question 9 May/June 2010 Paper 0610/22 question 8 Oct/Nov 2009 Paper 0610/02 question 4 Biology for IGCSE, Williams et al. Nelson Thornes 2009 p84–85
It helps the students to understand the importance of diffusion if the villus is compared with the alveoli in the lungs, Unit 4.4 The two structures can be compared as having a single cell membrane, good blood supply, moist surface area and a large surface area for efficient diffusion.
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p84
7
Syllabus ref
Learning objectives capillaries and lacteals • State the role of the hepatic portal vein in the transport of absorbed food to the liver. Identify the role of the small intestine and colon in the absorption of water (the small intestine absorbs 5-10 dm3 per day, the colon 0.3-0.5dm3 per day)
II 6.3.7
II 6.3.7 (S)
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2.9 Assimilation • Describe assimilation as movement of digested food molecules into the cells of the body where they are used, becoming part of the cells – Describe the role of the liver in the: metabolism of glucose to glycogen – Amino acids into proteins – The destruction of excess amino acids. • Describe the role of fat as an energy storage substance 2.9 • Define deamination as removal of the nitrogen-containing part of amino acids to form urea followed by the release of energy from the remainder of the amino acid • State that the liver is the site of breakdown of alcohol and other toxins
Suggested teaching activities
Learning resources
Student progress could be assessed using: May/June 2011 Paper 0610/31 question 1 Oct/Nov 2009 Paper 0610/31 question 2
For Core students, no detail of the hormonal control of glucose levels is required. They should, however, know that the liver stores excess glucose as glycogen (link back to Unit 2.2) and converts this back to glucose again if blood glucose levels fall.
Revision – Digestion: www.scool.co.uk/gcse/biology/nutrition/r evise-it/digestion
The conversion of excess amino acids to urea should be dealt with very simply; this will be covered again in Unit 5.4. Extension – the importance of the liver could be highlighted by looking at causes and effects of liver failure. Student progress could be assessed using: May/June 2008 Paper 0610/02 question 3 The importance of nitrogen in the body could be discussed in relation to DNA, hormones and enzymes.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p85
Student progress could be assessed using: May/June 2009 Paper 0610/31 question 2
Cambridge IGCSE Biology (0610)
8
Core 1
Animal Nutrition
page 1
Core 1 Fig. 1
Fig. 1 Fig 1
Animal Nutrition
page 2
Core 2 1
Table 1
Animal Nutrition
page 3
Core 2
[Total: 12]
Animal Nutrition
page 4
Core 3 Fig. 2
Fig. 2
2
[Total:7]
Animal Nutrition
page 5
Alternative to Practical 1
[Total: 8]
Animal Nutrition
page 6
Extension 1
Fig. 3
Fig. 3
Animal Nutrition
page 7
Extension 1
Animal Nutrition
page 8
Extension 2
[Total: 15]
Animal Nutrition
page 9
Core 1 a(i)
to change food into simple / small / soluble form / molecules for absorption / diffusion(into intestine wall / villi) / carriage in blood
(ii)
any two of these make small enough to swallow increase surface area of particles mix with saliva / enzyme / amylase
b(i)
any three of these contraction of (circular) muscles behind food / bolus relaxation of muscles in front occurs rhythmically / in waves food forced forward / along tube
(ii)
any one of these can swallow standing on head / hanging upside down can swallow in space with no gravity some mammals (standing on four legs) have horizontal oesophagus some mammals can regurgitate food against gravity
c(i)
A – label to salivary gland / mouth / pancreas B – label to stomach C – label to pancreas D – label to stomach / pancreas / small intestine
(ii)
protein / named protein amino acids / polypeptides / peptides
Animal Nutrition
Page 1
Core 2 a(i) (ii) b(i)
(ii) c(i)
(ii)
66 / 0.6 = 110 110 x 100 g fruit = 11 (kg) carbon, hydrogen, oxygen, nitrogen add to Benedict’s solution / Fehling’s reagent heat use of water bath / goggles / any other relevant safety practice colour change to orange (accept yellow / brick red/ red-brown) any one of these aids peristalsis / movement of food along gut(or alternative wording) prevents constipation(or alternative wording) reduces fat absorption / risk of bowel cancer(or alternative wording) any one of these vitamin C maintains healthy skin wounds heal more rapidly prevents scurvy assists uptake of iron
Animal Nutrition
Page 2
Core 3 a
labels correctly placed
b
any four of these liver production of bile / bile salts emulsifies fats / increases surface area (alternative wording) neutralises stomach acid / raises pH pancreas secretes lipase / enzyme digests / breaks down fats to fatty acids and glycerol
Animal Nutrition
Page 3
Alternative to Practical 1 a(i)
emulsion test – add ethanol / alcohol pour into water observation - cloudiness / white / milky / emulsion
(ii)
equal quantities of biscuit / same conditions one comparison described e.g. of cloudiness
b
lipase / esterase fatty acids and glycerol
Animal Nutrition
Page 4
Extension 1 a(i)
one mark for reduction / one mark for stating figures from reduce fat / saturated fat / unsaturated fat reduce fat content from 42% to 30% or by a quarter (or alternative wording) reduce saturated fat from 16% to 10 % or by a third or by 6%(or alternative wording) reduce unsaturated fat from 26% to 20% or by a fifth or by 6%(or alternative wording)
(ii)
any one from reference to problems of obesity (resulting from too much fat in the diet) reference to presence of cholesterol in (some) saturated fats can cause atherosclerosis / atheroma / blockage of arteries reference to heart problems(or alternative wording) reference to arthritis problems
b(i) starch / cellulose / hemicellulose / amylose / amylopectin / pectin / callose / insulin Reject glycogen glycogen / chitin Reject glucagon c(i)
reference to dental decay(or alternative wording) reference to problems with obesity(or alternative wording) leading to heart disease / diabetes
d reference to high blood pressure / greater risk of heart attack (or alternative wording) e
any three of these breast milk contains antibodies or greater protection from infection breast milk contains foodstuffs in correct proportions (or alternative wording) bottle milk may contain bacteria or cause intestine disease (accept breast milk is sterile) financial implications of bottle milk some babies are allergic to cow’s milk reference to correct temperature of breast milk reference to convenience of breast milk or preparation involved with bottle milk no additives / preservatives in breast milk reference to bonding through breast feeding reference to triggering reduction in size of uterus
Animal Nutrition
Page 5
Extension 2 a(i)
any eight of these reference to absorption of nitrogen-containing salts by roots ( accept reference to ions ) by diffusion / active transport reference to nitrogen-fixing bacteria in root nodules nitrogen salts transported in xylem reference to photosynthesis carbon dioxide is combined with / reacts with water using energy from (sun)light reference to chloroplasts / chlorophyll sugars produced nitrogen is combined with sugars to make amino acids / proteins
b(i)
amino acids pass through ileum wall / epithelium or lining or wall of villus absorbed into blood (stream) transported to muscles in plasma amino acids synthesized into proteins (or alternative wording)
(ii)
any four of these reference to growth / repair / formation of new cells reference to hormones reference to enzymes constituent of cell membranes(or alternative wording) reference to haemoglobin reference to collagen reference to keratin reference to antibodies reference to fibrinogen / fibrin
Animal Nutrition
Page 6
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 3: Plant nutrition and transport Recommended prior knowledge Students should have a basic knowledge of carbohydrates and proteins and their uses within the body, the structure of a plant cell, and the process of osmosis, all of which were dealt with in Units 1 and 2. They should have an understanding of energy transfers from one form to another. Context This unit builds on ideas from Units 1 and 2. Concepts from this unit will be revisited in Units 9 and 10. Outline This unit covers most of the plant physiology topics. There is a considerable range of practical work that can be carried out, much of which can be used to develop or to assess practical skills. Teachers working in countries where there are marked seasons will need to take this into consideration when planning the timing of this unit. The unit begins by looking at the way in which plants manufacture organic substances using sunlight and inorganic molecules as their raw materials. Candidates studying the supplement should look more deeply into how environmental factors affect the rate of photosynthesis, and how these factors can be controlled in glasshouse cultivation. Knowledge of cell structure that was covered in Unit 1, is extended to look more fully at the structure and function of cells and tissues in a leaf. The idea of adaptation of structure to function should be reinforced when studying the leaf structure. The movement of water from soil to air in xylem, and of organic products of photosynthesis in phloem, is considered. Candidates studying the supplement should be introduced to examples of adaptations of plants to living in extreme conditions such as deserts, tropical rainforests and tundra. Some wider issues relating to this unit, such as the position of plants as producers in an ecosystem, and problems associated with the use of fertilisers and pesticides, will be considered in Unit 10. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only)
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Syllabus ref II 6.2.1
Learning objectives 3.1 Photosynthesis • Define photosynthesis as the fundamental process by which plants manufacture carbohydrates from raw materials using energy from light • State the word equation for photosynthesis for the production of simple sugars and oxygen
Suggested teaching activities
Learning resources
Plants can be considered as 'food factories', in which all the food in the world is initially made.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p56–61
Students should compare the needs of animals for organic nutrients, Unit 2, with those of plants, which only require inorganic compounds such as carbon dioxide and water for photosynthesis.
PowerPoint presentation – Photosynthesis: www.biologyresources.com/biology-CD.html
Consumers compared with producers, this is a cross link with Unit 10.
Experiments in biology – Photosynthesis: www.biologyresources.com/biologyexperiments2.html
The initial products of photosynthesis are sugars (such as glucose) which can be converted to large, insoluble molecules such as starch for storage within the plant. Reference to fertilisers and agriculture in Unit 10.3. Student progress could be assessed using: May/June 2008 Paper 0610/02 question 4
Practical Biology – Photosynthesis: www.nuffieldfoundation.org/practica l-biology/photosynthesis PowerPoint and worksheets: www.saps.org.uk/secondary/teachi ng-resources/134-photosynthesisa-survival-guide Revision – Plant nutrition: gfl.skoool.co.uk/content/keystage4/ biology/pc/lessons/uk_ks4_plant_n utrition/h-frame-ie.htm
II 6.2.1
•
Investigate the necessity for chlorophyll, light and carbon dioxide for photosynthesis, using appropriate controls
The process of photosynthesis should be considered at a fairly basic level, the light-dependent and light-independent stages should not be introduced. The important point to get across is the conversion of light energy to chemical energy. Chlorophyll absorbs light energy and enables it to be used to drive the reactions. (Ensure that students do not think that chlorophyll attracts light!)
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Cambridge IGCSE Biology (0610)
Simple photosynthesis experiments: www.saps.org.uk/secondary/teachi ng-resources/190-using-cabombato-demonstrate-oxygen-evolutionin-the-process-of-photosynthesis-
2
Syllabus ref
Learning objectives • Describe the intake of carbon dioxide and water by plants • Explain that chlorophyll traps light energy and converts it into chemical energy for the formation of carbohydrates and their subsequent storage
Suggested teaching activities There is a wide variety of practical work that can be carried out. Students should know how to test a leaf for starch, and to carry out simple experiments into the need for light and chlorophyll for photosynthesis. The importance of controlled variables such as temperature can be introduced. The concentration of carbon dioxide can be changed using sodium hydrogencarbonate solution of different concentrations. The exchange of gases can be more easily understood when the structure of the leaf has been studied: Unit 3.2. Student progress could be assessed using: May/June 2011 Paper 0610/22 question 7b May/June 2009 Paper 0610/02 question 6
II 6.2.1 (S)
3.1 • State the balanced equation for photosynthesis in symbols 6CO2 + 6H2O → C6H12O6 + 6O2 •
•
•
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Investigate and state the effect of varying - light intensity - carbon dioxide concentration - temperature on the rate of photosynthesis (e.g. in submerged aquatic plants) Define the term limiting factor as something present in the environment in such short supply that it restricts life processes Explain the concept of limiting factors in photosynthesis
Investigations with Elodea (Canadian pondweed) can produce good quantitative data to illustrate the effect of light on the rate of photosynthesis. Light can be the limiting factor. Temperature could also be considered as a limiting factor but this is not so easy to carry out in the school lab. The concentration of carbon dioxide can be varied by adding sodium hydrogencarbonate to the water. Graphs of processed data can be used in class discussions on limiting factors. Strawberries, raspberries, rhubarb and cucumbers can be grown in glasshouses / under plastic covers where the carbon dioxide content can be increased and the temperature kept warm for maximum photosynthesis.
Cambridge IGCSE Biology (0610)
Learning resources Investigating the behaviour of leaf discs: www.saps.org.uk/secondary/teachi ng-resources/284-investigating-thebehaviour-of-leaf-discswww.saps.org.uk/secondary/teachi ng-resources/145-photosynthesisand-starch-production-inpelargonium-leaf-discsDatalogging: www.pascophysics.com/file_downlo ads/experiments/pdffiles/glx/biology/06-PhotosynthesisSV.pdf
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p62–65 Investigating photosynthesis using algal balls: www.saps.org.uk/secondary/teachi ng-resources/235-student-sheet23-photosynthesis-using-algaewrapped-in-jelly-balls Comparison with sun and shade plants: www.saps.org.uk/secondary/teachi ng-resources/113-the-response-ofleaf-discs-from-sun-and-shadeplants-to-green-light
3
Syllabus ref
Learning objectives •
II 6.2.2
Explain the use of - carbon dioxide enrichment - optimum light - optimum temperatures in glasshouse systems
3.2 Leaf Structure • Identify and label the cuticle, cellular and tissue structure of a dicotyledonous leaf, as seen in cross-section under the light microscope, and describe the significance of these features in terms of functions to include: • distribution of chloroplasts – photosynthesis • stomata and mesophyll cells – gas exchange • vascular bundles (xylem and • phloem) - transport and support
Suggested teaching activities Extension – students could attempt to play “Plant Force” maybe as a group activity on an interactive whiteboard. Student progress could be assessed using: May/June 2010 Paper 0610/31 question 2 Oct/Nov 2009 Paper 0610/31 question 3 Oct/Nov 2009 Paper 0610/32 question 3
Learning resources Plant Force – Plant growth simulation: puzzling.caret.cam.ac.uk/game.php ?game=16&age=2&PHPSESSID=d 2e7aca89ff56e24244ea02e780fa4b 3
Before considering the appearance of a section through a leaf, students should look at entire leaves and consider how they are adapted for photosynthesis.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p66–67
A section through a leaf can be shown on PowerPoint or from a model of a leaf (plant images available from the database plantscienceimages.org.uk). A simplified, labelled diagram should be made of a leaf section and the different parts are discussed.
Photomicrograph of Eleagnus leaf TS with vascular bundle: www.images.botany.org/set-13/13063v.jpg or www.plantscienceimages.org.uk/pa ges/image.aspx?sectionId=3&subs ectionId=21&imageId=46
Students should be familiar with the structure of a palisade cell, and they can discuss how it is specialised for photosynthesis. The role of the upper epidermis that allows the maximum sunlight to reach the palisade layers should be mentioned. It can be helpful to think of a leaf as an organ that: • takes in the raw inorganic materials • uses light energy to convert the materials into chemical energy producing organic products and their removal for distribution throughout the plant. Drawings of leaves, and comparisons between two or more different kinds of leaves, make good practice or assessment material for the practical skills of observation and recording, and also for magnification calculations (Unit 1.7). It is probably best not to go into any detail at this point about xylem and phloem function; they will be dealt with a little in Unit 3.4.
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Learning resources
Student progress could be assessed using: May/June 2011 Paper 0610/32 question 6 May/June 2011 Paper 0610/22 question 7a Oct/Nov 2010 Paper 0610/21 question 4 II 6.2.3
3.3 Mineral requirements • Describe the importance of: - nitrate ions for protein synthesis - magnesium ions for chlorophyll synthesis •
Describe the uses and the dangers of the overuse of nitrogen fertilisers
Students should be reminded that carbohydrates contain carbon, hydrogen and oxygen only; plants can therefore make these from carbon dioxide and water. However, proteins also contain nitrogen, so a nitrogen source is necessary before some of the carbohydrate can be converted to protein. Nitrate ions from the soil are the main source of nitrogen for plants.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p68–69 Practical Biology – Minerals: www.nuffieldfoundation.org/practica l-biology/investigating-effectminerals-plant-growth
Extension – students could plan an experiment to investigate mineral requirements in plants. It may be best not to study the use of nitrogen fertilisers here, but rather to cover this fully in Unit 10.3. Student progress could be assessed using: May/June 2010 Paper 0610/21 question 3 May/June 2010 Paper 0610/22 question 2
(S)
3.3 • Explain the effects of nitrate ion and magnesium ion deficiency on plant growth
For candidates studying the supplement, a link can be made to the uptake of ions by root hairs, Unit 1.9. This should be dealt with simply, considering the effects on a growing plant of a shortage of proteins or chlorophyll. A comparison can be made when plants are grown in culture solutions lacking magnesium, nitrates and a control. After a few weeks, the growth of each plant can be compared. Student progress could be assessed using: May/June 2011 Paper 0610/31 question 5d May/June 2010 Paper 0610/32 question 3 May/June 2009 Paper 0610/32 question 4
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Syllabus ref II 7.1
Learning objectives 3.4 Transport in plants • State the functions of xylem and phloem • Identify the positions of xylem and phloem tissues as seen in transverse sections of un-thickened, herbaceous, dicotyledonous roots, stems and leaves
Suggested teaching activities Root hair cells may already have been covered in Unit 1.6 as an example of a specialised cell. Here root hair cells are dealt with in the context of the whole plant. Osmosis may need to be revised, before discussing the uptake of water through the soil, across the root, and up through xylem vessels and into the leaves. It should be emphasised that mineral ions enter the roots dissolved in water. Xylem vessels may have been discussed in Unit 1.6 and Unit 3.2. Here xylem vessels are considered in the context of water transport from root to leaves. The structure of xylem vessels should be simply covered stating that the vessels are made of a long column of dead, empty cells with lignified walls, stacked end to end. Xylem vessels provide support to the plant. Students will find the path taken by the water easier to understand if they have some knowledge of the position of the vascular bundles in the plant. Simple diagrams can be made of a TS of a root and of a stem, showing the position of the xylem and phloem.
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p88–89 Experiments in biology – Transport in plants: www.biologyresources.com/biologyexperiments2.html Practical Biology – Transport in plants: www.nuffieldfoundation.org/practica l-biology/investigating-transportsystems-flowering-plant Revision – Plant transport: lgfl.skoool.co.uk/content/keystage4/ biology/pc/lessons/uk_ks4_plant_tr ansport/h-frame-ie.htm
Large and semi-transparent stems, such as the leaf petioles of celery, can be placed with their bases in a solution of a water-soluble dye (ink or food colouring). After a few days, the dye can be seen in the xylem vessels, spreading out into the veins in the leaves. If thin sections are cut, the positions of the xylem vessels show up clearly. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/22 question 9 Oct/Nov 2008 Paper 0610/02 question 10a
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Learning objectives
Suggested teaching activities
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p90–91
3.5 Water uptake • Identify root hair cells, as seen under the light microscope, and state their functions • State the pathway taken by water through: - root - stem - leaf - (root hair, root cortex, xylem,mesophyll cells) • Investigate, using a suitable stain, the pathway of water through the above-ground parts of a plant
The structure of the root hairs can be compared with those of the villi and alveoli in their adaptation to their function of diffusion. Unit 2.8 and 4.4.
(S)
3.5 • Relate the structure and functions of root hairs to their surface area and to water and ion uptake
Student progress could be assessed using: May/June 2009 Paper 0610/31 question 4 Oct/Nov 2010 Paper 0610/33 question 5
II 7.1.2
3.6 Transpiration • Define transpiration as evaporation of water at the surfaces of the mesophyll cells followed by loss of water vapour from plant leaves, through the stomata • Describe how water vapour loss is related to: - cell surfaces - air spaces and - stomata • Describe the effects of variation of: - temperature - humidity - light intensity on respiration rate
It is important to understand that transpiration involves the loss of water vapour from the underside of the leaf, mostly through open stomata. Water in the cell walls of mesophyll cells evaporates, and diffuses through the air spaces and out of the leaf. The effect of transpiration in pulling water up xylem vessels can be compared to the effect of sucking a liquid up a straw.
Practical Biology – Transpiration: www.nuffieldfoundation.org/practica l-biology/estimating-ratetranspiration-plant-cutting
Experiments using potometers not only help students to understand the effects of environmental factors on the rate of transpiration, but also provide good opportunities to improve, or to be assessed on, all four experimental skills.
Comparison of transpiration rates: www.saps.org.uk/secondary/teachi ng-resources/115-comparison-oftranspiration-rates
It is important, however, that it is understood that a potometer measures water uptake, which is not absolutely the same as water loss.
Data logging: www2.vernier.com/sample_labs/B WV-10-COMP-transpiration.pdf
II 7.1.1
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Extension – Root hairs can be looked at under a microscope from seeds germinated on cotton wool or blotting paper.
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p92–93
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Learning objectives
•
Describe how wilting occurs
Suggested teaching activities
Learning resources
There is no need for elaborate potometers, a long piece of capillary tubing with a length of rubber tubing at one end into which the cut end of a shoot is pushed is effective. All the apparatus and cut twigs should be kept under water while assembling the apparatus, to avoid air locks. Laurel or ash leaves work well. The experiments can be extended by removing one leaf from the branch and recording the reduced water uptake. This is repeated until no leaves remain. A graph showing a reduction in water loss (uptake by the potometer) with fewer leaves illustrates the effect of the number of leaves on the transpiration process. Transpiration can also be investigated by using a hair dryer to vary the humidity.
Measuring stomatal density: www.saps.org.uk/secondary/teachi ng-resources/299-measuringstomatal-density-
Extension – use of dataloggers to investigate transpiration rates. Wilting is a good way for a plant to avoid further water loss, by reducing the leaf area from which evaporation can occur. The concept of turgor can be mentioned as the leaf cells wilt and become flaccid. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 9
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II 7.1.3
Learning objectives
Suggested teaching activities
3.6 • Explain the mechanism of water uptake and movement in terms of transpiration producing a tension (pull) from above, creating a water potential gradient in the xylem, drawing cohesive water molecules up the plant • Discuss the adaptations of the: - leaf - stem - root to three contrasting environments, to include: pond garden desert with emphasis on local examples (where appropriate) and the factors described in the core
Candidates may already have met the term 'water potential' in Unit 1.10. In normal conditions, the water potential in the air is lower than that in the soil solution. Thus water moves down a water potential gradient as it moves from soil to air, through the plant. If students are shown a wilting plant, they can think about why it is only the leaves that wilt. This can introduce the idea of xylem vessels, present in vascular bundles in leaves and stem, helping with support.
3.7 Translocation • Define translocation in terms of the movement of sucrose and amino acids in phloem - from regions of production - to regions of storage OR to regions of utilisation in respiration or growth
This idea will probably already have been met earlier in this Unit, when discussing the functions of leaves. Here it should be re-emphasised that carbohydrates are transported through a plant in the form of soluble carbohydrates such as sucrose, glucose and proteins as amino acids through the phloem tubes.
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p94–95 Desert plant survival: www.desertusa.com/du_plantsurv.h tml
Although students should look at examples of plant adaptations using plants that grow locally, it is also very useful to think about plants that grow in especially wet or dry environments, such as rain forest or desert. Student progress could be assessed using: May/June 2011 Paper 0610/31 question 5 May/June 2010 Paper 0610/32 question 2 May/June 2009 Paper 0610/31 question 4
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p96–97
No detail of phloem structure or function is required. It should be made clear that substances can be transported in any direction in phloem, for example from photosynthesising leaves down to roots for storage or upwards to growing buds, flowers, leaves and fruits for respiration and growth. Translocation also occurs from storage organs such as the root tubers to all parts of the plant. Extension – Consideration of the effects of 'ringing' a tree can help students to bring together their knowledge of stem
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structure and function. Ringing removes the phloem, which is near to the surface of a stem. If the ring is cut below the leaves, then all the cells beneath the ring are deprived of products of photosynthesis from the leaves, and eventually die. Grey squirrels and other small mammals gnaw the bark and destroy the phloem that is in the inner bark region. This section can be explained by drawing a coloured flow diagram to indicate the movement of the solutes to and from different parts of a plant. II 7.1.3 (S)
3.7 • Describe translocation throughout the plant of applied chemicals, including systemic pesticides • Compare the role of transpiration and translocation in the transport of materials from sources to sinks, within plants at different seasons
Students should understand that systemic pesticides are sprayed onto the leaves of the plant, and then absorbed by it through the cuticle or stomata and into the phloem tubes. They move through the plant in the phloem (translocation) and are taken in by any insect eating the plant or sucking up phloem sap. The disadvantages of systemic pesticides can be discussed in Unit 9.2 as they may accumulate in the food chain. The students need to understand the term 'source' as where the substance is produced or enters the plant. • sucrose is produced in the leaves • nitrates are absorbed by the root hairs The term 'sink' refers to the part of the plant where the substrate can be stored. • starch in roots or stem • amino acids in the root tips Transpiration is important in relocating substances dissolved in water, cell sap such as amino acids. Students studying the supplement may discuss the role of water in the production of carbohydrates during photosynthesis and their subsequent translocation throughout the plant. Student progress could be assessed using: May/June 2011 Paper 0610/32 question 6
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Core 1
Plant Nutrition & Transport
page 1
Core 2 1
1
Plant Nutrition & Transport
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Core 2
Plant Nutrition & Transport
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Alternative to Practical 1
Plant Nutrition & Transport
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Alternative to Practical 1
Plant Nutrition & Transport
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Extension 1 3
3 3
1
1
Plant Nutrition & Transport
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Extension 1
Plant Nutrition & Transport
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Extension 2 4
4 4
Plant Nutrition & Transport
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Extension 2
Plant Nutrition & Transport
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Extension 3 5
Fig. 5 5 6
Fig. 6 Plant Nutrition & Transport
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Extension 3 6
Plant Nutrition & Transport
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Core 1 a
any three of these light intensity increases the stomata open increase in temperature greater rate of evaporation / transpiration / diffusion
b
factor-
temperature
explanation-
as light decreases the rate of loss continues to rise / temperature and water loss curves peak at the similar time
prediction-
rate of water loss / transpiration falls / lower
explanation-
air saturated / humid (thus less evaporation)
c
Plant Nutrition & Transportation
page 1
Core 2 a(i)
6CO2 / carbon dioxide 6O2 / oxygen
(ii)
sun / solar / sunlight
(iii)
chlorophyll
(iv)
magnesium / iron / nitrate / ammonium
b(i) (ii) (iii)
phloem starch is insoluble has no osmotic effect / easier to retain in storage / prevent it being moved cellulose
Plant Nutrition & Transportation
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Alternative to Practical 1 a
b(i) (ii)
c
d(i) (ii)
A
respiration / use of oxygen
B
transpiration / uptake of water / water loss
C
photosynthesis
carbon dioxide / CO2 one from glass beads stones empty tube boiled, sterile, dry or dead seeds one from moving air / wind / fan / dry air enclosed in a bag / increase humidity cold air hot air in darkness in light / sunny
speed up process slow process slow process speed up process slow process speed up process
oxygen / O2 any one of these lightintensity temperaturecarbon dioxidebiotic idea-
Plant Nutrition & Transportation
fixed position of bulb / keep light on / same wattage / heat shield / in water bath / heat filter add hydrogen carbonate to water use same piece of waterweed
page 3
Extension 1 a
any two from presence of segmented body or abdomen presence of jointed limbs or appendages presence of head or eyes presence of exoskeleton
b
tissue processes
c(i) sap vacuole concentration cytoplasm cell wall (ii)
d
phloem / sieve tubes reference to translocation reference to active transport or active uptake gets smaller / shrinks / loses water / reference to increase in moves away from (cell) wall no longer curves outwards
any three points water potential in vacuole / cell is higher than outside due to lower concentration of sugar molecules / higher concentration if water molecules in vacuole / cell so water moves out by osmosis through (cell) membrane pesticides are absorbed into the leaf / plant / stem aphids feed on / suck / remove poisonous sap
Plant Nutrition & Transportation
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Extension 2 a
A B C
b
upper surface C.Fistula has 18 stomata while B.Monhandra has none lower surface C.Fistula has no stomata while B.Monhandra has 22
c(i)
three of these points water is only lost if stomata are present stomata open during the day so water (vapour) is lost reference to transpiration
(ii)
stomata are closed at night
d
any three of these points reference to xylem water enters xylem vessel through pots in walls reference to transpiration stream / pull reference to capillary action reference to root pressure
e(i)
rate will decrease reference to smaller gradient for diffusion
(ii)
stoma / stomatal pore guard cell epidermal cell / epidermis
rate will increase more energy for evaporation warm air can hold more water vapour than cold air
Plant Nutrition & Transportation
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Extension 3 a
300 x 100 150 = 200%
b
container A depletion of salts / nutrients seeds released disease shortage of carbon dioxide reached end of life cycle container B photosynthesis growth nutrients not exhausted food stores sufficient carbon dioxide
c
container C least or no photosynthesis occurring respiration exceeds photosynthesis death of plant so bacteria active, using up oxygen
Plant Nutrition & Transportation
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Scheme of work – Cambridge IGCSE® Biology (0610) Unit 4: Respiration and the human transport system Recommended prior knowledge Students need to have some knowledge of energy transfer, and to be able understand simple chemical equations. Context Respiration is a fundamental process that will be referred to in most of the subsequent units. Transport can be linked to Unit 2. Outline This unit covers the important topic of respiration, which will be met again when the carbon cycle is dealt with in Unit 9. Gas exchange in humans, and the effects of cigarette smoke lead on from this. In animals, unlike plants, the transport system is involved in the carriage of gases between the gaseous exchange surface and the body tissues, and so coverage of this leads on naturally from a consideration of gas exchange. Some teachers, however, may prefer to deal with transport first, and then respiration; there are sound arguments for either sequence. There is considerable opportunity for practical work in the respiration topics, but the practical work on the transport section is probably limited to study of the structure of the various organs and tissues. Respiration and pulse rate can be linked by investigations of exercise. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref II 8
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Learning objectives
Suggested teaching activities
4.1 Respiration • Define respiration as the chemical reactions that break down nutrient molecules in living cells to release energy • State the uses of energy in the body of humans: - muscle contraction - protein synthesis - cell division - active transport - growth - the passage of nerve impulses - the maintenance of a constant
Students should understand that respiration is a reaction (or series of reactions) that takes place inside living cells: cell respiration. A very common error is to confuse it with 'breathing', and to think that it takes place only in the lungs. Students should also realise that every living cell including plant cells respire. Explain that carbon dioxide has to be removed from respiring cells.
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes 2009 p116–117 PowerPoint presentation – Respiration: www.biologyresources.com/biology-CD.html Experiments in biology – Respiration: www.biologyresources.com/biologyexperiments2.html
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Learning objectives
Suggested teaching activities
body temperature
Learning resources Introduction to respiration: www.biotopics.co.uk/humans/respr o.html Unit revision: lgfl.skoool.co.uk/content/keystage4/ biology/pc/lessons/uk_ks4_breathin g_and_respiration/h-frame-ie.htm
II 8.1
4.2 Aerobic respiration • Define aerobic respiration as the release of a relatively large amount of energy in cells by in the presence of oxygen • State the word equation for aerobic respiration
Emphasise that the function of respiration is to release energy from food (usually glucose) in a form that the organism can use. Students should not state that respiration 'produces' energy. A class discussion will probably pick out a good range of uses of energy.
Revision – Aerobic respiration: lgfl.skoool.co.uk/content/keystage4/ biology/pc/modules/breathing_respi ration/aerobic_respiration/index.htm l
It can be helpful to compare respiration with combustion - the overall equation is the same, but respiration occurs in a series of small reactions that do not suddenly release large amounts of heat energy. Link with carbon cycle in Unit 9.3. The energy content of a food, such as a potato crisp or a cube of bread, can be estimated by allowing it to heat a known volume of water as it burns in air. (This investigation is often done using peanuts, but teachers should be aware that an increasing number of children are allergic to nuts). This investigation can include variables such as volume of water and the mass of carbohydrate. Discussion about the errors and limitations of the investigation show the students that science experiments can be inaccurate. Extension – use of a calorimeter to demonstrate a more accurate method of determining energy content. Extension – aerobic respiration can also be studied in small invertebrates, maggots or woodlice, or germinating seeds such as mung beans, suspended over a solution of hydrogen carbonate for a few days.
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Learning objectives
(S)
4.2 • State the equation for aerobic respiration using symbols (C6H12O6 + 6O2 → 6CO2 + 6H2O)
II 8.2
4.3 Anaerobic respiration • Define anaerobic respiration as the release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen • State the word equation for anaerobic respiration: - in muscles during hard exercise (glucose to lactic acid) - and the microorganism yeast (glucose to alcohol and carbon dioxide) • Describe the role of anaerobic respiration in yeast during brewing and bread making • Compare aerobic respiration and anaerobic respiration in terms of relative amounts of energy released
Suggested teaching activities
Anaerobic respiration can be investigated using a suspension of yeast in boiled, cooled water. Boiling drives off all dissolved oxygen. The carbon dioxide released can be detected by passing it through lime water or hydrogencarbonate indicator solution. Students studying the supplement may already have investigated the use of yeast in bread-making, in Unit 2.2. This is a good opportunity for all students to investigate, for example, whether adding amylase or ascorbic acid, affects the rate at which dough rises. Extension – fermentation experiments.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p126–127 NCBE downloadable book on fermentation experiments: www.ncbe.reading.ac.uk/NCBE/PR OTOCOLS/fermentation.html Revision – Anaerobic respiration: www.lgfl.skoool.co.uk/content/keyst age4/biology/pc/modules/breathing _respiration/anaerobic_respiration/i ndex.html
Student progress could be assessed using: Oct/Nov 2010 Paper 0610/21 question 5
II 8.2 (S)
4.3 • State the balanced equation for anaerobic respiration in muscles: • C6H12O6 2C3H6O3 • and in the microorganism yeast: • C6H12O6 2C2H5OH + 2CO2 using symbols • Describe the effect of lactic acid in muscles during exercise (include oxygen debt in outline only)
Anaerobic respiration in muscles can be considered when investigating physical activity in Unit 4.4 It also links with yoghurt making, Unit 2.2 It helps students to understand oxygen debt if they know that lactic acid is oxidised after the exercise in the liver by the extra oxygen provided by fast breathing.
II 8.3
4.4 Gas Exchange • List the features of gaseous exchange surfaces in animals
The idea of gaseous exchange may already have been discussed in Unit 3.2, in the context of the intake and loss of gases from leaves. A gaseous exchange surface can be
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Learning resources
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p118–121 3
Syllabus ref
Learning objectives •
•
Identify on diagrams and name the: − larynx − trachea − bronchi − bronchioles − alveoli − associated capillaries State the differences in composition between inspired and expired air
•
Use lime water as a test for carbon dioxide to investigate the differences in composition between inspired and expired air
•
Investigate and describe the effects of physical activity on rate and depth of breathing
Suggested teaching activities
Learning resources
defined as a surface across which gases pass as they enter or leave the body. For animals, oxygen enters as carbon dioxide leaves. Students should relate their understanding of diffusion to the structure of the alveoli and cross reference to Unit 2.8 and Unit 3.5.
Practical Biology – Gas Exchange: www.nuffieldfoundation.org/practica l-biology/ventilation-systems
Students should be able to locate each structure on a diagram and to understand that there are two bronchi and several bronchioles. Link with transport in unit 4.5. The differences between expired and inspired air, in terms of carbon dioxide content and water vapour content, should be investigated experimentally. Lime water or hydrogencarbonate indicator may be used to test for carbon dioxide.
Breathing and asthma: www.abpischools.org.uk/res/coRes ourceImport/resources04/asthma/in dex.cfm Revision – Gas Exchange: lgfl.skoool.co.uk/content/keystage4/ biology/pc/modules/breathing_respi ration/gas_exchange/index.html
Pie charts or tables showing the percentage composition of air are useful and show that nitrogen remains constant. Students should be able to use their knowledge of gas exchange and respiration to explain these differences. This should be investigated experimentally. A simple, repeatable form of exercise, such as step-ups, is the most useful for generating quantitative results. Students can plan their own investigation by comparing activities such as walking, running, skipping or hopping with definite constant variables of time / distance. The importance of three or five trials per exercise can be introduced to obtain the mean of the raw data and to identify anomalies. Students should use their knowledge of aerobic and anaerobic respiration to explain why breathing rate does not drop immediately to normal when exercise stops. The concept of breathing rate / pulse rate 'at rest' can be introduced. Student progress could be assessed using: May/June 2010 Paper 0610/22 question 9
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Learning resources
Oct/Nov 2009 Paper 0610/02 question 8 II 8.3 (S)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p122–123
4.4 • Describe the role of the: − ribs − internal and external intercostal muscles − diaphragm in producing volume and pressure changes leading to the ventilation of the lungs
Students should link the structure of the respiratory studied in the Core with the muscles involved in breathing. A wooden or plastic model of the intercostal muscles can clarify the action. Students often find this topic difficult, and it is a good idea to use a model of some kind to illustrate how increasing the volume of the thorax leads to a reduction in pressure. The 'balloons in a bell jar' model shows this effectively. Physics students can relate the action to that of an engine piston.
Measuring lung capacity: www.biologycorner.com/worksheet s/lungcapacity.html
•
Explain the role of mucus and cilia in protecting the gas exchange system from pathogens and particles
The cilia are fine hairs that trap the mucus secreted by the goblet cells. Students can consider the role of the mucus in relation to coughing, pneumonia and tuberculosis. Asthma may be discussed if appropriate.
Revision – Breathing: lgfl.skoool.co.uk/content/keystage4/ biology/pc/modules/breathing_respi ration/breathing_respiration/index.h tml
•
Explain the link between: − physical activity and − rate and depth of breathing in terms of changes in the rate at which tissues respire and − therefore of carbon dioxide concentration and − pH in tissues and in the blood
Students should begin to understand the link between carbon dioxide in the blood and the change of the blood's pH due to carbonic acid. The increase of tidal volume with increased exercise should be understood. Unit 5.5 Drugs includes smoking and its effects on the body. Teachers could discuss smoking in this unit. Students should understand that cilia become less active, and goblet cells more active, when exposed to cigarette smoke, so that mucus collects in the lungs. Bacteria are likely to breed in it, leading to bronchitis and other infections. Alveoli lose their elasticity, and coughing may damage their walls, leading to breathlessness and eventually to emphysema. Cancer can be triggered by exposure to many of the chemicals in tar. This topic interests students and the teacher can ask them to conduct a survey on the smokers in school or to design a poster on the effects of smoking or to prepare a PowerPoint display. The teacher should mention the addictiveness of smoking due to the nicotine and how smoking can lead to taking non-prescribed drugs such as marijuana.
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Learning objectives
Suggested teaching activities
Learning resources
Smoking machines where a cigarette is connected a filter and the air is drawn through the cigarette by a water pump shows the tar extracted from one cigarette. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/31 question 3 Oct/Nov 2010 Paper 0610/32 question 3 II 7.2
4.5 Transport in humans • Describe the circulatory system as a system of tubes with a pump and valves to ensure one-way flow of blood • Describe the double circulation in terms of a low pressure circulation to the lungs and a high pressure circulation to the body tissues and relate these differences to the different functions of the two circuits
Diagrams of the heart, showing both external and internal structure, need to be known. Ensure that students realise that both sides of the heart beat together.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p100–101
The direction of blood flow through the heart, the separation of oxygenated and deoxygenated blood, and the functions of the valves should be understood.
The circulatory system: www.peer.tamu.edu/curriculum_mo dules/Organsystems/module_4/wha tweknow_circulation.htm
It is recommended that the idea of a double circulatory system, in which blood passes twice through the heart during one complete circuit of the body, is covered here, as this helps to make sense of the structure and function of the heart.
Heart and circulation: www.abpischools.org.uk/res/coRes ourceImport/resources04/heart/inde x.cfm
A model of the heart can be useful when explaining the structure.
Revision – Blood and circulation: lgfl.skoool.co.uk/content/keystage4/ biology/pc/lessons/uk_ks4_blood_a nd_circulation/h-frame-ie.htm
Student progress could be assessed using: May/June 2010 Paper 0610/21 question 8 II 7.2.1
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4.6 Heart • Describe the structure of the heart including: - the muscular wall - the septum - the chambers - the valves - the associated blood vessels • Describe the function of the heart in terms of: - muscular contraction
Diagrams with coloured arrow lines will help students to learn the structure of the heart. Students need to understand that the left ventricle has a thicker muscular wall than the right ventricle. Extension: A lamb’s heart can be used for dissection The effect of exercise on heart beat relates closely to the effects of physical activity on rate and depth of breathing, dealt with earlier in this Unit. The understanding of the roles of the heart valves be linked
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p102–103 Practical Biology – Heart dissection: www.nuffieldfoundation.org/practica l-biology/looking-heart Practical Biology – Control of heart rate: www.nuffieldfoundation.org/practica 6
Syllabus ref
Learning objectives • •
- the working of the valves Investigate, state and explain the effect of physical activity on pulse rate Describe coronary heart disease in terms of the blockage of coronary arteries and state the possible causes: - diet - stress - smoking and preventive measures
Suggested teaching activities to the double circulatory system in Unit 4.5. The role of the coronary arteries in supplying the heart muscle with oxygen. Students may already have some ideas about factors that increase the likelihood of suffering from heart disease, and class discussion will probably bring out most of the major influences. A person's genes are also thought to play a major role in this. There is scope for discussion on the effects of diet, exercise, smoking on the health of the heart throughout a person's life. Stress can cover many situations but at a simple level students can understand that problems at work and in the family cause stress and may increase blood pressure in adults. Blockage of the arteries can be covered here as the build-up of plaque. The importance of the coronary arteries in heart disease and the link to a diet high in saturated fats should be made.
Learning resources l-biology/observing-effectsexercise-human-body Structure of your heart: www.wehealnewyork.org/services/c ardiology/structure.html
Extension – Reference could be made to obesity and the possible connection with heart disease. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 8 Oct/Nov 2010 Paper 0610/21 question 3 Oct/Nov 2010 Paper 0610/22 question 7 May/June 2008 Paper 0610/02 question 5 II 7.2.2
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4.7 Arteries, veins and capillaries • Name the main blood vessels to and from the: − heart − lungs − liver − kidney • Describe the structure and functions of: − arteries
The teacher could reinforce that the hepatic portal vein carries glucose and amino acids from the small intestine.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p104–105
Transparencies or microscope slides of sections through an artery and a vein can be used to help students to understand the differences in structure.
Video clips – Circulation: www.bbc.co.uk/learningzone/clips/h uman-circulation/12223.html
Student progress could be assessed using: Oct/Nov 2008 Paper 0610/02 question 10b
www.bbc.co.uk/learningzone/clips/b reathing-and-circulation/10607.html
Cambridge IGCSE Biology (0610)
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A table can be used to compare the structure with the functions. Structure can be related to function between them.
Video clip: www.bbc.co.uk/learningzone/clips/h uman-circulatory-and-digestivesystem/12224.html
− veins − capillaries II 7.2.2 (S)
4.7 • Explain how structure and function are related in: − arteries − veins − capillaries •
Describe the transfer of materials between capillaries and tissue fluid
Emphasise that arteries do not pump blood and that capillaries are one cell thick. Rubber tubing of different sizes can illustrate the difference between an arterial wall and the thinner walls of veins. Students should understand that arteries have blood flowing at high pressure but at much lower pressure in veins. The narrow lumen of the arteries helps to maintain blood pressure while the large lumen of the veins reduces resistance to blood flow. Diffusion is responsible for the transfer of materials between capillaries and tissue fluid. Student progress could be assessed using: May/June 2010 Paper 0610/32 question 5 Oct/Nov 2009 Paper 0610/31 question 4
II 7.2.3
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4.8 Blood • Identify red and white blood cells as seen under a light microscope, on prepared slides and in diagrams and photomicrographs • List the components of blood as: − red blood cells − white blood cells − platelets − plasma • State the functions of blood • Red blood cells:
Students should see transparencies or microscope slides of stained blood samples, and be able to distinguish red cells, white cells and platelets. They should understand that red cells transport oxygen and also carbon dioxide, and know that they contain haemoglobin but do not have a nucleus. Links can be made back to Unit 2.2 and the need for iron in the diet. Discuss the adaptations of red blood cells to their functions as reinforcement for the function of specialised cells, covered in Unit 1.6.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p108–111 For images of blood cells: www.exploratorium.edu/imaging_st ation/gallery.php
White blood cells fight disease by providing protection from pathogens. They contain a nucleus and respond to different Cambridge IGCSE Biology (0610)
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Syllabus ref
Learning objectives
• • •
II 7.2.3 (S)
− haemoglobin and oxygen transport White blood cells: − phagocytosis and antibody formation Platelets: − causing clotting (no details) Plasma transport of: − blood cells − ions − soluble nutrients − hormones − carbon dioxide − urea − plasma proteins
4.8 • Describe the immune system in terms of: − antibody production − tissue rejection − phagocytosis • Describe the formation of the lymphatic system in: − circulation of body fluids and − the production of lymphocytes • Describe the process of clotting (fibrinogen to fibrin only)
Suggested teaching activities
Learning resources
antigens. Clotting should be mentioned, as a mechanism to prevent loss of blood and entry of pathogens, but Core students need no detail at all of how it takes place, other than that platelets are involved.
Defending against disease: www.bbc.co.uk/schools/gcsebitesiz e/science/aqa/human/defendingaga instinfectionrev1.shtml
Extension – students could research haemophilia. Students should appreciate the role of the plasma in transporting many substances including heat from the liver and muscles to all parts of the body. Tissue fluid can be thought of simply as plasma that has leaked out of capillaries. Students should understand that substances move from blood to tissues and vice versa by diffusion. Link with respiration, Unit 4.1. A relatively simple approach to this complex topic is required. Some white blood cells are phagocytes, and the process of phagocytosis should be understood. Lymphocytes, secrete antibodies (which are proteins) in response to contact with their particular antigen, which may be an invading pathogen or a foreign tissue that has been transplanted.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p110–113
Students may be interested to learn how immunity to a disease can be conferred by vaccination.
Infectious diseases – Immunity: www.abpischools.org.uk/page/mod ules/infectiousdiseases_immunity/in dex.cfm
This topic also links with kidney transplants, covered in Unit 5.6 – a transplanted organ triggers an immune response, antibodies are secreted and the organ may be rejected. The lymphatic system returns tissue fluid to the blood in the form of lymph fluid. It prevents the build-up of fluid in the tissues.
Bacterial and viral infection activity: www.bbc.co.uk/schools/gcsebitesiz e/science/aqa/human/defendingaga instinfectionact.shtml
Diagrams can help students understand this alternative transport system and links can be made to the lacteals in the villus and the absorption of fatty acids and glycerol: Unit 2.8. v1 2Y05
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Lymphocytes are produced by lymph glands during an infection. Students need to understand that fibrinogen is a soluble protein, which is converted to the insoluble fibrin when a blood vessel is damaged. Calcium is required for this, so links can be made back to Unit 2.2. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/31 question 4.
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Cambridge IGCSE Biology (0610)
10
Core 1
Respiration & Transport in Humans
page 1
Core 2 1 1
Respiration & Transport in Humans
page 2
Core 3 1
1 1
Respiration & Transport in Humans
page 3
Core 3 2
2 2
Respiration & Transport in Humans
page 4
Alternative to Practical 1 3
3
2
Respiration & Transport in Humans
page 5
Alternative to Practical 1
Respiration & Transport in Humans
page 6
Extension 1
[Total: 15]
Extension 2
[Total: 15]
Respiration & Transport in Humans
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Core 1 a(i)
any three of these growth movement irritability / sensitivity excretion reproduction
(ii)
photosynthesis
b animals in bright light green plants in bright light animals in the dark green plants in the dark
carbon dioxide released into the atmosphere Ö X Ö Ö
Respiration & Transport in Humans
oxygen released in to the atmosphere X Ö X X
page 1
Core 2 a
for three marks axes oriented correctly both axes labelled and with suitable scale on frequency axis all four columns correctly plotted
b
type reason
discontinuous variation there are no intermediate values between the four groups / there are distinctly separate sets of values
Respiration & Transport in Humans
page 2
Core 3 a(i)
A B
tricuspid / right atrio-ventricular / right cuspid valve pulmonary vein
(ii)
all of cavity of left ventricle shaded
(iii)
thicker wall can generate a greater pressurs / more powerful push / pump
(iv)
to pump / push / force blood further / all round the body / not just to the lungs
b(i)
any two of these smoking fat / cholesterol rich diet lack of exercise stress
(i)
restrict supply of oxygen / glucose / sugar to heart / ventricle muscle in area dies / heart ttack/ cannot respire
c(i)
label to liver
(ii)
label to kidney
(iii)
arrows from liver to heart and heart to kidneys arrows from heart to lungs and back to heart
Respiration & Transport in Humans
page 3
Alternative to Practical 1 a(i)
o
25 C 60 12
total mean (average)
0
35 C 90 18
(ii)
respiration / fermentation
(iii)
Effect
increase in number of bubbles released per min reference to a numerical increment
Explanation
reference to role of enzymes involved / kinetic energy / more molecular collisions of enzyme and substrate
b(i)
carbon dioxide
(ii)
limewater turns milky white
c
agitation of tubes equilibrium / temperature to be reached
Respiration & Transport in Humans
page 4
Extension 1 a(i)
any three from these receives blood from vena cava reference to blood being deoxygenated acts as reservoir reference to thin muscle wall contracts / reference to atrial systole to move blood to right ventricle
(ii)
any three of these receives blood from right atrium reference to thick / thicker muscle wall reference to builds up blood pressure contracts / reference to ventricular systole to move blood to lungs via pulmonary artery
(iii)
any three of these reference to position prevents backflow of blood / maintains blood flow in one direction reference to closing a ventricular systole / when pressure starts to build in right ventricle so blood can only leave via pulmonary artery
b
any six of these reference to high saturated or animal fat diet / reduce saturated or animal fat content of diet reference to too much cholesterol / reduce cholesterol content of diet fat / cholesterol builds up on coronary artery atherosclerosis / atheroma high salt diet / reduce salt content of diet stress / stress management high blood pressure smoking / stop smoking lack of exercise / take regular exercise obesity / take control of diet to reduce obesity
Respiration & Transport in Humans
page 5
Extension 2 a
any five of these breathing rate increases to increase amount of oxygen / to replace used oxygen needed for aerobic respiration reference to muscles repaying oxygen debt remova of lacic acid reove / exhale morecarbon dioxide control of breathing rate by brain
b
any four of these increased heart rate / pulse rate to move blood faster so more oxygen / glucose goes to muscles non-essential processes slow down increased air flow into lungs / breathing rate so aerobic respiration increases stimulates conversion of glycogen to glucose increases mental awareness
c
any six of these increase in sweat production secreted from sweat glands onto skin sweat evaporated removing heat from skin surface / reference to cooling effect vasodilation arterioles more blood flows near skin blood carries heat so heat is lost from skin panting causes heat loss from lungs hairs lowered to allow more heat loss
Respiration & Transport in Humans
page 6
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 5: Coordination, response and homeostasis Recommended prior knowledge Knowledge of cell structure, osmosis, respiration and enzyme activity will help students to understand why homeostasis is important in mammals. It will also be helpful if they have some understanding of the behaviour of light, lenses, and how to draw simple ray diagrams before beginning work on the human eye. Candidates studying the supplement will need a simple knowledge of the immune response in order to discuss the difficulties associated with kidney transplants. Context This unit provides several opportunities to reinforce ideas and facts that link the themes of this syllabus and covered in earlier units. It is important to take sufficient time to study this unit as many students find the concepts difficult to understand. Outline The theme running throughout this unit is communication within the body, through chemicals and the nervous system. Students should be encouraged to see the similarity of the mechanisms by which both plants and animals achieve responses to stimuli. Once the basic function of the nervous system has been covered, the effects on it of drugs such as alcohol and heroin are considered, this social aspect is interesting to students and discussions or a class survey can stimulate all the students. Homeostasis is illustrated for all candidates by temperature regulation in humans, while the supplement covers the control of blood glucose concentration and takes an overview of how negative feedback is involved in control mechanisms. A simple treatment of excretion in humans completes the unit. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref II 10.1
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Learning objectives 5.1 Nervous control in humans • Describe the human nervous system in terms of the: - central nervous system (brain and spinal cord as areas of coordination) and - the peripheral nervous system which together serve to
Suggested teaching activities Diagrams or models can be used to illustrate the positions of the brain, spinal cord and peripheral nerves in the body. A model of the human skeleton can also be useful. Students can label diagrams and should differentiate between the spinal cord and the vertebral column. The structure of nerve cells, neurones can lead into the role of a reflex arc. Students can draw a diagram with annotated Cambridge IGCSE Biology (0610)
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes 2009 p142–143 Experiments in biology – Human senses: www.biologyresources.com/biologyexperiments2.html 1
Syllabus ref
Learning objectives coordinate and regulate body functions •
II 10.1
labels of a motor neurone.
Identify: - motor (effector) - relay (connector) - sensory neurones from diagrams
•
Describe a simple reflex arc in terms of sensory, relay and motor neurones
•
Describe a reflex action as a means of automatically and rapidly integrating and coordinating stimuli with responses
The reflex arc is important to many organisms for selfprotection. Students will understand its structure if different reflexes are considered: knee jerk, touching a pin with one finger. It is important to understand the role of the spinal cord in a reflex action and the receptor and effector. Students should understand that reflex actions are not learnt responses but automatic.
State that muscles and glands can act as effectors
This can be shown by the labels on the reflex arc as arm muscles contract and move away from the stimulus. Salivary glands that respond to food when is in the mouth.
•
Describe the action of antagonistic muscles to include the biceps and triceps at the elbow joint
A simple experiment can show the action of the arm muscles. Students like to find out how strong they are by lifting different weights and to see the contraction of their biceps muscle. It is important to understand that muscles can contract and relax but cannot become shorter. Two muscles work together to move bones but they act antagonistically to produce the movement. The action of leg muscles and those in the oesophagus (Unit 2.5/2.6) can be discussed.
Define sense organs as groups of receptor cells responding to specific stimuli: - light - sound - touch
Learning resources Practical Biology – Human sensation and perception: www.nuffieldfoundation.org/practica l-biology/human-sensation-andperception Revision – The nervous system: www.lgfl.skoool.co.uk/content/keyst age4/biology/pc/lessons/uk_ks4_ne rvous_system/h-frame-ie.htm
•
•
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Suggested teaching activities
Students should understand that there are different types of stimuli, chemical or mechanical, and that a sense organ combines receptors with other cells. Simple experiments can demonstrate the response of sense organs. A circus around the lab will allow all students to Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p144–149 Practical Biology – Reflex actions: www.nuffieldfoundation.org/practica l-biology/reflex-nerves-andreactions This website has some ideas about reaction time: www.humanbenchmark.com/tests/r eactiontime/index.php Measuring reaction time: www.bbc.co.uk/science/humanbody /sleep/sheep/
Neuroscience for kids: www.faculty.washington.edu/chudle r/neurok.html Despite the title, some of the material at this site is a little advanced for IGCSE students.
2
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Learning objectives
•
Suggested teaching activities
Learning resources
- temperature - chemicals
investigate each stimulus.
Describe the structure and function of the eye including accommodation and pupil reflex
The relation between the eye as a receptor and an effector in response to the stimulus of light can be used to reinforce the concept of a response to external stimuli.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p150–151
A model of the eye can be used to illustrate the relevant structures.
Revision – The eye: www.bbc.co.uk/schools/gcsebitesiz e/science/edexcel/electrical/thenerv oussystemrev4.shtml
Extension – A cow or a sheep's eye can be dissected. A large round flask containing fluorescein with a convex lens at the front can be used to show how light is focussed on the retina (at the back of the flask). Students can be given a large unlabelled diagram of the eye. Laminated cards on which the 14 important labels are written can be used to actively label the eye diagram. The class can be divided into teams to ask questions about structure and function to aid learning and the understanding of the eye. Students can use small mirrors to draw their own eye(s). If the eyes are moved up and down and from side to side, the whites of the eyes are seen. Accommodation is shown by reading and then looking outside to a distant object. Close vision: Ciliary muscles Contract.
www.scool.co.uk/gcse/biology/nervesand-hormones/revise-it/the-eye
Student progress could be assessed using: May/June 2011 Paper 0610/21 question 4 Oct/Nov 2010 Paper 0610/22 question 3 May/June 2009 Paper 0610/02 question 7 May/June 2008 Paper 0610/02 question 10 Oct/Nov 2008 Paper 0610/02 question 8 II 10.1 (S)
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5.1 • Distinguish between voluntary and involuntary actions
The pupil reflex is a good example of a reflex action in which the pupil controls the amount of light falling on the retina for its protection. Students can work in pairs and investigate the effect on the
Cambridge IGCSE Biology (0610)
Revision – Reflex actions: www.bbc.co.uk/schools/gcsebitesiz e/science/aqa/human/thenervoussy stemrev3.shtml
3
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Learning resources
size of pupil of having the eyes closed for 10 seconds and then open. The effect of a torch shone into the eye and the change in pupil when looking at a near and then a distant object can all be investigated. Students can record their results and compare their reactions. Students should be able to suggest voluntary and involuntary responses. They should understand that a voluntary action involves the brain in its initiation, that it is a conscious thought to make an action. Involuntary actions are automatic and faster than voluntary actions. Refer to heart beat in Unit 4.6 and peristalsis in Unit 2.6. Student progress could be assessed using: May/June 2010 Paper 0610/32 question 1 •
Distinguish between rods and cones in terms of: - function and - distribution.
Revision – The eye: www.bbc.co.uk/schools/gcsebitesiz e/science/ocr_gateway/ourselves/3 _keeping_in_touch2.shtml
Rods and cones are light-sensitive receptor cells in the retina. Cones for Colour in the fovea. Rods for light intensity throughout the retina. Extension – students could investigate colour perception and colour blindness. Possible link to genetics (Unit 8). Student progress could be assessed using: May/June 2010 Paper 0610/31 question 1
II 10.2
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5.2 Hormones • Define a hormone as a chemical substance, produced by a gland, carried in the blood which alters the activity of one or more specific
Use a simple diagram of the human body to show the source and the site of action of different hormones.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p152–153
Students will know about the sex hormones and can add adrenaline to their diagram. Cambridge IGCSE Biology (0610)
4
Syllabus ref
Learning objectives
•
• •
target organs and is then destroyed by the liver State the role of the hormone adrenaline in the chemical control of metabolic activity, including increasing the blood glucose concentration and pulse rate Give examples of situations in which adrenaline secretion increases Compare nervous and hormonal control systems
Suggested teaching activities Adrenaline makes a good introduction to hormones as most students can relate to its effects. It should be mentioned that adrenaline bridges the gap between nervous and hormonal control because of its fast and short lived action. Students can discuss the effects on the body of the flight and fight hormone with their own examples.
Learning resources Hormones and their effects: www.abpischools.org.uk/page/mod ules/hormones/index.cfm Revision – Hormones: www.bbc.co.uk/schools/gcsebitesiz e/science/edexcel/electrical/hormon esrev2.shtml
Students may produce their own table of comparison with sub-titles of: form and pathway of transmission speed of transmission duration of effect of hormone response to hormone Student progress could be assessed using: Oct/Nov 2008 Paper 0610/02 question 8c
II 10.2 (S)
5.2 • Discuss the use of hormones in food production
The meat and cattle industries have used hormones for many years. The sex hormones are used to promote growth in calves and lambs but not in poultry. Synthetic growth promoters can make animals grow faster. The European Union, Japan, Canada, Australia banned the use of hormones in cattle in 1981 but the US still uses protein and steroid hormones for cattle growth and to increase their milk yield.
Posilac – An introduction: www.monsanto.com/newsviews/Pa ges/milk-labeling.aspx A view from the firm that makes and sells BST
Students should be able to discuss the use of hormones in food production using information from journals, newspaper articles and the web. II 10.3
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5.3 Tropic responses • Define and investigate: - geotropism as a response in which a plant grows towards or away from gravity, and - phototropism as a response in
Plants are able to respond to certain stimuli. Students can now study plant response to light and water. Geotropism and phototropism should be investigated with simple experiments using seeds that have been germinated before the start of the topic. It should be made clear that these are plant growth responses, auxin, a plant hormone, is Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p154–155
5
Syllabus ref
Learning objectives which a plant grows towards or away from the direction from which light is coming
Suggested teaching activities produced by the shoot and root tips of the growing plant. The direction of growth is related to the direction of the stimulus. Revision: www.www.bbc.co.uk/schools/gcsebitesize/science/add_gate way/living/controlplantgrowthrev1.shtml Extension – practical work using auxins and rooting compounds. Student progress could be assessed using: May/June 2010 Paper 0610/21 question 9
(S)
5.3 • Explain the chemical control of plant growth by auxins including geotropism and phototropism in terms of auxins regulating differential growth, and the effects of synthetic plant hormones used as weedkillers
Plant hormones are used to make fruit develop at the same time to allow for efficient picking. Weeds in fields of monoculture such as wheat are killed by selective weedkillers. Hormones can inhibit the fertilisation of fruit such as grapes that are then seedless. The students could discuss the advantages and disadvantages of human manipulation of plant development. Extension – effects of weedkillers on seedlings. Extension – effects of IAA on mustard seedlings.
Learning resources Experiments in biology: Germination and Tropisms www.biologyresources.com/biologyexperiments2.html The response of seedlings to light: www.saps.org.uk/secondary/teachi ng-resources/185-student-sheet-8the-response-of-seedlings-to-light Investigating geotropism: www.saps.org.uk/secondary/teachi ng-resources/184-student-sheet-7the-behaviour-of-hypocotyls Practical Biology – Plant responses to stimuli: www.nuffieldfoundation.org/practica l-biologyinterpreting-investigationplant-hormones Investigating plant growth regulators: www.saps.org.uk/secondary/teachi ng-resources/183-student-sheet-6investigating-plant-growthregulators An experiment involving the use of IAA on mustard seedlings: www.saps.org.uk/secondary/teachi ng-resources/111-investigating-theeffects-of-iaa-on-root-growth-inmustard-seedlings
II 10.4
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5.4 Homeostasis
The students should appreciate the importance of
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al.
6
Syllabus ref
Learning objectives • •
• •
•
Define homeostasis as the maintenance of a constant internal environment Identify, on a diagram of the skin: - hairs - sweat glands - temperature receptors - blood vessels - fatty tissue Describe the maintenance of a constant body temperature in humans in terms of insulation and the role of temperature receptors in the skin: - sweating - shivering - vasodilation - vasoconstriction of arteries supplying skin surface capillaries and the coordinating role of the brain
Suggested teaching activities maintaining an internal steady state to keep the conditions in the tissue fluid around the cells constant. The concepts of diffusion, osmosis, enzyme activity and respiration will guide the students to understand the importance of constant pH, oxygen and carbon dioxide concentrations, water, enzymes and hormones. Students could think how they feel when they have a high fever to discuss the importance of an internal steady state. Body temperature is related to homeostasis in which communication is through the nervous system. Students should understand that the blood capillaries do not move up and down in the skin during vasodilation and vasoconstriction respectively. Emphasise the cooling effect sweating due to the evaporation of water. The brain receives impulses from sensory receptors and responds by adjusting the condition to maintain an optimum. A clear example linked to the skin is temperature control. Extension – students could research hypothermia and heat stroke.
Learning resources Nelson Thornes, 2009 p130–133 PowerPoint presentation – Homeostasis: www.biologyresources.com/biology-CD.html Practical Biology – Sweating: www.nuffieldfoundation.org/practica l-biology/interpreting-informationabout-sweating-and-temperature Skin – structure and function: www.abpischools.org.uk/page/mod ules/skin/index.cfm A website to show penguin huddling: www.coolantarctica.com/Antarctica %20fact%20file/science/cold_peng uins.htm
Student progress could be assessed using: May/June 2011 Paper 0610/32 question 2 May/June 2011 Paper 0610/22 question 3 May/June 2010 Paper 0610/22 question 7 II 10.4 (S)
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5.4 • Explain the concept of control by negative feedback • Describe the control of: - the glucose content of the blood by the liver - insulin and glucagon from the pancreas
The control of temperature and glucose can illustrate negative feedback.
Control of blood sugar: www.abpischools.org.uk/page/mod ules/diabetes/index.cfm
Flow diagrams can show how this is achieved. The control of glucose content can be linked with diabetes, a relatively common disorder in many countries. The students should consider why it is important to control blood glucose content, thinking back to what they know about diet, including sweet fizzy drinks, osmosis and respiration. Correct spelling is essential to distinguish between glycogen Cambridge IGCSE Biology (0610)
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Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
and glucagon. Student progress could be assessed using: May/June 2009 Paper 0610/31 question 2c Oct/Nov 2010 Paper 0610/33 question 2 II 10.5
5.5 Drugs • Define a drug as any substance taken into the body that modifies or affects chemical reactions in the body • Describe the medicinal use of antibiotics for the treatment of bacterial infection • Describe the effects of the abuse of heroin: - a powerful depressant - problems of addiction - severe withdrawal symptoms - associated problems such as crime and infection e.g. HIV/AIDS •
•
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Describe the effects of excessive consumption of alcohol: - reduced self-control - depressant - effect on reaction times - damage to the liver - social implications
This topic lends itself to class discussion or group presentations. Students will understand that accepted drugs are used to relieve pain and to treat a disease or infection. Antibiotics are drugs that either disrupt the metabolic processes of growth of the bacterium or stop the growth of bacterial spores. The students should be allowed to discuss the implications of taking recreational drugs both socially and medically including their effect on the nervous system and their possible long-term effects. Students need to understand the effects, the symptoms and possible problems with taking heroin. Many recreational drugs can become addictive such as cigarette smoking and alcohol. Cigarette smoking can be linked with Unit 4.4. Student progress could be assessed using: May/June 2010 Paper 0610/22 question 5 Oct/Nov 2008 Paper 0610/02 question 2
Describe the effects of tobacco smoke and its major toxic components: - tar - nicotine - carbon monoxide - smoke particles on the gas exchange system
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p158–165 Practical Biology – Smoking: www.nuffieldfoundation.org/practica l-biology/going-smoke Teacher resource: Drug scenes complied by:Royal College of Psychiatrists. Drug Abuse published by Independence Educational Publishers Drug information: www.talktofrank.com/ Drug abuse: www.abpischools.org.uk/res/coRes ourceImport/resources04/drugs/ind ex.cfm Revision – Smoking: www.lgfl.skoool.co.uk/content/keyst age4/biology/pc/modules/breathing _respiration/smoking/index.html
Cambridge IGCSE Biology (0610)
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Suggested teaching activities
II 10.5 (S)
5.5 • Explain why antibiotics kill bacteria but not viruses
Viruses do not have their own metabolism but use the pathways of their host cell which prevents them from being destroyed by antibiotics.
II 9
5.6 Excretion in humans • Define excretion as the removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements • Substances should include: - carbon dioxide - urea - salts • Describe the function of the kidney in terms of the removal of urea and excess water and the reabsorption of glucose and some salts (details of kidney structure and nephron are not required) • State the relative positions of: - ureters - bladder - urethra in the body • State that urea is formed in the liver from excess amino acids • State that: - alcohol - drugs - hormones are broken down in the liver
Excretion can be considered as another way in which the environment of cells is controlled, by removing toxic materials, waste products of metabolism and substances in excess of requirements. Ensure that they understand the difference between egestion (the removal of substances from the alimentary canal, that have never been part of the body at all) and excretion. Only a simple understanding of the formation of urea from excess amino acids is required.
5.6 • Outline the structure of a kidney: - cortex - medulla
This should be dealt with very simply as even students studying the supplement may find details of nephron structure and the role of the kidney in reabsorption of glucose, salts and water difficult.
II 9 (S)
v1 2Y05
Learning resources
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p134–135 Kidneys: www.abpischools.org.uk/res/coRes ourceImport/resources04/kidneys/in dex.cfm
It is important to differentiate between ureter and urethra. Labelled diagrams will help the students to understand the structure of the kidney. Refer to Unit 7.1 for male reproductive system. Extension – A kidney from a sheep or a pig can be dissected to show the gross structure. Mention that hormones are also broken down by the liver. Student progress could be assessed using: May/June 2009 Paper 0610/02 question 2 Oct/Nov 2010 Paper 0610/21 question 9 May/June 2008 Paper 0610/02 question 11
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p136–139
9
Syllabus ref
Learning objectives •
•
•
• •
v1 2Y05
- the start of the ureter Outline the structure and functioning of a kidney tubule, including role of renal capsule in filtration from blood of: - water - glucose - urea - salts Role of tubule in reabsorption: - of glucose - most of the water - some of the salts back into blood leading to concentration of urea in the urine as well as loss of excess water and salts Explain dialysis in terms of maintenance of glucose and protein concentration in blood and diffusion of urea from blood dialysis fluid Discuss the application of dialysis in kidney machines Discuss the advantages and disadvantages of kidney transplants, compared with dialysis
Suggested teaching activities The structure of the kidney can lead into the use of dialysis and the machine's role in removing excess urea and water. The importance of homeostasis can be reinforced at this point as the kidneys are osmoregulators.
Learning resources Kidneys: www.abpischools.org.uk/res/coRes ourceImport/resources04/kidneys/in dex.cfm
The importance of retaining glucose must be emphasised and it is excess water, urea and salts that are excreted in urine. This will link back to Unit 5.4 which considers diabetes. Diagams of dialysis machines should be studied to enable students to understand the process and the role of the dialysis fluid. Students will need to remember what they know about osmosis and diffusion in order to understand how dialysis works. There is a link between the immune system and tissue rejection, when considering kidney transplants. Extension – Dissection of a kidney and teasing out of nephrons from the cortex tissue under a microscope.
Revision – Kidney failure: www.scool.co.uk/gcse/biology/homeostasi s/revise-it/dealing-with-kidneyfailure
Student progress could be assessed using: May/June 2011 Paper 0610/31 question 4 Oct/Nov 2010 Paper 0610/32 question 2 Oct/Nov 2009 Paper 0610/31 question 4 May/June 2008 Paper 0610/31 question 5
Cambridge IGCSE Biology (0610)
10
Core 1
Coordination, Response & Homeostasis
page 1
Core 2 1
1 1.
Coordination, Response & Homeostasis
page 2
Core 3
Fig. 2
Fig. 2
Coordination, Response & Homeostasis
page 3
Alternative to practical 1 Fig. 3
Fig. 3
Coordination, Response & Homeostasis
page 4
Alternative to practical 1
Coordination, Response & Homeostasis
page 5
Extension 1
[Total:15]
Extension 2
[Total:15]
Coordination, Response & Homeostasis
page 6
Core 1 a
homeostasis
b(i)
evaporation of sweat / water removes heat from the body / cools the body / reference to latent heat of vaporisation
(ii)
arterioles in skin relax increased blood flow through surface capillaries more heat loss from body by convection / radiation
Coordination, Response & Homeostasis
page 1
Core 2 a(i)
X – renal vein Y – urethra
(ii)
remove water / salts (from blood) or osmoregulation or control of water / salt content (of the blood)
b
any two from these alcohol drugs / named drug haemoglobin hormones / named hormone toxins
c
homeostasis
Coordination, Response & Homeostasis
page 2
Core 3 a(i)
reflex response / action / involuntary / automatic
(ii)
arm muscles / named arm muscle / muscle (unqualified)
(iii)
motor (neurone)
b(i)
A – contracts B – relaxes
(ii)
to pull leg / part of leg in opposite / different directions
(iii)
to pass / transmit all of muscle pull to skeleton / not to lose some pull in stretching the fibres
Coordination, Response & Homeostasis
reject – expands / stretches
page 3
Alternative to Practical 1 a(i)
diagram shows all seedlings with longer straight roots
(ii)
diagram shows all seedlings with curved roots towards source of gravity correct extended growth region
(iii)
root tip / root / radicle responds towards gravity / grows downwards / shows geotropism reject points downwards / bends (or alternative wording) correct reference to role of auxins
b(i)
any one from water / moisture air / oxygen correct temperature / heat / warmth reject carbon dioxide, light, minerals
(ii)
must link to b(i) water / moisture protective covering / glass / plastic box / keep seedlings moist / prevent seedlings drying out / adds water daily / supply water / soaked cotton wool warmth heat from lamp / in temperature box / facing the sun / out of air conditioned area / warm room air / oxygen ventilation / fan / breathing
c
keep apparatus in the dark / uniform continuous light / red light / in light from all directions / keep moist to avoid hydrotropism
Coordination, Response & Homeostasis
page 4
Extension 1 a(i)
automatic response to a stimulus and one from reference to very fast reference to innate / not learned
(ii)
any six points from these light shines on (or alternative wording) retina electrical impulse generated (or alternative wording) passed to brain via motor neurones to iris circular muscles contract reject references to ciliary muscles to make pupils smaller protects rods and cones / retina from damage reflex is very fast / does not require thought / does not require decision
b
any four from cones detect colour reference to three types of cones / detect red, green, blue cones needed for fine detail rods cannot detect colour / only produce image in black and white rods distributed all over retina cones concentrated in fovea / yellow spot cones only stimulated by bright light / rods sensitive to dim light
c
any three from these rods / cones / retina / damaged by bright light so not receptive lens cloudy or damaged so light cannot pass through cornea cloudy or damaged so light cannot pass through eyeball deformed / retina detached so cannot focus optic nerve damaged so no impulses transmitted (or alternative wording)
Coordination, Response & Homeostasis
page 5
Extension 2 a
any four points from these excretion removal from the body of waste products of metabolism reference to substances which are poisonous / in excess / surplus to requirements egestion removal of faeces from the body reference to via anus
b
drawing marks includes aorta, renal artery, kidney, ureter, bladder and urethra drawing clear and parts correctly labelled explanation reference to blood from aorta to renal artery blood enters kidney water filtered out reference to formation of urine urine passes down ureter reference to storage in bladder reference to sphincter muscle and role urine passes through urethra
c
any four from reference to deamination / breakdown of proteins or amino acids reference to formation of urea reference to breakdown of hormones / named hormones reference to breakdown of alcohol reference to breakdown of nicotine / other named drugs
Coordination, Response & Homeostasis
page 6
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 6: Reproduction in plants Recommended prior knowledge A basic knowledge of cell structure will be helpful, but otherwise the unit requires very little previous knowledge. Context This unit introduces the concept of reproduction that will be developed further in Unit 7 Human reproduction. Outline In this unit, general features of both asexual and sexual reproduction are considered, before looking in detail at sexual reproduction in plants. Many students have preconceived ideas about plants and the more interactive activities usually stimulate the class. The unit should therefore be covered at a time of year when suitable flowers are likely to be available. The sub-section on Growth and Development is included in this unit. It is suggested that mitosis and meiosis are briefly dealt with here, as the concept of cell division helps with the interpretation of the distinction between asexual and sexual reproduction, although some teachers may prefer to leave this until genetics is covered or the genetics Unit 8 Inheritance and evolution may be studied before this unit. This unit could also be combined with Unit 7, Human reproduction. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref III 1.1
Learning objectives
Suggested teaching activities
6.1 Asexual reproduction • Define asexual reproduction as the process resulting in the production of genetically identical offspring from one parent • Describe asexual reproduction in: - bacteria - spore production in fungi - tuber formation in potatoes
Ensure that students understand that 'asexual' means 'not sexual'. Asexual reproduction involves only one parent, which produces new, genetically identical organisms by mitosis. Extension – Agar plates that have had bacterial colonies grown on them can be set up by the class if great care is taken about safety issues. Fungal spores can be easily seen on bread moulds, soft tomatoes or mushroom gills, if these are allowed to develop well past the edible stage (Unit 1.2).
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p168 Practical Biology – Cloning: www.nuffieldfoudation.org/practicalbiology/cloning-living-organism
Video clip – Reproduction and cell division:
Asexual reproduction in potatoes is often difficult for students to understand. 'Old' potatoes can be used to show the 'eyes' v1 2Y05
Cambridge IGCSE Biology (0610)
1
Syllabus ref
III 1.1 (S)
III 3.2
Learning objectives
Suggested teaching activities
Learning resources
and to explain how these can develop and reproduce new identical tubers. Students could grow their own potato that should produce many new potatoes in about six months, flow diagrams help in understanding the asexual reproduction in potatoes.
www.bbc.co.uk/learningzone/clips/c ell-division-andreproduction/108.html
6.1 • Discuss the advantages and disadvantages to a species of asexual reproduction
Students can make a table to list the main points to compare asexual and sexual reproduction.
6.2 Mitosis • Define mitosis as nuclear division giving rise to genetically identical cells in which the chromosome number is maintained by the exact duplication of chromosomes • (details of the stages are not required) • State the role of mitosis in: - growth - repair of damaged tissues - replacement of worn out cells - asexual reproduction
Students have no knowledge of genetics that will be studied in Unit 8.3 but they will probably be aware that the nucleus of a cell contains chromosomes that carry genes.
Students should appreciate that many horticulturists exploit asexual reproduction in bulbs and rhizomes e.g. daffodils, orchids. Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p204
Mitosis is a type of cell division that produces cells with identical chromosomes and genes to the parent cell.
PowerPoint presentation: Cell division and specialisation www.biologyresources.com/biology-CD.html
A simple series of labelled diagrams showing how chromosomes behave during mitosis, with no names of stages or details of spindles, is all that is required. Students should be aware that mitotic division also occurs in body cells for growth or for replacement of worn out cells throughout the organism's life.
Interactive mitosis: www.cellsalive.com/mitosis.htm (includes detail above that required for IGCSE)
Mitosis is the cell division that produces identical individuals during asexual reproduction. The word 'clones' could be introduced as many students will have heard of cloning.
Cell division (and cancer): www.abpischools.org.uk/res/coRes ourceImport/resources04/cancer/in dex.cfm
Extension – students could look at cells dividing in garlic or onion root tip. Show video clip – Cell division: www.bbc.co.uk/learningzone/clips/cell-division-throughoutlife/109.html
v1 2Y05
Cambridge IGCSE Biology (0610)
2
Syllabus ref III 1.2
III 1.2 (S)
Learning objectives
Suggested teaching activities
6.3 Sexual reproduction • Define sexual reproduction as the process involving the fusion of haploid nuclei to form a diploid zygote and the production of genetically dissimilar offspring
Sexual reproduction should be described as a process in which gametes fuse together in a process called fertilisation, producing a zygote.
6.3 • Discuss the advantages and the disadvantages to a species of sexual reproduction
Unlike asexual reproduction, sexual reproduction introduces genetic variation amongst the offspring. This is a link with Unit 8.4.
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p169
Students should understand that this need not always involve two parents: self-fertilisation, which is not uncommon in plants, is still sexual reproduction.
A table can be drawn up to compare asexual with sexual reproduction. III 3.3
6.4 Meiosis • Define meiosis as a reduction division in which the chromosome number is halved from diploid to haploid (details of the stages are not required) • State that gametes are the result of meiosis • State that meiosis results in genetic variation so that the cells produced are not all genetically identical
Students can use coloured pipe cleaners or wool to visualise the different positions of the chromosomes during meiosis and to understand how the cell chromosome number is halved and how genetic variation can occur.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p205 Interactive meiosis: www.cellsalive.com/meiosis.htm
At this stage the important concept is that gametes are haploid cells: A link with Unit 7.1 Sexual reproduction in humans The description of meiosis should be kept as simple as possible, concentrating on its results rather than any details of the process itself. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 5
v1 2Y05
Cambridge IGCSE Biology (0610)
3
Syllabus ref III 1.2.1
v1 2Y05
Learning objectives 6.5 Sexual reproduction in plants • Identify and draw, using a hand lens if necessary: - sepals - petals - stamens - anthers - carpels - ovaries - stigmas of one locally available named insect-pollinated dicotyledenous flower • Examine the pollen grains under a light microscope or in photomicrographs • State the functions of the: - sepals - petals - anthers - stigmas - ovaries • Use a hand lens to identify and describe the anthers and stigmas of one locally available named windpollinated flower • Examine the pollen grains under a light microscope or in photomicrographs • Candidates should expect to apply their understanding of the flowers they have studied to unfamiliar flowers • Define pollination as the transfer of pollen grains from the male part of the flower (anther of stamen) to the female part of the plant (stigma)
Suggested teaching activities Students should look closely at the structure of a simple, radically symmetrical, insect-pollinated flower. They can dissect it to identify the different parts, using a light microscope or a hand lens. Annotate the diagrams to understand how the structure is adapted to its function. This is a good opportunity to develop or assess the practical skills of observation and recording. Students can find the terminology difficult to learn and different flowers should be available to study. Magnification can be calculated for the parts of the flower (Unit 1.7). The functions of these flower parts are more easily understood if they are included when the structure of a flower is being drawn. Extension – If there is time and the facilities, pollen grains can be collected from anthers of nasturtium, dead nettle or any flower with ripe stamens. A few pollen grains can be transferred to filter paper in a Petri dish and 1cm3 of 0.4M dm-3 sucrose solution added to the grains. The dish should be kept in the dark at room temperature and the pollen tube growth can be observed under a microscope after an hour or more. Fertilisation should be dealt with simply, there is no need for details of embryo sacs or the different nuclei involved. However, teachers should explain that germination involves the growth of a pollen tube from the pollen grain down the style to the ovary wall. The male nucleus (not the pollen grain) is the male gamete and fertilises an ovule. If the ovary contains many ovules, each will need to be fertilised by a different pollen nucleus. The fertilised ovule divides by mitosis (link with mitosis earlier in this unit) to form a seed.
Cambridge IGCSE Biology (0610)
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p170 – 177 Experiments in biology – Germination and tropisms: www.biologyresources.com/biologyexperiments2.html Flower structure: www.biology-resources.com/plantsflowers.html Flower structure: www.saps.org.uk/secondary/teachi ng-resources/547-the-structure-offlowers www.britannica.com/EBchecked/to pic/357598/dicotyledon Video clip – Fertilization in plants: www.bbc.co.uk/learningzone/clips/f ertilisation-in-plants/120.html Video clip – Insect pollination: www.bbc.co.uk/learningzone/clips/i nsect-pollination-of-plants/119.html
4
Syllabus ref III 1.2.1
Learning objectives • •
•
•
•
v1 2Y05
Name the agents of pollination Compare the different structural adaptations of insect-pollinated and wind-pollinated flowers Describe the growth of the pollen tube and its entry into the ovule followed by fertilisation (production of endosperm and details of development are not required) Investigate and describe the structure of a non-endospermic seed in terms of the embryo (radicle, plumule and cotyledons) and testa, protected by the fruit Outline the formation of a seed (limited to embryo, cotyledon, testa and role of mitosis) and fruit (produced from the ovary wall)
•
State that seed and fruit dispersal by wind and by animals provides a means of colonising new areas
•
Describe, using named examples, seed and fruit dispersal by wind and animals
Suggested teaching activities
Learning resources
The structure of seeds should be investigated practically. Soaked bean seeds are large and easy to see but need to be soaked at least two days before the lesson. If possible, students should be able to watch a flowering plant through all the stages from flowering through to fruit and seed development. This helps them to understand how fruits and seeds develop after fertilisation. A range of fruits should be looked at and the ways in which they are dispersed considered. A very common error is to confuse pollination with seed or fruit dispersal and care should be taken to avoid this. An experiment to measure the time taken for seeds of sycamore, lime or ash to fall can allow the students to investigate different variables of height, mass of seed and wind currents. At least 10 measurements for each type of seed will allow students to construct tally charts, to calculate the mean and to discuss the errors in such an investigation. Student progress could be assessed using: May/June 2010 Paper 0610/22 question 6 May/June 2009 Paper 0610/02 question 3 Oct/Nov 2010 Paper 0610/21 question 8 May/June 2008 Paper 0610/02 question 2
Cambridge IGCSE Biology (0610)
5
Syllabus ref III 1.2.1 (S)
Learning objectives 6.5 • Distinguish between selfpollination and cross-pollination • Discuss the implications to a species of self-pollination and cross-pollination
Suggested teaching activities
Learning resources
Samples of insect-pollinated and wind-pollinated flowers (grasses and cereals are good examples of the latter) can be studied and compared. Students should discuss the possible outcomes of self and cross-pollination in terms of the degree of variation amongst offspring, and to compare the effects this might have on populations. This could be reviewed in Unit 8.4 Variation. Ensure that the emphasis is on the species itself, not on advantages or disadvantages to farmers or gardeners who grow the plants. Student progress could be assessed using: May/June 2011 Paper 0610/32 question 4d/e Oct/Nov 2010 Paper 0610/31 question 1 May/June 2008 Paper 0610/31 question 1
III 2
v1 2Y05
6.6 Growth and development • Define growth in terms of a permanent increase in size and dry mass by an increase in cell number or cell size or both • Define development in terms of increase in complexity • Investigate and state the environmental conditions that affect germination of seeds: - requirement of water - oxygen - suitable temperature
Mention that development includes the differentiation of cells as they become specialised to carry out different tasks.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p178–179
Extension – this is an excellent opportunity for candidates to design a simple investigation for themselves. Note that most of the seeds that are used in laboratories are derived from crop plants, and these do not normally require light for germination.
Video clip – Germination: www.bbc.co.uk/learningzone/clips/a n-introduction-to-seed-germinationand-growth/63.html
Student progress could be assessed using: May/June 2010 Paper 0610/21 question 5
Cambridge IGCSE Biology (0610)
6
Core 1
Reproduction in Plants
page 1
Core 2 1
1
Reproduction in Plants
page 2
Extension 1
Reproduction in Plants
page 3
Extension 1
Reproduction in Plants
page 4
Extension 2
[Total:15]
Extension 3
[Total:14]
Reproduction in Plants
page 5
Core 1 (i)
any three of these amount / brightness of sunlight / light water availability mineral supply rooting space other soil factors e.g. pH disease infections / damage by herbivores / animals affected by competitor species
(ii)
any three of these meiosis leading to variations in ovules / female gametes / nuclei meiosis leading to variation on pollen grains / male gametes / nuclei second / male parent may be different for different seeds / fertilisation of ovules from different pollen grains possibility of mutations / specific mutagen action correct reference to different genotypes of parents / heterozygous state for some genes
Reproduction in Plants
page 1
Core 2 a
A ovule / ovary B sepal / calyx
b
C (petals are) coloured / bright / shaped / produce nectar / have nectar guides to attract insects D (stigma / style) receives pollen from pollinator / insect E (anther / stamen) produces pollen / place pollen on insect
c
fusion of gametes / nuclei / fertilisation plus any three of these pollen tube grows / develops / forms through / down style / to ovary to micropyle / ovule / embryo sac male gamete passes through pollen tube / moves to female gamete/nucleus zygote develops into embryo reference to female gamete as egg cell, ovum
Reproduction in Plants
page 2
Extension 1 a
growth at least one from increase in size or number of cells or dry mass / getting larger irreversible / permanent due to cell division development at least one from increase in complexity formation of different cells / tissues / organs / additions of new features
b
three references from mitosis chromosomes division of nucleus formation of new cells / daughter cells being identical / of same genetic composition
c(i)
osmosis / diffusion
(ii)
higher concentration of solutes than outside the cell / lower water potential in cell
(iii)
cell wall
(iv)
two points from cell swells up / becomes turgid / gets longer / elongates press against each other results in increase in overall length of root / whole root gets longer downward growth as a result of upper part of root being anchored cells elongate vertically
d(i)
group of cells of the same type carrying out the same function
(ii)
name of tissue (xylem) phloem / sieve tubes root hair (cells)
Reproduction in Plants
function transport of water or minerals / support (transport of sugars) (absorption of water from soil)
page 3
Extension 2 a
transfer of pollen from anther / stamen to stigma
b
ten marks from the following named insect-pollinated flower sepals, description of position or shape or appearance reference to protection of flower while in bud petals, description of position or shape or appearance attracting insects / acting as landing stage / guides present to direct insects to nectar stamen = anther + filament anther, description of position or shape or appearance pollen filament, description of position or shape or appearance supports anther carpel = stigma + style + ovary stigma, description of position or shape or appearance receives pollen style, description of position or shape or appearance supports stigma for pollination / acts as a pathway for pollen tube ovary, descriptions of position or shape or appearance contains ovules / reference to site of fertilisation / becomes the fruit nectary position / reference to scent produces nectar flower stem supports flower for greater visibility to insects receptacle acts as base for other flower parts ovule and position forms seeds
c
reference to mixing of genetic material can result in different genotypes so phenotypes / offspring appearance can be different
Reproduction in Plants
page 4
Extension 3 a
any nine from these chemical or artificial fertilisers provide more of named mineral or element results in greater crop yield (linked to above) pesticides / fungicides reduces crop damage by insects or fungi / farm animal infestation herbicides reduce competition between crop and weeds for named requirements (e.g.light / minerals / water) reference to use of machinery larger areas of land to be cultivated / saves time reference to artificial selection of crop types results in greater yield / ability to grow crops on harsh climates reference to genetic engineering / cloning one example of use reference to use of bacteria to make yoghurt reference to use of yeast in bread-making reference to use of single cell protein to make meat substitutes reference to controlled conditions in greenhouse reference to improved weather forecasting and application use of satellites to observe crop disease / need for fertiliser use of computerisation and application reference to intensive animal farming / fish farming use of animal food concentrates / balanced feeding use of antibiotics / hormones / other drugs for animal rearing / plant growing or fruit production reference to biological control of pests
b
any three of these needed for production of chlorophyll needed to trap sunlight reference to photosynthesis no sugars produced so protein synthesis not possible reference to chlorosis / yellowing of leaves / pale leaves
c
reference to decomposition / rotting by fungi / bacteria / saprophytes / named decomposers releases minerals into the soil
Reproduction in Plants
page 5
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 7: Human reproduction Recommended prior knowledge Students should have knowledge of the basic principles of sexual reproduction, which has been covered in Unit 6. They should also understand the nature of hormones, dealt with in Unit 5. Context This unit builds on the work on sexual reproduction covered in Unit 6, both units lead into study of genetics, to be covered in Unit 8. Outline This unit considers the biological aspects of human reproduction, and also provides the opportunity to discuss some of the social and ethical issues associated with birth control, artificial insemination and fertility drugs. It is a relatively short unit, with no real opportunities for practical work however it does lend itself to the interpretation of data and to discussion within the group on such topics as human development during adolescence, contraception and human population growth. This unit can easily be combined with either Unit 6 Reproduction in plants or Unit 8 Inheritance and evolution. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref III 1.2.2
v1 2Y05
Learning objectives 7.1 Sexual reproduction in humans • Identify on diagrams the male reproductive system: - the testes - scrotum - sperm ducts - prostate gland - urethra - penis • State the functions of these parts • Identify on diagrams of the female reproductive system: - the ovaries - oviducts - uterus
Suggested teaching activities
Learning resources
Diagrams and models can be used to illustrate the structure of the male and female reproductive systems. Students should be able to interpret either front or side views.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p182–193
Students need to be able to spell uterus and urethra correctly.
Video clips – Fertilisation: www.bbc.co.uk/learningzone/clips/a n-introduction-tofertilisation/116.html
Link with hormones from Unit 5.2. It should be emphasised that ovulation occurs monthly and that the cycle is repeated throughout a woman's fertile life.
www.bbc.co.uk/learningzone/clips/h uman-fertilisation/1849.html
Mention that fertilisation usually takes place in an oviduct, rather than the uterus.
Cambridge IGCSE Biology (0610)
1
Syllabus ref
Learning objectives
• • •
•
III 1.2.2
•
•
• III 1.2.2 (S)
v1 2Y05
- cervix - vagina State the functions of these parts Describe the menstrual cycle in terms of changes in the uterus and ovaries Outline sexual intercourse and describe fertilisation in terms of the joining of the nuclei of male gamete (sperm) and the female gamete (egg) Outline early development of the zygote simply in terms of the formation of a ball of cells that becomes implanted in the wall of the uterus Outline the development of the fetus: - describe the function of the placenta and the umbilical cord in relation to - exchange of dissolved nutrients - gases - excretory products (no structural details of the placenta are required) Describe the ante-natal care of pregnant women including special dietary needs and maintaining good health Outline the processes involved in labour and birth
7.1 • Compare male and female gametes: - in terms of size - numbers
Suggested teaching activities Diagrams should be drawn to show the relationship between the fetus, umbilical cord and placenta. The large surface area of the placenta can be compared to that of the villi or the alveoli that allows for the maximum diffusion across the membrane.
Learning resources Revision and animations – Human reproduction: www.bbc.co.uk/schools/gcsebitesiz e/science/aqa/evolution/reproductio nrev1.shtml
Understand that maternal blood and foetal blood do not mix. The mother may have a different blood group and her blood is at a much higher pressure. Students should understand that glucose and amino acids cross the placenta, not 'large' nutrients. Oxygen, glucose and amino acids diffuse into the blood of the fetus. It is important to emphasise the importance of the mother's diet during pregnancy and to emphasise the possible problems incurred by the fetus if the mother smokes, drinks, takes recreational drugs. Link with Unit 5.5 Drugs. Mention that hormones are involved in the process of birth. Discussion on the topic of birth may need to be controlled and it can be important for the teacher to have some knowledge of the group's family situation as many students will talk about cot deaths, stillborn babies, caesarean section births, miscarriages etc. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 3 May/June 2011 Paper 0610/22 question 4 May/June 2010 Paper 0610/21 question 6 May/June 2009 Paper 0610/02 question 8 Oct/Nov 2009 Paper 0610/02 question 6 Explain the importance of male and female gametes in sexual reproduction. Gametes could be compared as a table.
Cambridge IGCSE Biology (0610)
2
Syllabus ref
Learning objectives •
• •
- mobility Explain the role of hormones in controlling the menstrual cycle: - FSH - LH - progesterone - oestrogen Indicate the functions of the amniotic sac and the amniotic fluid Describe the advantages and disadvantages of breast-feeding compared with bottle-feeding using formula milk
Suggested teaching activities Students should draw a chart / graph and write in the hormones (in different colours) at the relevant times within the cycle. The role of hormones and the effect on the uterus and menstruation are difficult to understand. Protection of the fetus, the amniotic sac prevents entry of bacteria and the amniotic fluid supports the fetus from physical damage and absorbs the excretory materials of the fetus. This topic can be dealt with through discussion, perhaps after students have done a little research of their own. The biological advantages of breast-feeding are incontrovertible, but students should also be aware of social and health reasons why there are benefits to breast feeding. Student progress could be assessed using: May/June 2011 Paper 0610/32 question 3 May/June 2011 Paper 0610/31 question 3 May/June 2010 Paper 0610/31 question 3 Oct/Nov 2010 Paper 0610/31 question 2 Oct/Nov 2010 Paper 0610/33 question 6
III 1.3
7.2 Sex hormones • Describe the roles of testosterone and oestrogen in the development and regulation of secondary sexual characteristics at puberty
Learning resources
The general characteristics of hormones will already have been covered, and here the sex hormones are introduced. Puberty is when the sex organs become mature and start to produce hormones as well as gametes.
www.cyberparent.com/breastfeed/ some mothers find this difficult and prefer to use formula milk. www.nct.org.uk/parenting/feeding contains information on bottle and breast feeding. Breastfeeding advice: www.nhs.uk/Planners/breastfeedin g/Pages/breastfeeding.aspx Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p194–195
Students can make a table to compare the secondary sexual characteristics as shown by male and female. This can be a difficult topic to understand and past questions are a means of reinforcing the ideas. Candidates should be aware of the cyclical secretion of oestrogen and progesterone from the ovary. Progesterone is also secreted by the placenta during pregnancy. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/22 question 5 May/June 2008 Paper 0610/02 question 6 v1 2Y05
Cambridge IGCSE Biology (0610)
3
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
III 1.3 (S)
7.2 • Describe the sites of production and the roles of oestrogen and progesterone in the menstrual cycle and in pregnancy (cross reference to supplement III. 1.2.2)
Link with Unit 7.1 supplement.
Hormones in the menstrual cycle: www.bbc.co.uk/schools/gcsebitesiz e/science/aqa/human/hormonesrev 3.shtml
III 1.4
7.3 Methods of birth control • Outline the following methods of birth control: - natural (abstinence, rhythm control) - chemical (contraceptive pill, spermicide) - mechanical (condom, diaphragm, femidom, IUD) - surgical (vasectomy, female sterilisation)
A simple description of the biological basis of the different types of birth control is required.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p196–197
Students should also understand the relative effectiveness of each, and may want to discuss the ways in which religious or cultural beliefs can affect their use. Students should be shown examples of each type of contraceptive if at all possible.
www.avert.org/teens-condoms.htm
The advantages of condoms in reducing the risk of transmitting diseases such as HIV /AIDS should also be considered. Student progress could be assessed using: May/June 2011 Paper 0610/22 question 4b Oct/Nov 2008 Paper 0610/32 question 4a
III 1.4 (S)
III 1.5
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7.3 • Outline artificial insemination and the use of hormones in fertility drugs and discuss their social implications
A simple factual treatment of what artificial insemination is, and the use of fertility drugs, will be required before students can discuss the social and ethical issues associated with it.
7.4 Sexually transmissible diseases • Describe the symptoms, signs, effects and treatment of gonorrhoea • Describe the methods of transmission of human immunodeficiency virus (HIV) and
Gonorrhoea is used as an example of a relatively common sexually-transmitted disease caused by a bacterium, readily treated with antibiotics. Link with Unit 10.5 Drugs.
Controlling fertility: www.bbc.co.uk/schools/gcsebitesiz e/science/aqa/human/hormonesrev 4.shtml
Extension – these issues regularly find their way into the news, and it is useful to collect a range of articles from newspapers and magazines that could form the basis for discussion.
HIV, on the other hand, is caused by a virus, and as yet no cure is available. Although no detail is expected of the symptoms of AIDS, it could be useful to deal with these briefly, Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p198–199
HIV/AIDS: www.abpischools.org.uk/page/mod 4
Syllabus ref
Learning objectives the ways in which HIV/AIDS can be prevented from spreading
Suggested teaching activities with reference back to the functions of white blood cells in Unit 4.8 Blood and to the importance of using a mechanical barrier such as a condom during sexual intercourse if the person does not have a single partner.
Learning resources ules/diseases/diseases3.cfm
Link with Unit 5.5 Drugs, the action of antibiotics on bacteria but not on viruses. Extension – students could research current advances in HIV treatments and drugs. Student progress could be assessed using: Oct/Nov 2008 Paper 0610/02 question 5 Oct/Nov 2008 Paper 0610/32 question 4d III 1.5 (S)
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7.4 • Outline how HIV affects the immune system in a person HIV/AIDS
Student progress could be assessed using: Oct/Nov 2010 Paper 0610/32 question 4 Oct/Nov 2008 Paper 0610/32 question 4c
Cambridge IGCSE Biology (0610)
HIV/AIDS: www.abpischools.org.uk/page/mod ules/diseases/diseases3.cfm
5
Core 1
1
1
1
Human Reproduction
page 1
Core 1
Human Reproduction
page 2
Core 2 1 1
Human Reproduction
page 3
Core 2
Human Reproduction
page 4
Extension 1 2
2
Human Reproduction
page 5
Extension 1
Human Reproduction
page 6
Extension 2 (a) (b) (c)
(d)
Human Reproduction
page 7
Core 1 a
increase in numbers / producing new individuals requiring the fusion / joining of gametes / sperm and ovum / two special cells / genetic material / DNA form two individuals
b(i)
X – testis production of sperm / gametes production of testosterone / male hormone
(ii)
mark / cut shown clearly on sperm duct, not at the junction with the urethra
c
any two from deepening of voice / breaking of voice development of facial hair development of pubic / axillary hair widening of shoulder girdle enlargement of limb muscles
Human Reproduction
page 1
Core 2 a(i)
five marks awarded as follows vertical axis labelled logical scale points plotted accurately points joined lines identified
(ii)
10 / 11 years 14 / 15 years
(iii)
any two from mother’s diet genetic factors disease if mother smokes / passive smoking if it is a single / multiple birth / premature birth
b(i)
increase in mass in teenage years begins earlier / girls at 12 are heavier then boys (ii)
oestrogen
(iii)
any two of these onset of menstrual cycle / periods start / ovulation starts widening of hips development of breasts / mammary glands axillary hair / pubic hair redistribution of fat layer under skin
Human Reproduction
page 2
Extension 1 a
A = placenta
reference to transfer / exchange of materials, mother to foetus / v.v. B = amniotic fluid cushions foetus from physical damage / absorbs excretory materials from foetus / supports foetus C = amnion / amniotic sac / amniotic membrane contains amniotic fluid / secretes amniotic fluid
b(i)
reference to presence of 47 chromosomes / extra chromosome
(ii)
reference to mutation reference to unequal chromosome division reference to extra number 21 chromosome
c
reference to use of microscope / analyse or observe chromosomes presence of xx chromosomes = girl / female presence of xy chromosomes = boy / male
d
EITHER reference to testing for presence of glucose to test for diabetes OR reference to testing for protein reference to possible consequences of protein loss reference to testing for diseases reference to testing for drugs reference to checking hormone levels
Human Reproduction
page 3
Extension 2 a
any six of these points reference to placenta allows maternal blood to come close to that of foetus allows diffusion of materials reference to foetal capillaries reference to transfer of oxygen from maternal red blood cells / haemoglobin reference to transfer of glucose / amino acid / other named nutrient reference to transfer of antibodies reference to plasma, linked to above pass from placenta to foetus via umbilical cord / vein
b
any six of the following chancre / hard lump / painless sore / blister on part of body which contacted partner reference to rash / sore throat reference to raised temperature reference to headache reference to ulceration / sores on other parts of body reference to discharge any tertiary symptom or effect: hair loss / teeth / nose / skeleton / skin / brain / nervous system / liver / blood vessels / paralysis / blindness / infertility / insanity / aneurism / death / damage to foetus reference to 3 stage disease / stages named
c(i)
any four of these transmitted in named body fluid e.g. blood, semen passed during unprotected sex reference to use of shared needles / razors / unsterilised needles reference to blood transfusions with unscreened blood / organ transplants reference to transmission from mother to foetus
(ii)
any three of these reference to education about AIDS / HIV use of condom during sexual intercourse / reference to safe sex use of sterile needles / do not share needles / avoid contact with contaminated blood avoid casual sex
d
any two from syphilis is caused by a bacterium HIV is a virus, not AIDS antibiotics are not effective against viruses
Human Reproduction
page 4
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 8: Inheritance and evolution Recommended prior knowledge Basic knowledge of Unit 1 cell structure is required, and also an understanding of the processes involved in sexual reproduction. Context This unit builds on the topic of sexual reproduction, covered in Units 6 and 7. Outline The unit begins with the introduction of several new terms, before moving on to genetics and inheritance. Variation, affected by both genotype and phenotype, is investigated, before considering the ideas of natural selection and evolution. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
III 3
8.1 Inheritance • Define inheritance as the transmission of genetic information from generation to generation
Students to come up with a possible definition of inheritance.
Overview – Genes and inheritance: www.abpischools.org.uk/page/mod ules/genome/index.cfm
III 3.1
8.2 Chromosomes • Define the terms: - chromosome as a thread of DNA made up of a string of genes - gene as a length of DNA that is the unit of heredity and codes for a specific protein A gene may be copied and passed on to the next generation: - allele as any of two or more alternative forms of a gene - haploid nucleus as a nucleus containing a single set of
Students should know that a chromosome is a length of DNA, and that each chromosome carries a large number of genes. They may be interested to discuss the human genome project, which has mapped all the genes on the human chromosomes.
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p202–203
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Students may be familiar with the terms haploid and diploid when considering the processes involved in sexual reproduction. A haploid cell is one with a single set of chromosomes (for example a gamete) while a diploid cell has two complete sets. Meiosis produces haploid cells from a diploid cell. It is important to use the terms 'gene' and 'allele' correctly right from the start. Cambridge IGCSE Biology (0610)
The Human Genome Project: www.genome.gov/Education/ Includes factsheets and information on all aspects of genetics. Introduction to DNA/ chromosomes: www.learn.genetics.utah.edu/conte nt/begin/tour/
1
Syllabus ref
•
Learning objectives
Suggested teaching activities
Learning resources
unpaired chromosomes (e.g. sperm and egg) - diploid nucleus as a nucleus containing two sets of chromosomes (e.g. in body cells)
At Cambridge IGCSE level, it is enough to define a gene as a length of DNA giving instructions for a certain characteristic. However, teachers may say that a gene carries instructions for making a particular protein.
Build a DNA molecule: learn.genetics.utah.edu/content/beg in/dna/builddna/
Describe the inheritance of sex hormones (XX and XY chromosomes)
An allele is a variety / an alternative form of a gene, and many genes have many different alleles. Students can draw the structures and write the definition beside the diagram to help them to learn the words and their definitions. Flash cards can be useful for students to quiz themselves when working in small groups.
Practical Biology – DNA: www.nuffieldfoundation.org/practica l-biology/extracting-dna-livingthings DNA extraction: www.ncbe.reading.ac.uk/ncbe/proto cols/PRACBIOTECH/oniondna.html
It may be sufficient to state that males have XY sex chromosomes and females have XX sex chromosomes and to return to their inheritance later in Unit 8.3 Monohybrid inheritance. Extension – DNA extraction. Simple gel electrophoresis using coloured dyes. Student progress could be assessed using: Oct/Nov 2008 Paper 0610/02 question 4
III 3.4
v1 2Y05
8.3 Monohybrid inheritance • Define the following terms: - genotype as the genetic makeup - of an organism in terms of the alleles present (e.g. Tt or GG) - phenotype as the physical or other features of an organism due to both its genotype and its environment - (e.g. tall plant or green seed) - homozygous as having two identical alleles of a particular
It is best to consider the meanings of these terms before thinking about inheritance. They can best be illustrated and explained with reference to a particular characteristic. Choose something simple, and that is likely to appeal to students, such as coat colour of an animal. It should involve a gene with two alleles, one dominant and one recessive. Students should learn that one letter is used to represent these alleles, with an upper case letter for the dominant allele and a lower case letter for the recessive allele. They should also learn to write the dominant allele first. They will know that most cells are diploid and so should be Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p208–209 Genotype and phenotype: www.brooklyn.cuny.edu/bc/ahp/BioI nfo/GP/Definition.html Video clips – Inheritance: www.bbc.co.uk/learningzone/clips/i nheritance-of-eyecolour/10651.html 2
Syllabus ref
Learning objectives
-
-
•
gene (e.g. TT or gg). Two identical homozygous individuals that breed together will be pure breeding heterozygous as having two different alleles of a particular gene (e.g.Tt or Gg) and are not pure breeding dominant as an allele that is expressed if it is present (e.g. T or G) recessive as an allele that is only expressed when there is no dominant allele of the gene present (e.g. t or g)
Calculate and predict the results of monohybrid crosses involving 1 : 1 and 3 : 1 ratios
Suggested teaching activities able to understand that they therefore carry two copies of each gene. The terms genotype, phenotype, homozygous and heterozygous can be introduced and defined in relation to simple genetic crosses.
Learning resources www.bbc.co.uk/learningzone/clips/d ominant-and-recessivecharacteristics/4197.html
It is a good idea to spend some time with such examples, using a Punnett square for clarity especially with the Core students. Ensure that students are thoroughly confident using the terminology, before beginning to think about how inheritance occurs. Students should be reminded that gametes are haploid cells, and therefore carry only one copy of each gene. They can be asked to work out what kind of gametes will be produced by organisms with a range of different genotypes. It is good practice, and avoids confusion, if a circle is drawn around each gamete or the genotype when writing out a genetic cross. Discourage students from automatically writing down two gametes from each parent. This is only necessary if the parent is heterozygous and producing two different kinds of gamete. If it is homozygous, then only one kind of gamete is made, and only one needs to be written down. Students can then be introduced to the idea of random fertilisation, in which any kind of gamete from the male parent can fuse with any kind of gamete from the female parent. The offspring now have two copies of each gene again. Drawing lines from gamete to gamete often causes errors drawing a Punnett square is easier for students to understand. In the boxes, ensure that students understand that what they have worked out is the probability of particular genotypes being produced. The fact that, for example, four different genotypes are present amongst the offspring does not mean that the parents will have four children. Students need to be familiar with the monohybrid crosses 1:1 and 3:1.
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3
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
The inheritance of sex can be dealt with in the same way as the inheritance of genes, but this time the symbols X and Y are used to indicate whole chromosomes, not alleles of a gene. Students should be able to draw genetic crosses to show the expected 1:1 ratio. Extension – Students could try the Genetics Breeding Game. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/21 question 6 Oct/Nov 2010 Paper 0610/22 question 8 Oct/Nov 2009 Paper 0610/02 question 10 May/June 2008 Paper 0610/02 question 7 III 3.4 (S)
8.3 • Explain codominance by reference to the inheritance of ABO blood groups and phenotypes, A,B,AB and O blood groups and genotypes IA, IB and 1o
Codominance is the combination of two different alleles that will produce an effect that is a mixture of both of them. The correct use of symbols should be encouraged; where codominance exists, the gene is shown with an upper case letter, with superscripts to represent the different alleles. It is helpful to write down a list of all the possible genotypes for blood groups and the resulting phenotypes before attempting to deal with any crosses.
Genetic Breeders: www.puzzling.caret.cam.ac.uk/gam e.php?game=15&age=2
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p210–211 The Biology Project – Blood types: www.biology.arizona.edu/human_bi o/problem_sets/blood_types/Intro.ht ml
Ensure that the correct symbols, as used in the syllabus, are automatically used by students. Student progress could be assessed using: May/June 2011 Paper 0610/31 question 4c May/June 2011 Paper 0610/32 question 4 Oct/Nov 2010 Paper 0610/32 question 6 Oct/Nov 2009 Paper 0610/31 question 5 III 3.5
v1 2Y05
8.4 Variation • State that continuous variation is influenced by genes and environment, resulting in a wide range of phenotypes between two extremes: - e.g. height in humans
Continuous variation can be illustrated by almost any characteristic that is measurable on a human: height length of middle finger wrist circumference will each give a good range of results and not cause any embarrassment.
Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p214–217 Practical Biology – Variation in humans: www.nuffieldfoundation.org/practica l-biology/introducing-ideas-aboutinheritance 4
Syllabus ref •
•
•
•
Learning objectives
Suggested teaching activities
State that discontinuous variation is caused by genes alone and results in a limited number of distinct phenotypes with no intermediates: - e.g. A, B, AB, O blood groups in humans
Leaves or other plant material can also be used to generate a range of results. Students can see that a range of values is obtained.
Define mutation as a change in a gene or chromosome
Describe mutation as a source of variation, as shown by Down's syndrome
Outline the effects of ionising radiation and chemicals on the rate of mutation
To show them graphically, they will need to decide on 6 or 7 ranges and then draw up a tally chart to show how many values fit into each range. These can then be plotted on a histogram. A common misconception is that 'continuous variation' means something that changes through your life. Although this is true of the measurements students are likely to have made to illustrate this, it is not the correct meaning of the term. Use other features, such as hair or eye colour, to emphasise the real meaning of continuous variation. Students studying the supplement will already be familiar with the A, B, AB and O blood groups. Blood groups are a good example of discontinuous variation. Students can draw bar charts to show the relative proportions of people with the four blood groups. They will not find it difficult to understand that everyone fits into one of these four categories, with no inbetweens, and this is therefore an example of discontinuous variation. A second example is gender. Students should understand that discontinuous variation is caused purely by genes but continuous variation often involves influence by the environment as well. Mutation can be defined as an unpredictable change in the DNA content of a cell. It can affect a single gene, or whole chromosomes, and can happen at any stage, not only during cell division. Mutations can be positive for an organism, as in bacteria that developed resistance to certain antibiotics. Refer to Unit 8.4 Selection.
Learning resources Practical Biology – Variation in Ivy leaves: www.nuffieldfoundation.org/practica l-biology/recording-variation-ivyleaves Variation – continuous and discontinuous: www.bbc.co.uk/scotland/learning/bit esize/standard/biology/inheritance/ Video clip – Variation: www.bbc.co.uk/learningzone/clips/v ariation-and-inheritance/5519.html Sources of variation: learn.genetics.utah.edu/content/vari ation/sources/ Inheritance patterns in monogenic disorders: www.geneticalliance.org.uk/educati on2.htm Down’s syndrome as an example of mutation: www.bbc.co.uk/health/physical_hea lth/conditions/downssyndrome1.sht ml
Down's syndrome is used to illustrate a mutation that occurs during meiosis and affects the number of chromosomes in a cell. Students could look at karyotypes of people with Down's v1 2Y05
Cambridge IGCSE Biology (0610)
5
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
syndrome, and compare them with karyotypes of males and females with the normal number of chromosomes. Ionising radiation and mustard gas can be given as examples of factors that may cause mutations. Chernobyl in 1984 is an example of radiation that caused mutations in hundreds of people and unborn babies. The Fukushima nuclear disaster in Japan in 2011 may cause mutations. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 5b May/June 2011 Paper 0610/22 question 5 May/June 2010 Paper 0610/22 question 3 Oct/Nov 2008 Paper 0610/02 question 3 III 3.5 (S)
8.4 • Describe sickle cell anaemia and explain its incidence in relation to that of malaria
Sickle cell anaemia can be explained as the result of a mutation in the gene that codes for the production of haemoglobin. The effects of this on the carriage of oxygen, and the consequences for respiring cells in body tissues can be discussed. Its inheritance can also be considered. Students can look at maps showing the distribution of malaria and of sickle cell anaemia. Some students may have some degree of sickle cell anaemia and will be able to talk about it to the class. It is a good way to introduce the ideas of selection pressures, and natural selection.
Sickle cell anaemia: www.bbc.co.uk/health/physical_hea lth/conditions/sicklecell1.shtml
Student progress could be assessed using: May/June 2009 Paper 0610/31 question 5 III 3.6
8.5 Selection • Describe the role of artificial selection in the production of varieties of animals and plants with increased economic importance
Students are already aware that variation occurs within populations of organisms, and they will not find it difficult to think how humans may choose a particular variety of an animal or plant and use this to breed from. Examples include: Jersey cattle that have a high milk yield Wheat that has high seed yield and shorter stems that are easier to harvest. Rice that has roots tolerant to lactic acid in the water.
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Cambridge IGCSE Biology (0610)
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p218-220 Practical Biology – Modelling natural selection: www.nuffieldfoundation.org/practica l-biology/modelling-naturalselection
6
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
Maize has been bred to be able to adapt to low carbon dioxide concentrations.
Artificial vs natural selection: learn.genetics.utah.edu/content/vari ation/artificial/
It should be made clear that this selection needs to continue for many generations, and does not produce immediate results. •
Define natural selection as the greater chance of passing on of genes by the best adapted organisms
Natural selection game: www.biology4all.com/resources_libr ary/source/200.doc
The favourable characteristics are expressed in the phenotypes in some of the offspring and these offspring may be better able to survive and reproduce in a particular environment. If students have already studied sickle cell anaemia, they will already have thought about the ideas of differential survival and selection. These will pass on their alleles to their offspring, so that the alleles that confer the advantageous characteristics gradually become more common. Over time, this could lead to a change in the overall characteristics of the species. Extension – Natural selection activity.
III 3.6 (S)
8.5 • Describe variation and state that competition leads to differential survival of, and reproduction by, those best fitted to the environment • Assess the importance of natural selection as a possible mechanism for evolution •
v1 2Y05
Describe the development of strains of antibiotic resistant bacteria as an example of natural selection
The development of antibiotic-resistant strains of bacteria makes a good example to illustrate the ideas in the previous section. Changes in a species through natural selection over time are gradual due to environmental changes and can be a mechanism for evolution. Students are interested in this topic and groups within the class could present some ideas to the whole class. Bacteria reproduce rapidly and a slight mutation during asexual reproduction can produce some variation within the population. Bacteria that survive and reproduce may develop a resistance to the antibiotic that was meant to kill them. This successful, mutated bacterium will reproduce and pass on the antibiotic resistant gene to its offspring.
Cambridge IGCSE Biology (0610)
A selection of excellent resources explaining the process of evolution: learn.genetics.utah.edu/content/vari ation/
MRSA: www.dnadarwin.org/casestudies/9/ (advanced, but contains some useful information) Antibiotic resistance: www.abpischools.org.uk/page/mod ules/infectiousdiseases_medicines/i ndex.cfm 7
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
Student progress could be assessed using: May/June 2011 Paper 0610/31 question 6 May/June 2010 Paper 0610/32 question 4 May/June 2008 Paper 0610/31 question 4 III 3.7
8.6 Genetic Engineering • Define genetic engineering as taking a gene from one species and putting it into another species
Use simple diagrams of bacteria containing circular DNA to show how a section of human DNA can be inserted into the bacterial DNA. Extension – Students could research recent advances in biotechnology and report back. This might lead to student participation in the STEM project “Talking about genetics” (Science Across the World).
Biology for IGCSE, Williams et al. Nelson Thornes 2009 p221 Science Across the World – Genetic modification: www.nationalstemcentre.org.uk/elib rary/resource/1750/talking-aboutgenetics Biotechnology: www.abpischools.org.uk/page/mod ules/biotech/index.cfm
(S)
8.6 • Explain why, and outline how, human insulin genes were put into bacteria using genetic engineering
Explain that DNA can be cut in certain places using different restriction enzymes to select the correct gene. If the same restriction enzyme is used to cut the bacterial DNA then the ends of the human and bacterial DNA will stick together.
Information and animation of Genetic engineering: www.abpischools.org.uk/page/mod ules/geneng/index.cfm
Extension – simple gel electrophoresis.
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Cambridge IGCSE Biology (0610)
8
Core 1
Inheritance & Evoluion
page 1
Core 2
Inheritance & Evoluion
page 2
Core 3 2
2
Inheritance & Evoluion
page 3
Alternative to Practical 1 3
3
[3] Inheritance & Evoluion
page 4
Alternative to Practical 1 4
4 1 3
4. 1
Inheritance & Evoluion
page 5
Alternative to Practical 1
Inheritance & Evoluion
page 6
Extension 1
Inheritance & Evoluion
page 7
Extension 2
Inheritance & Evoluion
page 8
Extension 2
Inheritance & Evoluion
page 9
Core 1 a(i)
homozygous – both alleles present are the same / individual received the same allele from both parents / gametes recessive – an allele which is only exhibited when present in the homozygous state / when the dominant allele is not present / masked by dominant allele, not gene
(ii)
black
b(i)
up to 4 points are scored for the following use of capital B for dominant (black) allele / lower case b for recessive allele correct genotypes for both parents (Bb, bb) gametes correctly displayed (B, b and b, b or b) correct genotypes of offspring (Bb,bb) correct phenotypes identified (for all offspring)
(ii)
correct ratio predicted (1:1 or 1 in 2 or 50%, 50%)
Inheritance & Evolution
page 1
Core 2 a(i)
X – chromosomes Y – nucleus / nuclear membrane
(ii)
meiosis – four nuclei are produced / number of chromosomes / genetic material is halved / new nuclei haploid
(iii)
ovary / testis / gonad
b
fertilisation / fusion of sperm and ovum / gametes / formation of zygote
Inheritance & Evolution
page 2
Core 3 a
b(i)
recessive 4 has inherited PKU from parents (or alternative wording) as it is not apparent in 1 or 2 / neither parent shows it / if dominant a parent would show it / have PKU 1 – Hh 4 – hh
(ii)
HH and Hh
Inheritance & Evolution
page 3
Alternative to Practical 1 a
working includes squares to be marked on the feather breakdown of rows into sub-totals / tally grids total to be in the range 25 – 30 cm2
b
three visible differences to include references to shape, area, appearance of barb or blade, appearance of rachis (central rod), size or shape of quill
c(i)
insulation / traps air / keeps it warm / stops heat escaping / traps heat maintains body temperature / homiothermy / warm blooded reference to young birds do not fly or less active so generate less heat / large surface area to volume ratio / no regulation of body temperature / not able to keep temperature the same
(ii)
any three of these within the context of a fair test uses several feathers or any insulation to wrap around a body / glassware use of thermometer to follow cooling recorded at intervals comparison of apparatus with and without any covering or with flight feathers
Inheritance & Evolution
page 4
Extension 1 a(i)
Ff
(ii)
ff
b
normal man (parents)
FF
(gametes)
F
(F1)
FF normal
c
x
carrier woman
x
Ff
F
F
f
Ff
FF
Ff
carrier
normal
carrier so not possible
any two of these reference to trachea /bronchi / bronchioles / alveoli blocked or congested makes gaseous exchange more difficult reference to lack of energy / respiration impaired reference to being more susceptible to infections reference to digestion affected
Inheritance & Evolution
page 5
Extension 2 a(i)
biconcave disc
(ii)
reference to sickle / crescent shaped
(iii)
able to carry / absorb less oxygen
b(i)
HAHA
(ii)
HAHS
(iii)
HSHS
c(i)
HSHS
(ii)
HSHS man or sickle cell
d
woman or heterozygous HSHS
parents gametes
HS
HS
(F1)
H SHA H SHS
HAHS
x HA
x H SHA
HS H SHS
percentage = 50
Inheritance & Evolution
page 6
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 9: Organisms and environment Recommended prior knowledge Students should have knowledge of photosynthesis and respiration, and understand something of energy transfers. They should know the elements from which biological molecules are made, in order to understand nutrient cycles. Context This unit brings together ideas from several earlier units and lays the foundations for Unit 10. It also consolidates knowledge of photosynthesis and the topics on respiration and excretion. The seasons should be considered when teaching this unit as it may be appropriate to teach it immediately after Unit 3 when work on food chains and webs can be investigated outside. Outline It is hoped that students will be able to visit a local habitat, even if only in the school grounds, during this unit. The unit can begin with a review of the naming and classification of living organisms studied in Unit 1 although some teachers may prefer to teach Unit 1.1 and Unit 1.2 before food chains and food webs at the beginning of this unit - with some thought being given to their adaptations to their environment. The flow of energy and cycling of nutrients through ecosystems is covered. This unit sets the scene for a consideration of how human activities can affect ecosystems (Unit 10). (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref IV 1
Learning objectives 9.1 Energy flow: • State that the Sun is the principal source of energy input to biological systems •
Describe the non-cyclical nature of energy flow
Suggested teaching activities Having looked at the range of different types of organisms that live in different habitats, students now consider the relationships between them. The concept of energy is not an easy one, and students who are not studying physics or chemistry will need an opportunity to discuss what it means.
Learning resources Revision – Ecology (cycles): www.lgfl.skoool.co.uk/content/key stage4/biology/pc/lessons/uk_ks4 _ecology/h-frame-ie.htm
There is an important link to be made between photosynthesis and respiration including the concept that animals obtain energy-rich nutrients from plants. Refer to Unit 9.2 Food chains and food webs. All organisms directly or indirectly get their energy from the Sun. Energy given out by organisms is lost to the environment.
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Cambridge IGCSE Biology (0610)
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Syllabus ref IV 2
Learning objectives 9.2 Food chains and food webs Define the terms: •
•
•
• • • • •
• •
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food chain as a chart showing the flow of energy (food) from one organism to the next, beginning with a producer e.g. mahogany tree →caterpillar→ song bird→ hawk food web as a network of interconnected food chains showing the energy flow through part of an ecosystem producer as an organism that makes its own organic nutrients, usually using energy from sunlight through photosynthesis consumer as an organism that gets its energy by feeding on other organisms herbivore as an animal that gets its energy by eating plants carnivore as an animal that gets its energy by eating other animals decomposer as an organism that gets its energy from dead or waste organic matter ecosystem as a unit containing all of the organisms and their environment, interacting together, in a given area e.g. decomposing log or lake trophic level as the position of an organism in a food chain, food web or pyramid of biomass, numbers or energy
Suggested teaching activities If students have an opportunity to visit a habitat, even if only in the school grounds, then they should be able to construct food chains and food webs for themselves. The Sun should not be included in a food chain or food web. Emphasise that the arrows in a food chain represent the direction of energy flow, towards the eater. Definitions of each of these terms can be built up once students are comfortable with the concept of food chains. Student progress could be assessed using: May/June 2011 Paper 0610/22 question 8 May/June 2010 Paper 0610/21 question 4 Oct/Nov 2009 Paper 0610/02 question 7 Students who have studied physics may already understand that energy transfers are never 100% efficient, and that some energy is always lost as heat when energy is transferred from one form to another.
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p224–229 PowerPoint presentation – Interdependence of living things: www.biologyresources.com/biology-CD.html
Video clips – Energy transfer in food chains: www.bbc.co.uk/learningzone/clips /energy-transfers-and-foodchains-pt-1-2/197.html www.bbc.co.uk/learningzone/clips /energy-transfers-and-foodchains-pt-2-2/199.html
To understand the concept of heat lost from food chains and webs, students should discuss a particular example, such as energy transfer from grass in a field and cattle that are eating it. Once energy losses are understood, it should become apparent that food chains cannot go on for ever. Pyramids of numbers, biomass and energy can be drawn for a particular food chain or web. Students can think of them as a kind of graph, in which the areas of the boxes represent values for whatever is being plotted. Students can understand that producers have the largest numbers and access to a field, or wood will illustrate this.
Cambridge IGCSE Biology (0610)
Video clip – Pyramid of numbers: www.bbc.co.uk/learningzone/clips /food-chains-pyramid-ofnumbers/201.html
Interactive food chain: www.puzzling.caret.cam.ac.uk/ga 2
Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
•
Describe energy losses between trophic levels
Pyramids of numbers should be drawn with accurate horizontal bars. Exceptions should be shown, a single tree for example. Pyramids of biomass represent the amount of living material.
me.php?game=6&age=2&PHPSE SSID=0cb7707e04efead5a621c4 7d4b3b047f
•
Draw, describe and interpret pyramids of biomass and numbers
Extension – Collection of leaf litter and construction of a pyramid of numbers or mass based on classification of organisms found. Student progress could be assessed using: May/June 2011 Paper 0610/21 question 6 May/June 2011 Paper 0610/22 question 6c May/June 2008 Paper 0610/02 question 9 Oct/Nov 2008 Paper 0610/02 question 6
IV 2 (S)
9.2 • Explain why food chains usually have fewer than five trophic levels • Explain why there is an increased efficiency in supplying green plants as human food and that there is a relative inefficiency, in terms of energy loss, in feeding crop plants to animals
Emphasise that short food chains are more efficient in providing energy to the top consumer. Emphasise that approximately 90% of energy is lost to the environment between each trophic level. Students studying the supplement can now take the ideas of energy flow and losses between trophic levels a little further, and think of their implications for human populations. Some farmers keep their animals in pens to restrict the loss of energy from the animals.
Video clip – Energy in food chains: www.bbc.co.uk/learningzone/clips /what-happens-to-energy-in-foodchains/200.html Video clip - Intensive farming: www.bbc.co.uk/learningzone/clips /agricultural-change-in-the-parisbasin-intensive-farming/3944.html
Students could consider why, if it is inefficient in terms of energy, that so many human populations use animals for food. Links with Unit 2 Animal nutrition and Unit 8.5 Selection. Student progress could be assessed using: May/June 2011 Paper 0610/32 question 1 May/June 2009 Paper 0610/32 question 6 Oct/Nov 2010 Paper 0610/31 question 5 IV 3
9.3 Nutrient cycles •
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Describe the carbon and the water cycles
Students could be given cards showing stages of the carbon cycle or water cycle and arrange them into a complete cycle. These could then be turned into posters.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p230–231 Practical Biology – Carbon Cycle:
Cambridge IGCSE Biology (0610)
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Syllabus ref
Learning objectives
Suggested teaching activities Extension – what is meant by “carbon neutral”? Student progress could be assessed using: May/June 2011 Paper 0610/21 question 7 May/June 2009 Paper 0610/02 question 4 Oct/Nov 2010 Paper 0610/22 question 6 Oct/Nov 2008 Paper 0610/02 question 7
IV 3 (S)
9.3 • Describe the nitrogen cycle in terms of: - the role of microorganisms in providing usable nitrogencontaining substances by decomposition and by nitrogen fixation in roots - the absorption of these substances by plants and their conversion to protein - followed by passage through food chains, death, decay - nitrification and denitrification and the return of nitrogen to the soil or the atmosphere (names of individual bacteria are not required) •
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Students could be given cards or statements describing stages of the nitrogen cycle and arrange them into a complete cycle. These could then be turned into posters. Student progress could be assessed using: May/June 2011 Paper 0610/31 question 2 May/June 2009 Paper 0610/31 question 6 Oct/Nov 2009 Paper 0610/31 question 6 May/June 2008 Paper 0610/31 question 2e
Learning resources www.nuffieldfoundtation.org/practi cal-biology/microbes-ate-myhomework Revision – Carbon cycle: www.bbc.co.uk/schools/gcsebitesi ze/science/add_aqa/foodchains/fo odchains5.shtml Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p232–233 Video clip – Nutrient recycling: www.bbc.co.uk/learningzone/clips /recycling-nutrients/4172.html Video clip – Greenhouse effect: www.bbc.co.uk/learningzone/clips /carbon-dioxide-in-theatmosphere/4417.html
The effects of deforestation could be discussed using newspaper/media articles on deforestation. Link to Unit 3 photosynthesis and Unit 10.
Discuss the effects of the combustion of fossil fuels and the cutting down of forests on the oxygen and carbon dioxide concentrations in the atmosphere
Cambridge IGCSE Biology (0610)
4
Core 1
Organisms & Environment
page 1
Core 1
Organisms & Environment
page 2
Core 2 2
2 2
Organisms & Environment
2
page 3
Core 2 2
Organisms & Environment
page 4
Core 3 3
3
Organisms & Environment
page 5
Core 3
Organisms & Environment
page 6
Alternative to Practical 1 4
4
4
Organisms & Environment
page 7
Alternative to a practical 1 4
4
Organisms & Environment
page 8
Extension 1
[Total: 15]
Organisms & Environment
page 9
Extension 2 5
5 5
Organisms & Environment
page 10
Extension 2
Organisms & Environment
page 11
Core 1 Name of arthropod Anopheles Musca Ornithodorus Pediculus Pulex
Organisms & Environment
Letter B E C A D
page 1
Core 2 The table shows the correct answers, up to four correct gain credit. Check carefully that no extra ticks are added. Leaf A B C D E F
1a
1b
2a
2b
x x x x x
Organisms & Environment
3a
3b
4a
4b
x x x x x
5a
x x x
5b
Name of tree
x
Quercus Ilex Fraxinus Aesculus Magnolia
page 2
Core 3 a(i)
any one of these amino acid protein enzyme named plant protein enzyme
(ii)
urea
(iii)
nitrogen fixing bacteria in root nodules or roots of leguminous plants or a named example
b(i)
nitrogen cycle plant or crop material removed from field, less material to decay less nitrates released or formed crop yield would gradually decrease over a period of years less nitrates to form protein or new cells
(ii)
add fertilisers or manure use of leguminous crops or named example
Organisms & Environment
page 3
Alternative to Practical 1 a(i)
two from
16, 6, 13, 5, 2
(ii)
two from
14, 11, 10, 9, 7, 1
b
3
c
any two from these using a fine net / centrifuge / filter / sieve detail of how the apparatus is used sample soil from the river bed details of how this could be sorted shine light to attract organisms
16
Organisms & Environment
9
7
1
Links must carry arrows.
page 4
Extension 1 a(i)
any four from BACTERIA have a cell wall have DNA (strand) are larger have a slime capsule have a membrane have cytoplasm can reproduce outside cells show all life processes can have flagellum
(ii)
any four from ARACHNIDS have 4 pairs of legs / 8 legs have no antennae have simple eyes have chelicerae / poison fangs have a cephalothorax have thin / no carapace breathe with gill / lung books
(iii)
b
VIRUSES have a protein coat have RNA or DNA are smaller have no slime capsule have no membrane have no cytoplasm can only reproduce inside living cells only show reproduction no flagellum
CRUSTACEA have 5 pairs of legs / 10 legs or more have antennae / have two pairs have compound eyes have no chelicerae / poison fangs poorly defined cephalothorax have thick carapace have gills
any four from MONOCOTS have one cotyledon / food store / seed leaves
DICOTS have two cotyledons / food stores / seed leaves
have strap-shaped leaves flower parts are grouped into threes
have broader leaves flower parts are grouped in 4’s / 5’s / larger numbers
have fibrous roots
have tap roots
have stomata evenly distributed on both leaf surfaces
have stomata unevenly distributed on leaf surfaces
have vascular bundles scattered
vascular bundles arranged in ring
three of the following points named example using genus and species reference to two names for the organism reference to genus and species reference to use in classification
Organisms & Environment
page 5
Extension 2 a(i)
plants
(ii)
any two from reference to method of nutrition or no chlorophyll no cellulose cell walls or reference to chitin present hyphae present or reference to mycelium
b(i)
56.3 x 100 64.4 = 87.4%
(ii)
Possible features wings / impermeable cuticle or exoskeleton / antennae / 3 pairs of legs / compound eyes / small size / large numbers formed through reproduction Possible explanations linked to named features Wings: reference to flying, to find food, to escape from predators, to find a mate Cuticle: to reduce water loss, to survive in hot or dry places, muscle attachment, protection from predators, protection of internal organs Antennae: to sense food, early warning of predators, to sense a mate Small size: easy to hide from predators, only small amounts of food or water needed to survive Large numbers: some will survive to breed, reference to variation Spiracles: for ventilation, control of ventilation Reproduce in large numbers: so some will survive, increases chances of variation to cope with environmental change
c(i)
Presence of feathers/beak
(ii)
refernce to scales/eyes/tail/mouth/anus
d(I)
1700000 100 = 243100
X
Organisms & Environment
14.3
page 6
Scheme of work – Cambridge IGCSE® Biology (0610) Unit 10: Human influences on the environment Recommended prior knowledge Students should have covered Unit 9 Organisms and environment before beginning Unit 10. Context This unit builds on ideas studies in Unit 9, and brings together knowledge from many other areas of the syllabus such as cell division. Outline General features of population growth are considered, before looking in particular at problems associated with human population growth. A number of different effects of the growing human population on the environment are then considered. Some of these are complex issues, with no straightforward answers, and students should be encouraged to discuss and debate them. There is some opportunity to interpret data from population graphs and pollution data. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Syllabus ref IV 4
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Learning objectives 10.1 Population size • Define population as a group of organisms of one species, living in the same area at the same time • State the factors affecting the rate of population growth of an organism (limited to food supply, predation and disease), and describe their importance. • Identify: - the lag - the exponential (log) - the stationary - the death - phases in the sigmoid population growth curve for a population growing in an environment with
Suggested teaching activities Adequate food will enable the organisms to breed and to produce more offspring. A shortage of food can result in death, emigration and a decrease in the population. Predation can illustrate the delayed effect of the population and graphs to illustrate this are helpful. The interrelated populations of the snowshoe hare and the lynx in Canada is a clear example. Disease can spread quickly in crowded populations like myxomatosis that killed many rabbits in the UK about 40 years ago. The class could discuss how populations grow. Simple sketch graphs should be drawn to illustrate population growth, and possible factors that might cause a levelling off in population growth should be considered. Extension – modelling population growth. Cambridge IGCSE Biology (0610)
Learning resources Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p236–239 Revision – Ecology (human influences and conservation): www.lgfl.skoool.co.uk/content/keyst age4/biology/pc/lessons/uk_ks4_ec ology/h-frame-ie.htm Revision – Populations: www.lgfl.skoool.co.uk/content/keyst age4/biology/pc/lessons/uk_ks4_po pulations/h-frame-ie.htm Video clip – Bacterial growth: www.bbc.co.uk/learningzone/clips/b acterial-growth/209.html 1
Syllabus ref
Learning objectives
Suggested teaching activities
limited resources • Describe the increase in the human population size and its social implications • Interpret graphs and diagrams of human population growth
The ideas developed in the previous section are now applied to human population growth. Graphs showing how the human population has changed over the last two centuries and predictions for the future should be drawn. Students could be introduced to population pyramids and their interpretation for their own country. Comparisons could be made between developed and less developed countries and this would form a link with Geography for some students. They should discuss the possible implications of continued growth of the world human population, if possible with reference to particular examples collected from newspapers and other sources of up-to-date information and data. To include food and water shortages. Reference to Unit 7.3 Methods of birth control.
IV 4
Learning resources
Student progress could be assessed using May/June 2010 Paper 0610/22 question 4 Oct/Nov 2010 Paper 0610/21 question 2 Oct/Nov 2009 Paper 0610/02 question 5 May/June 2008 Paper 0610/02 question 8 IV 4 (S)
IV 5
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Video clip – Bacterial growth: www.bbc.co.uk/learningzone/clips/b acterial-growth/209.html
10.1 Supplement • Explain the factors that lead to - the lag phase - exponential (log) phase - stationary phase in the sigmoid curve of population growth, making reference, where appropriate, to the role of limiting factors
Limiting factors affect the size of the population such as lack of food when the population is too big for the available resources.
10.2 Human Influences on the ecosystem • outline the effects of humans on ecosystems, with emphasis on examples of international importance: - tropical rain forests - oceans - important rivers
This should be related both to the students' own country, and to other countries around the world. Students should be able to refer to one specific example of pollution in rain forests, oceans and important rivers.
Video clip – Threat to rain forest: www.bbc.co.uk/learningzone/clips/n atural-balance-threats-to-therainforest/4712.html
There are many relevant websites relating to human influences on the environment.
Video clip – Sea and river pollution: www.bbc.co.uk/learningzone/clips/ why-have-fish-stocks-decreased-inthe-north-sea-pt-1-2/4687.html
Lack of oxygen may affect a fish population in a polluted lake. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/31 question 6
Cambridge IGCSE Biology (0610)
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Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
Ideas to consider are the introduction of machinery: • tractors to replace draught animals, specialised machinery to sow and to harvest crops like carrots and wheat • the increasing use of pesticides and fertilisers • the breeding of new high-yielding crop varieties. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/22 question 4 IV 5.1
10.3 Agriculture • List the undesirable effects of deforestation: - extinction - loss of soil - flooding - carbon dioxide build up • Describe the over-use of fertilisers to include: - eutrophication of lakes and rivers
Deforestation may already have been considered in relation to the carbon cycle and more wide-ranging effects should be considered, such as loss of habitat and biodiversity and the increased soil erosion and flooding.
Video clips – Deforestation: www.bbc.co.uk/learningzone/clips/r ainforest-destruction-kalimantanindonesia-and-costa-rica/3096.html
The flooding of the river Indus in Pakistan in 2010 could be discussed or the Three Gorges dam on the Yangtze River in China. It is a good idea to try to introduce at least one specific example, as well as discussing the problems in general.
www.bbc.co.uk/learningzone/clips/s ustainable-forestry-using-animalpower/11966.html
The use of fertilisers containing nitrate can be concentrated on here and related back to the nitrogen cycle (dealt with in Unit 9.3 Nutrient cycles). Ensure that students realise that both organic (for example manure) and inorganic fertilisers can cause pollution problems. Leaching into waterways and subsequent eutrophication, should be described and explained. Extension – possible solutions to eutrophication could be researched. Student progress could be assessed using: May/June 2011 Paper 0610/31 question 2d Oct/Nov 2010 Paper 0610/33 question 4
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Syllabus ref IV 5.2
IV 5.2 (S)
Learning objectives
Suggested teaching activities
Learning resources
10.4 Pollution • Describe the undesirable effects of pollution to include: - water pollution by sewage and chemical waste - air pollution by sulfur dioxide - air pollution by greenhouse gases (carbon dioxide and methane) contributing to global warming - pollution due to pesticides including insecticides and herbicides - pollution due to nuclear fall-out
Students could research recent news articles on different types of pollution and report back.
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p242–249
Show video clip – pollution: www.bbc.co.uk/learningzone/clips/the-effect-of-humanactivity-on-the-environment/4173.html
Practical Biology – Indicator Species: www.nuffieldfoundation.org/practica l-biology/monitoring-water-pollutioninvertebrate-indicator-species
10.4 • Discuss the effects of nonbiodegradable plastics in the environment • Discuss the causes and effects on the environment of acid rain and the measures that might be taken to reduce its incidence • Explain how increases in greenhouse gases, carbon dioxide and methane are thought to cause global warming
Non-biodegradable materials will be detrimental to the environment if they are put in land fill sites. There is also a problem of too many huge land fill sites in many countries. Biodegradable plastics are being produced that are slow to be decomposed but this is an improvement on the removal of plastic waste and its recycling.
www.bbc.co.uk/learningzone/clips/carbon-dioxide-in-theatmosphere/4417.html Extension – different types of pesticide could be studies (link to bioaccumulation). Student progress could be assessed using: Oct/Nov 2010 Paper 0610/21 question 7
Extension: Science Around the World – Acid Rain: www.nationalstemcentre.org.uk/elib rary/resource/1728/acid-rain
Explain why plastics will produce air pollution if they are burnt in an incinerator.
Video clip: www.bbc.co.uk/learningzone/clips/a ir-pollution-and-its-effects-on-theenvironment/6008.html
The environmentally friendly option is to recycle materials such as paper, glass, metal and batteries. This reduces environmental pollution and saves energy in production costs although there is some disagreement about paper recycling as the chlorine required to bleach the paper and the temperature require energy.
Acid rain investigation: www.saps.org.uk/secondary/teachi ng-resources/186-student-sheet-5investigating-seed-germination
Students should understand that acid rain is caused by sulfur dioxide (released from the burning of oil and coal, for example in power stations) and nitrogen oxides (present, for example, in car exhausts). They should know something of the biological effects of acid rain.
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Syllabus ref
Learning objectives
Suggested teaching activities
Learning resources
Extension: students could investigate the effects of acid on germination rate. Discussion about the effect of greenhouse gases on climate should be discussed. The fact that no agreement has been made globally is relevant and many students will have an opinion on this problem that has many factors to be considered besides burning of wood and fossil fuels. Student progress could be assessed using: May/June 2010 Paper 0610/31 question 4 May/June 2010 Paper 0610/32 question 6 IV 5.3
10.5 Conservation • Describe the need for conservation of: - species and their habitats - natural resources (water) - and non-renewable materials including fossil fuels
It is best to look at some specific examples, either relating to the students' home country, or of international importance such as: tigers in India, elephants in Africa, sun bears from Cambodia or orangutans in Borneo. Extension – Students could become involved in the Science Around the World conservation project. Student progress could be assessed using: May/June 2008 Paper 0610/31 question 2 May/June 2008 Paper 0610/32 question 2
Biology for IGCSE, Williams et al. Nelson Thornes, 2009 p250–253 Science Around the World – Conserving Biodiversity: www.nationalstemcentre.org.uk/elib rary/resource/1738/biodiversityaround-us Video clips – Conservation: www.bbc.co.uk/learningzone/clips/b iodiversity-and-the-humanimplications/5505.html www.bbc.co.uk/learningzone/clips/l och-lomond-land-useconservation/1142.html
IV 5.3 (S)
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10.5 • Explain how limited and nonrenewable resources can be recycled: - recycling of paper - treatment of sewage to make the water that it contains safe to return to the environment or for human use
The influence of humans and the need for populations to maintain their viable numbers could be discussed. The importance of maintaining biodiversity on the planet for ecosystems, chemical compounds used for medicines and for their genetic diversity. Tropical rainforests have millions of species that should be preserved.
Cambridge IGCSE Biology (0610)
Video clip – Recycling: www.bbc.co.uk/learningzone/clips/r ecycling-and-the-incineration-ofwaste/1577.html Video clips – Sewage: www.bbc.co.uk/learningzone/clips/s ewage-treatment/4199.html
5
Syllabus ref
Learning objectives
Suggested teaching activities The practice of recycling and its importance is covered in many aspects throughout the Cambridge IGCSE courses.
Learning resources www.bbc.co.uk/learningzone/clips/ micro-organisms-at-work-in-asewage-farm/2278.html
Emphasis could be given to metals, batteries, glass as well as paper. Students should learn how sewage is dealt with in their own local area, and there may be an opportunity to visit a sewage treatment plant, or to obtain information from the water company responsible for this. Student progress could be assessed using: Oct/Nov 2010 Paper 0610/32 question 5
v1 2Y05
Cambridge IGCSE Biology (0610)
6
Core 1
Human Influences
page 1
Core 2
Human Influences
page 2
Core 2
Human Influences
page 3
Core 3 2
2
Human Influences
page 4
Alternative to Practical 1
1 1
2
2
Human Influences
page 5
Alternative to Practical 1 3
3
Human Influences
page 6
Extension 1
Human Influences
page 7
Extension 1
[4]
Human Influences
page 8
Extension 2
Human Influences
page 9
Core 1 a
any three of these predators of the mink competition with other predators for the same food prey limited by availability of prey’s food disease / parasites
b
any three of these humans have no natural predators food supplies may be moved from areas of excess to areas of shortage medical advances in disease prevention medical advances in curing / treating patients humans modify habitats for themselves limited use of family planning programmes
Human Influences
page 1
Core 2 a(i)
grass or plant grass or plant bird
grasshopper water buffalo
elephant shrew tick
Scops owl / oxpecker
linked by arrows pointing towards the consumers (ii)
named producer example makes its own food / glucose / gains energy by photosynthesis named consumer example gains energy / takes in / eats ready made food / other organisms
b(i)
Scops owl population would rise – plague of grasshoppers would increase elephant shrew population / food if Scops owl will increase water buffalo population would fall – more grass eaten by grasshoppers / less food available for water buffalo
(ii)
grasshoppers eat more grass so less food for gazelles either gazelles eat more acacia so less food for giraffes and population falls or gazelle population falls and eats less acacia so more food for giraffes so population rises
Human Influences
page 2
Core 3 a
1.25 million
b(i)
any two from these most of offspring surviving little / no competition for / plenty of food / space few / no natural parasites / predators / diseases no limiting factors
(ii)
any two of these births equal deaths some factor / food supply limiting / competition for food / space / because of overcrowding introduction of / increase in parasites / disease / predators / competitor species / deliberate husbandry
Human Influences
page 3
Alternative to Practical 1 a(i)
in order in the table 40 32 28
(ii)
the pie chart should show correct proportions for the segments correct order of segments (largest starting at 12 position and going clockwise in decreasing size)
b
wet / damp darkness (or alternative wording)
c
to include four of these points hand search and / or Tullgren funnel sample standard area same time of year identify animals and trophic levels repetition of samples
Human Influences
page 4
Extension 1 a(i)
any two from four limbs body covering (or alternative wording) backbone warm blooded lungs
(ii)
any two from, provided feature linked to correct group birds have feathers / animals have fur birds lay eggs / mammals produce live young mammals suckle young birds have a beak birds have scales on legs
b
birds can fly over water or it is difficult for mammals to swim long distances
c
few predators present hay fields present for nesting hay fields provide a food source (or alternative wording)
d
any two of these hedgehogs eat corncrake eggs hedgehogs eat the same food / reference to insects or worms corncrakes nest on the ground
e
hedgehog corncrake (eggs) insects worms seeds leaves
f
any two of these remove / exterminate hedgehogs from the island create corncrake sanctuaries (which are hedgehog-fre) introduce corncrakes to other islands reference to captive breeding programme
Human Influences
page 5
Extension 2 a
any five of the following points reference to the presence of nitrates / phosphates effect of above i.e. plants grow faster reference to light blocked out for deeper plants plants die (linked of the above points) dead plants provide food for bacteria numbers of bacteria increase animals in water die due to lack of oxygen bacteria respire (aerobically), using up oxygen reference to eutrophication reference to possible presence of disease- causing organisms
b
any six of the following points sewage screened (or alternative wording) to remove large objects settling tanks allow grit to settle out sludge allowed to settle out reference to anaerobic conditions killing aerobic pathogens, linked to above remaining liquid sprayed onto stones or clinker reference to presence of protoctists / bacteria microorganisms feed on sewage harmful substances removed, linked to above reference to aerobic stage killing many anaerobic bacteria reference to clear water effluent produced (or alternative wording) reference to chlorination
c
any four of these thick cuticle reduced number of stomata stomata only open at night rolled leaves hairs on leaves leaves reduced to spines deep or long roots fleshy stem
Human Influences
page 6
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