Science Form 4

 

chapter 3

heredity and variation

1. CELL DIVISION 1. The nucleus of a cell c contains ontains many small-thread small-thread like structures called chromosomes. chromosomes. 2. Chromoso Chromosomes mes are built built from molecu molecules les called called Deoxyribon Deoxyribonucle ucleic ic acids. (DNA) (DNA) 3. Each DNA molec molecules ules contain contains s tho thousan usands ds o off gen genes. es. 4.

Genes exist in pairs. O One ne gen gene e is inherited inherited from th the e father and and one one from the mother. mother. NUCLEUS

CELL  

CHROMOSOME

DNA

GENE

MITOSIS & MEIOSIS i. i i. iii. ii i. iv. v.

Mi Mito tosi sis s oc occu curs rs in all all som somat atic ic cell cells, s, ex exce cept pt in se sex x cell cells. s. It produces 2 d au aughter cells. Me Meio iosi sis s occ occur urs s in in s sex ex or orga gans ns to pr prod oduc uce e gam gamet etes es.. One One pare parent nt cell cell produ produce ces s 4 dau daugh ghter ter ce cells lls.. Th The e number number of chrom chromoso osomes mes is half half of the number in parent cell. Th Ther ere e ar are e 2 stag stages es in me meio iosi sis, s, call called ed meio meiosi sis_I s_I_ _ an and d meio meiosi sis s II II_. _.

THE STAGES IN MITOSIS Parent cell The chromosomes shorten, fatten and become clearly visible

Chromosome replication into thread – like structures called chromatids.

Chromosomes align themselves at the equatorial plate



 

Sister chromatids separate and move to the opposite poles Centromeres divide  At the same time time cell begins begins to divide





 

The new nuclear membrane is formed Two daughter cells are produced





26 The new nuclear  membrane are formed Two daughter cells are produce

 

THE STAGES IN MEIOSIS Parent cell

Chromosomes in nucleus shorten and fatten

Replication and crossing over in chromatids occur 

Chromosomes are arranged at equatorial plate

Chromatids separate and move to opposite poles

2 daughter cells formed

Chromosomes are arranged at the centre of  the cell

 

 

Chromatids Cell begin toseparate split

Each daughter cell contains half  the number of chromosomes of  the parent cell 27

 

Compare and Contrast between Mitosis and Meiosis Mitosis 1 2 Same Yes In somatic cells To produce new cells for growth and to replace damaged cells

Cell division Product Number of chromosomes Genetically identical Place

Meiosis 2 4 Half the number  No In sex cells

Purpose

Gametes

Difference between mitosis and meiosis

 

The Importance of Mitosis and Meiosis MITOSIS

1.Mitosis form new cells for growth and to replace a damaged or died cells. 2.To ensure that the number of chromosomes in daughter cell is identical to that of the parent cell. MEIOSIS

1. To produce gametes with half the number of chromosomes of the parent cells. 2. It allows a species to maintain a constant number of chromosomes in the offspring. 3. To form variation between species.

 

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2. INHERITANCE 1. Inheritance is a process of of passing genetic information of characteristics characterist ics or traits from parents to offspring. 2. Genes are divided into 2, dominant and recessive recessive.. 3. Human beings have _46 chromosomes. This means that we have _23_ pairs of homologous chromosomes. 4. Combinatio Combination n of genes it possesses possesses is called genotype. 5. The characteristics that can be observed or determined is called phenotype. 6. Arecessive dominant gene characteristics teristics it controls when it pairs with a gen. is a gene which can show the charac 7. The recessive gene only shows its characterist characteristics ics when paired with another recessive gene.  Characteristics

Dominant characteristic

Recessive characteristic

Tongue rolling

Ability to roll the tongue

Inability to roll the tongue

Ear-lobe

Presence of ear-lobe

Absence of ear-lobe

Eye colour

Brown eyes

Blue eyes

Skin pigment

Normal skin pigment

Absence of skin pigment(Albinism)

  Mechanism of Inheritance of Traits Father Parents

Mother

(Free ear lobe)

 

(Attached ear lobe)

EE

ee

Meiosis

Gamet

E

E

e

e

Fertilization

Offspring E

E

E

E

e

e

e

e

 All free ear lobe The schematic diagram shows the inheritance of ear lobe 

 

 

Dominant genes are represented by capital letters whereas recessive genes are represented by small letters. ‘E’ represents the genes for free ear lobe, which is the dominant gene. ‘e’ represents the gene for attached ear lobe which is the recessive gene.

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Monohybrid cross Y for dominant traits ( yellow seeds) y for recessive traits (green seeds)

Parents:

YY

X

Phenotype:

__Yellow __

Gametes:

Y

Genotype: Phenotype:: Phenotype

yy ___Green ___Green___  ___ 

Y

y

___Yy___ ___Yy__

y

Yy

__yellow___ yellow

____Yy___ 

yellow

yellow

 ____________________  _____________ _____________ _____________ ______________ ______________ ______________ ______________ ______________ ___________  ____    F1 Generation:

Yy

Phenotype:: Phenotype

X

yellow seed

Gametes:

Y

Genotype: Phenotype:

YY __yellow_

Yy _yellow seed__ 

y

Yy ___yellow

Y

Yy __yellow_

y

yy _green

Phenotype ratio: ____3 yellow_____:_____1 green_____ 

3.

SEX DETERMINATION AND THE OCCURANCE OF TWINS 1. Human has 23 pairs of chromosomes, 22 pairs are autosomes and 1 pairs is sex chromosomes. 2. Type of the sex chromosomes are _X_ and _Y__. 3. Females have _XX_ sex chromosome, while male have _XY_ sex chromosomes. 4. Female has contains 22 pairs of autosomes and 2 sex chromosomes XX(44 + XX) while male has 22 pairs of autosomes and 2 types of sex chromosomes X and Y(44 + XY) 5. The sex of a child is determined by the father according to the type of sperm.

 

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The schematic diagram below show how sex is determined.

Parents:

Father XY

Mother  XX

Meiosis

Gametes:

X

Y

X

X

Fertilisation

Genotype:

XX

Phenotype: Girl Genotype ratio: Phenotype ratio:

XY

XX

Boy 1XX 1 girl

: :

Girl 1XY 1 boy

XY Boy

TWINS 1. 2. 3. 4. 5.

There are two types of twins, identical and non-ide non-identical ntical twins. Identical twins are formed from _1 _ sperm and_1_ and_1_ ovum, ovum, while non-identical non-identical twins twins are formed formed from _2_ sperms and _2_ ova. Identical twins have same genetic traits, sex _ and appearance_ appearance_.. Non-identical twins may have different_genetic traits and may have similar or different sex. In identical twins, if the two embryos do not completely separate, they are called  _siamese_ twins. twins. The differences between identical twins and non-identical twins. Characteristic Number of ovums involved Number of sperms involved Number of zygotes produce Number of placentas Sex of child (same / different) Genetic traits (same / different)

Identical twins 1 1 1 1 Same same

Non-identical twins 2 2 2 2 Same/different different

6.

The similarities between this two types of twins are born through pregnancy. 4. MUTATION 1. What What is muta mutati tion on? ? The spontaneous random change to the structute of genes or chromosomes of an organism. 2. There There are ttwo wo types types of mutati mutation, on, ge gene ne mu mutati tation on and chrom chromosom osomes es mutatio mutation. n. 3. The chang change e that occurs occurs iin n chem chemical ical str structur ucture e of a gen gene e is gene mutatio mutation. n. 4. The cha change nge of gene gene sequence sequence in a chromo chromosome some or the change change in the number of chromosomes chromosomes is chromosomes mutation. 5. The example examples s of gene muta mutation tion are are albinis albinism, m, colou colourr blindness blindness and haemop haemophili hilia. a. 6. The examples of chro chromosome mosome mutation are Down Down’n ’n synd syndrome, rome, Klinefelter’s and Turner’s Turner’s syndrome. 7. The Down Down’s ’s syndrom syndrome e is caused caused by the presence of one extra chromosome chromosome at chromosome chromosome 21 21 in the somatic cells. 8. The characteristics characteristics of Klinefelter Klinefelter’s ’s syndro syndrome me a are re nar narrow row sh shoulders oulders and small testes. testes. 9. The Turn Turner’s er’s sy syndro ndrome me is a women women w who ho la lacks cks on one e X chromos chromosome. ome. 10. There are some some factors that can increase increase the chance chance of mutation : High frequency frequency radiowaves, toxic chemical and nuclear ra radiation. diation.  

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11. 11.

Th The e ad adva vant ntag ages es an and d disa disadv dvan anta tage ges s of of m mut utat atio ion: n:  Advantages  Advanta ges Causes variations and organisms able to adapt to the environment More resistant to diseases, wheather and polluted environment

Disadvantages Disadvantages Causes infertility Causes physical, mental and foetus retardation

5. GENETIC RESEARCH 1. Genetic research have contributed to the field of _medicine_an _medicine_and d agriculture_. 2. The example of contribution in each field: Medical To make human insulin for diabetics Sheep can produce milk which contains protein that can cure haemophilic 3. 4.

Agriculture Species Tenera a new breed of oil palm fruits The sahiwal Friesian cows which produce more milk

Sel ele ectiv ctive e bre breeding ing iis s ve very im importa ortant nt.. It is done one on on cr crops an and lliive ves sto tock ck.. The imp importa ortanc nce e of se sele lect ctiv ive e bre breedin eding g in pla lan nts and live lives sto tock ck’s ’s ar are e: i. Resi Resist stan antt to to d dis isea ease ses. s. ii.. Sh ii Shor orte terr grow growth th p per erio iod. d. iii. ii i. Hi High gher er yiel yield. d.  iv.. Be iv Bett tter er qua quali lity ty.. 

6. VARIATION 1. 2. 3. 4. 5. 6. 7.

Variation is the difference among individuals of the same group. The examples of variation in human are fingerprints, ability to roll a tongue, ear lobe and blood group. There are two types of variation, continuous and discontinuous. The example of continuous variation are height, body weight, intelligence, skin colour, width of shoulder and length of sole. The examples of discontinuous variation are blood group, fingerprint, ability to roll the tongues, ear lobe, left-handedness and presence of dimples. The similarity of continuous and discontinuous variation is caused by crossing over in meiosis and mutation. The differences between the two types of variation:

Type Has Ha s di dist stin inct ct char charac acte teri rist stic ics s

Continuous variation Smal Smalll degr degree ee of vari variat atio ion n

Discontinuous variation Cl Clea earr-cu cutt di diff ffer eren ence ces s

En C avnirboenm ine hn etraitlefdactors

A Nfofected

N ost affected Ye

8. 9. 10.

There are two factors that cause variation, genetic and environmental. Mutation may also be another factor of variation and it will produce new variety. Variation is very important for us. The example of the important of variation are: i. Enabl Enable e ea each ch iind ndivi ividu dual al to b be e diffe differen rentt fr from om other others. s. ii. Mor More e resist resistant ant to chan changes ges in the the surroun surrounding ding.. iii. iii. To form form ne new w bre breed eds. s. 

7. CODE OF ETHICS IN G GENETIC ENETIC RESEARCHES   Misused of knowledge in genetics can cause various controversial issues concerning religion and humanity. Code of ethics in genetic researches is important to ensure that genetic researches benefit mankind. Example: Human cloning and the marketing of genetically modified products have become hot issues debated at present.If present.If cloning is carried out on humans, serious problems would arise. Religious people consider humans produced by cloning as not having souls.

 

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PAPER 1 1. Which of of the following following is the uni unitt of inheritance found in in chromosomes? chromosomes?  A B

Gene Sperm

C D

Gamete Nucleus

2. What is the function function of cell division division through meiosis? A B C D

3.

Produces more siblings Replaces Replaces damaged tissues Increases the size of an organism Creates variation in a population population of organisms

The diagram below shows four stages of mitosis mitosis in a plant plant cell.

Which of the following is the correct sequence of mitosis process?    A P,R,Q,S C Q,P,R,S B R,P,S,Q D S,P,R,Q

4.

A goldfish goldfish has 100 100 chromosomes chromosomes in each each body body cell. cell. How How many many chromosomes are found in each male gamete?  A 25 C 75 B 50 D 100

5. What is the number of chromosomes chromosomes found found in a female female human human skin cell? cell?  A B

22+ X 22+ Y

C D

44 +XX 44+XY

6. Which of the following processes in plants involves meiosis?

 

 A

Bud growth

C

Repair of tissue tissue

B

Root growth

D

Formation of pollen

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7. Chromosomes duplicate during cell division. How many times does replication of  chromosomes occur during mitosis and meiosis?   Mitosis Meiosis  A once once B once twice C twice once D twice twice

8.

What is the the name of the thread-liked thread-liked structure found found within the nuclei nuclei of a cell?  A B

Gene Autosome

C D

Nucleus Chromosomes

  9. The diagram diagram below below shows a process process in the human body. body. Parent cell

Process Y Daughter cells   What is the name of the process?  A B

Mitosis Fertilization

C D

10. Where does mitosis take place?    A Sperm C B Anther D

11.

Meiosis Cross-over 

Ovary Somatic cells

The diagram below shows cell division in an animal cell.

Which of the following following statement is correct about the cell division?  

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A B C D 12. The

Cell divides once only Four identical cells are produced Have the same kind of chromosomes chromosomes Similar number of chromosomes as parent cell diagram diagram below below shows shows four stages of of meiosis.

Which of the following shows the correct sequence? A B 13.

Q,S,P,R Q,R,P,S

Occurs in ovary Produces gametes Produces two daughter nuclei Chromosomes number is halved

What are dominant genes? A B C D

15.

C D

Which of the following following statements is true about mitosis? A B C D

14.

P,R,S,Q R,S,P,Q

Cannot reproduce themselves Fully express their characteristics Do not express their characteristics characteristics Multiply to produce more daughter cells

When can the recessive genes be expressed fully? A B C D

Dominant genes are absent Dominant genes are present Both dominant dominant and and recessive recessive genes genes are absent Both dominant dominant and and recessive recessive genes genes are present

16. The diagram diagram shows shows the stages in human human reproduction. reproduction.

 

Sperm

Testes Stage X Ovaries

Stage Y Zygote

Baby

Ovum

What are stages X and Y?

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 A B C D

X Mitosis Meiosis Meiosis Mitosis

Y Mitosis Mitosis Meiosis Mitosis

 

17.

Which of of the following processes is involved involved in in the formation of zygote? A B

Mitosis Meiosis

C D

Mutation Fertilization

18. Which of the the following following is dominant trait in human? A B

Curly hair Blue eyes

C D

Left handed Attached ear lobe

19. The gene for tall characteristics characteristics T of a pea tree is more dominant than t, which reveals the short characteristics. Which of the t he cross below will produce half of the filial which are tall?    A TT and tt C TT and Tt B Tt and Tt D Tt and tt

20. Azman who has the ability to roll his tongue has gene Aa and marries Siti who who has the same ability and has gene Aa too. What is the percentage of having having children that are not able to roll t tongue?  A

100%

C

50%

B

75%

D

25%

21. The diagram shows sex determinat determination ion in human Parent

Gamete

Offspring

44+XY

P

x

22+Y

44+XX

Q

44+XX

22+X

44+XY

22+X

44+XY

Which of the following chromosomes are found in gamete P and offspring Q ?  

 

P

Q 36

 

A B C D

22

22+Y 22+X 22+Y 22+X

22+ X 44+XX 44+XX 44+XY

What is the chromosome in a normal human egg cell ? A 23+XY 22+ X B

C D 22+Y 23+XX

23. The diagram diagram shows a first generation generation of cross breeding of of two flowers   Parents red flower x white flower 

First Generation

red flower

red flower

white flower

white flower 

R represents the dominant genes for red flower  r represent s the rec recessive essive genes for for white flower  What are the genes for the parents?

A B C D

Male RR RR Rr rr

Female Rr  rr  rr  Rr 

24. Farid who is able to roll his tongue has the genotype Gg. He married Sara who is also able to roll her tongue and has the genotype Gg. What percentage of their  children will be able to roll their tongues? A B

25% 50%

C D

75% 100%

25. What determines determines the gender gender of a baby baby ? A B C D

Chromosomes in the ovum Type of sex chromosome chromosomes s in the sperm Number of chromosomes in the sperm Number of chromosomes in the ovum

26. Which of the following is the correct genotype? genotype?    A

Male XX

Female XY

B C D

XY YY XX

XX XX YY 37

 

27. What is is the percentage probability probability that a couple will have a baby girl? girl? A 25%

B 50%

C

75%

D 100%

28. What is the chromosome chromosome number of a female foetus? A 22+X B 22+Y

C 44+XX D 44+XY

29. How are identical twins formed? A B C

Two ova fertilized by two different sperms One ovum fertilized by two different sperms Two ova fertilized by one sperm before splitting into two

D

One ovum fertilized by one sperm before splitting into two

30. Why can non-identical non-identical twins twins be of different different sexes ?  A B C D 31.

Which of the following describes Siamese twins? A B C D

32.

Born separately Have different genetic content Have underdeveloped body parts Identical twins do not separate completely

Two children children are identical twins. Which of the following following characteristic is not common between them?  A B

33.

They arise from the same same zygote The same sperm fertilizes two different ova Two different sperms fertilize two different ova Two different sperms fertilize the same ovum

Sex Height

C D

Blood group group Ability to roll tongue

What is the term used for the sudden and permanent changes in the DNA ? A B

Mitosis Mutation

C D

Variation Crossing over 

34. Which of the following can cause cause mutation?  

38

 

A B C D

Changes in the shape Random physical changes Changes in the genes structure Random fusion of a sperm and an ovum

  35.

The nucleu nucleus s of a boy’s boy’s skin cell cell has has 47 chromos chromosomes omes.. What is the the name name of the geneti genetic c disorder the the boy is suffering suffering from ?  A B

Albinism Down’s syndrome

C D

Sickle cell anemia anemia Turner’s syndrome

C D

Hormone imbalance Changes in chromosomes number 

36. What causes albinism? A B 37.

Virus infection Mutation of a gene

Which Which of the follo followin wing g pair pairs s is is correc correct? t? Mutation Down’s syndrome Klinefelter’s syndrome

Characteristics 47 chromosomes in the nucleus XYY in the gene

Turner’s syndrome  Albinism

Lack of on one Y chromosome in the gene Additional Y chromosomes chromosomes in the the gene

A B C D

38. What is the advantages advantages of mutation? A B C D

Form underdeveloped individuals Produce more varieties of new species Stop the process of growth in organisms Encourage the process of growth in organisms

39. The information information shows shows the characteristics of an individual. individual. • • •

Lacks pigmentation in the skin Has white skin, eye lashes and hair  Skin is sensitive to sunlight

What is the name of genetic disorder disorder the individual is suffering suffering from? A B

 

Albinism Haemophilia

C Colour blindness D Down’s syndrome

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40.

Which of the following is a result of gene mutation? A Haemoplilia B Down’s syndrome C Turner’s syndrome D Klinefelter’s Klinefelter’s syndrome

41. The diagram diagram shows the cross between between two different different varieties of mango

Mango K -has thick flesh - sweet -small fruit

Mango L -slightly thinner flesh -not so sweet -big fruit

X

Mango M   What is the purpose of crossing Mango K with Mango L? A Plenty of fruits B Big and sweet fruits C Trees bear fruits faster  D Big fruits with thick flesh

42. What is is the term used for the selection of plants plants or or animals animals of desirable traits? A Gene screening B Artificial breeding C Natural selection D Selective breeding   43. What is the production of genetically genetically identical individuals individuals called? A B

Cl Clon onin ing g Breeding

C D

Back Back-c -cro ross ssin ing g Hybridization Hybridization

44. The diagram shows shows the breeding breeding of two different types types of oil palm

Oil Palm X

X

Oil Palm Y

  small fruit thin mesocarp thin endocarp

bigger fruit thicker mesocarp thicker endocarp

Oil Palm Z  

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What is the result of of breeding breeding these oil oil palms palms ? A Plenty of oil palm B Sweeter oil palm C Oil palm Z produces plenty of palm oil D Oil palm Z becomes more resistant to disease

45. Which of of the following following is is an example example of a continuous continuous variation? variation? A Fingerprint B Blood group

46.

C Height D Type of ear lobe

Which of of the following graphs correctly shows the the distribution distribution frequency frequency of  continuous variation? A

B

C

D

 

47. Which of the following is the example of discontinuous discontinuous variation? A B C D

48.

Height Skin colour  Blood group Body weight

What is the meaning of variation? A B C D

Sudden change in hereditary material Sudden change in external appearance caused by the environment Different expression of similar characteristics characteristics among individuals individuals of  the same species Different expression of similar characteristics characteristics among individuals individuals of  the different species

49. Which of the following does does not involve genetic engineering? engineering? A

Gene therapy for treating cancer  41

 

B C D

The production of Tenera oil palm The production of insulin by bacteria The production of genetically genetically modified food

50. What is the characteristics characteristics desired from from the genetic genetic research done on plants? plants?    A Matures faster  B C D

Produces less fruit Easy to get diseases Has short life span

PAPER 2 SECTION A 1.  

Pupils in in a certain certain class had their weight measured. measured. The The data obtained obtained is shown below: Weight of pupils ( kg ) 36 58 47

41 59 50 50

45 51 43

46 45 51 51

45 46 38 38

43 4 48 8 47 47

44 45 49 49

40 47 48 48

53 49 54

52 44 46 46

(a) Complete Table 1 using using the given data. Weight of pupils (kg)

35-39

40-44

45-49

50-54

55-59

Number of pupils

TABLE 1 (b) Using the data in table table 1, draw a histogram below to show the distribution distribution of  of  the weight of pupils. Number of pupils 14

 

42

 

12

8

4

  0

35-39

(c)

40-44 

50-54

45-49

55-59

What type of variation is shown by a pupil’s weight ?

Weight (kg)

[2 Marks]

………………………………………………………………………………………… [ 1 Mark] (d)

Other than weight, state two examples that show the same type of variation.

  ……………………………………………………………………………………… [ 1 Mark] SECTION B 1.  

Diagram 1 shows the process involved in the formation of twins Ovum

sperm

Process Q

 

Process R

Two zygote formed

 

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  DIAGRAM 1 (a) Name the process that takes takes p place lace at at Q ……………………………………………………………………………………. …………… [ 1 Mark] (b) Name the type of cell cell division division that takes place place at R ………………………………………………………………………………………………… [ 1 Mark] (c) State the type of twins formed formed in the the figure shown above. above. ………………………………………………………………………………………………… [ 1 Mark] (d) State two similarities similarities found in the zygote formed formed after process process R. …………………………………………………………………………………….…………… …………………………………………………………………………………….…………… [ 1 Mark]

(e) What type of of twins that will will be formed formed if process process R is incomplete? incomplete? ……………………………………………………………………………………. …………… [ 1 Mark] (f) If the spermatozoa in the figure carries carries 22+Y 22+Y chromosome, chromosome, (i) what will be the sex o off the zygotes? ……………………………………………………………………………………. …………… [ 1 Mark] (ii) state the number number and the type of sex chromosomes chromosomes in both both the zygotes   …………………………………………………………………………………….…………… [ 1 Mark] 2. Diagram 3 shows shows the cross-breeding cross-breeding of pea plants. plants. T represents the dominant genes while t represents the recessive gene.

Parent

Tall plant

x

Short plant

  Genotype

Gamete

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Genotype

Tt  Tt 

Phenotype

Tall

Tall

Tall

Tall

DIAGRAM 3 (a)  

What is meant by gene?

…………………………………………………………………………………….…………… [ 1 Mark] (b) The above pea plant have a pair of Tt genes which show the tall trait. Explain this.   ……………………………………………………………………………………. ………………… [ 1 Mark] (c)

3.

Complete the above figure by writing the possible genotypes of the parent, gamete and offspring [2 Marks] The bar chart below shows the result of a study in a group of of students. Number2. of  students

80   60 40 20  

Roll tongue

able

unable

(a) Calculate the the percentage percentage of students who are able able to roll roll their tongues. tongues.

…………………………………………………………………………………….…………… [ 1 Mark] (b) i) What are the the characteristics characteristics shown by the graph above? …………………………………………………………………………………….…………   ……………………………………………………………………….………………… [ 1 Mark] ii) What is is the type of variation in this this situatio situation? n? …………………………………………………………………………………….…………  

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[ 1 Mark] (c) i) Is ‘ the presence or absence absence of ear lobes’ the same type of variation variation as (b)ii? (b)ii? …………………………………………………………………………………….………… [ 1 Mark] ii) Give reasons for your your answer answer in (c) i.i.  

…………………………………………………………………………………….…………… …………………………………………………………………………………….………… [1 Mark]

4

(a) What does cell division refers to? ……………………………………………………………………………………….

(b)

………………………………………………………………………………………. [ 1 Mark] What is meiosis?

  ………………………………………………………………………………………. ………………………………………………………………………………………. [ 1 Mark] (c)

Compare the number number of chromosomes chromosomes in the daughter daughter cells cells and in the parent cell …………………………………………………………………………………………

(d)

………………………………………………………………………………………… [ 1 Mark] State two importance of meiosis in organisms i)

………………………………………………………………………………………

ii)

……………………………………………………………………………………….

[2 Marks]

 

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5. (a) What is mutation? ……………………………………………………………………………… ……………………………………………………………………………… [ 1 Mark] (b) State two types of mutation and and explain explain each of them

1.

………………………………………………………..

2.

………………………………………………………... [2 Marks]

  (c) Give two examples of consequences of each mutation named in (b) 1. ……………………………………………………… 2. ……………………………………………………… [2 Marks]   (d) i) What is Klinefelter’s Klinefelter’s syndrome? ……………………………………………………………………………. [ 1 Mark]   ii) What is is the cause of Klinefelter’s Klinefelter’s syndrome?  

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…………………………………………………………………………………… . [ 1 Mark]

SECTION C

1.

No two individuals are alike. Every person is unique in himself 

(a) Examine the above statement, then then suggest suggest a suitable suitable hypothesis hypothesis for an investigation investigatio n to determine the weight of forty students (boys and girls) who are all 18 years of age. [1 Mark] (b) Describe an an experiment experiment that could be carried in the classroom classroom to verify verify your  hypothesis. Your description should include the following: (i) Aim of the investigation [1 Mark] (ii) Identification Identification of variables [3Marks] (iii) List of apparatus [1 Mark] (iv Tabulation of data [1 Mark] (v) Conclusion Conclusion [1 Mark]

2. Study the statement below

The length of leaves is a type of continuous variation  

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(a) Suggest a suitable hypothesis to investigate this statement. (b) Design an experiment experiment to test your your hypothesis this s statement tatement (i) Aim of the experiment (ii) Identification of variables variables ii)) ((iiv (v) (vi)

3.

L Misetthoof dmaterials and apparatus Recording and analyzing Conclusion

[1 Mark]

[1 Mark] [2 Marks] [3[1MM aa rkrsk]] [1 Mark] [1 Mark]

(a) State four differences between cell division through mitosis and meiosis. [4 Marks] (b)

 

Hair 

Skin

Cell division

Liver 

Red blood cell

The cell division that takes place in the body parts of a student is shown above. Explain how you would build a concept based on the information above. Your explanation should include the following. (i) Identify two common features (ii) Build an initial concept (iii) Give one one example example of body part part that undergoes this cell cell division division and one example of body part that does not undergo this cell division. Give reason for each example. (iv) Explain the actual concept [6 Marks]

 

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