CLS_aipmt-15-16_XI_zoo_Study-Package-1_SET-1_Chapter-2A.pdf

Chapter

2

Structural Organisation in Animals (Animal Tissues) Solutions SECTION - A School/Board Exam. Type Questions Very Short Answer Type Questions : 1.

Name the cells which secrete mucus.

Sol. Goblet cells. 2.

What is blood plasma?

Sol. It is slightly alkaline non-living intercellular substance which constitutes about 55% of the blood. It consists of water, proteins, salts, hormones, glucose, oxygen, excretory products, etc. 3.

How are tight junctions formed between neighbouring cells of epithelial tissue?

Sol. Plasma membranes of adjacent cells get fused at intervals to form tight junctions. 4.

What is the significance of basement membrane?

Sol. Basement membrane provides elastic support and also anchors the epithelial tissue to the underlying connective tissue for obtaining nutrients. 5.

Name the cells which are packed around neurons in the nervous tissue.

Sol. Neuroglia 6.

Which type of epithelial tissue is found in ovaries and testes?

Sol. Germinal (Cuboidal) epithelium. 7.

What is the role of cilia in the respiratory tract?

Sol. In respiratory tract, cilia helps in expelling the mucus and particles trapped in it, towards the pharynx. 8.

What are adipocytes?

Sol. Fat-storing cells of adipose tissue are called adipocytes. 9.

Which is the site for production of blood cells?

Sol. Bone marrow. 10. Which blood corpuscle helps in clotting of blood? Sol. Thrombocytes. Aakash Educational Services Pvt. Ltd. - Regd. Office : Aakash Tower, Plot No.-4, Sector-11, Dwarka, New Delhi-75 Ph.011-47623456

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Structural Organisation in Animals (Animal Tissue)

Solution of Assignment (Set-1)

Short Answer Type Questions : 11. Write the four types of animal tissues based on location and function in the body. Sol. (i) (ii)

Epithelial tissue Connective tissue

(iii) Muscular tissue (iv)

Nervous tissue

12. What is brush-bordered cuboidal epithelium? What is its significance? Sol. When the cuboidal epithelial cells bear minute finger-like projections (known as microvilli) on their free surface, they are called brush-bordered cuboidal epithelium. Microvilli increases the surface area to several times. 13. Where do you find the following? (a)

Ciliated cuboidal epithelium

(b)

Ciliated columnar epithelium

Sol. (a) (b)

Ciliated cuboidal epithelium occurs in certain parts of nephrons of the kidneys. Ciliated columnar epithelium occurs in the lining of respiratory tract and oviducts.

14. What is compound epithelium? State its function. Sol. Compound epithelium is a multilayered tissue that is made up of more than one layer of epithelial cells. Its main function is to provide protection against chemical and mechanical stresses. 15. (a) (b) Sol. (a) (b)

How do endocrine glands secrete their products? Give two examples of exocrine glands. Endocrine glands secrete their products directly into the fluid bathing the gland i.e., blood and lymph. Salivary gland and sweat gland.

16. Briefly describe the general structure of a connective tissue. Sol. A connective tissue is made up of three components: matrix, cells and fibres. The matrix is mainly a mixture of modified polysaccharides and proteins, which are secreted by the component cells of the tissue. Different types of cells such as fibroblasts, mast cells, adipose cells etc. occur in the matrix. In all connective tissues except blood, the cells secrete fibres made of collagen or elastin protein. These fibres provide strength, elasticity and flexibility to the tissue. 17. Draw a flowchart to show the types and sub-types of connective tissues. Sol.

Connective Tissue

Loose Connective Tissues

Areolar Tissue

Adipose Tissue

Dense Connective Tissues

Dense Regular Connective Tissue

Tendon

Ligament

Specialized Connective Tissues

Skeletal Dense Irregular Connective Connective Tissue Tissue

Bone

Cartilage

Fluid Connective Tissue

Blood

Lymph

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Structural Organisation in Animals (Animal Tissue)

33

18. State the function of the following cells: (a)

Fibroblasts

(b)

Plasma cells

Sol. (a) (b)

Fibroblasts produce and secrete fibres and matrix. Plasma cells produce antibodies.

19. What role does adipose tissue play in our body? Give two points. Sol. (1) (2)

It serves as a fat reservoir. It forms a shock-absorbing cushion around the eyeballs and kidneys.

20. Differentiate between Tendons and Ligaments. Sol.

Differences between Tendons and Ligaments Tendons

Ligaments

1. Inelastic in nature.

1. Elastic in nature

2. Join muscle to bone.

2. Connect bone to bone

3. Made up of white collagen 3. Made up of white collagen as fibres. well as yellow elastic fibres. 21. Which component of blood is known as ‘soldiers of the body’? Why? Sol. Leucocytes or WBCs are known as ‘soldiers of the body’ because these cells protect the body against diseases by engulfing bacteria and other foreign particles (phagocytosis). They also provide resistance against diseases by producing antibodies. 22. What is lymph? State two functions of lymph. Sol. Lymph is a colourless or light yellow-coloured fluid that filters out of the blood capillaries. Function : 1.

It acts as a middle man for the exchange of various materials between the blood and various body tissues.

2.

It keeps the body cells moist and maintains the volume of blood.

23. Discuss the following: (a)

Muscle

(b)

Myofibrils

(c)

Intercalated discs

Sol. (a)

Muscle : Muscle is made up of many long, cylindrical, fibre-like cells called muscle fibres. These muscle fibres are present in the form of sheets or bundles and are held together by connective tissues.

(b)

Myofibrils : Myofibrils are long, thread-like proteinaceous fibrils present in the sarcoplasm of muscle fibres.

(c)

Intercalated discs : These are present in the cardiac muscle fibres. These are specialized regions of cell membrane of two adjacent fibres and function as boosters of contraction wave.

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34

Structural Organisation in Animals (Animal Tissue)

Solution of Assignment (Set-1)

24. Draw a well-labelled diagram of a neuron. Sol. Dendrites Nissl’s granules Cell body Nucleus

Schwann cell

Axon

Myelin sheath Node of Ranvier

Axon terminal Synaptic knob

Nerve cell 25. Differentiate between Striated, Unstriated and Cardiac muscles on the basis of – (a)

Location

(b)

Number of nuclei present

(c)

Striations

Sol. Point of difference

Striated muscle

Non-striated muscle

Cardiac muscle

(a) Location

Occurs in the limbs, body wall, face, neck etc.

Occurs in posterior part of oesophagus, urinogenital tract, iris of eye etc.

Occurs in the walls of heart.

(b) N u mb e r o f nuclei

Multinucleated.

Uninucleated.

Uninucleated.

(c) Striations

Myofibrils show alternate light and dark bands.

Myofibrils do not show light and dark bands.

Myofibrils show faint light and dark bands.

26. Draw diagrams to show the difference in structures of Squamous, Cuboidal and Columnar epithelium. Sol.

Cytoplasm Nucleus Cell membrane

Simple Squamous Epithelium Cubical cell

Nucleus

Basement mambrane

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Solution of Assignment (Set-1)

Structural Organisation in Animals (Animal Tissue)

35

Microvilli Mucus Cytoplasm Goblet Cell Nucleus Basement Membrane Absorptive Cell

Simple Columnar Epithelium

27. Explain the different types of glands on the basis of number of cell. Give examples of each. Sol. Based on cell number, glands are of two types: (a)

Unicellular glands : These glands consist of isolated single cells, which function as glands e.g., goblet cells of alimentary canal.

(b)

Multicellular glands : These glands are made up of a cluster of cells e.g., salivary glands, sweat glands etc.

28. Tell the location of the following tissues: (a)

Areolar tissue

(b)

Cartilage

(c)

Squamous epithelium

Sol. (a)

Areolar tissue : It is present beneath the skin, fills spaces inside organs and is found around muscles, blood vessels and nerves.

(b)

Cartilage : It is present in the tip of nose, outer ear joints, between adjacent bones of vertebral column, limbs and hands in adults.

(c)

Squamous epithelium : It occurs in the walls of blood vessels and lymph vessels, alveoli of lungs, wall of Bowman’s capsule etc.

29. Give one word for the following: (a)

Activities, under the control of organism’s will power.

(b)

Study of tissues

(c)

Connective tissue with a fluid matrix

Sol. (a)

Voluntary activities

(b)

Histology

(c)

Blood

30. Match the items in column A and with their in column B. Column A

Column B

a.

WBCs

(i)

Storage of fat

b.

Phagocytosis

(ii) To engulf foreign particles in solid state

c.

Axon and dendrites

(iii) Soldiers of the body

d.

Adipose tissue

(iv) Neurons

Sol. (a)-(iii), (b)-(ii), (c)-(iv), (d)-(i). Long Answer Type Questions : 31. Elaborate the following: (i)

Epithelial tissue

(iii) Muscular tissue (v) Sol. (i)

(ii) Connective tissue (iv) Nervous tissue

Histology Epithelial tissue is the protective tissue that covers or lines the external and internal surfaces of various body parts. It is made up of one or more layers of cells resting on a basement membrane.

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36

Structural Organisation in Animals (Animal Tissue)

(ii)

Solution of Assignment (Set-1)

Connective tissue is the most widely distributed tissue in the body of animals which connects different tissues or organs and provides support to various body structures. It consists of living cells embedded in abundant non-living intercellular matrix.

(iii) Muscular tissue is the tissue that helps in bringing about movement and locomotion in the body. It constitutes the muscles which are made up of many long cylindrical fibre-like cells called muscle fibres. (iv)

Nervous tissue is the tissue made up of some specialized cells called as neurons. These cells are capable of transmitting messages in our body and thus, help in controlling all the body activities.

(v)

Study of tissues is known as Histology.

32. State the location of following tissues in the body: (i)

Squamous epithelium

(ii) Cuboidal epithelium

(iii) Areolar tissue (v) Sol. (i) (ii)

(iv) Cardiac muscles

Neurons Squamous epithelium : Alveoli of lungs, blood vessels etc. Cuboidal epithelium : Tubular parts of nephrons of kidneys, ducts of glands etc.

(iii) Areolar tissue : Spaces inside the organs, around the muscles, blood vessels and nerves. (iv)

Cardiac muscles : Heart

(v)

Neurons : Brain and Spinal cord.

33. State the functions of the following tissues: (i)

Ciliated cuboidal epithelium

(iii) Smooth muscles (v)

(ii) Ciliated columnar epithelium (iv) Cartilage

Compound epithelium

Sol. (i)

Ciliated cuboidal epithelium helps in the flow of urine in the nephrons of kidneys.

(ii)

Ciliated columnar epithelium helps in the passage of ovum through fallopian tube.

(iii) Smooth muscles help in bringing about involuntary movements in our body such as peristalsis in alimentary canal. (iv)

Cartilage provides support and flexibility to the body parts and smoothens the surfaces at joints.

(v)

Compound epithelium covers the dry surface of skin and provides protection against chemical and mechanical stresses.

34. (i) (ii) Sol. (i)

Describe briefly the generalised structure of connective tissue. Write two differences between tendons and ligaments. Structure of connective tissue : Generally, a connective tissue is made up of three components: matrix, cells and fibres. The matrix (ground substance) is mainly a mixture of modified polysaccharides and proteins, which are secreted by the component cells of the tissue. Different types of cells such as fibroblasts, macrophages, mast cells, adipose cells etc. occur in the matrix. In all connective tissues except blood, the cells secrete fibres made of structural proteins called collagen or elastin. These fibres provide strength, elasticity and flexibility to the tissue.

(ii)

Differences between Tendons and Ligaments Tendons

Ligaments

1. Inelastic in nature

1. Elastic in nature

2. Join muscle to bone

2. Connect bone to bone

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Solution of Assignment (Set-1)

Structural Organisation in Animals (Animal Tissue)

37

35. Mark whether the following statements are true or false. Rewrite the false statements after correcting them. (i)

Collagen fibres are inelastic in nature.

(ii)

Ligaments attach muscle with bone.

(iii) Central body of nerve cell is called axon. (iv)

Adipose tissue prevents the loss of heat from the body.

(v)

Simple squamous epithelium is present in the skin.

Sol. (i) (ii)

True False, ligaments connect bone to bone.

(iii) False, central body of nerve cell is called cyton. (iv)

True

(v)

False, stratified squamous epithelium keratinised (compound epithelium) is present in the skin.

36. Explain cuboidal epithelium in terms of following points: (i)

Structure

(ii)

Location

(iii) Function Also draw its labelled diagram. Sol. (i)

Structure : Cuboidal epithelium consists of a single layer of cube-like (cubical) cells, lying on a basement membrane. Nuclei are rounded and lie in the centre of the cells. Free surfaces of the cells may be smooth or bear minute finger-like projections known as microvilli. This gives a brush-like appearance to their free border and also increases the surface area to several times. Such an epithelium is known as brush-bordered cuboidal epithelium.

(ii)

Location : It is generally found in the tubular parts of nephrons in kidneys, ducts of glands (such as salivary glands, sweat glands, exocrine pancreas), thyroid follicles, ovaries and testes etc.

(iii) Function : 1.

Brush-bordered cuboidal epithelium present in the proximal convoluted tubules (PCT) of nephrons of kidney, is responsible for reabsorption of useful substances.

2.

Secretion and excretion by glands.

Cubical cell

Nucleus

Basement mambrane

(A)

Brush border Cytoplasm Nucleus (C)

Basement membrane

(B) Simple Cubical or Cuboidal Epithelium. (A) Vertical section, (B) Surface view, (C) A cell with brush border Aakash Educational Services Pvt. Ltd. - Regd. Office : Aakash Tower, Plot No.-4, Sector-11, Dwarka, New Delhi-75 Ph.011-47623456

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Structural Organisation in Animals (Animal Tissue)

37. (i) (ii)

Solution of Assignment (Set-1)

What is glandular epithelium? Classify glands on the basis of mode of pouring of secretion.

Sol. Glandular Epithelium : Some of the cells of epithelium get specialized for secretion and are called glandular epithelium. Cells of glandular epithelium are columnar or cuboidal in outline. The glands are formed from the glandular epithelium. A gland may be made up of a cell, tissue or organ. Classification of glands on the basis of mode of pouring of secretion : On the basis of the mode of pouring of their secretions, glands are of two types: exocrine and endocrine glands. (a)

Exocrine glands : These glands drain out their secretion to the body surfaces (exterior) and surfaces continuous with it, e.g., alimentary tract, respiratory tract etc. The secretion is passed out either by ducts or poured directly over the substrate. These include salivary glands, gastric glands, intestinal glands, oil glands, mammary glands, tear glands etc.

(b)

Endocrine glands : These glands lack ducts, so these glands are commonly called ductless glands. They secrete their products (hormones) directly into the fluid bathing the glands i.e., blood and lymph. The blood and lymph carry hormones to the target organs. Endocrine glands include thyroid, pituitary, adrenals, hypothalamus etc.

38. Match the following: Column-I

Column-II

(i)

Leucocytes

(a) Neuron

(ii)

Phagocytosis

(b) Unstriated muscles

(iii) Axon and Dendrites

(c) Soldiers of the body

(iv)

Involuntary muscles

(d) Striated muscles

(v)

Multinucleated muscles

(e) To engulf foreign particles in solid state

Sol. (i)-(c), (ii)-(e), (iii)-(a), (iv)-(b), (v)-(d). 39. Give one word for the following: (i)

Group of cells performing specific function

(ii)

Bundle of yellow fibres connecting bones together

(iii) Activities under the control of organism’s will power. (iv)

Connective tissue with a fluid matrix

(v)

Short, branched processes arising from the cyton

Sol. (i)

Tissue

(iii) Voluntary activities (v) 40. (i) (ii)

(ii)

Ligaments

(iv)

Blood

Dendrites Name the connective tissue that forms the structural framework of our body. Explain its structure and two functions along with a labelled diagram.

Sol. Bone (skeletal tissue) forms the structural framework of our body. It is a very strong and non-flexible tissue. Structure : The matrix of bone is very hard because of the presence of salts, such as calcium phosphate, calcium carbonate etc. and proteins like ossein protein and collagen fibres. In the solid matrix are present longitudinal canals called haversian canals. Each haversian canal contains an artery, a vein, a lymph vessel, a nerve and some bone cells, all packed in with connective tissue. The matrix is present in the form of layers called lamellae. In these lamellae are present ring-shaped fluidfilled spaces called lacunae. The lacunae contain bone-forming cells, called osteocytes. Aakash Educational Services Pvt. Ltd. - Regd. Office : Aakash Tower, Plot No.-4, Sector-11, Dwarka, New Delhi-75 Ph.011-47623456

Solution of Assignment (Set-1)

Structural Organisation in Animals (Animal Tissue)

39

In long bones such as limb bones, a cavity called bone marrow cavity is present. This cavity is filled with a soft and semisolid fatty tissue termed as bone marrow. The bone marrow in some bones is the site of production of blood cells (such as RBCs, WBCs, Platelets etc.)

Interstitial Haversian system lamellae

Nucleus

Protoplasmic processes

Concentric lamellae Lacunae with bone cells Matrix Haversian canal Canaliculi

Osteoblast (A) (B) (A) T.S. of long bone showing Haversian system; (B) Osteoblasts and their processes. Functions : 1.

It supports and protects softer tissues and organs such as brain, heart, lungs etc.

2.

It provides surface for the attachment of muscles.

41. Given below are two figures A and B.

W

Y X

Z (B)

(A) (i)

Identify figures A and B.

(ii)

Label W, X, Y and Z.

(iii) Which one acts as impulse booster? (iv) Sol. (i) (ii)

Which one is under control of our will? Figure A is cardiac muscle fibre and figure B is skeletal or striated muscle fibre. W - Nucleus X - Intercalated disc Y - Light band Z - Dark band

(iii) Intercalated disc (X) acts as an impulse booster. (iv)

Skeletal or striated muscles are voluntary.

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Structural Organisation in Animals (Animal Tissue)

Solution of Assignment (Set-1)

42. What is Blood? What are its components? Describe briefly. Sol. Blood : It is a red-coloured sticky, alkaline, slightly saltish in taste, heavier than water, fluid connective tissue. Components of Blood : It is composed of a watery fluid, called plasma and floating cells called corpuscles. (1)

Plasma : It is slightly alkaline non-living intercellular substance which constitutes about 55% of the blood. Major constituent of plasma is water that forms about 90% of it. The remaining 10% of plasma is made up of proteins, salts, hormones and other materials meant for transportation in the body such as digested food, gases, excretory products etc.

(2)

Corpuscles : These are wandering and non-dividing cells that form about 45% of the blood. These are of three types:

(i)

RBCs i.e., Red Blood Corpuscles or Erythrocytes.

(ii)

WBCs i.e., White Blood Corpuscles or Leucocytes.

(iii) Blood Platelets or Thrombocytes. (i)

Erythrocytes or RBCs : These are the most abundant corpuscles. They have a red-coloured respiratory pigment called haemoglobin that helps in the transportation of oxygen.

(ii)

Leucocytes or WBCs : These cells protect the body against diseases by engulfing bacteria and other foreign particles (phagocytosis) and are hence called ‘soldiers of the body’. They also provide resistance against diseases by producing antibodies.

(iii) Thrombocytes or Blood platelets : They help in the clotting of blood. 43. Fill in the blanks: (i)

Lining of small intestine is made up of __________.

(ii)

Skeletal muscle fibres are bounded by an elastic but tough covering known as __________.

(iii) Thyroid is an __________ gland. (iv)

The skeletal tissue found more abundantly in vertebrate embryos is __________.

(v)

Matrix of bone is very hard because of the presence of __________ protein.

Sol. (i)

Columnar epithelium

(iii) Endocrine (v) 44. (i) (ii) Sol. (i)

(ii) Sarcolemma (iv) Cartilage

Ossein Explain the structure of cardiac muscle fibres along with a labelled diagram. List the function of striated muscles. Structure of cardiac muscle fibres is in between the striped and unstriped muscle fibres. Cardiac muscles are composed of branched fibres, the branches join to form a network. Each fibre or cell is surrounded by sarcolemma and has cytoplasm (sarcoplasm) with longitudinal myofibrils and a centrally located nucleus (i.e., each cell is uninucleate). The myofibrils have transverse faint dark and light bands, which alternate with each other. In addition, these muscle fibres show densely-stained crossbands called intercalated discs at intervals. The intercalated discs are specialized regions of cell membrane of two adjacent fibres. The intercalated discs function as boosters of contraction wave and permit the wave of muscle contraction to be transmitted from one cardiac fibre to another. So, all the fibres contract as a unit.

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Solution of Assignment (Set-1)

Structural Organisation in Animals (Animal Tissue)

41

Nucleus Cell Membrane Oblique Bridge Intercalated Disc Dark Bands Light Bands Muscle Fibres

(ii)

Cardiac Muscle Tissue Function : Striated muscles provide the force for locomotion and all other voluntary movements of the body.

45. Complete the following table showing the classification of animal tissues.

Animal Tissues

Epithelial Tissues

Simple Epithelial (Single Layered)

Connective Tissues

Compound Epithelial (Multi Layered)

(a)

Striped

Unstriped

Nervous Tissues

Cardiac

Squamous Cuboidal

Loose Connective Tissue Dense Connective Tissue Specialized Connective Tissue

(b) Sol. (a)

Ciliated Muscular tissues

(c)

Adipose

(e)

Cartilage

Areolar

(c)

(d)

Ligament

Bone

(e)

Blood Lymph

(b) Columnar (d) Tendon

SECTION - B Model Test Paper Very Short Answer Type Questions : 1.

Name the specialized granules present in the neuron.

Sol. Nissl’s granules 2.

Name the connective tissue that joins skeletal muscles to bones.

Sol. Tendons 3.

Name the simple epithelium present in the thyroid follicles.

Sol. Cuboidal epithelium 4.

Name two heterocrine glands.

Sol. Pancreas and gonads (testes & ovaries) Aakash Educational Services Pvt. Ltd. - Regd. Office : Aakash Tower, Plot No.-4, Sector-11, Dwarka, New Delhi-75 Ph.011-47623456

42 5.

Structural Organisation in Animals (Animal Tissue)

Solution of Assignment (Set-1)

What is the name given to the bone-forming cells?

Sol. Osteocytes 6.

Why smooth muscles are called non-striated muscles?

Sol. Because in smooth muscles, the myofibrils do not show any light and dark bands. Short Answer Type Questions : 7.

State the location of the following tissues: (i)

Nervous tissue

(ii)

Smooth muscles

Sol. (i) (ii) 8.

Brain and spinal cord Stomach and intestine

Write a short note on adipose tissue.

Sol. Adipose tissue is a loose connective tissue that is located mainly beneath the skin. It consists of several spherical or oval adipose cells which are specialized to store fat. The excess of nutrients which are not used immediately are converted into fat and stored in this tissue.

Fat storage area Nucleus Plasma membrane Adipose tissue consisting of adipocytes 9.

List two differences between Tendons and Ligaments.

Sol.

Tendons

Ligaments

1. Are inelastic

1. Are elastic

2. Join muscle to bone

2. Join bone to bone

10. Give two unique features of cardiac muscles. Sol. (i) (ii)

Cardiac muscle fibres are branched. They have intercalated discs which act as boosters of contraction wave.

11. What is the fatty tissue that occurs in the cavity of limb bones? State its function. Sol. It is bone marrow. It is the site of production of blood cells such as RBCs, WBCs and platelets. Short Answer Type Questions : 12. Draw well-labelled diagrams of the following : (i)

Striated muscle fibres

(ii)

Areolar connective tissue

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Solution of Assignment (Set-1)

Sol. (i)

Structural Organisation in Animals (Animal Tissue)

43

Light Bands

Dark Bands Sarcolemma

Striped Muscle Fibres Nuclei

Striated muscle fibres (ii)

Macrophage Fibroblast Collagen fibres

Mast cell Areolar Connective Tissue 13. What are the following and where do you find them in the body of animals? (i)

Dendrites

(ii)

Chondrocytes

(iii) Microvilli Sol. (i)

Dendrites : These are short branched processes arising from the cyton of a neuron. They carry impulses towards the cell body. They are found in the nervous tissue or neurons.

(ii)

Chondrocytes : These are large, rounded mature cells occurring in groups in the matrix of the cartilage. Cartilage is found in the pinna, tip of nose, nasal septum etc.

(iii) Microvilli : These are minute finger-like projections occurring on the free surface of cuboidal or columnar epithelium. They increase their absorptive surface area. 14. Differentiate between the following: (i)

Exocrine and Endocrine gland

(ii)

Axon and Cyton

(iii) Blood and Lymph Sol. (i)

Exocrine glands release their secretions via ducts whereas endocrine glands are ductless. They pour their secretion directly into the blood stream.

(ii)

Axon is a single long cylindrical process arising from the cyton or cell body of the neuron and conducts impulses away from neuron. Cyton, on the other hand, is the main cell body of neuron having a nucleus and dense cytoplasm.

(iii) Blood is a red-coloured fluid connective tissue that transports different substances in the body. Whereas, lymph is a colourless fluid that oozes out from the blood capillaries as it surrounds the body tissues. Aakash Educational Services Pvt. Ltd. - Regd. Office : Aakash Tower, Plot No.-4, Sector-11, Dwarka, New Delhi-75 Ph.011-47623456

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Structural Organisation in Animals (Animal Tissue)

Solution of Assignment (Set-1)

15. Briefly describe the parts of a neuron. Sol. Neurons : Neurons are the structural and functional units of nervous tissue. Each neuron has the following parts: Dendrites Nissl’s granules Cell body Nucleus

Schwann cell

Axon

Myelin sheath Node of Ranvier

Axon terminal Synaptic knob

1.

Cyton or Cell body It consists of a central nucleus and cytoplasm (called neuroplasm) with characteristic deeply stained particles, called Nissl’s granules. Nissl’s granules are large and irregular masses of ribosomes and RER.

2.

Dendrites These are short and branched processes arising from the cyton. They carry impulses towards the cell body.

3.

Axon It is a single long cylindrical projection of uniform thickness. The axon ends in a group of branches (axon endings), termed as terminal arborizations. The axon carries impulses away from the cyton.

16. Tell the functions of the following: (i)

Fibroblasts

(ii)

Mast cells

(iii) Neuroglial cells Sol. (i) (ii)

Produce and secrete fibres and matrix. Produce histamine, heparin and serotonin.

(iii) To support neurons. Aakash Educational Services Pvt. Ltd. - Regd. Office : Aakash Tower, Plot No.-4, Sector-11, Dwarka, New Delhi-75 Ph.011-47623456

Solution of Assignment (Set-1)

17. (i) (ii) Sol. (i) (ii)

Structural Organisation in Animals (Animal Tissue)

45

What are multicellular glands? State the location and function of ciliated cuboidal epithelium. Glands made up of a cluster of cells are known as multicellular glands e.g., salivary glands, sweat glands etc. Location : Certain parts of nephrons of the kidneys. Function : Help in flow of urine in the nephrons of the kidneys.

18. Differentiate between skeletal, smooth and cardiac muscle fibres. Sol.

Skeletal striated muscle

Smooth non-striated muscle

Cardiac muscle

1. Occur in the limbs, body wall, 1. Occur in posterior part of 1. Occur in the walls of heart. face, neck, etc. oesophagus, urinogenital tract, iris of eye etc. 2. Cylindrical in shape.

2. Spindle shaped.

2. Cylindrical in shape.

3. Multinucleated muscle fibres. 3. Uninucleate muscle fibres.

3. Uninucleate muscle fibres.

4. Nuclei are peripheral.

4. Nucleus is central.

4. Nucleus is central.

5. Myofibrils show alternate 5. Myofibrils are without light 5. Myofibrils show faint light and dark bands. light and dark bands. and dark bands. 6. Fibres are unbranched.

6. Fibres are unbranched.

6. Fibres are branched.

7. Intercalated discs are absent. 7. Intercalated discs are absent. 7. Intercalated discs are present. 8. They soon get fatigued.

8. They do not get fatigued.

8. They never get fatigued.

9. Voluntary in action.

9. Involuntary in action.

9. Involuntary in action.

19. Name the following : (i)

Tissue present in the spinal cord

(ii)

Connective tissue with a fluid matrix

(iii) Cells which are known as ‘soldiers of the body’ Sol. (i) (ii)

Nervous tissue Blood

(iii) WBCs Long Answer Type Questions : 20. What is squamous epithelium? Explain its structure, location and function along with a labelled diagram. Sol. Squamous Epithelium : It consists of a single thin layer of flattened cells with irregular boundaries. The cells are closely fitted like the tiles in a floor. Hence, it is also known as Pavement epithelium. If we see the cells from the surface, they seem to be polygonal in shape. The nuclei of the cells are flat and often lie at the centre of the cells. Location : This epithelium occurs in the walls of blood vessels, air sacs (alveoli) of the lungs, lymph vessels, wall of Bowman’s capsule, loops of Henle of the nephrons of the kidneys, coelomic cavities etc. Function : 1.

Filtration in Bowman’s capsule.

2.

Exchange of materials between blood capillaries and tissue fluid.

3.

Exchange of gases

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46

Structural Organisation in Animals (Animal Tissue)

Solution of Assignment (Set-1)

Cytoplasm Nucleus

Cytoplasm

Cell membrane

Nucleus

Basement membrane

(a)

(b)

Simple squamous epithelium : (a) Surface view, (b) Vertical section 21. (i)

Write short notes on the following: (a) Bone (b) Blood

(ii) Sol. (i)

Draw a labelled diagram of cartilage. (a) Bone : Bone is the hardest tissue in the body. Its matrix is tough containing both inorganic and organic substances such as calcium salts, collagen fibres etc. The matrix has numerous bone cells, the osteocytes. An osteocyte is surrounded by a fluid-filled space, the bone lacuna. (b) Blood : Blood is a fluid connective tissue containing plasma, red blood cells, white blood cells and platelets. It is the main circulating fluid that helps in the transport of various substances. RBCs are involved in transport of oxygen and carbon dioxide. WBCs act as soilders of the body and blood platelets help in clotting of blood.

(ii)

Lacunae Collagen fibres Cartilage cell (chondrocyte)

Cartilage







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