ADDITIONAL QUESTIONS AND ANSWERS:
1. Name one place or region or region in a living organisms where each of the following tissue are found.
a) Intercalary Meristem
b) Stratified squamous epithelium
c) Areolar connective tissue
d) Columnar epithelium
e) Smooth muscles
f) Nervous tissue
g) Adipose tissue
Ans:
a) At the base of the leaves and the internodes of twigs
b) Skin of animals.
c) Between the skin and the muscles, around the blood vessels and the nerves and in the bone marrow
d) Inner lining of the organs like intestines, stomach and colon
e) Iris of eye, ureters, Bronchi of the lungs
f) Brain, spinal Cord and nerves
g) Skin, Bone marrow, internal organs.
2. State the function of Aerenchyma
Ans: Contain large air gaps due to which they become light and float on water
3. What does Suberin present in the cork do.
Ans: Suberin present in the walls of cork makes it impervious to gases and water.
4. What is the function of cilia in the respiratory tract.
Ans: Cilia helps in the outward movement of mucus and other solid particles that may enter the respiratory tract.
5. State the function of sclerenchyma
Ans: Sclerenchyma tissues make plant hard and stiff and provide strength to the different parts of the plant.
6. State the function of stomata on the epidermis of a leaf.
Ans: . The exchange of gases during photosynthesis and respiration take place through the stomata. A plant loses water by transpiration through the stomata.
7. Write the functions of xylem.
Ans: Xylem (tracheids) transports water and mineral salts from the roots to different parts of the plant. Xylem parenchyma stores food and helps in lateral conduction of water. Xylem fibres provide support to the plant
8. Write the functions of Parenchyma.
Ans: Parenchyma serves as a packing tissue to fill the spaces between other tissues. They provide support to the plant. They also store food. Parenchyma of stems and roots store nutrients and water
9. State the functions of epithelium.
Ans: Epithelium is a protective tissue which covers most of the organs and cavities within the body. They separate the different body tissues.
10. What are the functions of bones.
Ans: Bones provide skeletal support. They give shape to the body. They anchor the muscles. They protect vital organs
11. Define Tissue
Ans: A tissue is a group of cells which have similar structure and /or work together to achieve a particular function.
12. Define Differentiation
Ans: Differentiation is the process by which cells derived from meristematic tissue take up a permanent shape size and function of tissues
13. Define Transpiration
Ans: Transpiration is the process by which the plants lose water through the stomata present on the epidermis of leaves.
14. Why are plant tissues supportive and meant to give structural strength to it
Ans: Plants are autotrophic and stationary. They do not move from one place to another. Hence the tissues are meant to give them support and structural strength.
15. How is a bark or cork developed on the stem of a plant.
Ans: As the plant grows old, a secondary meristem replaces the epidermis of the stem. It gives off new cells on both its sides. The cells from outside are cut off by the secondary meristem. These outer cells form a several layered thick cork or the bark.
16. How are permanent plant tissues formed.
Ans: Permanent plant tissues are formed from the meristematic tissues. Meristematic tissues lose their ability to divide and thus take a permanent shape, size and function to form permanent tissues
17. How does the bark or the cork protect the plant.
Ans: The cork is made up dead cells and they are compactly arranged. They have a chemical called Suberin in their walls which makes them impervious to gases and water.
18. When are the tissues of a plant said to be complex tissue
Ans: The tissues are said to be complex tissues when they are made of more than one type of cells performing a common function.
19. Most of the plant cells are dead cells. Give reason.
Ans: Most of the plant cells are dead cells because dead cells need less maintenance. Also, they give the same mechanical support as the live cells.
20.Epidermis forms the outermost layer of the plants.
Ans: Epidermis forms the outermost continuous layer of the plant because its important function is protection of the plant.
21. Why do desert plants have a thicker coating of cutin on their outer surface
Ans: Cutin is a waxy layer which prevents loss of water. In deserts there is always a scarcity of water and plants cannot afford the loss of water. So desert plants have a thicker coating of cutin on their outer surface.
22. Give two distinguishing points between:Voluntary and involuntary muscles.
Ans:
| Voluntary muscles | Involuntary muscles |
| The movement of voluntary muscles is at our will | The movement of involuntarymuscles is not at our will |
| They are striated muscles since their cells show alternate dark and bright bands when stained | They are smooth muscles orunstriated muscles |
| Their cells are long and cylindrical, with non-tapering ends | The cells are spindle-shapedwith tapering ends |
| The cells have many nuclei. | The cells have a single nucleus |
23. Striated muscle fibres and unstriated muscle fibres.
Ans:
| Striated muscle fibres | Unstriated muscle fibres |
| Their fibres show alternate dark and bright bands when stained. | Their fibres do not show alternate dark and bright bands when stained. |
| The fibres are long cylindrical with non-tapering ends | The fibres are spindle-shaped with tapering ends |
| They have many nuclei. | They have a single nucleus |
24. Bone and Cartilage
Ans:
| Bone | Cartilage |
| Matrix is composed of calcium and phosphorus compounds |
Matrix is composed of protein and sugars
|
| Forms the framework that supports the body | It smoothens the bore surfaces at the joints |
| Bones cannot be bent | Cartilage can be bent |
25. Give one term for the following:
- Cells of plant tissue capable of cell division.
- A group of cells performing a common function
- Plant tissues not capable of dividing
- The parenchyma containing chlorophyll.
- Parenchyma having large air cavities present in them
Ans:
1). Meristematic tissues.
2). Tissue,
3). Permanent tissue.
4).Chlorenchyma.
5). Aerenchyma
26. Which part of neutron receives impulse and which part takes it away from neuron
Ans: The dendrite receives impulse and axon takes away the impulse from the cell body .
27. State the specific work of each of the following
What is the function of Chlorophyll present in chlorenchyma.
Ans: Chlorophyll is present in chlorenchyma to carry on photosynthesis
28. Why are large air cavities present in parenchyma of Hydrilla.
Ans: To enable the Hydrilla to float
29. Why is Cutin secreted by aerial parts of the plant.
Ans: It prevents the plant from loss of water and protects the plant from mechanical injury and infection by parasitic fungi.
30. What are the functions of Collenchyma tissues.
Ans: They make plants flexible. They allow the leaves, stem, and so on bend without breaking
31. Epidermal cells of the aerial parts of the plant often secrete a waxy resistant layer on their outer surface. Give reason.
Ans:Ans: The waxy and water resistant substance secreted on the outer surface helps the plant in preventing loss of water as well as protects it from mechanical injury and infections by parasitic fungi.
32. State one function of each of the following Apical meristem , Lateral meristem,
Chlorenchyma
Ans: Apical meristem increases the length of a plant
Lateral meristem increases the girth of a plant
Chlorenchyma contains chlorophyll and so they can carry photosynthesis.
33. State the characteristics of meristematic tissues.
Ans: They are dividing tissues
They are located only in certain regions.
Their cells are very active.
The cells have a dense cytoplasm.
Their cells have a thin cell wall
They do not have vacuoles.
34. Describe how epidermis protects a plant.
Ans: Epidermal cells of the aerial parts of the plant secrete a waxy, water resistant layer of cutin on their outer surface. This layer prevents the loss of water, and protects the plant from mechanical injury and infection by parasitic fungi.
As the plant grows old, it develops a thick cork or bark around the stem of the tree. The cells of the cork are dead cells and are compactly arranged. They have a chemical called suberin in their walls which makes them impervious to gases and water.
35. Give two distinguishing points between:
(a) Apical meristem and lateral meristem
Ans:
| Apical meristem | Lateral meristem |
| Apical meristems are present at the growing tips of stems and roots. | Lateral meristems are beneath the bark of a tree. |
| They increase the length or height of a tree. | They increase the girth of a tree. |
(b) Parenchyma and Sclerenchyma
Ans:
| Parenchyma | Sclerenchyma |
| (i) The cells of parenchyma are live cells. | (i) The cells of sclerenchyma consist of dead cells |
| (ii) The cells have a thin cell wall. | (ii) The cell walls are thickened with lignin |
| (iii) They provide support to the plant and store food | (iii) They provide strength to different parts of the plant |
(c) Plants and animals.
Ans:
| Plants | Animals |
| (i) Plants are stationary. | (i) Animals move from place to |
| (ii) Most of the plant tissues are dead cells | (ii) Most of the animal tissues are living tissues |
| (iii) The growth in plants is only in certain regions | (iii) The growth in animals is uniform. |
(d) Xylem and phloem.
Ans:
| Xylem | Phloem |
| Xylem consists of tracheids, vesselsand xylem parenchyma and xylem fibres. | Phloem consists of sieve tubes companion cells, phloem fibre and phloem parenchyma. |
| Except for xylem parenchyma, all xylem cells are dead cells. | Except tor phloem fibres, all phloem cells are living cells |
| Xylem transports water and mineral salts from the roots to the other parts of the plant | Phloem transports material in both directions |
36. What is the specific function of the cardiac muscle ?
Ans: The specific function of cardiac muscles is that they show rhythmic contraction and relaxation throughout the life without any fatigue under normal conditions .
37. Which mineral is most abundantly found in bones ?
Ans :Ans: Calcium phosphate is most abundantly found in bones .
38. Why are smooth muscles called visceral muscles ?
Ans: As they are found in the wall of the wall of visceral organs , e.g. stomach , intestine .
39. Which type of muscle cells show rhythmic contraction ?
Ans: Cardiac muscle cells show rhythmic contraction .
40. Name the type of cells from which phloem is made up of .
Ans: Phloem is made up of five type of cells which are sieve cells , sieve tubes , companion cells , phloem fibres and the phloem parenchyma .
41. State the difference between the tissue of the outer layer of the branch of the tree and the outer layer of a young tree stem .
Ans: The outer layer of a tree is made up of bark (dead cells) whereas outer layer of a young tree stem is made up of epidermis (living cells) .
42. What is xylem ? Name the four elements of xylem .
Ans: Xylem is a complex permanent tissue which conducts water and mineral salts upward from roots to leaves . The four elements of xylem are :
Tracheids , vessels , xylem parenchyma and xylem fibres .
43. What are the functions of stomata ?
Ans: The functions of stomata are :
i) Exchange of gases like O2 and CO2 between the plants and the atmosphere takes place through stomata .
ii) Plants eliminate excessive water in the form of vapour through stomatal openings .
iii) Stomatal opening gets closed when there is shortage of water . Thus , reduces loss of water .i.e. they regulate transpiration .
44. What are the characteristics features of meristematic tissues ?
Ans: The characteristics features of meristematic tissues are :
i) The cells of this tissue are similar in structure and are thin-walled .
ii) The shape may be oval , spherical , rectangular or polygonal .
iii) They contain dense cytoplasm with single large nucleus and few vacuoles .
45. Describe the functions of any four types of epithelial tissues and name an organ where each one of them is found.
Ans: The structure of the epithelium depends upon its function. Accordingly the epithelial tissues are classified as
(i) Squamous epithelium (simple and stratified) is found in the lining of blood vessels or lung alveoli. It consists of thin and flat cells which allow transportation of substances through a selectively permeable membrane.
(ii) Columnar epithelium consists of pillar-like cells. It helps in absorption and secretion. It is found in the inner lining of intestines, stomach and colon.
(iii) Ciliated epithelium is found in the respiratory tract has hair like projections called cilia which help in outward movement and other solid particles that may enter the respiratory tract
(iv) Cuboidal epithelium is made up of cube-shaped cells. It is found in the lining of kidney tubules and ducts of salivary glands. Cuboidal epithelium helps in absorption and secretion and provides mechanical support.
(v) Glandular epithelium consists of epithelial cells called glandular cells which secrete substances at the epithelial surface. A portion of such an epithelial tissue folds inwards to form a multicellular gland.
47. Name any four types of connective tissues and explain the function of each.
Ans: (i) Blood is a connective tissue having a fluid (liquid) matrix called plasma. It transports gases, digested food, hormones and waste material to different parts of the body.
(ii) Bone is a connective tissue which is strong and non-flexible. Bones provide skeletal support and gives shape to the body. They anchor the muscles and protect vital organs.
(iii) Ligament is an elastic and strong connective tissue. It connects two bones to each other.
(iv) Tendons are connective tissues with great strength but limited flexibility. They connect bones to muscles.
(v) Cartilage is a flexible connective tissue. It is present in the nose ear, trachea and larynx. It smoothens the bone surfaces at the joints.
(vi) Areolar connective tissue fixes the skin to the muscles. They serve as supporting and packing tissues between the organs and repair the tissues after an injury.
(vii) Adipose connective tissues are fat storing tissues which are found below the skin and in -between the internal organs (around the kidneys). They act as an insulator of heat.