CBSE Class 9 Science Tissues Sure Shot Questions Set 02

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ASSIGNMENT QUESTIONS SET - 2
CHAPTER - 6
TISSUES

1. The study of tissues is called ... [1 Mark]
a) cytology
b) embryology
c) histology
d) pathology

Answer: (c) histology

1. Histology is the specialized branch of biology that studies the microscopic structure of tissues.
2. Cytology is the study of cells, and embryology is the study of embryo development.
3. Hence, the correct option is (c).

Teacher's Note:
a) Histology deals with tissue organization.
b) Direct factual recall question from basic biology.

2. Which of the following statement is NOT true? [1 Mark]
(a) Most of the plant tissues are supportive type.
(b) Tissues ensure division of labour.
(c) Sedantry existence contribute to the organ system design in animals.
(d) Organ systems are far more complex in animals than in plants.

Answer: (c) Sedantry existence contribute to the organ system design in animals.

1. Animals exhibit active locomotion in search of food, mates, and shelter, which requires complex organ systems.
2. Plants are stationary or sedentary, hence they do not require complex locomotor or nervous organ systems.
3. Therefore, statement (c) has cause and effect reversed and is factually incorrect.
4. Hence, the correct option is (c).

Teacher's Note:
a) Careful reading of plant and animal physiological differences is essential.
b) Sedentary lifestyle is a characteristic of plants, not animals.

3. Many kinds of tissues organise to form a/an [1 Mark]
(a) organ
(b) organ system
(c) body system
(d) organelle

Answer: (a) organ

1. Cells group together to form tissues, and different types of tissues combine to form an organ.
2. Organs further group together to form organ systems.
3. Hence, the correct option is (a).

Teacher's Note:
a) Follow the biological hierarchy: Cell \(\rightarrow\) Tissue \(\rightarrow\) Organ \(\rightarrow\) Organ System \(\rightarrow\) Organism.
b) Multiple tissue types coordinate to execute specific organ functions.

4. Parenchyma is a type of ____ [1 Mark]
(a) simple tissue
(b) complex tissue
(c) xylem
(d) phloem

Answer: (a) simple tissue

1. Plant tissues are broadly classified into meristematic and permanent tissues.
2. Permanent tissues are further divided into simple permanent tissues (parenchyma, collenchyma, sclerenchyma) and complex permanent tissues (xylem, phloem).
3. Hence, the correct option is (a).

Teacher's Note:
a) Simple tissues are made of only one type of structurally and functionally similar cells.
b) Xylem and phloem are complex tissues made of multiple cell types.

5. Which of the following is not a simple tissue? [1 Mark]
(a) xylem
(b) parenchyma
(c) collenchyma
(d) sclerenchyma

Answer: (a) xylem

1. Parenchyma, collenchyma, and sclerenchyma are all simple permanent tissues in plants.
2. Xylem is a complex permanent tissue composed of tracheids, vessels, xylem parenchyma, and xylem fibers.
3. Hence, the correct option is (a).

Teacher's Note:
a) Complex tissues transport water, minerals, and food across the plant body.
b) Pay close attention to the negative word 'not' in the question stem.

6. The husk of the coconut is made up of? [1 Mark]
(a) collenchyma
(b) sclerenchyma
(c) apical meristem
(d) intercalary meristem

Answer: (b) sclerenchyma

1. Sclerenchyma tissue is composed of dead, thick-walled cells containing lignin depositions.
2. It provides mechanical strength, rigidity, and hardness to plant parts such as the husk of coconut.
3. Hence, the correct option is (b).

Teacher's Note:
a) Lignin acts as a chemical cement that hardens cell walls.
b) A classic NCERT textbook example for the function of sclerenchyma cells.

7. The basic principle based on which categorise plant tissues as meristematic and permanent is: [1 Mark]
(a) capacity to do photosynthesis
(b) capacity to divide
(c) capacity to locomote
(d) complexity to perform a function.

Answer: (b) capacity to divide

1. Plant tissues are broadly classified based on their ability to divide actively.
2. Meristematic tissues consist of actively dividing cells, whereas permanent tissues have lost the capacity to divide.
3. Hence, the correct option is (b).

Teacher's Note:
a) Plant classification depends on cell division capability.
b) Do not confuse physiological functions like photosynthesis with tissue types.

8. Which type of tissue has lignified cell walls? [1 Mark]
(a) Parenchyma
(b) Collenchyma
(c) Sclerenchyma
(d) cambium

Answer: (c) Sclerenchyma

1. Sclerenchyma cells are dead at maturity and possess thick, lignified secondary cell walls.
2. Lignin acts as a chemical substance that acts as cement and hardens the cell walls.
3. Hence, the correct option is (c).

Teacher's Note:
a) Lignin provides mechanical strength and rigidity to plant parts.
b) Parenchyma has thin cellulose walls, and collenchyma has pectin/cellulose thickenings.

9. Which tissue is responsible for the length of the plant? [1 Mark]
(a) Apical meristem
(b) lateral meristem
(c) Intercalary meristem
(d) Epidermis

Answer: (a) Apical meristem

1. Apical meristems are located at the growing tips of stems and roots.
2. They are primarily responsible for an increase in the length of the plant axis.
3. Hence, the correct option is (a).

Teacher's Note:
a) Apical meristems drive primary growth in plants.
b) Lateral meristems are responsible for thickness rather than length.

10. The girth of the stem or root increases due to ___ [1 Mark]
(a) Apical meristem
(b) Cambium
(c) Intercalary meristem
(d) Epidermis

Answer: (b) Cambium

1. Lateral meristems, such as the cambium, are found along the lateral sides of stems and roots.
2. They cause secondary growth, increasing the girth or thickness of the plant.
3. Hence, the correct option is (b).

Teacher's Note:
a) Lateral meristems are responsible for secondary growth.
b) Intercalary meristems increase length at internodes.

11. Which meristem is present at the base of the leaves or internodes on twigs? [1 Mark]
(a) Apical meristem
(b) Cambium
(c) Intercalary meristem
(d) Epidermis

Answer: (c) Intercalary meristem

1. Intercalary meristems lie localized at the internodes or the base of leaves.
2. They help in increasing the length of plant parts such as leaves and internodes.
3. Hence, the correct option is (c).

Teacher's Note:
a) Intercalary meristem is a derivative of apical meristem trapped behind.
b) It is commonly active in monocots and grasses.

12. Which of the following statements is incorrect? [1 Mark]
(a) Some tissues in plants divide throughout the life
(b) Cell growth in animals is more uniform as compared to plants
(c) Animals have more dead tissues as compared to plants
(d) There is no demarcation of dividing and non-dividing regions in animals

Answer: (c) Animals have more dead tissues as compared to plants

1. Plants possess a large amount of dead supportive tissues like sclerenchyma and cork to provide structural rigidity.
2. Animals mostly consist of living tissues, making statement (c) incorrect.
3. Hence, the correct option is (c).

Teacher's Note:
a) Plant structural habits demand dead mechanical tissue support.
b) Animal growth is uniform, and meristematic regions are absent in them.

13. What are the identifying features of meristematic tissues? [1 Mark]
(a) thick cellulose wall, small vacuoles, dense cytoplasm, small nuclei
(b) thin cellulose wall, almost no vacuoles, dense cytoplasm, prominent nuclei
(c) thin cellulose wall,no vacuoles, sparse cytoplasm, prominent nuclei

Answer: (b) thin cellulose wall, almost no vacuoles, dense cytoplasm, prominent nuclei

1. Meristematic cells are actively dividing and require dense cytoplasm and prominent nuclei.
2. They have thin cellulose walls to facilitate easy cell division and lack large vacuoles as they do not store waste or water.
3. Hence, the correct option is (b).

Teacher's Note:
a) Vacuoles are absent or extremely small in meristematic cells.
b) Watch out for options confusing thin cell walls with thick cell walls.

14. A permanent slide shows thin walled isodiametric cells with a large vacuole. The slide contains: [1 Mark]
(A) Parenchyma cells
(B) Nerve cells
(C) Sclerenchyma cells
(D) Collenchyma cells

Answer: (A) Parenchyma cells

1. Parenchyma cells are living, thin-walled, and isodiametric in shape with a prominent central vacuole.
2. Collenchyma cells have unevenly thickened cell walls.
3. Sclerenchyma cells have thick, lignified secondary cell walls.
4. Hence, the correct option is (A).

Teacher's Note:
a) Parenchyma is a type of simple permanent tissue.
b) Remember that isodiametric means roughly equal in all dimensions.

15. Aditi observed following observations while looking into a permanent slide. [1 Mark]
(i) Cells are long and cylindrical
(ii) Light and dark bands are present.
It could be a slide of :
(A) striated muscle fibre
(B) smooth muscle fibre
(C) neuron
(D) parenchyma cells

Answer: (A) striated muscle fibre

1. Striated muscle fibres are long, cylindrical, unbranched, and multinucleate with alternating light and dark bands.
2. Smooth muscle fibres are spindle-shaped without bands.
3. Neurons are elongated cells with an axon, dendrites, and cell body.
4. Hence, the correct option is (A).

Teacher's Note:
a) Light and dark banding (striations) is characteristic of skeletal or striated muscle tissue.
b) Striated muscles are voluntary muscles attached to bones.

16. The inner lining of blood vessels is made up of which tissues? [1 Mark]
(A) Nervous tissue
(B) Epithelial tissue
(C) Connective tissue
(D) Muscle tissue

Answer: (B) Epithelial tissue

1. The inner lining of blood vessels is formed by simple squamous epithelium, known as endothelium.
2. Epithelial tissues form protective coverings and barriers in the body.
3. Hence, the correct option is (B).

Teacher's Note:
a) Simple squamous epithelium consists of a single layer of flat, tile-like cells.
b) It facilitates rapid diffusion of substances across surfaces.

17. What is a tissue? [1 Mark]

Answer:
1. A tissue is a group of cells that are similar in structure and work together to achieve a particular function.
2. All cells in a tissue originate from a common embryonic origin.

Teacher's Note:
a) Cells of a tissue may or may not be identical in shape.
b) Division of labour occurs at the tissue level in multicellular organisms.

18. What is histology? [1 Mark]

Answer:
1. Histology is the branch of biology that studies the microscopic structure of tissues.
2. It is also known as microanatomy.

Teacher's Note:
a) Histology involves sectioning, staining, and examining tissues under a microscope.
b) It helps in understanding the correlation between tissue structure and function.

19. Explain the statement 'Tissues exhibit division of labour'. Give examples. [2 Marks]

Answer:
1. In multicellular organisms, different groups of cells specialize to perform specific functions, which is known as division of labour at the tissue level.
2. Examples include muscle tissue specialized for movement, and nervous tissue specialized for transmission of messages.

Teacher's Note:
a) Division of labour increases the overall efficiency of a complex organism.
b) In plants, vascular tissues specifically handle the transport of water and food.

20. What is the utility of tissues in multi-cellular organisms? [2 Marks]

Answer:
1. Tissues provide structural strength and mechanical support to multicellular bodies.
2. They bring about division of labour, allowing different organs to perform specialized tasks efficiently.

Teacher's Note:
a) Organisms with higher complexity require distinct tissues to manage physiological demands.
b) It allows multicellular organisms to maintain higher levels of organization and survival efficiency.

21. Why do plants have more dead tissues as compared to animals? [2 Marks]

Answer:
1. Plants lead a stationary or fixed lifestyle, requiring immense mechanical support to stand upright against wind and gravity.
2. Dead supportive tissues like sclerenchyma provide this structural rigidity without needing metabolic energy for maintenance.

Teacher's Note:
a) Dead tissues deaden metabolic upkeep costs for stationary organisms.
b) Animals are mobile and require living tissues to respond actively to their environment.

22. Why do plant tissue require less amount of energy in comparison to animal tissues? [2 Marks]

Answer:
1. Plants are stationary and do not move from place to place, so they expend very little energy on locomotion.
2. A large proportion of plant tissues consists of dead cells that do not require active metabolic maintenance.

Teacher's Note:
a) Energy demands in plants are far lower than in animals.
b) Most living cells in plants are restricted to meristematic regions.

23. Why do animals tissues require more energy as compared to plant tissues? [2 Marks]

Answer:
1. Animals are motile and constantly move in search of food, shelter, and mates, which demands high energy.
2. Most animal tissues are composed of living cells with high metabolic rates.

Teacher's Note:
a) Locomotion requires coordinated action of muscular and nervous tissues.
b) Higher metabolic activity necessitates continuous nutrient and oxygen supply.

24. Name types of simple tissues. [1 Mark]

Answer:
1. The three main types of simple plant tissues are Parenchyma, Collenchyma, and Sclerenchyma.

Teacher's Note:
a) Simple tissues are composed of only one type of structurally and functionally similar cells.

25. Where is apical meristem found? [1 Mark]

Answer:
1. Apical meristem is found at the growing tips of roots and stems, such as the apex of root and shoot.

Teacher's Note:
a) It is responsible for primary growth, which increases the length of the plant body.

26. Which tissue helps in increasing the length of stem and root? [1 Mark]

Answer:
1. Apical meristematic tissue helps in increasing the length of stem and root.

Teacher's Note:
a) It undergoes continuous cell division to add new cells to plant axes.

27. Which tissues are responsible for the axial growth of plants? [1 Mark]

Answer:
1. Apical meristems are responsible for the axial growth of plants.

Teacher's Note:
a) Axial growth refers to elongation along the main vertical axis of the plant.

28. Which tissue makes up the husk of coconut? [1 Mark]

Answer:
1. Sclerenchymatous tissue makes up the husk of a coconut.

Teacher's Note:
a) Sclerenchyma cells have thick lignified walls that provide extreme rigidity and tensile strength.

29. What are the constituents of phloem? [2 Marks]

Answer:
1. Phloem is composed of four elements: sieve tubes, companion cells, phloem parenchyma, and phloem fibres.

Teacher's Note:
a) Except for phloem fibres, all phloem elements are living cells.
b) Phloem is responsible for the transport of food material from leaves to other parts.

30. Name the tissue responsible for the movement in our body. [1 Mark]

Answer:
1. Muscular tissue is responsible for movement in our body.

Teacher's Note:
a) Muscle cells contain contractile proteins that shorten and lengthen to cause movement.

31. What does a neuron looks like? [2 Marks]

Answer:
1. A neuron consists of a central cell body (cyton) containing a nucleus and cytoplasm.
2. Hair-like extensions called dendrites arise from the cell body, and a long, cable-like process called the axon extends from it.

Teacher's Note:
a) Neurons are specialized for conducting nerve impulses rapidly.
b) They are the longest cells in the human body.

32. Identify which of the following plant tissues are living or dead? [3 Marks]
- Apical Meristem
- Parenchyma
- Aerenchyma
- Collenchyma
- Sclereids
- Tracheids
- Xylem Fibres
- Xylem Parenchyma
- Phloem fibre
- Phloem Parenchyma
- Vessel
- Sieve Tubes

Answer:
1. Apical Meristem: Living
2. Parenchyma: Living
3. Aerenchyma: Living
4. Collenchyma: Living
5. Sclereids: Dead
6. Tracheids: Dead
7. Xylem Fibres: Dead
8. Xylem Parenchyma: Living
9. Phloem fibre: Dead
10. Phloem Parenchyma: Living
11. Vessel: Dead
12. Sieve Tubes: Living (lacking a nucleus at maturity)

Teacher's Note:
a) Plant tissues are broadly classified into living (metabolically active cytoplasm) and dead (lacking protoplasm at maturity) types.
b) Xylem parenchyma is the only living element in xylem, while phloem fibres are the only dead element in phloem.
c) Sieve tubes are considered living because they possess cytoplasm and organelles despite lacking a nucleus.

33. Give three features of cardiac muscles. [3 Marks]

Answer:
1. Cardiac muscle fibres are cylindrical, branched, and uninucleate.
2. They are involuntary muscles that show rhythmic contraction and relaxation throughout life without fatigue.
3. Dark and light bands are present, and adjacent cells are joined at intercalated discs.

Teacher's Note:
a) Cardiac muscles are exclusively found in the walls of the heart.
b) Intercalated discs allow rapid spread of contraction impulses across cells.
c) Mentioning involuntary nature and branching is essential for full credit.

34. What are the functions of areolar tissue? [2 Marks]

Answer:
1. It acts as a supporting and packing tissue between organs lying in the body cavity.
2. It helps in the repair of tissues and fixes skin to underlying muscles.

Teacher's Note:
a) Areolar tissue is a type of loose connective tissue found between skin and muscles.
b) It contains fibroblasts, macrophages, and mast cells that aid in tissue repair and immunity.

35. List the characteristics of meristematic tissues. [3 Marks]

Answer:
1. Cells are actively dividing and have dense cytoplasm with prominent nuclei.
2. Cell walls are thin and made of cellulose.
3. Vacuoles are generally absent to prevent unnecessary storage and maintain high metabolic activity.

Teacher's Note:
a) Meristematic tissues are responsible for the growth in plants.
b) They are located at specific regions like root tips and shoot tips (apical meristems).

36. Where do we find intercalary meristem? [1 Mark]

Answer:
Intercalary meristem is found at the base of leaves or internodes, such as in the twig of grasses.

Teacher's Note:
a) It is located at the internodes and helps in increasing the length of plant parts.

37. Which tissues are responsible for the secondary growth of plants? [1 Mark]

Answer:
Lateral meristems (such as cork cambium and vascular cambium) are responsible for the secondary growth of plants.

Teacher's Note:
a) Secondary growth leads to an increase in the girth or thickness of the stem and root.

38. What do you mean by 'Differentiation' in plant tissues? [2 Marks]

Answer:
1. It is the process by which cells derived from meristematic tissue take up a permanent shape, size, and function.
2. Specialized cells lose their ability to divide and form permanent tissues.

Teacher's Note:
a) Differentiation transforms unspecialized embryonic cells into specialized functional tissues.
b) It is essential for division of labor in multicellular organisms.

39. What is the shape of Parenchyma cells? [1 Mark]

Answer:
Parenchyma cells are generally isodiametric, meaning they have roughly equal dimensions (spherical, oval, or polygonal).

Teacher's Note:
a) They have thin cell walls and large central vacuoles for storing food and water.

40. What is the structure and nature of Parenchyma tissue? [2 Marks]

Answer:
1. Parenchyma is a living permanent tissue with thin cell walls made of cellulose and large intercellular spaces.
2. Cells possess a distinct nucleus, dense cytoplasm, and a large central vacuole for storage.

Teacher's Note:
a) It forms the fundamental packing tissue in plants.
b) Intercellular spaces allow gaseous exchange and storage.

41. Where do you find Parenchyma cells in Plants? [1 Mark]

Answer:
Parenchyma cells are found in the soft parts of plants such as the cortex and pith of stems and roots, and the mesophyll of leaves.

Teacher's Note:
a) They are widely distributed in ground tissues of all plant organs.

42. What are the identifying features of collenchyma tissue? [2 Marks]

Answer:
1. Collenchyma cells are living with irregular thickenings at the corners due to pectin and cellulose deposition.
2. They have very little intercellular space.

Teacher's Note:
a) Pectin deposition at corners provides mechanical support and high tensile strength.
b) It is primarily found in the peripheral regions of stems.

43. Where do you find collenchyma tissues in plants? [1 Mark]

Answer:
Collenchyma tissues are found in the leaf stalks (petioles), below the epidermis in stems, and in the margins of leaves.

Teacher's Note:
a) Its distribution provides mechanical support to growing plant organs.

44. Which tissue primarily attributes to easy bending of various parts of plants (like stem, leaves)? [1 Mark]

Answer:
Collenchyma tissue.

Teacher's Note:
a) Collenchyma provides flexibility and mechanical support, enabling easy bending without breaking.

45. Which plant tissues are often called as stone cells? [1 Mark]

Answer:
Sclereids (a type of sclerenchyma tissue).

Teacher's Note:
a) Sclereids have extremely thick, lignified walls with narrow lumens, giving them a hard, stone-like texture.

46. Deepa was shown two slides of plant tissues: parenchyma and sclerenchyma. She can identify sclerenchyma by the [1 Mark]
(a) location of nucleus
(b) size of cells
(c) thickness of cell walls
(d) position of vacuoles

Answer: (C) thickness of cell walls

1. Sclerenchyma cells possess heavily lignified, thick secondary cell walls.
2. Parenchyma cells have thin cellulose cell walls.
3. Therefore, the thickness of cell walls is the key identifying feature.
4. Hence, the correct option is (C).

Teacher's Note:
a) Lignin deposition makes sclerenchyma walls uniformly thick and dead at maturity.

47. What is aerenchyma? [1 Mark]

Answer:
Aerenchyma is a specialized type of parenchyma tissue containing large air cavities, found in aquatic plants to provide buoyancy.

Teacher's Note:
a) It helps hydrophytes float and facilitates gaseous exchange in aquatic environments.

48. What is the primary surface tissue of the entire plant? [1 Mark]

Answer:
Epidermis.

Teacher's Note:
a) The epidermis forms a continuous single-layered outer covering that protects the inner plant organs from mechanical injury and water loss.

49. How does epidermis help xerophytes? [2 Marks]

Answer:
1. In xerophytes, the epidermis may be thicker to protect against water loss.
2. It often secretes a thick, waxy, water-resistant layer on outer surfaces called cutin to prevent excessive transpiration.

Teacher's Note:
a) Xerophytes are plants adapted to dry habitats.
b) The waxy cuticle acts as a major barrier against desiccation in harsh environments.

50. Which meristem replaces epidermis as the protective covering? [1 Mark]

Answer:
1. Cork cambium (phellogen) replaces the epidermis as a protective secondary meristem in older woody stems and roots.

Teacher's Note:
a) Secondary growth forms periderm from cork cambium.
b) This protects internal tissues from mechanical injury and water loss.

51. List the functions of epidermis. [3 Marks]

Answer:
1. It provides protection against mechanical injury and pathogen invasion.
2. It prevents excessive loss of water by secreting a cuticular layer.
3. Stomata present in the epidermis allow gaseous exchange and transpiration.

Teacher's Note:
a) The epidermis forms the outermost continuous protective layer of the plant body.
b) Specialized epidermal cells like root hairs absorb water and minerals.
c) Mentioning stomatal regulation adds completeness to the answer.

52. Which tissue is known as living mechanical tissue? [1 Mark]

Answer:
1. Collenchyma is known as the living mechanical tissue.

Teacher's Note:
a) It provides mechanical strength along with flexibility to plant organs.
b) Unlike sclerenchyma, collenchyma cells possess living protoproplasm.

53. Why the cell walls of collenchyma tissues are unevenly thickened? [2 Marks]

Answer:
1. The cell walls of collenchyma show localized depositions of pectin and cellulose.
2. These depositions are specifically concentrated at the corners of the cells, resulting in uneven thickening.

Teacher's Note:
a) Pectin deposition provides high tensile strength and flexibility.
b) This structural adaptation allows bending without breaking.

54. Are Collenchyma tissues present in roots of the plants? [1 Mark]

Answer:
1. No, collenchyma tissues are generally absent in the roots of plants.

Teacher's Note:
a) They are typically found in the hypodermis of dicot stems and petioles.
b) Roots do not require the flexible mechanical support provided by collenchyma.

55. Usually Shrubs and herbs grow in open places and are exposed to forceful winds. But they do not break. Why? [2 Marks]

Answer:
1. They possess collenchyma tissue in their peripheral regions.
2. Collenchyma provides mechanical support with high flexibility, allowing them to bend easily in high winds without breaking.

Teacher's Note:
a) Flexibility is crucial for herbaceous plants subjected to dynamic environmental stresses.
b) The uneven cell wall thickening aids this specialized resilience.

56. Name the chemical released by cork cells? [1 Mark]

Answer:
1. Suberin

Teacher's Note:
a) Suberin makes cork cells impermeable to gas and water molecules.
b) It protects the underlying plant tissues effectively.

57. How are complex tissues different from simple tissues? [3 Marks]

Answer:
1. Simple tissues are made of only one type of structurally and functionally similar cells, whereas complex tissues consist of more than one type of cells.
2. Simple tissues perform uniform tasks such as storage, photosynthesis, or support.
3. Complex tissues coordinate to perform common specialized tasks like long distance transport of water and food.

Teacher's Note:
a) Parenchyma, collenchyma, and sclerenchyma are simple tissues.
b) Xylem and phloem are examples of complex tissues.
c) Division of labor is more advanced in complex tissues.

58. Name two types of complex tissues. [1 Mark]

Answer:
1. Xylem and Phloem

Teacher's Note:
a) Both are vascular tissues found in vascular plants.
b) They form continuous conducting channels through roots, stems, and leaves.

59. Why are Xylem and Phloem called vascular or conducting tissues? [2 Marks]

Answer:
1. They form a tube-like vascular system in the plant body.
2. They conduct water, minerals, and organic food materials across different plant organs, hence called conducting tissues.

Teacher's Note:
a) Vascular bundles facilitate bulk transport over long distances.
b) Xylem transports upwardly while phloem is bidirectional.

60. Which plant tissue is considered to have played an important role in survival of terrestrial plants? [1 Mark]

Answer:
1. Vascular tissue (Xylem and Phloem)

Teacher's Note:
a) Efficient internal transport made large land plants evolutionarily successful.
b) It solved the challenge of water scarcity away from aquatic sources.

61. Why vascular tissue is considered a distinctive feature responsible for survival of plants in terrestrial plants? [3 Marks]

Answer:
1. Terrestrial plants have their absorptive organs (roots) separated from photosynthetic organs (leaves).
2. Vascular tissues provide the necessary transport mechanism to move water from roots to leaves and manufactured food from leaves to other parts.
3. They also provide mechanical strength to withstand terrestrial conditions.

Teacher's Note:
a) Without vascular tissue, tall plant growth on land would be impossible.
b) It represents a major evolutionary milestone in botany.
c) Lignified elements in xylem provide structural rigidity.

62. Is xylem (or phloem) homogenous tissue or heterogeneous tissue? [1 Mark]

Answer:
1. Heterogeneous tissue

Teacher's Note:
a) They are heterogeneous because they are composed of multiple types of cells working together.
b) Contrast with simple tissues which are homogeneous.

63. List the cellular elements of xylem tissue? [2 Marks]

Answer:
1. Tracheids, vessels, xylem parenchyma, and xylem fibres.

Teacher's Note:
a) Except for xylem parenchyma, all other xylem elements are dead at maturity.
b) Tracheids and vessels are the main water-conducting elements.

64. What is the role of xylem tissue? [2 Marks]

Answer:
1. Transport of water and dissolved minerals upwards from roots to aerial parts.
2. Providing mechanical strength and rigidity to the plant body.

Teacher's Note:
a) Movement is largely unidirectional.
b) Lignified walls contribute to structural support.

65. Name the cellular elements of Phloem tissue. [2 Marks]

Answer:
1. Sieve tubes, companion cells, phloem parenchyma, and phloem fibres.

Teacher's Note:
a) Phloem fibres are dead, while the other three elements are living cells.
b) Sieve tubes are the primary food-conducting channels in angiosperms.

66. List functions of phloem tissue? [2 Marks]

Answer:
1. Transport of organic food material synthesized during photosynthesis from leaves to storage organs and growing regions.
2. Transporting food bidirectionally as per plant requirements.

Teacher's Note:
a) Phloem transport requires metabolic energy input.
b) Companion cells help control sieve tube activities.

67. Which Phloem cellular element has tubular structure with perforated walls? [1 Mark]

Answer:
1. Sieve tube element

Teacher's Note:
a) Perforated end walls form sieve plates.
b) This structure facilitates easy translocation of food sap.

68. Why are Xylem and Phloem known as conducting tissues? [2 Marks]

Answer:
1. They act as channels for the conduction of materials through the plant.
2. Xylem conducts water and minerals, whereas phloem conducts prepared food.

Teacher's Note:
a) Conduction implies active internal translocation.
b) They span continuously from root tips to leaf tips.

69. Why are Xylem and Phloem called as vascular tissues? [2 Marks]

Answer:
1. They are organized into distinct pipe-like strands known as vascular bundles.
2. The term vascular derives from the Latin word for little vessels, reflecting their fluid-carrying pipeline nature.

Teacher's Note:
a) Vascular bundles are foundational components of plant anatomy.
b) They run parallel or form a ring depending on plant type (monocot vs dicot).

70. Why are Xylem and Phloem known as complex permanent tissues? [2 Marks]

Answer:
1. They are complex because they are made of more than one type of cells.
2. They are permanent because their constituent cells have lost the ability to divide and have attained a mature, specialized state.

Teacher's Note:
a) Permanent tissues arise from differentiation of meristematic cells.
b) Complex permanent tissues perform specialized physiological transport functions.

71. Why do meristematic cells lack vacuoles? [2 Marks]

Answer:
1. Meristematic cells are actively dividing cells with dense cytoplasm and thin cellulose walls.
2. Vacuoles provide turgidity and store cell sap in mature cells, which would hinder rapid division and metabolic activity if present in excess.

Teacher's Note:
a) Prominent nuclei and abundant cytoplasm are key features of meristematic cells.
b) Vacuolization occurs only after cells undergo differentiation into permanent tissues.

72. Muscles contain special proteins called ________ that help in muscle movement. [1 Mark]
(A) recptor proteins
(B) enzymes
(C) nucleo proteins (DNA, RNA)
(D) contractile proteins (actin and myosin)

Answer: (D) contractile proteins (actin and myosin)

1. Muscle contraction and relaxation are brought about by specialized proteins.
2. Actin and myosin are the primary contractile proteins found in muscle tissue.
3. Hence, the correct option is (D).

Teacher's Note:
a) Muscle tissue enables body movements through contraction and relaxation cycles.
b) Actin and myosin filaments slide past each other during contraction.