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Q1. Sclerenchyma cells are:
Sclerenchyma cells are long and narrow with tapering ends. They are thick-walled due to the deposition of lignin, which makes them hard and rigid. These cells are dead at maturity and provide mechanical support to the plant. They are commonly found in the husk of coconut, fibres, and xylem vessels.
Q2. Differentiation results in formation of:
Differentiation is the process by which cells derived from meristematic tissue undergo structural changes to become specialised for specific functions. This process results in the formation of permanent tissues (like parenchyma, collenchyma, and sclerenchyma) that have lost the ability to divide.
Q3. Cells seen under microscope in stem section are:
A stem section viewed under a microscope shows different types of cells—parenchyma, collenchyma, sclerenchyma, xylem, and phloem. These cells vary in shape, size, and wall thickness, reflecting their different functions in the plant. This diversity is what makes plant tissues complex.
Q4. Permanent tissues are formed from:
Permanent tissues are formed from meristematic cells. Meristematic cells divide and produce new cells. These new cells undergo differentiation and lose their ability to divide, becoming permanent tissues specialised for specific functions like support, storage, or conduction.
Q5. Cambium is an example of:
Cambium is an example of lateral meristem. It is located along the sides of stems and roots and is responsible for secondary growth (increase in girth). Lateral meristems include the vascular cambium and cork cambium, which help in increasing the thickness of woody plants.
Q6. Removal of root tips stops growth because:
Removal of root tips stops growth because the apical meristem (a type of meristematic tissue) is removed. Apical meristems are responsible for growth in length (primary growth). When the tips are cut, the meristematic cells are no longer present to produce new cells for elongation.
Q7. Intercellular spaces in collenchyma are:
Intercellular spaces in collenchyma are very little or absent. Collenchyma cells are closely packed with only small spaces between them. The cells have thickened corners, which provide mechanical support while still allowing flexibility, making collenchyma ideal for supporting growing plant parts.
Q8. Meristematic tissue is absent in:
Meristematic tissue is absent in mature permanent tissue. Meristematic tissues are found only in specific growing regions of the plant (root tips, shoot tips, and cambium). Once cells differentiate into permanent tissues, they lose their ability to divide and are no longer meristematic.
Q9. Newly formed meristematic cells are:
Newly formed meristematic cells are similar to the original meristem cells. They are undifferentiated, have thin cell walls, dense cytoplasm, and a prominent nucleus. They retain the ability to divide and can later differentiate into various permanent tissues.
Q10. Collenchyma cells are:
Collenchyma cells are living and elongated with irregularly thickened cell walls. They provide mechanical support and flexibility to growing plant parts. Their cell walls are thickened at the corners, and they are found in leaf stalks, stems, and petioles.
Q11. Sclerenchyma provides:
Sclerenchyma provides strength to the plant. Its cells have thick, lignified walls and are dead at maturity. This tissue makes the plant hard and rigid, helping it withstand various stresses. It is found in fibres, husk, and xylem vessels.
Q12. Which tissue is responsible for plant growth?
Meristematic tissue is responsible for plant growth. It consists of actively dividing cells that produce new cells for growth in length (apical meristems) and girth (lateral meristems). This allows plants to grow throughout their lives.
Q13. Growth does not occur in permanent tissue because cells:
Growth does not occur in permanent tissue because the cells have lost their ability to divide. Permanent tissues are differentiated and specialised for specific functions like support, conduction, or storage. They do not undergo cell division.
Q14. Function of parenchyma is mainly:
The main function of parenchyma is the storage of food. Parenchyma cells are living, thin-walled, and have large intercellular spaces. They store starch, proteins, and other nutrients. Parenchyma also functions in photosynthesis (chlorenchyma) and aerenchyma (buoyancy).
Q15. Sclerenchyma cells are:
Sclerenchyma cells are dead at maturity. They have thick, lignified cell walls that provide mechanical support. Because they are dead, they do not have a nucleus or cytoplasm, making them more efficient at providing rigid support without requiring energy.
Q16. Intercalary meristem is located:
Intercalary meristem is located near the nodes (at the base of internodes) in plants. It is a type of meristematic tissue found in grasses and some other monocots. It helps in the regrowth of grass after grazing and in the elongation of internodes.
Q17. Which meristem increases the length of roots and stems?
Apical meristems increase the length of roots and stems. They are located at the tips of roots and shoots and are responsible for primary growth (growth in length). The cells produced by apical meristems differentiate to form various tissues, allowing the plant to grow taller and roots to grow deeper.
Q18. Cells that lose the ability to divide form:
Cells that lose the ability to divide form permanent tissue. These cells are differentiated and specialised for specific functions. They are derived from meristematic cells but no longer divide. Permanent tissues include parenchyma, collenchyma, sclerenchyma, xylem, and phloem.
Q19. Flexibility in plants is due to:
Flexibility in plants is due to collenchyma. Collenchyma cells have irregularly thickened walls and are living. They provide mechanical support and flexibility, allowing plant parts to bend without breaking. This tissue is found in leaf stalks, petioles, and young stems.
Q20. Collenchyma provides:
Collenchyma provides mechanical support to young and growing plant parts. Its thick-walled cells give strength and flexibility, allowing the plant to bend without breaking. This tissue is particularly important in regions where the plant is still growing.
Q21. Parenchyma cells have:
Parenchyma cells have thin cell walls. They are living cells with a prominent nucleus and cytoplasm. Their thin walls allow for easy exchange of materials, making them ideal for storage and metabolic functions.
Q22. Photosynthesis occurs in:
Photosynthesis occurs in chlorenchyma, a type of parenchyma that contains chloroplasts. Chlorenchyma is found in the mesophyll of leaves and in some stems. It is responsible for capturing light energy and converting it into chemical energy through photosynthesis.
Q23. Cell walls of collenchyma are:
Collenchyma cells have cell walls that are irregularly thickened at the corners. This uneven thickening provides mechanical support while still allowing flexibility. The thickening is due to the deposition of cellulose and pectin.
Q24. Collenchyma is found:
Collenchyma is found in leaf stalks (petioles) just below the epidermis. It is also found in young stems, petioles, and the veins of leaves. Its location provides mechanical support and flexibility to these growing plant parts.
Q25. Coconut husk is made of:
Coconut husk is made of sclerenchyma. The husk consists of thick-walled, dead sclerenchyma cells that provide strength and rigidity. These fibres are used in making ropes, mats, and brushes. Sclerenchyma is also found in other plant parts like stems and fruit walls.
Q26. Root tips stop growing after cutting because:
Root tips stop growing after cutting because the meristematic tissue (apical meristem) is removed. The apical meristem is responsible for producing new cells for root growth. Without it, the root can no longer grow in length. This demonstrates the importance of meristematic tissue in plant growth.
Q27. Simple permanent tissue is made of:
Simple permanent tissue is made of only one type of cells. These tissues are relatively uniform and perform a single function. Examples include parenchyma (storage), collenchyma (support), and sclerenchyma (strength). Complex tissues, like xylem and phloem, are made of multiple cell types.
Q28. Meristematic tissue cells are:
Meristematic tissue cells are highly active. They continuously divide to produce new cells. These cells have dense cytoplasm, thin cell walls, and a prominent nucleus. They are responsible for the growth and development of the plant.
Q29. Sclerenchyma is present:
Sclerenchyma is present around vascular bundles, forming a sheath that provides strength and protection. It is also found in fibres, seed coats, and fruit walls. Its thick, lignified walls make it an important supportive tissue in plants.
Q30. Dividing tissue is also known as:
Dividing tissue is also known as meristematic tissue. It consists of cells that are actively dividing and are responsible for growth in plants. Meristematic tissues are found in root tips, shoot tips, and lateral meristems (cambium).
Q31. Sclerenchyma is mainly responsible for:
Sclerenchyma is mainly responsible for rigidity in plants. Its thick, lignified cell walls make the plant hard and stiff. This tissue provides structural support and helps the plant withstand mechanical stress, making it essential for standing upright.
Q32. Process by which cells become specialised is called:
Differentiation is the process by which cells become specialised to perform specific functions. During differentiation, cells derived from meristems undergo structural changes, developing into different tissue types like parenchyma, collenchyma, and sclerenchyma.
Q33. Internal space in sclerenchyma cells is:
Internal space (lumen) in sclerenchyma cells is often absent or very small. The cells have thick, lignified walls that fill most of the cell volume. At maturity, the protoplast dies, leaving a narrow lumen, which makes the tissue rigid and strong.
Q34. Fig. 12.4 shows types of:
Fig. 12.4 typically shows the types of simple permanent tissues: parenchyma, collenchyma, and sclerenchyma. These tissues are simple because they are made of only one type of cell and perform specific functions like storage, support, and strength.
Q35. Parenchyma cells are:
Parenchyma cells are living and relatively unspecialised. They have thin cell walls, large intercellular spaces, and perform various functions like storage, photosynthesis (chlorenchyma), and buoyancy (aerenchyma). They are the most common type of plant tissue.
Q36. Growth in plants occurs only in specific regions because:
Growth in plants occurs only in specific regions because meristematic tissue is present only there. Meristems are located at root tips, shoot tips, and lateral regions. These are the only places where cells actively divide, allowing the plant to grow in length and girth.
Q37. Meristematic cells lack:
Meristematic cells lack large vacuoles. They have dense cytoplasm and a prominent nucleus. The absence of large vacuoles allows these cells to divide actively without being hindered by large central vacuoles, which are typical of mature permanent cells.
Q38. Longest roots are found in onion:
Longest roots are found in onions with intact tips. The intact root tips contain apical meristem, which allows the root to grow continuously. When the tips are cut, the meristem is removed, and growth stops, resulting in shorter roots.
Q39. Meristematic cells have:
Meristematic cells have dense cytoplasm. They have a prominent nucleus and thin cell walls. The dense cytoplasm allows for rapid cell division and growth. These cells are metabolically active and ready to divide.
Q40. Aerenchyma helps plants to:
Aerenchyma helps plants to float. It is a specialised parenchyma tissue found in aquatic plants that contains large air spaces (cavities). These air spaces provide buoyancy, allowing the plant to float in water, and also help in gas exchange.
Q41. Onion with intact root tips shows:
Onions with intact root tips show normal growth. The intact root tips contain meristematic tissue (apical meristem), which allows the roots to grow continuously. This demonstrates that meristematic tissue is essential for normal root growth.
Q42. Tissue that makes plant hard and stiff is:
Sclerenchyma makes the plant hard and stiff. Its thick, lignified cell walls provide mechanical strength. This tissue is responsible for the hardness of woody plants, coconut husk, and seed coats.
Q43. Which meristem is responsible for increase in girth?
Lateral meristem is responsible for an increase in girth (secondary growth). It is found in the cambium, which produces new cells that add to the thickness of stems and roots. This is different from apical meristems, which increase length.
Q44. The most common simple permanent tissue is:
The most common simple permanent tissue is parenchyma. It is found in nearly all parts of the plant and serves various functions like storage, photosynthesis, and secretion. Parenchyma cells are living, thin-walled, and relatively unspecialised.
Q45. Meristematic tissue helps in:
Meristematic tissue helps in growth. It consists of actively dividing cells that produce new cells for the growth of the plant. These cells are responsible for increasing the length (apical meristems) and girth (lateral meristems) of the plant.
Q46. Cell walls of meristematic tissue are:
Cell walls of meristematic tissue are thin and cellulosic (made of cellulose). They are not thickened or lignified, allowing the cells to divide easily. This thinness is characteristic of actively dividing cells.
Q47. Parenchyma containing chlorophyll is called:
Parenchyma containing chlorophyll is called chlorenchyma. It is found in the mesophyll of leaves and in some stems. Chlorenchyma cells perform photosynthesis, converting light energy into chemical energy.
Q48. Aerenchyma is found in:
Aerenchyma is found in aquatic plants. It is a type of parenchyma with large air spaces that provide buoyancy and help in gas exchange. This tissue allows aquatic plants to float in water and obtain oxygen for respiration.
Q49. Walls of sclerenchyma are thick due to:
The walls of sclerenchyma are thick due to the deposition of lignin. Lignin is a complex organic polymer that gives strength and rigidity to plant cell walls. It makes the tissue hard, woody, and water-resistant, providing excellent mechanical support.
Q50. Apical meristem is found at:
Apical meristem is found at the growing tips of roots and stems. It is responsible for primary growth, increasing the length of roots and shoots. The cells in the apical meristem continuously divide, producing new cells that differentiate into various tissues.