TWO MARKS QUESTIONS
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6. List the characteristic features of meristematic tissue
7. Differentiate between sclerenchyma and parenchyma tissues.
8. Water hyacinth floats on water surface. Explain.
9. Why is epidermis important for the plants?
10. List the constituents of xylem and phloem.
Answers
Answer:
6. They have very small and few vacuoles.
The meristematic tissue is living and thin-walled.
The protoplasm of the cells is very dense
7. Parenchyma:
(1) Cells are thin walled and unspecialised. (2) These are living cells. (3) Cells are usually loosely packed with large intercellular space. (4) Stores nutrients and water in stem and roots. (5) Some cells contain chlorophyll, called as chlorenchyma and perform photosynthesis. Other cells have large air cavities, called as aerenchyma, which provide buoyancy to the hydrophytic plants.
Sclerenchyma:
(1) Cells are thick walled and lignified. (2) Tissues are made up of dead cells. (3) No intercellular spaces between the cells are found. (4) Provides strength to the plant parts. (5) The cells are long and narrow, make the plant hard and stiff. The tissue is present in the stem around vascular bundles, in veins of leaves and hard covering of seeds and nuts.
8. many aquatic plants, parenchyma cells have large air cavities to give buoyancy to the plant and enable them to float in water. Such, parenchyma cells are called as aerenchyma. Water hyacinth possess such cells, which make them enable to float in water.
9. Epidermis, in botany, outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant. The epidermis and its waxy cuticle provide a protective barrier against mechanical injury, water loss, and infection.
10. xylem- tracheids, vessel elements, xylem parenchyma, xylem sclerenchyma and xylem fibres.
phloem- companion cells, sieve tubes, bast fibres, phloem fibres, intermediary cells and the phloem parenchyma.
Explanation: