This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Transpiration”.
1. Loss of water from plants in the form of water vapour is called___________
a) Surface tension
c) Ascent of sap
Explanation: Transpiration is the process by which aerial part of the plant (mainly leaves) looses water in the form of water vapour.
2. Mark the one, which is NOT the form of transpiration?
a) Radical transpiration
b) Cuticular transpiration
c) Lenticular transpiration
d) Stomatal transpiration
Explanation: Transpiration is termed on the basis of its occurrence through the plant like stomata, cuticle, and lenticles and called as stomatal, cuticular, and lenticular transpiration.
3. Which of the following statement is NOT true regarding the cuticles of the plant?
a) Wax like covering of leaves
b) Cutin is the principal substance
c) Polymer of long chain fatty acids
d) It is mainly composed of the only cutin
Explanation: Cuticle is a layer of wax covering over a leaf and is primarily composed of both wax and cutin. It is meant to check transpiration.
4. What are lenticels?
a) Epidermal structure
b) A wax layer of leaves
c) Opening in the bark
d) Channel to transfer water
Explanation: Lenticels are the small opening in the bark of the plants, mainly in stem and root and allow the exchange of gases between the atmosphere and the inner cells.
5. Stomata acts as turgor-operated valves?
Explanation: Stomata is responsible for the exchange of gases between environment and plants and acts as a turgor operated valve.
6. How much percentage of total transpiration is done by stomata?
Explanation: Stomatal transpiration accounts for 90% of total transpiration done by plants while cuticular transpiration is 5-10% and lenticular transpiration is 1-5%.
7. Mark the one, which is NOT the characteristics of the guard cell?
a) Thickened inner wall
b) Connected end to end
c) Does not have chloroplast
d) Radial micellation
Explanation: The epidermal cells of guard cell show chloroplast. They have a thin outer wall and thick inner wall and constitute an important functional element of the plant.
8. Which light modulates osmoregulation of guard cell?
Explanation: Blue light activates proton pumping and stimulates the synthesis of osmotically active organic solutes and maintains the osmoregulation of guard cell.
9. What is guttation?
a) Exudation of xylem sap
b) Root pressure
c) Radial movement
d) Field capacity
Explanation: Guttation is the exudation of xylem sap from the leaves of the plants as the liquid droplets from the tip or edge.
10. Name the specialized pores from where guttation takes place.
c) Guard cell
Explanation: Hydathodes are the specialized pores in the leaves from where exudation of sap takes place by positive hydrostatic root pressure.
11. Which of the following statement is INCORRECT for transpiration?
a) It occurs by stomata, lenticels, and cuticle
b) Water comes out as water vapour
c) It occurs in all plants
d) Root pressure is involved
Explanation: Transpiration is a universal process that occurs in all plants. It does not involve root pressure but the water comes out from a plant in the form of water vapour.
Sanfoundry Global Education & Learning Series – Life Sciences.
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