Viva Voce: Stomata | Lab Manuals for Class 10 PDF Download

Q.1. Why is the number of stomata greater on the lower surface of a dicot leaf?

Stomata helps in gaseous exchange and transpiration. The sides least exposed to the sun rays, i.e. lower surface of leaf has more number of stomata so that the plant can exchange maximum oxygen with minimal water loss.

Q.2. What is the shape of guard ceils in stoma of grass leaf?

Grass is a monocot plant in which the guard ceil is dumbbell shaped.

Q.3. Guard cells are different from other epidermal cells in what context?

Guard cells have chloroplasts while other epidermal cells lack in it. Shape of guard cells is different in monocots (dumb-bell) and dicots (bean), while epidermal cells are irregular in shape in both.

Q.4. Can you suggest any two factors which cause stomata to close?

Two factors that can cause, stomata to close are
(i) Absence of light
(ii) Lack of carbon dioxide in the atmosphere.

Q.5. Before conducting this experiment, if the plant is keptln dark, what will be the condition of stomata?

Stomatal pore will be closed.

Q.6. Name a plant in which stomatas are absent.

Aquatic plant Hydrilla

Q.7. Why do guard cells bend, when they swell up?

The guard cells bend because of the differential thickenings of its inner and outer walls. The inner wall of guard cell is thicker and less stretchable as compared to the outer wall.

Q.8. Name a plant hormone which can cause stomatal closure.

Abscisic Acid (ABA)

Q.9. Staining of the leaf peel plays what role in the observations?

The leaf peel is transparent, thus the cells present in it, will also be transparent. Staining helps in precise observation of cells.

Q.10. What happens, if we do not keep the isolated peel in water?

The peel will dry up and become useless.

Q.11. The number of stomata is same in all plants. True/false, give reason supporting your answer.

False. All plants have different number of stomata. It depends on the habitat and type of plant. Even the number of stomata are different within a single leaf like in a dicot leaf where upper surface has less number of stomata than lower surface.

Q.12. Do guard cells have a rigid or elastic walls? Justify your answer.

Guard cells regulate the opening and closing of stomatal cells, when they are turgid or flaccid respectively. Hence, there walls are elastic which facilitates the changes in their shape due to change in the level of water and salts at the given time.

Q.13. Why are stomata absent in roots?

Roots are present underground in the soil hence, the stomatal functions will be blocked. Also, stomata are used for transpiration hence, there presence is observed in leaves.

Q.14. What is the function of guard ceils in stomata?

Guard cells regulates the opening and closing of the stomata depending on the state they are in, i.e. whether they are turgid or flaccid.