Science
A stomata closes when :
(a) it needs carbon dioxide for photosynthesis.
(b) it does not need carbon dioxide for photosynthesis.
(c) water flows out of the guard cells.
(d) water flows into the guard cells.
The correct reason(s) in this process is/are:
options
- (a) only
- (a) and (c)
- (b) and (c)
- (b) and (d)
Answer
(b) and (c)
Reason — Stomata are tiny pores on the surface of leaves that control the exchange of gases and water.
When a plant does not need carbon dioxide for photosynthesis or wants to prevent water loss, the guard cells lose water and become flaccid, causing the stomata to close.
So, stomata close when:
- it does not need carbon dioxide for photosynthesis, and
- water flows out of the guard cells.
Hence, correct reasons are (b) and (c).
Related Questions
Chromosomes :
(a) carry hereditary information from parents to the next generation.
(b) are thread like structures located inside the nucleus of an animal cell.
(c) always exist in pairs in human reproductive cells.
(d) are involved in the process of cell division.
The correct statements are :
options
- (a) and (b)
- (c) and (d)
- (a), (b) and (d)
- (a) and (d)
In a nerve cell, the site where the electrical impulse is converted into a chemical signal is known as:
options
- Axon
- Dendrites
- Neuromuscular junction
- Cell body
At what distance from a convex lens should an object be placed to get an image of the same size as that of the object on a screen?
options
- Beyond twice the focal length of the lens.
- At the principal focus of the lens.
- At twice the focal length of the lens.
- Between the optical centre of the lens and its principal focus.
The lens system of human eye forms an image on a light sensitive screen, which is called as :
options
- Cornea
- Ciliary muscles
- Optic nerves
- Retina