Question

Given below is a diagram of the stomatal apparatus. Which option identifies labelling a,b,c, d correctly:

(a) A- subsidiary cell, B- epidermal cells, C- Guard cells, D- stomatal aperture
(b) A- Guard cell, B- stomatal aperture, C- subsidiary cell, D- epidermal cell
(c) A- epidermal cell, B- Guard cell, C- stomatal aperture, D- subsidiary cell
(d) A- epidermal cell, B- subsidiary cell, C- stomatal aperture, D- guard cell.

Answer 1

Hint: Stomata are the small openings that we can see on the epidermis of leaves. They help the plant in gaseous exchange. The opening and closing of the stomata are done by the guard cells. Guard cells surround each stoma.

Complete answer:
Here in brief we must see the structure of the stomata. The stomata have small pores called stomata surrounded by a pair of guard cells.
Guard cells are bean-shaped and contain chloroplasts. They contain chlorophyll and capture light energy.
The subsidiary cells surround the guard cells. They are present between guard cells and epidermal cells. When the guard cells expand, these subsidiary cells help to protect epidermal cells.
Keeping in mind the above structure of stomata ,now going through with the options –
In option (a), the outermost layer is named as subsidiary cell which is epidermal cell and second layer of cell which is subsidiary cell , has been named as epidermal which is not correct, c and d option showing guard cell and stomatal aperture and been named the same here. But a and b markings are incorrect here.
So “option (a)” is not the correct answer.
In option (b), A is been named as Guard cell , but studying structure of stomata it was found that guard cell are surrounded by stomatal aperture, also B, C, D, were given in option as stomatal aperture, subsidiary cell, epidermal cell respectively which is again incorrect markings.
So, “option (b)” is not the correct answer.
In option (c) the epidermal cell is only named right, but B, C, D, showing which are subsidiary cells, stomatal aperture, guard cell respectively are named here as guard cell, stomatal aperture, subsidiary cell which is again incorrect here.
So “option (c)” is not the correct answer.
Yes, in option (d), A, B, C, D was named as, as epidermal cell, subsidiary cell, stomatal aperture, guard cell which is exactly right as marked in the given diagram.

So “option (d)” is the correct answer.

Note:
Stomatal opening and closing help in the exchange of gases.
And so it is structured to perform its functions
Turgor pressure,caused due to osmotic flow of water into guard cells, determines the stomatal opening and closing.
When the guard cells take water, they become turgid leading to its expansion which results in the opening of stomata.
When the guard cells lose water, they become flaccid leading to stomatal closure
And so is the structure of stomata that is; stoma surrounded by guard cell which again surrounded by subsidiary cell which in turn surrounded by epidermal cell.