Question

15. The diagram given below represents a structure found
in a leaf.
-A
-B
Study the same and answer the questions that follow:
(i) Name the parts labelled A and B.
(ii) What is the biological term for the above structure?
(iii) What is the function of the part labelled A ?
(iv) Mention two structural features of A, which help
in the function mentioned in (iii) above.
(v) Where is this structure likely to be found in a
leaf?
(vi) The above structure helps in the process of
transpiration. Explain the term transpiration.
(vii) How many other cells are found surrounding this
structure as seen in the diagram.​

Answer 1

Answer:

(i) A= Guard cell, B= Stomatal pore.

(ii) Stomata

(iii) Guard cells are located in the leaf epidermis and pairs of guard cells surround and form stomatal pores, which regulate CO2 influx from the atmosphere into the leaves for photosynthetic carbon fixation. Stomatal guard cells also regulate water loss of plants via transpiration to the atmosphere.

(iv) Between each pair of guard cells is a stoma (a pore) through which water and gases are exchanged. The opening and closing of these pores (collectively known as stomata) is made possible by the thickening and shrinking of guard cells on the epidermis.

(v) The majority of stomata are located on the underside of plant leaves reducing their exposure to heat and air current. In aquatic plants, stomata are located on the upper surface of the leaves.

(vi) The movement of sucrose and other substances like amino acids around a plant is called translocation . In general, this happens between where these substances are made (the sources) and where they are used or stored (the sinks): from sources in the root to sinks in the leaves in early spring time.

(vii) Anomocytic - A small number of subsidiary cells surround the stomata. For the most part, these cells (subsidiary cells) are identical to the other epidermal cells. Cruciferous - The stoma is surrounded by three types of subsidiary cells that vary in size.

Hope this helps!