Question

Tapetum is
(A) Parietal in origin
(B) Innermost wall layer of pollen sac
(C) Nutritive and provides wall material to pollen grains
(D) All the above

Answer 1

Hint: The pollen grains have the homogeneous mass of the cells of male reproductive part in the flower. These are transmitted to the other by means of water, wind, insects etc. at the time of pollination. Pollen grains are protected from damage by means of several protective covers. Out of which tapetum is notable.

Complete answer:
It is protected by three covers. At the top, there is the single layer of epidermis and it is the outer cover of the pollen grains. Below the epidermis there are two to three layers of tissues which are parietal in origin. These tissues are called archesporial cells, they are separated into two, and the outer group of cells are called parietal cells and the inner group if cells are called sporogenous cells.

Tapetum is the innermost layer of cells that is found below the epidermis and above the anther. Tapetum is the one of the walls of the anther and it locates at the innermost area. It is the first layer that covers the spongy tissues. These cells have more than one nucleus and have the denser and thicker cytoplasm in it. It provides nutrition to the pollen grains for its growth. These layers are not permanent and it breaks or degenerates at the time of maturity of the pollen grains. Hence while considering all the above reasons, Tapetum is the innermost wall of pollen and is parietal in origin that provides nutritive and wall material to the pollen grains.

Thus, the option (D) is correct.

Note:Tapetum synthesis ubisch bodies which combine with the pollen grains and form the outer body to it. So, it helps in making the wall material of the anther. So, it is referred to as a source of precursors for the pollen grain coat.