Read the following statements about the anther and choose the correct ones.
I. The outer three wall layers of the microsporangium nourish the developing pollen grains.
II. Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.
III. In a dithecous anther, each lobe has two theca, giving four microsporangia in all.
IV. The microsporangia develop further and become pollen sacs.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → II, III and IV only
A typical anther is bilobed, and each lobe has two theca, so the anther has four microsporangia. Each microsporangium is surrounded by four wall layers. The outer three (epidermis, endothecium and middle layers) protect it and help the anther to open, while the innermost layer, the tapetum, feeds the developing pollen grains.
I. The outer three wall layers of the microsporangium nourish the developing pollen grains. — False. The outer three layers perform the function of protection and help in dehiscence of the anther. Nourishing the pollen grains is the work of the tapetum.
II. Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus. — True. Tapetal cells are rich in cytoplasm and are often bi-nucleate.
III. In a dithecous anther, each lobe has two theca, giving four microsporangia in all. — True. The anther is a four-sided structure with four microsporangia at the corners, two in each lobe.
IV. The microsporangia develop further and become pollen sacs. — True. The pollen sacs run along the length of the anther and are packed with pollen grains.
So II, III and IV are correct.
NCERT Extract:
Stamen, Microsporangium and Pollen Grain – “… The anther is a four-sided (tetragonal) structure consisting of four microsporangia located at the corners, two in each lobe. The microsporangia develop further and become pollen sacs. They extend longitudinally all through the length of an anther and are packed with pollen grains.”
Stamen, Microsporangium and Pollen Grain – “… It is generally surrounded by four wall layers (Figure 1.3b)– the epidermis, endothecium, middle layers and the tapetum. The outer three wall layers perform the function of protection and help in dehiscence of anther to release the pollen. The innermost wall layer is the tapetum. It nourishes the developing pollen grains. Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus.”