Question

Suppose in a flower of mustard, each microsporangium possesses $20$ pollen mother cells then, the total number of male gametes formed by this flower will be?
(A) $3840$
(B) $480$
(C) $240$
(D) $120$

Answer 1

Hint: Androecium is the male reproductive organ of the plants. This part in the plants consists of the anthers, filaments and the pollen grains. At the time of reproduction, pollen grains move into the ovule of the flower for the process of fertilization.

Complete Answer:
At first understand that each flower consists of the stamens. Stamens are the combination of the parts of the both anther and the filament. In the filament, the anther is attached. The anther is the combination of both microsporangium and pollen grains. Microsporangium is the cover in which the pollen grains are placed.

In the flower of the mustard it is given that
Number of mother pollen cells = $20$
Each pollen cell may produce $4$ daughter pollen grains.
Hence number of male gametes in mustard = $4 \times 20$
Number of pollen grains = $80$
Each pollen produce $2$ male gametes
Number of male gametes in mustard = $80 \times 2$ = $160$
Mustard is dithecous in nature and hence each stamen has $4$ microsporangia in it.
Number of male gametes in mustard = $160 \times 4 = 640$
Number of stamens in mustard = $6$
Thus, total number of the male gametes formed by the flower with $20$ pollen mother cells is $640 \times 6 = $3840$

Thus option (A) is correct.

Note: Remember that mustard possesses $6$ stamens and there are $4$ microsporangia in each stamen. One mother cell of the pollen will give rise to $4$ pollen grains. And the single pollen grain is capable of producing $2$ male gametes.