Question

A male germ unit in Brassica sp. comprises of -----------
1. The entire pollen grains
2. One sperm and the vegetative nucleus
3. The two sperms
4. Both the sperms and the vegetative nucleus

Answer 1

Hint:- Brassica is the second-largest oilseed crop next to soybean.It is the genus of the mustard
family. There are about 37 species under the genus Brassica . Brassica is a small, branched green
plant.

Complete step-by-step solution:-
The pollen grain is called the male gametophyte.
-It is made up of a small generative cell and a large vegetative cell.
-The male germ unit consists of an association between the vegetative nucleus and the
generative nucleus.
-The male germ unit or reproductive unit is transported through a pollen tube and delivered
to the female embryo sac.
1. Entire pollen grain- A pollen grain consists of exine as an outer membrane and intine as an inner membrane. Inside it contains a vegetative cell and generative cell.
2. One sperm and the vegetative nucleus- Before the shedding of the pollen grain from another, the generative cell undergoes meiotic division and forms three celled stages. Now it
contains two nuclei in generative cells and one vegetative cell.
3. Two sperms- The generative cell after the meiotic division contains two nuclei, now it is called as two sperms. One fuses with the egg cell to form a zygote and the other with secondary nuclei to form endosperm.
4. Both sperm and the vegetative cell- It is the male germ unit which contains one germ cell and vegetative cell. The germ cell undergoes meiosis and forms two nuclei.
A male germ unit in Brassica sp. comprises of Both sperm and the vegetative cell. Thus the correct
answer is option D.

Note:-
-The pollen has the presence of outer exine with different stratifications.
-The inner intine is thin without any stratification.
-It has the presence of a pore which is called a germ pore.
-Through this pore, the pollen tube arises and reaches the embryo sac.