Question

Germination of the pollen grain on the stigma is
(a) Autogamy
(b) In vivo germination
(c) In vitro germination
(d) None of the above

Answer 1

Hint: The condition where the germination of the pollen grains occurs in natural conditions without the use of any synthetic medium. This process of germination occurs after pollination. The process of transferring pollen grains from males to the stigma of females is called pollination.

Complete answer
The process of pollination is where the pollen from one plant lands on the stigma of another flower or the same flower. The germination of the pollen grain on the stigma starts when the pollen tube extends and moves towards the ovule of the female where it secretes two male gametes (sperms) and then fuses when the egg cell of the female and results in fertilization. This process occurs in the natural biological conditions without producing any change in the available surroundings thus called In vivo germination. After the process of pollination where the transferring of male gametes takes place towards the female gamete, the process of fertilization begins in the flowers. This process occurs with the help of various insects, birds, and other organisms that are termed the pollinating agents. These pollinating agents are differentiated into two categories: biotic (living) factors like insects, birds, etc, and abiotic (non-living) factors like wind, water, etc.
-Fertilization occurs mainly in four stages:
(a) Germination of pollen tube on stigma
(b) Growth of pollen tube
(c) Pollen tube entry into the embryo sac
(d) Fusion of gametes

So, the correct answer is ‘In vivo germination’.

Note:
During angiosperm reproduction, two products are formed: a zygote and the endosperm. A zygote will grow and develop into an embryo, or into a baby plant. The food source of plant embryos is the endosperm formed. This process is called double fertilization, and it is a unique characteristic of a flowering plant.