Question

In the prothallus of a vascular cryptogam, the antherozoids and eggs mature at different times. As a result?

• A. Self fertilization is prevented
• B. There is high degree of sterility
• C. One can conclude that the plant is apomictic
• D. There is no change in success rate of fertilization

Answer 1

The correct option is A

Self fertilization is prevented

The correct option is A.

Explanation for correct answer:

1. Prothallus is the gametophyte phase of the pteridophytes.
2. The male gamete ( antherozoids) and female gamete (egg) of a Prothallus matured at different times thus, preventing any chances of self-pollination.
3. Self-pollination is said to be accomplished when the pollination of anther takes place with the stigma of the same flower or another flower of the same plant.

Explanation of the incorrect answers:

Option B:

1. Sterility is not the result as only the chances of self-pollination are prevented because of maturing of gametes at different times. There is still the chance of cross-pollination.
2. Sterility is the condition in which the organism can not produce offspring.

Option C:

1. Apomixis means asexual seed formation.
2. In this the seed is produced without the male gamete.
3. This is not possible in the above question as Apomixis is not the characteristic feature of pteridophytes.

Option D:

1. There is no effect on the success rate of the fertilization as only self-pollination is prevented, cross-pollination can cause the fertilization.

Final answer: In the prothallus of a vascular cryptogam, because of the different times of maturation of the male and female gamete, self-pollination is prevented.