Question

Which event is considered as a precursor to seed habit?

• A. Retention of female sporophyte on parent gametophyte
• B. Retention of male sporophyte on parent gametophyte
• C. Retention of male gametophyte on parent sporophyte
• D. Retention of female gametophyte on parent sporophyte

Answer 1

The correct option is D Retention of female gametophyte on parent sporophyte

Retention of female gametophyte on parent sporophyte for a considerable period of time is considered as a precursor to seed habit.

Origin of seed habit can be observed in Selaginella. Selaginella shows the following features.
1. Heterospory, where two different kinds of spores are produced, called microspores and megaspores, by the sporophyte.
2. Germination of megaspore into female gametophyte on the parent sporophyte.
3. Female gametophytes produce eggs that get fertilised forming zygote.
4. Zygote develops into an embryo while still attached to the parent sporophyte.

From the above observations, it is concluded that the life history of Selaginella approaches towards seed habit. Instead of developing independently, the female gametophyte of Selaginella depends upon parent sporophyte until the embryo is formed. The same is observed in seed-bearing plants also. The gametophyte of seed-bearing plants draws nourishment from the parent sporophyte until it forms an embryo.