Question

Free nuclear divisions are characteristics of

• A. Cellular endosperm
• B. Nuclear endosperm
• C. Helobial endosperm
• D. Both B and C

Answer 1

The correct option is D Both B and C

On the basis of development, endosperm is of three types:

1. Cellular Endosperm: It is found in 25% angiospermic families, particularly dicotyledons. During the development of cellular type of endosperm, the primary endosperm mother cell divides by mitotic divisions and each division is followed by cell wall formation.

2. Nuclear Endosperm: It is more common and found in 56% of angiospermic families. During the development of nuclear type of endosperm, the primary endosperm mother cell divides by free nuclear divisions, and these divisions are not followed by cell wall formation. Thus, the free nuclei remain in the cytoplasm of the embryo sac.

3. Helobial Endosperm: It is found in 19% of angiospermic families, particularly monocotyledons. This type of endosperm is intermediate between cellular and nuclear endosperms and is formed due to the formation of a large micropylar and a small chalazal chamber by a mitotic division in the primary endosperm mother cell. The nucleus of chalazal chamber remains undivided or divides by a few mitotic divisions whereas the nucleus of micropylar chamber divides by free nuclear divisions, which are followed by centripetal cell wall formation.

Hence, both nuclear and helobial type of endosperm involve free nuclear divisions.

So, the correct answer is D.