Question

Give reasons why : (i) most zygotes in angiosperms divide only after certain amomit of endosperm is formed.
(ii) ground nut seeds are exalbuminous and caster seeds are albuminous.
(iii) Micropyle remains as a small pore in the seed coat of a seed. (iv) integuments of an ovule harden and the water content is highly reduced,as. the seed matures. apple and cashew are not called true fruits.

Answer 1

To obtain nutrition from the endosperm for the developing embryo.
(ii) The groundnut seeds are exalbuminous because the endosperm is completely consumed Whereas, caster seeds are albuminous because the endosperm persists.
(iii) For the entry of water and oxygen required for germination.
(iv) To protect the embryo and keep the seed viable, until favourable conditions return for germination.
In apple and cashew, ovary does not take partin fruit formation, instead thalamus contributes to fruit formation.