CBSE Class 12-science Answered

(i) Endosperm is the food laden tissue formed during the development of angiospermous seed which provides essential nutrients to the growing embryo and also the young seedling at the time of seed germination. So, most zygotes in angiosperms divide only after certain amount of endosperm is formed.

(ii) The seeds in which the endosperm is used up are called exalbuminous seeds. In groundnut, the endosperm is used and the reserve food material is stored in cotyledons. So, groundnut seeds are exalbuminous. The seeds having ample amount of endosperm tissue are called albuminous seeds. Castor seeds have persistent endosperm. So, castor seeds are albuminous.

(iii) Double fertilisation in angiosperms brings about some changes in the ovule during the development of seed. The micropyle remains in the form of a fine pore on the surface of seed to allow the entry of water during seed germination.

(iv) Integuments of an ovule harden and the water content is highly reduced as the seed matures to ensure the survival of seeds.

(v) The fruit derived from the ovary of a flower not associated with any non-carpellary part is called a true fruit. In apple and cashew, the main edible part of the fruit is the fleshy receptacle. So, they are not true fruits. Such fruits derived from the ovary along with other accessory floral parts are called false fruits.