Question

Draw labelled diagram of the following (i) Gram seed (ii) V.S. of maize seed.

Answer 1

Seed is a ripened ovule which contains an embryo and reserve food material for its development. Angiosperms are the seed plants in which seeds are developed inside fruits. Based on the number of cotyledons, angiosperms are divided into two classes: monocotyledons (monocots) and dicotyledons (dicots). Monocots contain a single cotyledon and dicots have two cotyledons.

Complete answer:
Gram seed: It is a dicotyledonous seed formed inside a small pod or legume. The seed is covered by two seed coats: testa (outer seed coat) and tegmen (inner seed coat). The embryo is enclosed by the seed coats. The embryo contains a short and straight embryo axis which is pressed between two large cotyledons, attached by short stalks. The micropylar end of the embryo axis has a radicle which forms the future roots. The other end of the embryo axis is the plumule which gives rise to shoots. The food is stored in the cotyledons. The hilum is the point where the stalk of the seed is attached.

Maize seed: It is a monocotyledonous seed comprising five main parts. The seed has a protective covering known as seed coat. Below the seed coat, embryo and endosperm are present. Endosperm is bulky and consists of reserve food material. The embryo and endosperm are separated by a proteinaceous layer called aleurone layer. The embryo consists of a plumule, radicle and a single cotyledon. The plumule is enclosed in a sheath called coleoptile from which the first leaf germinates during germination. The radicle is enclosed in a sheath called coleorhiza from which forms first roots.

Note: Food reserve of the seeds may or may not be stored in the endosperm. Gram seed is a dicot seed in which endosperm is absent, therefore, it is non-endospermic. In gram seed, nutrition is provided by cotyledon to the embryo. Maize seed is a monocot seed consisting of endosperm.