Question

Exine and intine are the parts of
A. Embryo Sac
B. Pollen grain
C. Stigma
D. Seed

Answer 1

Exine and intine are the two wall layers of the male gametophyte of a flower. The landing of the male gametophyte on the stigma of the female gametophyte results in pollination.

Complete Answer:
- A flower is the reproductive structure of a plant that contains the male and female gametophytes. The male reproductive structure is the androecium, represented by a whorl of stamens and the female reproductive structure is the gynoecium.
- Stamens are structures that contain pollen in terminal sac-like structures called microsporangia or anthers, also known as microsporophylls. Each anther is made up of four structures containing four microsporangia, two in each lobe, situated at the corners. Microsporangia develop further into pollen sacs. They extend throughout the anther's length and are filled with pollen grains.
- The pollen grains represent the male gametophytes. Pollen grains are usually spherical with a diameter of around 25-50 micrometers. It has a recognizable two-layered wall. The rough outer layer is called the exine, composed of sporopollenin. The inner wall is known as intine. It is a thin, continuous layer composed of cellulose and pectin.
- Pistil is the female reproductive component of the flower. Each pistil has three parts-a stigma, a style and an ovary. The stigma functions as a landing ground for pollen grains. The embryo forms after fertilisation of the flowers of the plant and is usually contained within the seed or bud.

Thus, the correct answer is option B. Pollen grain.

Note: A young anther has a cluster of compactly organised homogeneous cells known as sporogenous tissue in the middle of each microsporangium. The microspores separate and grow into pollen grains as the anthers mature and dehydrate.