Tag: modes of reproduction

Anther is the part of plant is suitable for the study of meiosis. A typical anther contains four microsporangia. The microsporangia form sacs or locules in the anther. The two separate locules on each side of an anther may fuse into a single locule. Each microsporangium is lined with a nutritive tissue layer called as the tapetum and initially contains diploid pollen mother cells. These undergo meiosis to form haploid spores. The spores may remain attached to each other in a tetrad or separate after meiosis.

• In plants, meiosis is occurring as in diploid sporophyte to produce haploid spores. 
• The haploid spores are germinating to produce structures called gametophytes. The gametophytes then produce gametes. 
• Gametic or the terminal meiosis occurs in all multicellular animals. It takes place in the gonads and hence as results in the formation of gametes. 
• It is responsible for gametogenesis and does not give rise to gametophytes.
• The correct option is D.

In a mature pollen grain, the generative cell is smaller and the tube(or vegetative) cell is larger. In the later stages of development of pollen grain, callose dissolves and the naked generative cell comes to lie freely in the cytoplasm of the tube cell. The tube cell has a cytoplasm that is rich in the food reserve (starch, protein, fat with mostly unsaturated fatty acids).

Sporic meiosis, has mitosis in two stages, both the diploid and haploid stages, termed diplobiontic.