NEET BIOLOGY

Detailed explanation-1: -The minimum number of pollen grains that might be involved are 240, as 240 viable seeds are formed. This is because each pollen grain contains 2 male gametes, out of which one fuses with egg forming zygote that gives rise to seeds.

Detailed explanation-2: -(c) The minimum number of pollen grains to land under the pollination stigma is 360 and there are two male gametes in each pollen grain. One fuses with polar nuclei and forms endosperm from these two gametes, while the other male gamete fuses with the egg cell to create the zygote that finally gives birth to the seeds.

Detailed explanation-3: -Thus, for fertilization of one ovule, a minimum one pollen grain with two male gametes and one egg (female gamete) are involved. Thus, for the production of 200 seeds, a minimum of 200 pollen grains and 600 gametes (400 male gametes and 200 female gametes) are needed.

Detailed explanation-4: -(a) The number of ovules minimally involved in this process would be 200 as the number of viable seeds are 200. After fertilisation, the ovary turns into a fruit and the ovule turn into a seed.

Detailed explanation-5: -Therefore, for the formation of 200 pollen grains 50 meiosis in 50 microspore mother cells are required (2004=50 ). However, when one diploid megaspore mother cell divides by meiosis, it also forms 4 linearly arranged hapolid megaspore, out of which 3 degenerate and only 1 megaspore develops into egg.