Question

1)Cross pollination is not a reliable method of fertilisation. justify the statement?
2) women can reproduce till certain age but men can reproduce for lifetime. justify?

Answer 1

1). In cross pollination the pollen has to reach the appropriate stigma for the fertilizations to occur. To ensure this large number pollens has to be produced, so there is wastage of pollen. The cross pollination between the distant plant will not at all be successful if they produce only less pollen. The flowers should posses the characteristic properties to attract the biotic agents or the pollinators. The flower must be large, coloured, sweet odour and nectar producing to attract the pollinators. Harmful dominant character get expressed in the offsprings. All these substantiate that the cross pollination cannot be considered as a reliable method of fertilizations.

2). The first occurrence of the menstruation is known as the menarche. From the menarche onwards the female human body undergoes a cycle of events known as the menstruation cycle. There are four main phases in the menstrual cycle, they are;
• Menstruation
• Follicular phase
• Ovulation
• Luteal phase
In the ovulation phase, the egg is produced which then fuses with the sperm to form the zygote. The ending phase of the menstrual cycle or stoppage of menstruation is called the menopause where the menstruation stops . It usually occurs in the age of 45-50. After menopause the menstrual cycle stops so there will not be the process like the menstruation, ovulation etc and the women will not be able to reproduce after this. But testes, the male reproductive organ continuously produces the sperm from the puberty to end of the life.