Human Health and Disease — BIOLOGY STD 12 Science — Question

Describe the Darwin's theory of natural selection.

Describe the roles of pituitary and ovarian hormones during the menstrual cycle in a human female.

Explain the process of fertilisation in human female, and trace the postfertilisation events in a sequential order up to implantation of the embryo.

OR

Explain the process of fertilisation and implantation in humans.

About 8% of human male population suffers from colourblindness whereas only about 0.4% of human female population suffers from this disease. Write an explanation to show how it is possible.

Describe the functions of the following:
Trophoblast.

What functions do the female reproductive system perform?

State and explain the “law of independent assortment” in a typical Mendelian dihybrid cross.

What is menstrual cycle. Explain its various events with the help of diagram.###Describe in detail the various stages of menstrual cycle with the help of diagram.###Write a detail note on different stages of menstrual cycle and also sketch out these stages of
menstrual cycle by graphical diagram.###Define sexual reproduction. Explain the process of menstrual cycle.

1. Explain the development of female gametophyte from a megaspore mother cell in an angiosperm.
2. Draw a leballed diagram of a fully-developed embryo sac.

OR

1. Describe the process of megasporogenesis in angiosperms, until 8-nucleate stage.
2. Draw the labelled structure of mature embryo sac.

What is tissue culture? What are the different types of tissue culture? Describe briefly.###Write an essay on tissue culture.