Human Health and Disease — BIOLOGY STD 12 Science — Question

Abscissic acid/ABA

On the basis of the functions mentioned below, identify each one correctly.

1. It helps in the movement of spermatozoan in a fluid medium.
2. It contains hydrolytic enzymes and is used to contact and penetrate the egg during fertilisation.

How t-RNA act as an adapter molecule?
Explain in detail with the help of a diagram.

How is ‘Rosie’ considered different from a normal cow? Explain.

Linkage and crossing–over of genes are alternatives of each other. Justify with the help of an example.

Describe the structure of female gametophyte of angiosperms.

DDT content in the water of a lake that supplies drinking water to the nearby villages, is found to be 0.003 ppm. The kingfishers of that area are reported to have 2 ppm of DDT. Why has the concentration increased in these birds? What harm will this cause to the bird population? Name the phenomenon.

Intensely lactating mothers do not generally conceive. Is it true? If yes, explain the reason.

What are the advantages of breeding for disease resistance in plants?

List any two molecular diagnostic techniques and write one application of each of them.