Human Reproduction — BIOLOGY STD 12 Science — Question

List any four symptoms of Down's syndrome. What is the basis of this disorder?

A vector is engineered with three features, which facilitates its cloning within host cell. List three features and explain each one of them.

The traits are inherited through generations. This fact is based on the principles proposed by Gregor Mendel in 1865. However, Mendel did not discover these principles of inheritance by studying human beings, then how his principles are applied in case of humans.

Draw a labelled schematic sketch of replication fork of DNA. Explain the role of the enzymes involved in DNA replication.

What is the role of histamine in inflammatory response? Name few drugs which reduce the symptoms of allergy.

Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?

Compare polymerase chain reaction and gene cloning.

How many sperms will be produced from 50 primary spermatocytes?

Answer the following questions:
Mention any four strategies adopted by flowering plants to prevent self-pollination.