Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

A large number of married couples the world over are childless. It is shocking to know that in India the female partner is often blamed for the couple being childless.

1. Why in your opinion the female partner is often blamed for such situations in India? Mention any two values that you as a biology student can promote to check this social evil.
2. State any two reasons responsible for the cause of infertility.
3. Suggest a technique that can help the couple to have a child where the problem is with the male partner.

When a cross in made between tall plant with yellow seeds (TtYy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspring could be expected to be,

1. Tall and green.
2. Dwarf and green.

Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro.

What criteria should one use in categorizing a species as threatened?

Answer the following questions:
How do flowers reward their insect pollinators? Explain.

Draw the diagram of a mature embryo sac and show its 8-nucleate, 7-celled nature. Show the following parts: antipodals, synergids, egg, central cell, polar nuclei.

Discuss the mode of action and advantages/ disadvantages of hormonal contraceptives.

Two independent monohybrid crosses were carried out involving a tall pea plant with a dwarf pea plant. In the first cross, the offspring population had equal number of tall and dwarf plants, whereas in the second cross it was different. Work out the crosses, and explain giving reasons for the difference in the offspring populations.

What are transgenic plants? Give some example.

A spermatogonial cell has 30 chromosomes. How many chromosomes will be found in:

1. The primary spermatocyte.
2. The spermatid?