Ecosystems — BIOLOGY STD 12 Science — Question

Answer the following questions:
Why is follicular phase in the menstrual cycle also referred as proliferative phase? Explain.

Describe the dihybrid cross carried on Drosophila melanogaster by Morgan and his group. How did they explain linkage, recombination and gene mapping on the basis of their observations?

What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.

Briefly describe the following: Polymorphism

A gene was identified in a fungus by a research worker in a lab which was considered to be of a great importance in the field of agriculture. As a student of biotechnology, write the steps you would suggest to (i) Isolate this gene of interest from the fungus and (ii) amplify this gene for further experimentation and research.

In the given flow diagram, the replication of retrovirus in a host is shown. Observe and answer the following questions,

1. Fill in (1) and (2).
2. Why is the virus called retrovirus?
3. Can the infected cell survive while viruses are being replicated and released?

Write an article on vaccination and immunization.

Answer the following questions:
Explain the role of ovarian hormones in inducing changes in the uterus during menstrual cycle.

Unless the vector and source DNAs are cut, fragments separated and joined, the desired recombinant vector molecules cannot be created.

1. How are the desired DNA sequences cut?
2. Explain the technique used to separate the cut fragments.
3. How are the resultant fragments joined to the vector molecule?

Study the graph given below and answer the questions that follow:

Explain the ovarian events (i), (ii) and (iii) under the influence of hormones ‘X’ and ‘Y’.