Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

1. Explain the role of regulatory gene, operator, promoter and structural genes in lac operon, when E.coli is growing in a culture medium with the source of energy as lactose.
2. Mention what would happen, if lactose is withdrawn from the culture medium.

OR

Describe how the lac operon operates both in the presence and absence of an inducer in E.coli.

The following is the illustration of the sequence of ovarian events (a-i) in a human female.

Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event.

What is pest management? What do you understand by integrated pest management?

With the help of suitable diagram describe the logistic population growth curve.

More than 25% of human population is suffering from hunger and malnutrition. Scientists have developed techniques where microbes are grown on industrial scale as a source of good protein which can be grown from waste water, animal manure and even sewage.
Based on the above information answer the following questions.

1. In what ways would it be helpful to humans?
2. What can be the response to such new ventures?
3. What values have been manifested in the above case?

How is sex determined in human beings?

With the help of one example each, provide genetic explanation for the following observations:
F₁-generation resembles both the parents.

Draw a diagram of replication of AIDS virus, Name the pathogen of AIDS and describe the infection and symptoms of AIDS.

Write the symptoms of haemophilia and sickle-cell anaemia in humans. Explain how the inheritance pattern of the two diseases differ from each other.

Explain co–dominance taking an example of human blood groups in the population.