Control and Co-ordination — BIOLOGY STD 12 Science — Question

We are able to hear the chirping of the birds and recognize the sound of the bird.

In which way has the study of biology helped us to control infectious diseases?

Answer the following questions:
Explain the changes the primary oocyte undergoes while in different follicular stages before ovulation.

Factors that maintain good health.

Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident’s Welfare Association of your locality organised an awareness programme entitled "Bury not burn". They invited you, being a biology student to participate.

1. How would you justify your arguments that promote burying and discourage burning? (Give two reasons)
2. With the help of flow charts, one for each practice depict the chain of events that follow.

Describe the various methods of birth control to avoid pregnancy.

During the reproductive cycle of a human female, when, where and how does a placenta develop? What is the function of placenta during pregnancy and embryo development?

What role does pituitary gonadotropins play during follicular and ovulatory phases of menstrual cycle? Explain the shifts in steroidal secretions.

Explain "the law of independent assortment" with a suitable example.

Following is the sequence of nucleotide in two strands of DNA. Observe the strands and answer the preceding questions.

1. Name the special term used for such an arrangement of nucleotide.
2. Name the special type of enzymes which work/ function at this specific points.
3. Name the enzyme, that cut DNA between GA sequence.
4. Name the single strands produced after the action of the enzyme.