Strategies for Enhancement in Food Reproduction — BIOLOGY STD 12 Science — Question

Give reasons:
(a) Oxytocin is 'birth hormone'.
(b) People living in hilly region are advised to use iodised salt.
(c) Old age persons show weakened immune response.
(d) Pancreas is a dual gland.

With the help of a suitable diagram, describe the conducting system of human heart.

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

Long Answer Questions
What is parthenogenesis? Explain the haplodiploid method of sex determination in honey bee.

Differentiate between an inbred line and a hybrid variety of crop. Explain the steps involved in the production of the hybrid variety.

1. State one difference and one similarity between geitonogamy and xenogamy.
2. Explain any three devices developed in flowering plants to discourage self pollination and encourage cross-pollination.

Discuss the clinical manifestation of AIDS.

Fill in the blanks,

Look at the figure below depicting lac operon of E.coli.

1. What could be the series of events when an inducer is present in the medium in which E. coli is growing?
2. Name the Inducer.

Read the following and answer any four questions from (i) to (v) given below:
Transgenic animals can serve as factories that in some cases, may produce large amount of proteins more efficiently. Transgenic mice have been engineered to express human antibodies by introducing large segment of human DNA encoding human immunoglobulin genes. In transgenic large animals such as cow or sheep proteins of pharmaceutical value can be produced in large quantities in milk which is later purified. Transgenesis can be used to alter many phenotypic properties including growth rate, fat composition, milk production, hair texture, etc.

1. The production of transgenic animals includes

1. Identification and separation of desired gene.
2. Combining the desired gene with appropriate vector.
3. Introduction of vector in cells, tissues or embryos.
4. All of these.

2. In transgenic animals, i.e., cow and sheep proteins of pharmaceutical value are produced in large quantities in the

1. Blood.
2. Accumulated fat.
3. Mammary glands.
4. None of these.

3. Mouse is mostly preferred animal for studies on gene transfer because.

1. Short oestrous cycle.
2. Long gestation period.
3. Short generation time.
4. Production of one or two offspring per pregnancy.

1. Both (A) and (C)
2. Both (A) and (B)
3. Only D
4. Both (C) and (D).

4. Transgenic genes alter many phenotypic properties including:

1. Growth rate.
2. Fat composition.
3. Milk production.
4. All of these.

5. Assertion: Transgenic mice have been engineered to express human antibodies.

Reason: Large segment of human DNA encoding human immunoglobulin have been transferred to mice.

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.