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

How does the transmission of each of the following diseases take place?

1. Amoebiasis.
2. Malaria.
3. Ascariasis.
4. Pneumonia.

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.

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

Draw a labelled sketch of the structure of a human ovum prior to fertilisation.

Using Punnett square demonstrate the law of independent assortment in a dihybrid cross involving two heterozygous parents.

A flower of tomato plant following the process of sexual reproduction produce 240 viable seeds.
Answer the following questions giving reasons:
How many male gametes were involved in this case?

Answer the following questions:
Describe the temperature treatment that enhances the bacteria to take up the rDNA.

Explain the chromosomal theory of inheritance.

A bright student of class XI, under peer pressure started taking drugs. He started neglecting studies, misbehaving with parents and friends in school. The principal of school counselled him, but it had no effect. His parents took him to a rehabilitation center. After a few months, he came back recovered.

1. What is drug abuse?
2. Name some commonly abused drugs and their source.
3. What should be the attitude of his parents after his return?
4. What values did the principal reflect through his initiative?

Draw a labelled diagram of an anther lobe at microspore mother cell stage. Mention the role of different wall layers of anther.

Trace the path of spermatozoa from the testes upto the ejaculatory duct only.

OR

Schematically represent and explain the events of spermatogenesis in humans.