Human Health and Disease — BIOLOGY STD 12 Science — Question

You have a friend whose parents are too indulgent in his/her daily affairs. They think him/her to be still young which makes him/her sad and is upset all the time. As he/she feels that the parents should give him/her opportunity to take independent decision on some issues.

1. Would you support your friend and why?
2. Write the characteristics of this age group.
3. List two curative measures.

(i) Write full name of AIDS.
(ii) Write four ways of transmission of HIV infection.
(iii) Write a way to prevent HIV infection.

Identify a, b and c in the table given below:

S. No.	Pattern of inheritance	Monohybrid F1 phenotypic expression
(i)	Co–dominance	a
(ii)	b	The progeny resembled only one of the parents.
(iii)	Incomplete dominance	c

Describe the molecular structure of DNA by making a labelled diagram.

“Maintenance of personal and public hygiene is necessary for prevention and control of many infectious diseases”. Justify the statement giving suitable examples.

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.

What is the difference between “d” and “e” ?

Pragyan takes fruits, vegetables, bread and egg curry in a day's menu. While his teacher was giving a lecture on trophic level, he got fascinated and asked following questions from his teacher.

1. How many trophic levels does he occupy in different food chains?
2. Represent atleast three food chains.
3. Which among them gives him the maximum amount of energy? Give reason.
4. What values are shown by Pragyan?

Explain the Law of Dominance using a monohybrid cross.