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

Read the following text carefully and answer the questions that follow:
The image below shows the menstrual cycle of a human female. On the basis of this cycle:

i. Explain the menstrual phase in a human female. State the level of ovarian and pituitary hormones during this phase. (1)
ii. Why is follicular phase in the menstrual cycle also referred as proliferative phase? Explain. (1)
iii. Explain the events that occur in a Graafian follicle at the time of ovulation and thereafter. (2)
OR
Draw a Graafian follicle and label antrum and secondary oocyte. (2)

Read the following text carefully and answer the questions that follow:
The diagram shows the replication of the retrovirus in the host.


i. Fill in the missing data in boxes labelled 1 & 2. (1)
ii. Why is it named as retrovirus? (1)
iii. While the virus is being replicated and released, does the infected cell survive and why the virus infected cells prevent spreading of virus to healthy cells? (2)
OR
What is the effect of HIV infection on immune system? (2)

Read the following and answer any four questions from (i) to (v) given below:
Translation is the process of polymerisation of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence bases in the mRNA. The amino acids are joined by a bond called peptide bond. Ribosome is the site of protein synthesis.

1. Which ion is essential for association of both units of ribosome at the time of protein formation?

1. Mg²⁺
2. Mn²⁺
3. CI^-
4. Ca²⁺

2. During translation, how many initiation factors are required in eukaryotes for initiation reactions?

1. 3
2. 6
3. 7
4. 9

3. Which part of mRNA contains untranslated regions (UTR)?

1. 3' end
2. 5' end
3. Either 3' or 5' end
4. Both 5' end and 3' end

4. Name the enzyme that helps in combining amino acid to its particular tRNA?

1. Activating enzyme
2. Amino-acyl tRNA-synthetas
3. PeptidyI transferase
4. Both (a) and (b)

5. From the given list, select the translation machinery.

1. mRNA
2. Ribosomes
3. Amino acids
4. tRNAs
5. Peptidyl transferase
6. Amino acyl tRNA synthetase
7. Pyrophosphatase

1. (1), (2), (3), (4) and (6)
2. (1), (2), (3), (4) and (5)
3. (1), (2), (3), (4), (5) and (6)
4. (1), (2), (3), (4), (5), (6) and (7)

Read the following and answer any four questions from (i) to (v) given below:

In today's world, 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. Single cell proteins are such products. TI1e biomass or protein is extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria. These are a very good source of food for human consumption.

1. Why the name single cell protein is applied?

1. It contains only one type of protein.
2. It is obtained from unicellular edible microbes.
3. It contains only one type of microorganism.
4. All of these.

2. Which of the following is considered under single cell protein?

1. Algae.
2. Fungi.
3. Cyanobacteria.
4. All of these.

3. Microorganisms can be a useful food resource for increasing human population because:

1. These are easy to harvest.
2. These can grow in water system.
3. They have a high rate of multiplication thus producing huge biomass.
4. They have high level of nucleic acid.

4. Single cell protein can be grown from:

1. Waste water.
2. Animal manure.
3. Sewage.
4. All of these.

5. Assertion: Production of single cell protein reduces pollution.

Reason: Single cell protein can be grown from waste water and even sewage.

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.

Read the following and answer any four questions from (i) to (v) given below:
Disposal of untreated sewage into the river or freshwater pond causes huge water pollution. Four water samples from different sources (A, B, C, D) are collected and tested for BOD value in a lab to assess their quality. The BOD values are presented in the given table. Water samples are collected from primary effluent, secondary effluent, untreated sewage and river water. Study the given table and answer the following.

Sample	BOD
A	20mg/ L
B	5mg/ L
C	300mg/ L
D	400mg/ L

1. The source of sample 'C' is:

1. River water.
2. Primary effluent.
3. Secondary effluent.
4. Untreated sewage water.

2. If sewage in untreated condition is disposed off in a freshwater body then.

1. BOD and dissolved oxygen both will increase.
2. BOD will increase and dissolved oxygen will decreas.
3. BOD will decrease and dissolved oxygen will increase.
4. BOD and dissolved oxygen both will decrease.

3. A large number of pathogenic microbes can be present in water sample of:

1. C
2. A
3. D
4. Both (a) and (c).

4. High value of BOD in sample O is due to:

1. High amount of organic wastes and aerobic microbes.
2. High amount of inorganic wastes and anaerobic microbes.
3. High amount of organic wastes and anaerobic microbes.
4. High amount of inorganic wastes and aerobic microbes.

5. River water is represented by the sample.

1. A
2. B
3. C
4. D

Explain pBR322 with its cloning sites, enzymes with well labeled diagram.###Explain: cloning sites. (Diagram is not necessary)

Describe the process of DNA Fingerprinting in detail.

Read the following text carefully and answer the questions that follow:
Cancer refers to any one of a large number of diseases characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue. Cancer often has the ability to spread throughout your body. Cancer is the second-leading cause of death in the world.

i. How does a cancerous cell differ from a normal cell? (1)
ii. Benign tumor is less dangerous than malignant tumor. Why? (1)
iii. Describe causes of cancer. (2)
OR
Mention two methods of treatment of the disease. (2)

Explain co-dominance in humans with the help of example.

Read the following and answer any four questions from (i) to (v) given below:
The first menstruation is called menarche, that usually occurs between 12 and 15 years. In human females, menstruation is repeated at an average interval of about 28/29 days and is called menstrual cycle. It is regulated by certain hormones, as pituitary gland is stimulated by releasing factors produced in the hypothalamus. The hormones produced by pituitary gland influence the ovaries. The hormones secreted by the ovaries affect the walls of the uterus.

1. The breakdown of endometrium is characteristic of:

1. Proliferative phase.
2. Luteal phase.
3. Ovulatory phase.
4. Menstrual phase.

2. Which days of the menstrual cycle marks the proliferative phase?

1. 1-5
2. 15-28
3. 6-13
4. 10-14

3. Which of the following occurs during secretory phase?

1. Empty Graafian follicle changes into corpus luteum.
2. Primary follicle changes into Graafian follicle.
3. Endometrium rebuilds and estrogen secretion increases.
4. LH surge, inducing release of an ovum.

4. Identify the hormones that attain peak level during ovulatory phase.

1. FSH.
2. Progesterone.
3. LH.
4. Both (a) and (c).

5. Withdrawal of which hormone causes degeneration of corpus luteum?

1. FSH.
2. LH.
3. Progesterone.
4. Estrogen.