Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

1. Select the option that correctly identifies autoimmune diseases of Reema, Jai and Ankit.

2. Reema's autoimmune condition is characterised by

1. Undersecretion of insulin.
2. Destruction of RB Cs and low RB C count.
3. Undersecretion of adrenal cortex hormones.
4. Low production of intrinsic factor required for absorption of B₁₂

3. What do you think is the major cause of Jai's condition?

1. Deterioration of myelin sheath around nerve cells, leading to loss of precise muscle control
2. Destruction of heart cells, leading to weakening of entire heart wall.
3. Destruction of beta cells, leading to undersecretion of insulin.
4. Deposition of immune complexes of IgM, IgG and complement in joints thereby inflaming joints, destroying articular cartilage and fusing bones.

4. How do you think Ankit's condition got diagnosed?

1. Low level of thyroid hormone and elevated levels of TSH in Ankit's blood.
2. Presence of antibodies against thyroid pen oxidase (TPO antibodies) in Ankit's blood.
3. Elevated erythrocyte sedimentation rate (ESR), reduced C-reactive protein (CRP) in Ankit.
4. Both (a) and (b)

5. Assertion: Immunosuppressive drugs often reduce the severity of autoimmune disorders.

Reason: Monoclonal antibodies have been successfully used in the treatment of autoimmune disease.

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.

1. Name the linkage present between the nitrogen base and pentose sugar in DNA.

1. Phosphodiester bond
2. Phosphodiester bond
3. Hydrogen bond
4. None of these

2. The double helix structure of DNA was proposed by.

1. James Watson and Francis Crick.
2. Earwin Chargaff
3. Federick Griffith
4. Hershey and Chase.

3. The double chain of B-DNA is coiled in a helical fashion. The spiral twisting of B-DNA duplex produces.

1. Right and left part.
2. Major and minor grooves.
3. Upper and lower side.
4. Linear and circular part.

4. Assertion: The two strands of DNA helix have uniform distance between them.

Reason: A large sized purine always paired opposite to a small sized pyrimidine.

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.

5. Which of the following describes the structure of B-DNA?

1. Reverse transcriptase enzyme was discovered by:

1. Temin and Baltimore.
2. Cohen and Boyer.
3. Arber and Nathan.
4. Paul Berg.

2. During cDNA formation, what would happen if DNA formed by reverse transcriptase is not treated with the alkali?

1. cDNA will not be digested.
2. mRNA will not be digested.
3. Hydrogen bonds will not form between base pairs.
4. rnRNA will not be formed.

3. Enzyme that helps in the formation of double stranded cDNA is:

1. DNA synthetase
2. Ligase
3. DNA polymerase
4. Helicase.

4. DNA polymerase can be obtained form:

1. Retrovirus.
2. Agrobacteriurn.
3. Tobacco mosaic virus.
4. Thermus aquaticus.

5. DNA synthesised without a template is referred to as:

1. Complementary DNA.
2. Random DNA.
3. Synthetic DNA.
4. Z-DNA..

1. Which of the following is/ are the function(s) of structure Y?

1. To carry waste products away from the anther.
2. To supply oxygen to the cells of the anther.
3. To transport food and mineral salts to the anther.
4. To supply water to the anther.

1. Conly.
2. C and D only.
3. A, B and D only.
4. A, B, C and D.

2. Which of the following most accurately describes the structures found in compartment X?

1. They contain two haploid nuclei resulting from meiosis.
2. They contain two haploid nuclei resulting from mitosis.
3. They contain two haploid male gametes, resulting from mitosis.
4. They contain a vegetative nucleus and pollen tube nucleus.

3. Which of the following is a distinctive characteristic of insect-pollinated flower?

1. All of them have nectar guides on their flowers.
2. They produce sugary fruit.
3. Their pollen grains tend to have rough surfaces.
4. They produce abundant quantities of pollen to make up for pollen grains that might be removed by the wind.

4. Which of the following are likely characteristics of the structures found in X and stamens of this plant?

5. Spiny or sticky pollen grains and large, attractively coloured flowers are associated with:

1. Hydrophily.
2. Entomophily.
3. Ornithophily.
4. Anemophily.