Question 1

Q1. During DNA replication in prokaryotes, which enzyme is primarily responsible for relieving supercoiling ahead of the replication fork?

Accepted Answer

Option C: DNA gyrase. DNA gyrase (a type of topoisomerase) removes supercoiling tension ahead of the replication fork. Helicase unwinds DNA strands but does not remove supercoils.

Question 2

Q2. In Mendelian inheritance, a dihybrid cross showing 9:3:3:1 ratio deviates when genes are linked. What is the most likely outcome?

Accepted Answer

Option B: Parental traits appear more frequently. Linked genes do not assort independently, so parental combinations are observed more frequently than recombinants.

Question 3

Q3. Which hormone is directly responsible for ovulation in humans?

Accepted Answer

Option B: LH. The LH surge triggers ovulation by rupturing the Graafian follicle.

Question 4

Q4. Which pyramid of ecology can be inverted in shape?

Accepted Answer

Option C: Pyramid of numbers. Pyramid of numbers can be inverted depending on ecosystem (e.g., tree-based ecosystems).

Question 5

Q5. The function of restriction endonucleases in biotechnology is to:

Accepted Answer

Option B: Cut DNA at specific recognition sites. Restriction enzymes cut DNA at specific palindromic sequences, enabling recombinant DNA technology.

Question 6

Q6. A child shows blood group O while both parents are A and B respectively. What is the most probable genotype explanation?

Accepted Answer

Option B: IAi × IBi. Both parents must carry recessive allele i to produce an O blood group child.

Question 7

Q7. In PCR, which step ensures denaturation of DNA strands?

Accepted Answer

Option C: 94–95°C. High temperature (94–95°C) breaks hydrogen bonds between DNA strands.

Question 8

Q8. A farmer selects plants with high yield and disease resistance over several generations. This process is known as:

Accepted Answer

Option B: Artificial selection. Human-directed selection of traits is artificial selection.

Question 9

Q9. According to Hardy-Weinberg equilibrium, if allele frequency remains constant, which condition is violated?

Accepted Answer

Option D: Presence of natural selection. Natural selection alters allele frequencies, violating equilibrium conditions.

Question 10

Q10. In gel electrophoresis, DNA fragments move towards:

Accepted Answer

Option B: Positive electrode. DNA is negatively charged due to phosphate groups and moves towards the anode.

Question 11

Q11. A couple wants a reversible contraceptive method with no hormonal side effects. Best option is:

Accepted Answer

Option B: Copper-T. Copper-T is non-hormonal and reversible, preventing fertilization.

Question 12

Q12. Bt cotton is genetically modified to:

Accepted Answer

Option C: Resist insect pests. Bt gene produces toxin that kills specific insect pests.

Question 13

Q13. Excessive discharge of nutrients in a lake leads to:

Accepted Answer

Option B: Eutrophication. Nutrient enrichment causes algal bloom and oxygen depletion.

Question 14

Q14. Assertion (A): Crossing over occurs during pachytene stage of prophase I. Reason (R): It leads to genetic recombination.

Accepted Answer

Option A: Both A and R are true and R explains A. Crossing over occurs in pachytene and results in genetic recombination.

Question 15

Q15. Assertion (A): Lac operon is always active in presence of lactose. Reason (R): Lactose acts as an inducer by inactivating the repressor.

Accepted Answer

Option A: Both true and R explains A. Lactose inactivates repressor allowing transcription.

Question 16

Q16. Case Study: A pedigree shows a trait appearing in every generation and affects both males and females equally. What is most likely inheritance pattern?

Accepted Answer

Option B: Autosomal dominant. Vertical transmission in every generation indicates dominant trait.

Question 17

Q17. Case Study: In recombinant insulin production, human gene is inserted into bacteria. What is the key reason bacteria are used?

Accepted Answer

Option C: They multiply rapidly and express genes easily. Bacteria reproduce quickly and are easy to genetically modify.

Question 18

Q18. Which observation best supports Darwin's theory of natural selection?

Accepted Answer

Option B: Overproduction of offspring. Overproduction leads to competition and selection of fittest.

Question 19

Q19. During ecological succession, pioneer species are typically:

Accepted Answer

Option B: Lichens and mosses. Pioneer species are first colonizers like lichens in bare areas.

Question 20

Q20. A DNA sample shows 30% adenine. What is the percentage of guanine?

Accepted Answer

Option A: 20%. A=T=30%, so A+T=60%. Remaining 40% is G+C → G = 20%.

Mock Test 02 Performance Solutions

Detailed Question Analysis

Q1. During DNA replication in prokaryotes, which enzyme is primarily responsible for relieving supercoiling ahead of the replication fork?

Q2. In Mendelian inheritance, a dihybrid cross showing 9:3:3:1 ratio deviates when genes are linked. What is the most likely outcome?

Q3. Which hormone is directly responsible for ovulation in humans?

Q4. Which pyramid of ecology can be inverted in shape?

Q5. The function of restriction endonucleases in biotechnology is to:

Q6. A child shows blood group O while both parents are A and B respectively. What is the most probable genotype explanation?

Q7. In PCR, which step ensures denaturation of DNA strands?

Q8. A farmer selects plants with high yield and disease resistance over several generations. This process is known as:

Q9. According to Hardy-Weinberg equilibrium, if allele frequency remains constant, which condition is violated?

Q10. In gel electrophoresis, DNA fragments move towards:

Q11. A couple wants a reversible contraceptive method with no hormonal side effects. Best option is:

Q12. Bt cotton is genetically modified to:

Q13. Excessive discharge of nutrients in a lake leads to:

Q14. Assertion (A): Crossing over occurs during pachytene stage of prophase I. Reason (R): It leads to genetic recombination.

Q15. Assertion (A): Lac operon is always active in presence of lactose. Reason (R): Lactose acts as an inducer by inactivating the repressor.

Q16. Case Study: A pedigree shows a trait appearing in every generation and affects both males and females equally. What is most likely inheritance pattern?

Q17. Case Study: In recombinant insulin production, human gene is inserted into bacteria. What is the key reason bacteria are used?

Q18. Which observation best supports Darwin's theory of natural selection?

Q19. During ecological succession, pioneer species are typically:

Q20. A DNA sample shows 30% adenine. What is the percentage of guanine?

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Mock Test 02 Performance Solutions

Detailed Question Analysis

Q1. During DNA replication in prokaryotes, which enzyme is primarily responsible for relieving supercoiling ahead of the replication fork?

Q2. In Mendelian inheritance, a dihybrid cross showing 9:3:3:1 ratio deviates when genes are linked. What is the most likely outcome?

Q3. Which hormone is directly responsible for ovulation in humans?

Q4. Which pyramid of ecology can be inverted in shape?

Q5. The function of restriction endonucleases in biotechnology is to:

Q6. A child shows blood group O while both parents are A and B respectively. What is the most probable genotype explanation?

Q7. In PCR, which step ensures denaturation of DNA strands?

Q8. A farmer selects plants with high yield and disease resistance over several generations. This process is known as:

Q9. According to Hardy-Weinberg equilibrium, if allele frequency remains constant, which condition is violated?

Q10. In gel electrophoresis, DNA fragments move towards:

Q11. A couple wants a reversible contraceptive method with no hormonal side effects. Best option is:

Q12. Bt cotton is genetically modified to:

Q13. Excessive discharge of nutrients in a lake leads to:

Q14. Assertion (A): Crossing over occurs during pachytene stage of prophase I. Reason (R): It leads to genetic recombination.

Q15. Assertion (A): Lac operon is always active in presence of lactose. Reason (R): Lactose acts as an inducer by inactivating the repressor.

Q16. Case Study: A pedigree shows a trait appearing in every generation and affects both males and females equally. What is most likely inheritance pattern?

Q17. Case Study: In recombinant insulin production, human gene is inserted into bacteria. What is the key reason bacteria are used?

Q18. Which observation best supports Darwin's theory of natural selection?

Q19. During ecological succession, pioneer species are typically:

Q20. A DNA sample shows 30% adenine. What is the percentage of guanine?

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