1. The enzyme ferredoxin–NADP+ reductase (FNR) catalyzes the formation of:

  • A. ATP from ADP
  • B. NADPH from NADP+
  • C. Oxygen from water
  • D. Glucose from glyceraldehyde-3-phosphate

Answer: B. NADPH from NADP+

Explanation: Ferredoxin–NADP+ reductase transfers electrons from ferredoxin to NADP+, producing NADPH required for the Calvin cycle.

2. Which exchangeable cation generally dominates the exchange complex of sodic soils?

  • A. Calcium (Ca²⁺)
  • B. Magnesium (Mg²⁺)
  • C. Potassium (K⁺)
  • D. Sodium (Na⁺)

Answer: D. Sodium (Na⁺)

Explanation: Sodic soils have a high proportion of exchangeable sodium, resulting in poor soil structure, dispersion, and reduced infiltration.

3. Which DNA polymerase is primarily responsible for chromosomal DNA replication in Escherichia coli?

  • A. DNA Polymerase I
  • B. DNA Polymerase II
  • C. DNA Polymerase III
  • D. DNA Polymerase IV

Answer: C. DNA Polymerase III

Explanation: DNA Polymerase III is the principal replicative enzyme in bacteria, whereas DNA Polymerase I mainly removes RNA primers and fills the resulting gaps.

4. Which disease of pigeonpea is caused by Fusarium udum?

  • A. Sterility mosaic
  • B. Wilt
  • C. Phytophthora blight
  • D. Powdery mildew

Answer: B. Wilt

Explanation: Fusarium wilt of pigeonpea is caused by Fusarium udum, a soil-borne fungus that blocks vascular tissues and causes plant wilting.

5. Which experimental design is particularly suitable when one factor requires larger experimental units than another?

  • A. Completely Randomized Design (CRD)
  • B. Latin Square Design (LSD)
  • C. Split Plot Design
  • D. Factorial CRD

Answer: C. Split Plot Design

Explanation: Split Plot Design is used when one treatment factor is difficult or expensive to apply and therefore occupies larger main plots.

6. Which plant growth regulator is commonly used commercially to synchronize flowering in pineapple?

  • A. Indole-3-acetic acid (IAA)
  • B. Ethylene (Ethephon)
  • C. Gibberellic acid (GA₃)
  • D. Abscisic acid

Answer: B. Ethylene (Ethephon)

Explanation: Ethephon releases ethylene, which induces uniform flowering in pineapple plantations for synchronized harvesting.

7. Which insect pest is commonly referred to as the "American bollworm" of cotton?

  • A. Earias vittella
  • B. Pectinophora gossypiella
  • C. Helicoverpa armigera
  • D. Spodoptera litura

Answer: C. Helicoverpa armigera

Explanation: Helicoverpa armigera, formerly known as the American bollworm, is a major polyphagous pest causing severe damage to cotton and several other crops.

8. Which enzyme catalyzes the conversion of fumarate to malate in the tricarboxylic acid (TCA) cycle?

  • A. Fumarase
  • B. Malate dehydrogenase
  • C. Succinate dehydrogenase
  • D. Citrate synthase

Answer: A. Fumarase

Explanation: Fumarase hydrates fumarate to form malate, which is subsequently oxidized to oxaloacetate by malate dehydrogenase.

9. Which irrigation efficiency represents the ratio of water stored in the crop root zone to the water delivered to the field?

  • A. Conveyance efficiency
  • B. Storage efficiency
  • C. Application efficiency
  • D. Distribution efficiency

Answer: C. Application efficiency

Explanation: Application efficiency measures the percentage of delivered irrigation water that is actually stored within the crop root zone.

10. In population genetics, the random fluctuation of allele frequencies due to chance alone is known as:

  • A. Gene flow
  • B. Mutation
  • C. Genetic drift
  • D. Natural selection

Answer: C. Genetic drift

Explanation: Genetic drift is the random change in allele frequencies from one generation to the next, especially in small populations.