1. Which enzyme catalyzes the conversion of pyruvate to phosphoenolpyruvate during gluconeogenesis in germinating oilseeds?

  • A. Pyruvate kinase
  • B. Phosphoenolpyruvate carboxylase
  • C. Phosphoenolpyruvate carboxykinase (PEPCK)
  • D. Enolase

Answer: C. Phosphoenolpyruvate carboxykinase (PEPCK)

Explanation: PEPCK catalyzes the formation of phosphoenolpyruvate during gluconeogenesis, enabling conversion of stored lipids into sugars in germinating seeds.

2. Which clay mineral exhibits the greatest shrink-swell behavior, causing deep cracks in Vertisols?

  • A. Kaolinite
  • B. Illite
  • C. Montmorillonite
  • D. Halloysite

Answer: C. Montmorillonite

Explanation: Montmorillonite is an expanding 2:1 clay mineral with high water absorption capacity, producing severe swelling and shrinkage.

3. Which resistance is governed by many minor genes and generally provides durable protection against plant diseases?

  • A. Vertical resistance
  • B. Monogenic resistance
  • C. Horizontal resistance
  • D. Cytoplasmic resistance

Answer: C. Horizontal resistance

Explanation: Horizontal resistance is polygenic, non-race-specific, and usually remains effective for longer periods than vertical resistance.

4. Which insecticide group acts by irreversibly inhibiting acetylcholinesterase?

  • A. Neonicotinoids
  • B. Pyrethroids
  • C. Organophosphates
  • D. Diamides

Answer: C. Organophosphates

Explanation: Organophosphate insecticides inhibit acetylcholinesterase, causing continuous nerve stimulation and insect death.

5. Which crop is the principal host of the nitrogen-fixing bacterium Bradyrhizobium japonicum?

  • A. Chickpea
  • B. Soybean
  • C. Groundnut
  • D. Lentil

Answer: B. Soybean

Explanation: Bradyrhizobium japonicum forms effective nitrogen-fixing nodules specifically with soybean plants.

6. Which physiological process is directly measured using a pressure chamber (pressure bomb)?

  • A. Photosynthetic rate
  • B. Leaf water potential
  • C. Respiration rate
  • D. Chlorophyll content

Answer: B. Leaf water potential

Explanation: The pressure chamber estimates plant water status by determining the balancing pressure required to force xylem sap to the cut surface.

7. Which statistical parameter is obtained by dividing the standard deviation by the mean and expressing it as a percentage?

  • A. Standard error
  • B. Coefficient of variation
  • C. Variance
  • D. Correlation coefficient

Answer: B. Coefficient of variation

Explanation: The coefficient of variation expresses variability relative to the mean and is widely used to compare experimental precision.

8. Which cereal crop possesses the highest chromosome number among the following?

  • A. Rice (2n=24)
  • B. Maize (2n=20)
  • C. Bread wheat (2n=42)
  • D. Barley (2n=14)

Answer: C. Bread wheat (2n=42)

Explanation: Bread wheat is a hexaploid species (AABBDD genomes) with 42 chromosomes.

9. Which deficiency symptom is characteristically known as 'whiptail' in cauliflower?

  • A. Boron deficiency
  • B. Molybdenum deficiency
  • C. Zinc deficiency
  • D. Copper deficiency

Answer: B. Molybdenum deficiency

Explanation: Molybdenum deficiency causes severe narrowing of leaf blades in cauliflower, producing the characteristic whiptail symptom.

10. Which enzyme is responsible for biological nitrogen fixation in Rhizobium-legume symbiosis?

  • A. Nitrate reductase
  • B. Nitrite reductase
  • C. Nitrogenase
  • D. Glutamine synthetase

Answer: C. Nitrogenase

Explanation: Nitrogenase catalyzes the ATP-dependent reduction of atmospheric nitrogen (N₂) into ammonia within root nodules.