1. Which enzyme catalyzes the conversion of glutamate and ammonia into glutamine during primary nitrogen assimilation in plants?

  • A. Glutamate synthase (GOGAT)
  • B. Glutamine synthetase (GS)
  • C. Aspartate aminotransferase
  • D. Nitrate reductase

Answer: B. Glutamine synthetase (GS)

Explanation: Glutamine synthetase catalyzes ATP-dependent incorporation of NH₄⁺ into glutamate to form glutamine, the first step of the GS-GOGAT pathway.

2. Which soil moisture constant represents the upper limit of plant-available water after gravitational water has drained away?

  • A. Permanent wilting point
  • B. Hygroscopic coefficient
  • C. Field capacity
  • D. Saturation percentage

Answer: C. Field capacity

Explanation: Field capacity is the soil water content remaining after excess gravitational water has drained, representing the upper limit of available water.

3. Which breeding method is most suitable for improving a single simply inherited trait in an otherwise superior variety?

  • A. Bulk population method
  • B. Pedigree method
  • C. Backcross breeding
  • D. Recurrent selection

Answer: C. Backcross breeding

Explanation: Backcross breeding transfers one or a few desirable genes from a donor parent into an elite recurrent parent while retaining most of its genome.

4. Which pathogen causes bacterial blight of rice?

  • A. Pseudomonas syringae
  • B. Xanthomonas oryzae pv. oryzae
  • C. Erwinia chrysanthemi
  • D. Ralstonia solanacearum

Answer: B. Xanthomonas oryzae pv. oryzae

Explanation: Bacterial blight of rice is caused by Xanthomonas oryzae pv. oryzae and is one of the most destructive bacterial diseases of rice.

5. Which measure of variability is expressed in the same units as the original observations?

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

Answer: C. Standard deviation

Explanation: Standard deviation is the square root of variance and is expressed in the same units as the measured variable.

6. Which plant hormone delays leaf senescence by promoting protein synthesis and chloroplast maintenance?

  • A. Ethylene
  • B. Abscisic acid
  • C. Cytokinin
  • D. Jasmonic acid

Answer: C. Cytokinin

Explanation: Cytokinins delay senescence by maintaining chlorophyll content, protein synthesis, and chloroplast integrity.

7. Which entomopathogenic fungus is extensively used for the biological control of whiteflies, aphids, and thrips?

  • A. Beauveria bassiana
  • B. Aspergillus flavus
  • C. Penicillium chrysogenum
  • D. Rhizopus stolonifer

Answer: A. Beauveria bassiana

Explanation: Beauveria bassiana is a broad-spectrum entomopathogenic fungus widely used against several sucking and chewing insect pests.

8. Which enzyme catalyzes the phosphorylation of glucose to glucose-6-phosphate in the first step of glycolysis?

  • A. Aldolase
  • B. Hexokinase
  • C. Enolase
  • D. Phosphoglycerate kinase

Answer: B. Hexokinase

Explanation: Hexokinase catalyzes the ATP-dependent phosphorylation of glucose to glucose-6-phosphate, the first irreversible step of glycolysis.

9. Which growth analysis parameter is defined as the ratio of total leaf area to the land area occupied by the crop?

  • A. Net Assimilation Rate (NAR)
  • B. Relative Growth Rate (RGR)
  • C. Leaf Area Index (LAI)
  • D. Crop Growth Rate (CGR)

Answer: C. Leaf Area Index (LAI)

Explanation: Leaf Area Index is the one-sided green leaf area per unit ground area and is an important indicator of crop canopy development.

10. Which evolutionary force introduces completely new alleles into a population?

  • A. Mutation
  • B. Genetic drift
  • C. Natural selection
  • D. Non-random mating

Answer: A. Mutation

Explanation: Mutation is the ultimate source of new genetic variation because it creates novel alleles that can subsequently be acted upon by evolutionary forces.