1. Which gene in wheat is primarily responsible for reducing plant height and played a crucial role during the Green Revolution?

  • A. Lr34
  • B. Rht-B1
  • C. Pm21
  • D. Sr31

Answer: B. Rht-B1

Explanation: The Rht-B1 dwarfing gene reduces stem elongation, improves lodging resistance, and significantly increases wheat yield potential.

2. Which soil process involves the downward movement of clay particles from the A horizon to the B horizon?

  • A. Laterization
  • B. Calcification
  • C. Lessivage
  • D. Gleization

Answer: C. Lessivage

Explanation: Lessivage is the translocation of clay from upper horizons to lower horizons, forming an argillic horizon.

3. Which photosynthetic enzyme has both carboxylase and oxygenase activity?

  • A. PEP carboxylase
  • B. Rubisco
  • C. Malate dehydrogenase
  • D. Carbonic anhydrase

Answer: B. Rubisco

Explanation: Rubisco catalyzes both CO₂ fixation and oxygenation of RuBP, leading to photosynthesis and photorespiration, respectively.

4. Which pathogen causes loose smut of wheat?

  • A. Puccinia graminis
  • B. Ustilago tritici
  • C. Alternaria triticina
  • D. Bipolaris sorokiniana

Answer: B. Ustilago tritici

Explanation: Loose smut of wheat is caused by Ustilago tritici, a seed-borne internally infecting fungal pathogen.

5. Which beneficial insect is widely used in biological control of aphids?

  • A. Helicoverpa armigera
  • B. Coccinella septempunctata
  • C. Nilaparvata lugens
  • D. Bemisia tabaci

Answer: B. Coccinella septempunctata

Explanation: The seven-spotted ladybird beetle is an efficient predator of aphids and is widely used in biological pest management.

6. Which nutrient is most closely associated with increased oil content in oilseed crops?

  • A. Nitrogen
  • B. Sulphur
  • C. Calcium
  • D. Iron

Answer: B. Sulphur

Explanation: Sulphur plays an important role in oil synthesis and improves both seed quality and oil percentage.

7. Which experimental design is most appropriate when the number of treatments is large and field variability is high?

  • A. Completely Randomized Design
  • B. Randomized Block Design
  • C. Lattice Design
  • D. Strip Plot Design

Answer: C. Lattice Design

Explanation: Lattice designs improve precision when evaluating many treatments under heterogeneous field conditions.

8. Which microorganism forms vesicular-arbuscular mycorrhizal (VAM) associations with plant roots?

  • A. Azospirillum brasilense
  • B. Glomus spp.
  • C. Rhizobium leguminosarum
  • D. Bacillus subtilis

Answer: B. Glomus spp.

Explanation: Species of Glomus are arbuscular mycorrhizal fungi that enhance phosphorus uptake and improve plant growth.

9. Which hormone is primarily responsible for breaking seed dormancy in many plant species?

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

Answer: C. Gibberellic acid

Explanation: Gibberellic acid stimulates enzyme synthesis, mobilizes stored food, and promotes seed germination by overcoming dormancy.

10. Which nitrogen-fixing microorganism forms a symbiotic association with the aquatic fern Azolla?

  • A. Nostoc
  • B. Anabaena azollae
  • C. Frankia
  • D. Azotobacter chroococcum

Answer: B. Anabaena azollae

Explanation: Anabaena azollae lives symbiotically in Azolla leaves and fixes atmospheric nitrogen, making Azolla an excellent biofertilizer for rice fields.