1. In a diallel mating design involving n parents (excluding reciprocals), the total number of F₁ hybrids produced is:

  • A. n(n−1)
  • B. n(n+1)/2
  • C. n(n−1)/2
  • D. (n−1)/2

Answer: C. n(n−1)/2

Explanation: In a half-diallel (excluding reciprocals and selfs), the number of F₁ crosses is n(n−1)/2.

2. Which of the following microorganisms is primarily responsible for anaerobic ammonium oxidation (Anammox) in soils and aquatic ecosystems?

  • A. Nitrosomonas europaea
  • B. Planctomycetes bacteria
  • C. Azotobacter chroococcum
  • D. Nitrobacter winogradskyi

Answer: B. Planctomycetes bacteria

Explanation: Anammox bacteria belonging to the phylum Planctomycetes convert ammonium and nitrite directly into nitrogen gas under anaerobic conditions.

3. Which chromosome type possesses nearly equal arms due to the centromere being located approximately in the middle?

  • A. Acrocentric
  • B. Telocentric
  • C. Metacentric
  • D. Submetacentric

Answer: C. Metacentric

Explanation: Metacentric chromosomes have centrally located centromeres, producing two arms of nearly equal length.

4. The toxin victorin, associated with host-selective pathogenicity, is produced by which fungal pathogen?

  • A. Alternaria alternata
  • B. Cochliobolus victoriae
  • C. Magnaporthe oryzae
  • D. Ustilago maydis

Answer: B. Cochliobolus victoriae

Explanation: Victorin is a host-selective toxin produced by Cochliobolus victoriae, causing Victoria blight of oats.

5. Which statistical technique transforms correlated variables into a smaller number of uncorrelated variables called principal components?

  • A. Cluster analysis
  • B. Canonical correlation
  • C. Principal Component Analysis (PCA)
  • D. Discriminant analysis

Answer: C. Principal Component Analysis (PCA)

Explanation: PCA reduces data dimensionality by converting correlated variables into orthogonal principal components.

6. Which phytohormone is synthesized from the amino acid methionine?

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

Answer: B. Ethylene

Explanation: Ethylene is synthesized from methionine via S-adenosyl methionine (SAM) and ACC (1-aminocyclopropane-1-carboxylic acid).

7. Which insecticide acts primarily by blocking voltage-gated sodium channels in insect nerve cells, causing paralysis?

  • A. Imidacloprid
  • B. Cypermethrin
  • C. Cartap hydrochloride
  • D. Chlorantraniliprole

Answer: B. Cypermethrin

Explanation: Cypermethrin is a synthetic pyrethroid that prolongs sodium channel opening, leading to repetitive nerve firing and paralysis.

8. Which Calvin cycle enzyme catalyzes the regeneration of ribulose-1,5-bisphosphate (RuBP) from ribulose-5-phosphate?

  • A. Aldolase
  • B. Transketolase
  • C. Phosphoribulokinase
  • D. Fructose-1,6-bisphosphatase

Answer: C. Phosphoribulokinase

Explanation: Phosphoribulokinase phosphorylates ribulose-5-phosphate to regenerate RuBP using ATP.

9. The resistance encountered by water moving through the soil-plant-atmosphere continuum is referred to as:

  • A. Hydraulic conductivity
  • B. Diffusion pressure deficit
  • C. Hydraulic resistance
  • D. Osmotic adjustment

Answer: C. Hydraulic resistance

Explanation: Hydraulic resistance determines the ease with which water moves through soil, roots, stems, leaves, and the atmosphere.

10. Which mating system maintains maximum heterozygosity in a breeding population by avoiding self-fertilization?

  • A. Selfing
  • B. Sib mating
  • C. Random mating
  • D. Backcrossing

Answer: C. Random mating

Explanation: Random mating preserves heterozygosity and genetic variability by allowing alleles to assort freely across generations.