Selected MCQ

Current Question
Crossing over during meiosis contributes directly to:
  • A. DNA replication arrest
  • B. Genetic recombination
  • C. Chromosome number doubling
  • D. Cytokinesis prevention
Correct Answer: B
Explanation:
Exchange between homologous chromatids creates new allele combinations.
Related Question 1
Which phase of meiosis involves crossing over?
  • A. Prophase I
  • B. Metaphase II
  • C. Anaphase I
  • D. Telophase II
Correct Answer: A
Explanation:
Homologous recombination occurs in prophase I.
Related Question 2
Which gas contributes to ozone depletion?
  • A. CO₂
  • B. CFC
  • C. N₂
  • D. O₂
Correct Answer: B
Explanation:
CFCs release chlorine radicals.
Related Question 3
Which gas contributes most to greenhouse effect after water vapor?
  • A. Methane
  • B. CO₂
  • C. Ozone
  • D. Nitrogen
Correct Answer: B
Explanation:
CO₂ is major anthropogenic greenhouse gas.
Related Question 4
Which process most directly forms soil horizons over long timescales?
  • A. Instantaneous melting
  • B. Weathering combined with organic accumulation and leaching
  • C. Oceanic spreading
  • D. Lunar tidal forcing
Correct Answer: B
Explanation:
Soil profiles develop from parent material alteration plus biological and hydrologic processes.
Related Question 5
Natural selection acts directly on:
  • A. Genotypes only
  • B. Phenotypes affecting fitness
  • C. Mutations before expression
  • D. Species as indivisible units only
Correct Answer: B
Explanation:
Selection filters expressed traits that influence survival and reproduction.