Selected MCQ

Current Question
Which of the following is a key executioner caspase in the apoptosis pathway?
  • A. Caspase-3
  • B. Caspase-8
  • C. Caspase-1
  • D. Caspase-9
Correct Answer: A
Explanation:
Caspase-3 is an executioner caspase that cleaves various cellular substrates to carry out apoptosis. Caspase-8 and -9 are initiators.
Related Question 1
Which of the following is NOT characteristic of the lysosomal degradation pathway?
  • A. Lysosomes contain acid hydrolases active at low pH
  • B. Autophagosomes deliver cytoplasmic components to lysosomes
  • C. Degraded macromolecules are exported to the cytosol for reuse
  • D. Ubiquitinated proteins targeted for degradation are broken down in lysosomes
Correct Answer: D
Explanation:
Lysosomes degrade extracellular and organelle material. The proteasome, not lysosomes, primarily degrades ubiquitinated proteins.
Related Question 2
Which of the following best describes polygenic inheritance?
  • A. One gene affects multiple traits (e.g., pleiotropy)
  • B. Many genes contribute to one trait (e.g., skin color)
  • C. A trait determined by genes only on the X chromosome
  • D. Inheritance of mitochondrial DNA
Correct Answer: B
Explanation:
Polygenic inheritance means multiple genes (often with additive effects) determine a single phenotype, such as height or skin color, producing continuous variation.
Related Question 3
Which of the following is NOT typically controlled during industrial fermentation in a bioreactor?
  • A. Temperature
  • B. pH
  • C. Oxygen concentration
  • D. DNA sequence of the microorganism
Correct Answer: D
Explanation:
A, B, and C (temperature, pH, oxygen) are critical parameters controlled in fermentation. The chosen strain fixes the DNA sequence and is not a controlled parameter during the run.
Related Question 4
Which of the following techniques compares short tandem repeat (STR) regions among individuals for identification?
  • A. Western blot
  • B. DNA microarray
  • C. DNA fingerprinting
  • D. Northern blot
Correct Answer: C
Explanation:
DNA fingerprinting analyzes highly polymorphic regions, especially STRs, to distinguish individuals (used in forensics and paternity testing).
Related Question 5
Which DNA repair pathway primarily corrects UV-induced thymine dimers?
  • A. Base-excision repair
  • B. Nucleotide-excision repair
  • C. Mismatch repair
  • D. Non-homologous end joining
Correct Answer: B
Explanation:
Nucleotide-excision repair recognizes bulky lesions like thymine dimers from UV exposure and removes a short single-stranded DNA segment including the damage.