Selected MCQ

Current Question
Which organelle is primarily involved in the detoxification of hydrogen peroxide (H₂O₂) in eukaryotic cells?
  • A. Lysosome
  • B. Mitochondrion
  • C. Peroxisome
  • D. Golgi apparatus
Correct Answer: C
Explanation:
Peroxisomes contain the enzyme catalase, which converts H₂O₂ to water and oxygen. They specialize in detoxifying reactive oxygen species.
Related Question 1
Which organelle is primarily responsible for lipid synthesis and detoxification of drugs in liver cells?
  • A. Rough endoplasmic reticulum
  • B. Smooth endoplasmic reticulum
  • C. Golgi apparatus
  • D. Mitochondrion
Correct Answer: B
Explanation:
Smooth ER contains enzymes involved in lipid metabolism and drug detoxification (e.g., cytochrome P450s), especially in hepatocytes.
Related Question 2
Which organelle in animal cells contains its own circular DNA and is involved in ATP production?
  • A. Mitochondrion
  • B. Golgi apparatus
  • C. Peroxisome
  • D. Endoplasmic reticulum
Correct Answer: A
Explanation:
Mitochondria have a circular genome and produce ATP through oxidative phosphorylation.
Related Question 3
In flow cytometry, cells are labeled with fluorescent antibodies and passed in a stream through a laser. This technique primarily measures:
  • A. Cell size and internal complexity
  • B. DNA sequence variants
  • C. Protein structure by X-ray diffraction
  • D. Glycolytic activity
Correct Answer: A
Explanation:
Flow cytometry measures light scattering (size and granularity) and fluorescence from labeled markers, allowing rapid analysis of cell populations (size, complexity, marker expression).
Related Question 4
Small interfering RNAs (siRNAs) are primarily involved in which cellular process?
  • A. DNA replication
  • B. RNA interference (RNAi) leading to mRNA degradation
  • C. Protein synthesis
  • D. Glycolysis
Correct Answer: B
Explanation:
siRNAs guide the RNA-induced silencing complex (RISC) to complementary mRNA, causing its cleavage and degradation, a form of RNA interference.
Related Question 5
Which organelle contains hydrolytic enzymes and is involved in the degradation of cellular components during autophagy?
  • A. Lysosome
  • B. Proteasome
  • C. Golgi apparatus
  • D. Smooth endoplasmic reticulum
Correct Answer: A
Explanation:
Lysosomes contain acid hydrolases that fuse with autophagosomes to degrade cellular organelles and proteins.