Selected MCQ

Current Question
Crawling movement of cells (e.g., fibroblasts) primarily depends on the polymerization of which cytoskeletal component?
  • A. Microtubules
  • B. Intermediate filaments
  • C. Actin microfilaments
  • D. Centrioles
Correct Answer: C
Explanation:
Lamellipodia and filopodia are actin-based protrusions. Actin polymerization at the leading edge drives cell crawling and motility.
Related Question 1
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 2
Which cytoskeletal filament requires ATP hydrolysis for its polymerization?
  • A. Microtubules
  • B. Actin microfilaments
  • C. Intermediate filaments
  • D. Cellulose microfibrils
Correct Answer: B
Explanation:
Actin polymerization uses ATP. Microtubules use GTP for tubulin assembly; intermediate filaments do not use nucleotide hydrolysis.
Related Question 3
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 4
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 5
Which chromatography technique separates proteins primarily based on size using a gel matrix?
  • A. Ion-exchange chromatography
  • B. Gel filtration (size-exclusion) chromatography
  • C. Affinity chromatography
  • D. Reverse-phase chromatography
Correct Answer: B
Explanation:
Gel filtration chromatography (size-exclusion) separates proteins by size: larger molecules elute first because they enter fewer pores in the matrix, while smaller molecules elute later.