Selected MCQ

Current Question
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 1
Which of the following best describes clathrin function in eukaryotic cells?
  • A. It mediates the transport of proteins from the ER to the Golgi.
  • B. It forms a coat around vesicles during receptor-mediated endocytosis.
  • C. It phosphorylates tyrosine residues in signaling receptors.
  • D. It generates a proton gradient in endosomes.
Correct Answer: B
Explanation:
Clathrin polymerizes into a lattice on the inner surface of the plasma membrane, forming coated pits and vesicles that internalize receptors and ligands.
Related Question 2
A red blood cell (internal osmolarity ~290 mOsm) is placed in a 100 mM NaCl solution (assume full dissociation). Which best describes the movement of water?
  • A. The cell loses water and shrinks
  • B. The cell gains water and swells
  • C. No net water movement
  • D. The cell bursts immediately
Correct Answer: B
Explanation:
100 mM NaCl yields ~200 mOsm outside (hypotonic to the cell). Water enters the cell, causing it to swell.
Related Question 3
Which term describes genes that are located on the same chromosome and inherited together more often than by chance?
  • A. Linked genes
  • B. Epistatic genes
  • C. Polygenic genes
  • D. Independent genes
Correct Answer: A
Explanation:
Linked genes are near each other on the same chromosome. They tend to be inherited together, and their recombination frequency is less than 50%.
Related Question 4
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 5
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).