Selected MCQ

Current Question
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 1
During the G1/S transition in the eukaryotic cell cycle, phosphorylation of the retinoblastoma (Rb) protein results in which of the following?
  • A. Release of E2F transcription factors, activating S-phase gene expression
  • B. Activation of cyclin-dependent kinase inhibitors to halt cell cycle progression
  • C. Induction of apoptosis via activation of p53
  • D. Inhibition of cyclin D synthesis
Correct Answer: A
Explanation:
Phosphorylated Rb releases bound E2F transcription factors, which then activate genes required for DNA replication in S phase.
Related Question 2
Alternative splicing occurs during gene expression at the level of:
  • A. DNA replication
  • B. Transcription initiation
  • C. Pre-mRNA processing (RNA splicing)
  • D. Protein folding
Correct Answer: C
Explanation:
Alternative splicing of pre-mRNA allows different exons to be joined or skipped, producing multiple mRNA variants from one gene during RNA processing.
Related Question 3
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 4
In tissue engineering, a scaffold material must typically be:
  • A. Non-biodegradable only
  • B. Biocompatible and biodegradable
  • C. Made of metal only
  • D. Radioactive
Correct Answer: B
Explanation:
Tissue scaffolds are usually biocompatible (non-toxic, no immune response) and biodegradable so that they eventually degrade as new tissue forms in the scaffold’s place.
Related Question 5
In Western blotting, proteins are typically detected using:
  • A. DNA probes
  • B. RNA probes
  • C. Enzyme-linked antibodies
  • D. Radioactive amino acids
Correct Answer: C
Explanation:
Western blot uses antibodies (often enzyme-linked) that bind specific proteins on the membrane, allowing visualization via a colorimetric or chemiluminescent reaction.