Selected MCQ

Current Question
One gene’s product is epistatic to another gene’s product, meaning:
  • A. Both genes contribute equally to a single trait
  • B. One gene’s effect masks or hides the effect of another
  • C. The two genes are linked on the same chromosome
  • D. The genes show incomplete dominance
Correct Answer: B
Explanation:
Epistasis occurs when the expression of one gene masks the effect of another gene (e.g., a loss-of-function in one gene may prevent the other gene from having an effect).
Related Question 1
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 2
In gene therapy using a viral vector, what is a major concern related to using retroviruses?
  • A. They cannot infect human cells
  • B. They only integrate into mitochondrial DNA
  • C. Insertional mutagenesis by random integration into the host genome
  • D. They cannot carry large genes
Correct Answer: C
Explanation:
Retroviral vectors integrate randomly into the host genome, risking insertional mutagenesis (disrupting host genes), which can cause cancer or other issues.
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
Somatic cell nuclear transfer (SCNT) for reproductive cloning involves:
  • A. Injecting somatic cell DNA into a fertilized egg with its nucleus intact
  • B. Fusing a diploid somatic cell with an enucleated egg cell
  • C. Using only oocyte mitochondria from a donor
  • D. Cloning via binary fission
Correct Answer: B
Explanation:
SCNT (as in cloning Dolly the sheep) entails transferring the nucleus of an adult somatic cell into an enucleated oocyte, and then stimulating the resulting cell to divide as an embryo.
Related Question 5
Human insulin production by recombinant DNA technology was first achieved in:
  • A. Yeast cells
  • B. Bacterial cells
  • C. Mammalian cells
  • D. Plant cells
Correct Answer: B
Explanation:
The first human protein successfully produced by genetic engineering was insulin, expressed in genetically modified Escherichia coli bacteria.