Selected MCQ

Current Question
Genetically modified crops containing the Bt (Bacillus thuringiensis) toxin gene are resistant to:
  • A. Herbicides
  • B. Insect pests
  • C. Drought
  • D. Viral infection
Correct Answer: B
Explanation:
The Bt gene encodes an insecticidal protein. Plants expressing Bt produce a toxin that targets specific insect pests, providing built-in insect resistance.
Related Question 1
Golden rice has been genetically engineered to produce which nutrient precursor?
  • A. Vitamin C
  • B. Beta-carotene (provitamin A)
  • C. Vitamin E
  • D. Folic acid
Correct Answer: B
Explanation:
Golden rice contains genes for beta-carotene biosynthesis, which is a precursor of vitamin A, to help alleviate vitamin A deficiency.
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
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 4
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 5
In a cloning vector, what is the purpose of including an antibiotic resistance gene?
  • A. To replicate the plasmid in host cells
  • B. As a selectable marker to identify transformed cells
  • C. To transcribe the cloned gene at high levels
  • D. To initiate DNA replication
Correct Answer: B
Explanation:
The antibiotic resistance gene allows selection: only bacteria that have taken up the plasmid (and express resistance) will grow on antibiotic-containing media.