Selected MCQ

Current Question
Which structural feature is shared by B-DNA, A-DNA, and Z-DNA?
  • A. Right-handed double helix
  • B. 10 bases per turn
  • C. Uniform major groove
  • D. Two strands paired by base complementarity
Correct Answer: D
Explanation:
All DNA forms (B, A, Z) are double-stranded helices with complementary base pairing. However, B and A are right-handed (10 and ~11 bp/turn), and Z is left-handed.
Related Question 1
Prokaryotic mRNAs often encode multiple proteins on a single transcript. This feature is known as:
  • A. Monocistronic transcription
  • B. Polycistronic transcription
  • C. Post-transcriptional splicing
  • D. Alternative splicing
Correct Answer: B
Explanation:
Polycistronic mRNA contains several open reading frames, each encoding a different protein. This is common in bacteria (e.g., operons).
Related Question 2
Which feature of mitochondrial structure most directly facilitates ATP synthesis via oxidative phosphorylation?
  • A. Large pores in the outer membrane allowing free movement of ions
  • B. Extensive folding of the inner membrane into cristae
  • C. Circular DNA encoding the majority of electron transport proteins
  • D. Abundant ribosomes within the mitochondrial matrix
Correct Answer: B
Explanation:
The inner mitochondrial membrane is highly folded into cristae, increasing surface area for the electron transport chain complexes and ATP synthase to produce ATP.