MCQ practice · SSC Biology Board questions · Chapter 12: Heredity in Organisms and Biological Evolution
What is the diameter of the DNA double helix everywhere?
Think it through first, then pick an option.
- a 3.4 Å
- b 10 Å
- c 20 Å
- d 34 Å
Answer and explanation
Correct answer: c 20 Å
The diameter of the DNA double helix is 20 Å everywhere.
Why the other options are wrong
- a 3.4 Å: 3.4 Å is the distance between adjacent nucleotides, not the diameter.
- b 10 Å: Not 10 Å; that is the number of nucleotides per turn, and the diameter is 20 Å.
- d 34 Å: 34 Å is the length of one complete turn, not the diameter.
Your account is open, so all 30,000+ MCQs from every chapter are yours. Start practising SSC Biology →
Want to keep going?
A free account carries you on to the next questions and opens 30,000+ MCQs from every chapter. Join before launch and Chirkut bundles are 60% off.
The ones you missed, worth one more look