MCQ practice · SSC Biology Board questions · Chapter 12: Heredity in Organisms and Biological Evolution
What is the length of two complete turns of the DNA molecule?
Think it through first, then pick an option.
- a 3.4 Å
- b 34 Å
- c 68 Å
- d 102 Å
Answer and explanation
Correct answer: c 68 Å
Two turns = 2 × 34 = 68 Å.
Why the other options are wrong
- a 3.4 Å: 3.4 Å is the gap between two nucleotides, not the length of turns.
- b 34 Å: 34 Å is one turn; the question asks for two.
- d 102 Å: 102 Å is three turns (3 × 34). The right answer is 68 Å.
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