Question

According to Watson and Crick model __ base pairs are present in each turn of helix.

• A. 18
• B. 12
• C. 10
• D. 11

Answer 1

The correct option is C 10

In B – DNA each strand appears like a helical staircase. Each step of ascent is represented by a pair of bases. At each step of ascent, the strand turns ${36}^o$. One full turn of the helical strand would involve ten steps or ten base pairs.