Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine, and cytosine forms hydrogen bonds with guanine. What is the significance of the structural arrangement?

The correct answer will be - this base pairing allows the complementation like lock and key

Explanation:

In DNA, the nitrogenous bases on one strand pairs with the nitrogenous bases on another strand.

Experiments of Erwin Chargaff showed that purine bind pyrimidines where the adenine binds thymine and guanine bind cytosine via double and triple hydrogen bonds respectively.

This hydrogen bonding between the purines and pyrimidines provides structural stability as it is based on the complementation. This complementary base pairing allows the two strands to fit like a key and a lock.

Thus, this base pairing allows the complementation like lock and key is the correct answer.