In DNA, hydrogen bonds form between which base pairs?

In DNA, hydrogen bonds form between which base pairs?

• A. Between A-T and C-G
• B. Between A-T and A-C
• C. Between G-C and C-T
• D. Between A-C and G-T

Answer: (A)

Hydrogen bonding between complementary bases stabilizes the DNA double helix. Adenine pairs with thymine via two hydrogen bonds, and cytosine pairs with guanine via three hydrogen bonds. This A–T and G–C pairing provides the proper geometry and stability needed for the two strands to fit together and for accurate replication. Other pairings like A–C or G–T do not form the correct hydrogen-bonding pattern and would destabilize the helix, so the pairs that form hydrogen bonds in DNA are A–T and C–G.

Hydrogen bonding between complementary bases stabilizes the DNA double helix. Adenine pairs with thymine via two hydrogen bonds, and cytosine pairs with guanine via three hydrogen bonds. This A–T and G–C pairing provides the proper geometry and stability needed for the two strands to fit together and for accurate replication. Other pairings like A–C or G–T do not form the correct hydrogen-bonding pattern and would destabilize the helix, so the pairs that form hydrogen bonds in DNA are A–T and C–G.