Question

What are complementary bases? Draw structure to show
hydrogen bonding between adenine and thymine and
between guanine and cytosine.​

Answer 1

Complementary Base Pairing

You see, cytosine can form three hydrogen bonds with guanine, and adenine can form two hydrogen bonds with thymine. Or, more simply, C bonds with G and A bonds with T. It's called complementary base pairing because each base can only bond with a specific base partner.

Answer 2

noun Genetics.

either of the nucleotide bases linked by a hydrogen bond on opposite strands of DNA or double-stranded RNA: guanine is the complementary base of cytosine, and adenine is the complementary base of thymine in DNA and of uracil in RNA.