Question

in a dna double helix an adenine of one strand always pairs with a(n) __ of the complementary strand, and a guanine of one strand always pairs with a(n) __ of the complementary strand. thymine... cytosine cytosine... uracil cytosine... thymine guanine... adenine uracil... cytosine

Explanation:

In DNA, base - pairing rules state that adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). Uracil (U) is found in RNA, not DNA. So, we check each option based on these rules.

• For the first blank (adenine pairing), we look for thymine.
• For the second blank (guanine pairing), we look for cytosine.

Answer:

thymine... cytosine