Question

weak hydrogen bonds between the nitrogenous bases hold the two strands of a dna molecule together. but hydrogen bonds can only form between certain nitrogenous bases. this is called complementary base pairing. in any dna molecule, adenine pairs only with thymine, and guanine pairs only with cytosine. complete the paragraph to describe the model. the dna model above shows nucleotides. according to the rules of complementary base pairing, thymine always pairs with , and guanine always pairs with .

Explanation:

1. To find the number of nucleotides: Count the nitrogenous base pairs. Each pair has 2 nucleotides, and there are 4 pairs, so \(4\times2 = 8\) nucleotides.
2. For complementary base pairing: From the text, thymine (\(T\)) pairs with adenine (\(A\)), and guanine (\(G\)) pairs with cytosine (\(C\)).

Answer:

8; adenine; cytosine