In human DNA, adenine (A) makes up approximately 30.9% of the bases, and guanine (G) makes up approximately 19.9% of the bases; therefore the percentage thymine (T) and cytosine (C) are (A) 19.8% T and 19.8% C. (B) 19.8% T and 29.4% C. (C) 29.4% T and 19.8% C. (D) 29.8% T and 29.8% C. (E) 19.9% T and 30.9% C. Can you please explain with some details?

(1) Answers

In human DNA, there are nitrogenous base pairings- A, T C and G. A pairs with T and C pairs with G. Because they're a pair, the ratio of A:T and C:G should be as close to 1:1 as possible. Since A makes up approx 30.9%, T should be either C or D. As G makes up approx 19.9%, we can rule out option D, therefore the answer is C! Hope this helps (:

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