Question

If DNA of a particular species was analyzed and it was found that it contains 27% A, what would be the percentage of C?

a) 23%
b) 27%
c) 46%
d) 54%

Answer 1

c) 46%.

Step-by-step explanation:

In DNA, adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with guanine (G). The percentage of A is equal to the percentage of T, and the percentage of C is equal to the percentage of G. Since the total percentage of A and T must add up to 100%, if A is 27%, Tis also 27%. This leaves 46% for the combination of Cand G. Therefore, the percentage of C is 46%.

Answer 2

Option a.According to Chargaff's rules, the percentage of cytosine (C) in the DNA of a species that contains 27% adenine (A) is 23%, because adenine pairs with thymine and guanine pairs with cytosine, with equal amounts of A+T and G+C.

Step-by-step explanation:

If DNA of a particular species was analyzed and it was found that it contains 27% adenine (A), then the percentage of cytosine (C) would be determined based on Chargaff's rules, which states that DNA is composed of base pairs where adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). Since the DNA is double-stranded, the amount of adenine will be equal to the amount of thymine, and likewise, the amount of guanine is equal to the amount of cytosine.

In this case, if there is 27% A, then there must also be 27% T, making a combined total of 54% for A and T. This leaves 46% of the DNA composition to be divided equally between guanine (G) and cytosine (C), since their combined amount must equal that of A and T due to base pair bonding rules. Therefore, the percentage of C is 23%. The answer is a. 23%.