AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA MAKES RNA MAKES PROTEIN

 Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
If 20% of a DNA sequence is thymine, T, what percentage of the sample is made up of cytosine, C?
 A 15% B 30% C 35% D 50%
Explanation:

Detailed explanation-1: -Answer and Explanation: A double-stranded DNA molecule with 20% thymine would contain 30% guanine.

Detailed explanation-2: -Therefore, Guanine would be 20% and total of G+C = 40% and hence A+T would be 60% that is 30% each. Hence, option C is correct answer.

Detailed explanation-3: -Since adenine is 20%, then thymine is 20% as well. The total of both is 40%. From 100 remains 60% which is divided equally between guanine and cytosine, so each is 30%.

Detailed explanation-4: -Thus, If a double stranded DNA has 20% of cytosine, it has 20% of guanine. Thus, cytosine plus guanine make 40% of the total bases. The remaining 60% includes both adenine and thymine which are in equal amounts.

There is 1 question to complete.