Which of the following statements must be True? Check all that apply.
The number of Adenines in single-stranded DNA equals the number of Thymines.
The number of Guanines in single-stranded DNA equals the number of Adenines.
The number of Thymines in double-stranded DNA equals the number of Cytosines.
The number of Cytosines in double-stranded DNA equals the number of Guanines.
To determine which statements must be true, we need to understand the base pairing rules in DNA. In DNA, Adenine (A) always pairs with Thymine (T), and Guanine (G) always pairs with Cytosine (C).
Let's analyze each statement:
1. "The number of Adenines in single-stranded DNA equals the number of Thymines" - This statement must be true because in single-stranded DNA, each Adenine will always pair with a Thymine. Therefore, the number of Adenines should be equal to the number of Thymines.
2. "The number of Guanines in single-stranded DNA equals the number of Adenines" - This statement is not necessarily true. In single-stranded DNA, there is no requirement for the number of Guanines to be equal to the number of Adenines. The base pairing rule only applies to Adenine and Thymine.
3. "The number of Thymines in double-stranded DNA equals the number of Cytosines" - This statement must be true. In double-stranded DNA, each Adenine on one strand pairs with a Thymine on the opposite strand, and each Cytosine pairs with a Guanine. Therefore, the number of Thymines should be equal to the number of Cytosines.
4. "The number of Cytosines in double-stranded DNA equals the number of Guanines" - This statement must be true. The base pairing rule dictates that for every Cytosine on one strand, there should be a Guanine on the opposite strand. Therefore, the number of Cytosines should be equal to the number of Guanines.
Based on the analysis, the statements that must be true are:
- The number of Adenines in single-stranded DNA equals the number of Thymines.
- The number of Thymines in double-stranded DNA equals the number of Cytosines.
- The number of Cytosines in double-stranded DNA equals the number of Guanines.