Final answer:
Chargaff's rules state that DNA from any source contains about the same amount of guanine as cytosine. The amount of adenine is also equal to the amount of thymine. These base ratios are consistent within tissues of the same individual and between individuals of the same species.
Step-by-step explanation:
Chargaff's rules state that the amount of A is similar to the amount of T, and the amount of G is similar to the amount of C. This means that DNA from any source contains about the same amount of guanine as cytosine. For example, if a DNA molecule has 20 guanine units, it would also have approximately 20 cytosine units. These base ratios are consistent within tissues of the same individual and between individuals of the same species.