The correct answer is:
Presence or absence of thymine
Here's an explanation for each option:
1. Presence or absence of guanine:
- Both DNA and RNA contain guanine. Guanine is one of the four nitrogenous bases found in both DNA and RNA.
2. Presence or absence of thymine:
- Thymine is found in DNA, but it is replaced by uracil in RNA. This is a key difference between DNA and RNA. DNA contains thymine, while RNA contains uracil.
3. Type of sugar in sugar-phosphate backbone:
- Both DNA and RNA have a sugar-phosphate backbone, but they differ in the type of sugar present. DNA contains deoxyribose sugar, while RNA contains ribose sugar.
4. Presence or absence of uracil:
- Uracil is found in RNA instead of thymine. As mentioned earlier, this is a significant difference between DNA and RNA.
In summary, the key difference between DNA and RNA in the context of the given options is the presence of thymine in DNA and the presence of uracil in RNA.
