Advanced Placement (AP) Biology Practice Exam

What are the components of nucleotides?

1. Nitrogen base only

2. Pentose sugar and phosphate group only

3. Three parts: nitrogen base, pentose sugar, phosphate group

4. Single ring nitrogen base

The correct answer is: Three parts: nitrogen base, pentose sugar, phosphate group

The correct response identifies that nucleotides are composed of three distinct parts: a nitrogenous base, a pentose sugar, and a phosphate group. This is fundamental to understanding the structure of nucleotides, which serve as the building blocks of nucleic acids, such as DNA and RNA. The nitrogenous base can be classified into two main types: purines (adenine and guanine) and pyrimidines (cytosine, thymine, and uracil). The pentose sugar can either be ribose (found in RNA) or deoxyribose (found in DNA), which is crucial in differentiating nucleic acids. The phosphate group is linked to the 5' carbon of the sugar and plays a significant role in forming the backbone of nucleic acid structures through phosphodiester bonds. Overall, recognizing all three components of a nucleotide is essential because it highlights their role in encoding genetic information and how they interact to form complex structures essential for biological functions.