Final answer:
Folate (vitamin B9) is the vitamin that is required for DNA synthesis as it is directly involved in purine and pyrimidine synthesis, and it is also stored in the body. Without adequate levels of folate, DNA synthesis can be negatively affected.
Step-by-step explanation:
DNA synthesis requires various nutrients and co-factors to proceed correctly, including certain vitamins that participate directly in the synthesis of purines and pyrimidines, the building blocks of DNA. The correct vitamin that is a co-enzyme needed for DNA synthesis and actively participates in the synthesis of both purines and pyrimidines is folate (vitamin B9). This vitamin facilitates the process of converting uracil to thymine, which is one of the four nucleotide bases of DNA. Without adequate folate, DNA synthesis can be impaired leading to potential problems in cell division and replication.
In addition to its role in DNA synthesis, folate is also stored in the body, primarily in the liver. Folic acid, a form of folate, includes para-amino benzoic acid (PABA) as a component. In humans, folate is critical and must be obtained through diet or supplementation, unlike microorganisms that can synthesize it from PABA. Folate's significance is further highlighted in the role it plays alongside vitamin B12 as co-enzymes critical for the synthesis of new cells, including erythrocytes (red blood cells).
Therefore, the correct answer to the student's question is d. folate.