Which element is found in both DNA and proteins?

• A. Sulfur
• B. Nitrogen
• C. Chlorine
• D. Sodium

Answer: (B)

Verified step by step guidance

1. Understand the composition of DNA and proteins by identifying the key elements that make up each molecule.
2. Recall that DNA is composed of nucleotides, which include a sugar, phosphate group, and nitrogenous bases; these bases contain nitrogen atoms.
3. Recognize that proteins are made of amino acids, which contain nitrogen in their amino groups (–NH2).
4. Compare the elements listed in the options (Sulfur, Nitrogen, Chlorine, Sodium) and determine which are present in both DNA and proteins.
5. Conclude that nitrogen is the common element found in both DNA (in the nitrogenous bases) and proteins (in the amino groups of amino acids).