Question

dna is a double - stranded nucleic acid formed by millions of linked nucleotides that each contain the sugar deoxyribose, a phosphate group, and one of four nitrogenous bases. how does the structure of dna allow it to store hereditary information?
a. each nucleotide in a strand of dna codes for one specific trait in an organism.
b. each strand of dna codes for one specific trait in an organism.
c. the sugar deoxyribose codes for all of the specific traits of an organism.
d. the unique order of the nitrogenous bases codes for specific traits in an organism.

Explanation:

• Option A: A single nucleotide does not code for a specific trait; traits are coded by sequences of nucleotides (genes), so A is incorrect.
• Option B: A single strand of DNA doesn't code for one trait. Traits are coded by specific sequences (genes) which can be on either strand, and multiple traits are coded in a DNA molecule, so B is incorrect.
• Option C: Deoxyribose is a sugar component of the nucleotide, it does not code for traits. The coding is done by the nitrogenous base sequence, so C is incorrect.
• Option D: The sequence (order) of nitrogenous bases (A, T, C, G) in DNA forms the genetic code. Different sequences code for different proteins, which in turn determine specific traits in an organism. This matches how DNA stores hereditary information.

Answer:

D. The unique order of the nitrogenous bases codes for specific traits in an organism.