Which molecule stores genetic information and is typically found in a double-stranded helical form?

• A. DNA
• B. RNA
• C. Protein
• D. Carbohydrate

Answer: (A)

DNA stores genetic information and is typically found in a double-stranded helical form. The two antiparallel strands are held together by base pairing (A with T, G with C) and form a stable, long polymer that can be accurately copied during replication and read by the cellular machinery to produce RNA and proteins. This double-helix structure provides both durability and a ready template for precise transmission of hereditary information.

RNA can carry genetic instructions in some contexts, but it is usually single-stranded and folds into various shapes rather than forming a canonical double helix. Proteins and carbohydrates do not store hereditary information; proteins act as the functional products of genes, and carbohydrates mainly serve energy storage or structural roles.