DNA Structure and Genetic Terms

Steps:

• Statement 1: Chromosomes contain one continuous DNA molecule coiled with proteins, forming the genetic material.
• Statement 2: Genes are specific DNA segments on chromosomes that encode proteins or RNA.
• Statement 3: Alleles are variant forms of a gene located at the same chromosomal position, not subregions within a gene.
• Correct statements are 1 and 2, matching option B.

Why B is correct:

• Aligns with the biological definition where chromosomes hold one DNA molecule and genes are DNA sections on them.

Why the others are wrong:

• A: Includes false statement 3, as alleles are gene variants, not internal regions.
• C: Omits true statement 1 about chromosome composition.
• D: Includes false statement 3 and omits true statement 2.

Final answer: B