Question

question 54
the order of the base pairs in a dna molecule
○ differs from cell to cell in a given organism.
○ is identical in all organisms.
○ is identical in organisms of the same species.
○ differs from species to species.

Explanation:

• For the first option: In a given organism, most cells have the same DNA (base - pair order) as they come from the same zygote via mitosis, so this is wrong.
• For the second option: Different organisms (e.g., humans and bacteria) have different DNA base - pair orders, so this is wrong.
• For the third option: Even within the same species, there are genetic variations (e.g., different alleles) among individuals, so the base - pair order is not identical in all organisms of the same species, this is wrong.
• For the fourth option: Different species have different genetic codes, which means the order of base pairs in their DNA molecules differs. This is in line with our knowledge of genetics.

Answer:

D. differs from species to species.