Question

Two fruit flies have different parents. One fruit fly has orange eyes while the other has red eyes. Why do the fruit flies have different eye colors?
Responses

a
Each fruit fly has a different eye color because offspring from different parents will have different eye colors.
Each fruit fly has a different eye color because offspring from different parents will have different eye colors.

b
Each fruit fly has a different eye color because they have different versions of the gene for eye color that connect together to make different eye colors.
Each fruit fly has a different eye color because they have different versions of the gene for eye color that connect together to make different eye colors.

c
The fruit flies have different versions of the gene for eye color, which instruct for different proteins that connect in different ways to make different eye colors.
The fruit flies have different versions of the gene for eye color, which instruct for different proteins that connect in different ways to make different eye colors.

d
The fruit flies have different versions of the gene for eye color, and the genes are different colors in each fruit fly’s eyes.

Answer 1

Correct answer: c.

Why: The two flies carry different versions (alleles) of the gene that controls eye color. Those different alleles encode different proteins (or enzymes) or versions of proteins, which change how pigments are made or deposited in the eye, producing different eye colors.

Why not the others:
- a is just restating the observation, not explaining the mechanism.
- b mentions different gene versions but is vague about how they cause color differences.
- d is wrong because genes themselves are not colored; they code for proteins that affect pigment.