Question

a the clownfish species amphiprion ocellaris and amphiprion percula have similar color patterns despite genetic differences. b genetically identical arabidopsis thaliana plants develop green stems when grown in low - light or in high - light conditions. c two drosophila melanogaster flies have different versions of a gene, causing one to have white eyes and the other to have red eyes. d two stems cut from a single hydrangea macrophylla plant grow to have pink or purple flowers depending on soil ph.

Explanation:

To solve this, we analyze each option to see which shows a trait determined by genes (genetic variation) rather than environment:

• Option A: Two clownfish species have genetic differences but similar color patterns. This compares different species (not the same genetic background), so it’s not about genetic variation within a species.
• Option B: Genetically identical plants have the same trait (green stems) in different environments. This shows environmental stability, not genetic variation.
• Option C: Two Drosophila (same species) have different gene versions, leading to different eye colors. This directly shows a trait (eye color) caused by genetic variation (different gene versions) within the same species.
• Option D: Stems from the same plant (genetically identical) have different flower colors due to soil pH (environment), not genetics.

Answer:

C. Two Drosophila melanogaster flies have different versions of a gene, causing one to have white eyes and the other to have red eyes.