Auxin Distribution in Phototropism

Steps:

• In experiment 1 with full light, auxin is produced symmetrically and distributes evenly around the seedling stem.
• In experiment 2 with unilateral light, light causes auxin to migrate to the shaded side, creating an uneven distribution.
• Equal auxin distribution occurs only in uniform light conditions like experiment 1.
• Uneven distribution in experiment 2 leads to bending toward light, confirming asymmetry.

Why B is correct:

• Auxin distribution is symmetric in uniform light (experiment 1) per the Cholodny-Went theory of phototropism, but asymmetric in directional light (experiment 2).

Why the others are wrong:

• A: Incorrect, as experiment 2 shows unequal auxin due to lateral light.
• C: Incorrect, as experiment 1 has equal distribution in full light.
• D: Incorrect, as experiment 1 maintains equal distribution.

Final answer: B