BIOMOLECULES AND ENZYMES

Detailed explanation-1: -In a stem, the shaded side contains more auxin and grows longer, which causes the stem to grow towards the light. The plant does NOT bend towards the light. It grows because the auxin causes the cells to elongate on the shaded side, so this side grows more.

Detailed explanation-2: -When light hits one side of the coleoptile, the phototropins are more active on the side with light, causing the auxin to flow down the shady side. The side of the coleoptile with less auxin has less elongated cells, and the side with more auxin has more elongated cells, causing the tip to bend toward the light.

Detailed explanation-3: -In a stem, the cells on the shaded side contain more auxin and grow longer than the cells on the light side. This causes the stem to grow towards the light. It is vital to note that the plant does NOT bend towards the light. Auxins have the opposite effect in roots.

Detailed explanation-4: -In roots, where auxin tends to inhibit cell elongation, auxin accumulates on the lower side in roots oriented perpendicularly to gravity, causing these cells to elongate less and the root to bend toward gravity.

Detailed explanation-5: -Auxin build-up at the lower side of stimulated shoots promotes cell expansion, whereas in roots it inhibits growth, leading to upward shoot bending and downward root bending, respectively.