Question

question 21 (1 point) ✓ saved if a light shines on a plat stem from one side, auxin moves from the tip to the bright side of the stem moves from the tip to the shaded side of the stem distributes evenly throughout the stem does not move

Explanation:

When light shines on a plant stem from one side, auxin (a plant hormone) moves towards the shaded side. This is because auxin promotes cell elongation. The shaded side, having more auxin, will have more cell elongation, causing the plant to bend towards the light (phototropism). The option "moves from the tip to the bright side of the stem" is incorrect as auxin moves to the shaded side. The option "distributes evenly throughout the stem" is wrong because light causes an uneven distribution. The option "does not move" is also incorrect as light - induced auxin redistribution is a key plant response.

Answer:

B. moves from the tip to the shaded side of the stem