Question

1. ★staar question★

in the late 19th century, charles darwin and his son performed a series of experiments on young grass seedlings to observe the plants response to sunlight. they grouped the seedlings as shown on the list:

• they removed the tips of a first group of seedlings.
• they placed opaque caps over the tips of a second group of seedlings.
• they placed transparent caps over the tips of a third group of seedlings.

the results of the experiment are shown in the diagram.
diagram showing three potted plants: one with plant tip removed, one with plant tip covered by opaque cap, one with plant tip covered by transparent cap, with direction of light indicated
based on the diagram, which statement best supports the results of the experiment?
○ the direction of light is detected by cells on the roots, and plants respond by bending toward the light.
○ the direction of light is detected by cells within the roots, and plants respond by bending in the direction of gravity.
○ the direction of light is detected by cells on the shoot tips, and plants respond by producing chlorophyll.
○ the direction of light is detected by cells on the shoot tips, and plants respond by bending toward the light.

Explanation:

The experiment tests grass seedlings' response to light. Seedlings with removed tips or opaque caps on tips do not bend toward light, while those with transparent caps (allowing light to reach tips) bend. This shows light detection occurs at shoot tips, and the response is bending toward light.

Answer:

The direction of light is detected by cells on the shoot tips, and plants respond by bending toward the light.