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 in the list:

Question

They removed the tips of one 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.

Direction of light. Plant tip removed. Opaque cap. Plant tip covered by opaque cap. Transparent cap. Plant tip covered by transparent cap.

Based on the diagram, which statement BEST supports the results of the experiment?

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 roots, and plants respond by bending toward the light.

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

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

Answer 1

The statement that BEST supports the results of the experiment is:

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

This conclusion is based on the fact that the experiments varied how the tips of the seedlings were treated (removing, covering with opaque caps, covering with transparent caps) and demonstrated that the shoot tips are crucial for detecting light direction, as those seedlings with their tips removed or covered with opaque caps did not bend toward the light, while those with transparent caps could still respond to the light direction.