Question

Hon placed aquatic plants in several test tubes that were filled with water. Then, he placed half of the test tubes in a dark closet and the other half in a well-lit room. When he recorded his data, some of the plants had formed many small bubbles on the leaves, and some did not.

Which describes what Hon most likely observed and the reason for these results?
The plants in the dark formed bubbles because they released hydrogen gas.
The plants in the dark formed bubbles because they released water vapor.
The plants in the light formed bubbles because they released carbon dioxide gas.
The plants in the light formed bubbles because they released oxygen gas.

Answer 1

The plants in the light formed bubbles because they released oxygen gas.

Explanation: In light, aquatic plants photosynthesize (CO2 + H2O → sugars + O2) and the O2 produced forms visible bubbles on the leaves. In the dark photosynthesis stops, so fewer or no bubbles appear.