Question

Students are observing an aquatic plant. They understand that the bubbles they see rising from the cut stem of the plant are the gases produced during photosynthesis.Which of the following observations provides the best evidence that light is the source of energy for photosynthesis?

A. Plants observed in artificial or in natural light were both seen to produce bubbles.Plants observed in artificial or in natural light were both seen to produce bubbles.
B. The bubbles always rise to the surface of the water, moving towards the light.The bubbles always rise to the surface of the water, moving towards the light.
C. The orientation of the light seems to have no effect on the production of bubbles.The orientation of the light seems to have no effect on the production of bubbles.
D. The frequency of bubbling increases in bright light and slows to a stop in darkness.

Answer 1

The best evidence that light is the source of energy for photosynthesis in an aquatic plant is the observation that the frequency of oxygen bubbles rises with bright light and ceases in darkness.

Step-by-step explanation:

In observing an aquatic plant during photosynthesis, if the goal is to find the best evidence that light is the source of energy for photosynthesis, option D provides the most compelling evidence. This observation that the frequency of bubbling increases in bright light and slows to a stop in darkness directly correlates the rate of photosynthesis with the presence of light. The bubbles represent oxygen, a byproduct of photosynthesis, indicating that with more light, photosynthesis occurs at a higher rate, while in the absence of light, the process ceases.

As we know, photosynthesis is dependent on light to supply the energy needed for the chemical reactions that convert carbon dioxide and water into glucose and oxygen. In aquatic ecosystems, this is particularly important due to variations in light intensity with depth due to factors such as water transparency and the presence of other photosynthetic organisms. photoautotrophs like plants and algae require chlorophyll to absorb light and perform this essential process, supporting both their survival and that of the trophic levels that depend on them.