A scientist fills a glass container with water and places an aquatic plant inside the container, then closes the lid and plays the container in direct sunlight. The scientist observes small bubbles on the surface of the plant's leaves on day 1 and 2, but no bubbles on day 3. The scientist concludes that the bubbles were caused by photosynthesis. Which substance should be added to the water in order for the bubbles to reappear?

Question

a. carbon dioxide
b. hydrogen gas
c. glucose
d. oxygen

Answer 1

The bubbles observed on the plant's leaves were likely caused by the release of oxygen, a byproduct of photosynthesis, which occurs when the plant converts water and carbon dioxide into glucose and oxygen using sunlight.

On day 3, the absence of bubbles may indicate that the plant's access to carbon dioxide was limited, since it needs carbon dioxide to carry out photosynthesis effectively. Therefore, to facilitate photosynthesis and encourage the production of oxygen (and thus the appearance of bubbles), the scientist should add:

a. carbon dioxide

Adding carbon dioxide to the water would help replenish the gas needed for photosynthesis, potentially leading to oxygen production and the formation of bubbles again.