Biology Regents Practice Exam

If carbon dioxide is completely removed from a plant's environment, what is the most likely outcome for sugar production?

1. Continue at the same rate

2. Increase and oxygen production will also increase

3. Increase and oxygen production will stay the same

4. Decrease and eventually stop

The correct answer is: Decrease and eventually stop

In the process of photosynthesis, plants use carbon dioxide, water, and sunlight to produce glucose (sugar) and oxygen. Carbon dioxide is one of the essential raw materials in this process. If carbon dioxide is completely removed from a plant's environment, the plant will not be able to perform photosynthesis effectively. Without carbon dioxide, the chemical reactions that convert light energy into chemical energy (in the form of glucose) cannot occur. This means that the rate of sugar production will decrease significantly and eventually stop altogether because the necessary components for photosynthesis are no longer present. The plant relies on this process not only to generate sugars for energy and growth but also to release oxygen as a byproduct. Since sugar production is halted, oxygen production will also cease as a direct consequence of the lack of photosynthesis. Therefore, the most likely outcome is a decrease in sugar production, ultimately leading to a complete stop in that process.