Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What are the products of photosynthesis?

1. Oxygen and carbon dioxide

2. Glucose and water

3. Carbohydrates and oxygen

4. Nitrogen and glucose

The correct answer is: Carbohydrates and oxygen

Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. The overall chemical reaction for photosynthesis can be summarized by the equation: \[6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2\] This indicates that carbon dioxide and water, in the presence of light energy, are transformed into glucose and oxygen. Glucose is a simple sugar and a type of carbohydrate, which serves as an energy source for the plant and is the building block for more complex carbohydrates. While oxygen is indeed a product of photosynthesis, the correct emphasis in this context is on the production of carbohydrates like glucose, which are critical for the plant's energy needs. Thus, the correct answer highlights both glucose and the oxygen produced as a byproduct, making it an accurate representation of the products of photosynthesis as it captures the essential role of carbohydrates in the process. The other options do not fully encapsulate the products of photosynthesis. For instance, options that include carbon dioxide