Living Environment Regents Practice Test

In an experiment examining the rate of photosynthesis, what is the independent variable?

1. The amount of light received

2. The type of corn plant used

3. The air temperature

4. The volume of water provided

The correct answer is: The air temperature

In the context of an experiment investigating the rate of photosynthesis, the independent variable is the factor that is purposely changed or manipulated to observe its effects on the rate of photosynthesis. Among the options provided, the correct independent variable is the amount of light received. Light intensity is fundamental because it directly influences the rate at which photosynthesis occurs, allowing researchers to analyze how varying levels of light can lead to different rates of this crucial process in plants. Changes in light exposure will affect the plant's ability to convert carbon dioxide and water into glucose and oxygen through photosynthesis, making it a key variable to test within the experimental design. The other options, such as the type of corn plant used, the air temperature, and the volume of water provided, are important variables for the experiment but are not being manipulated in terms of their influence. They can be considered dependent variables or controlled variables, as they impact the photosynthesis rate but are not what the experimenter is systematically changing to observe effects. Therefore, focusing on the amount of light received is essential for establishing the relationship with the photosynthesis rate in the experiment.