Question

A researcher is investigating how the amount of carbon dioxide in the air influences the rate of photosynthesis in a certain type of plant. The researcher uses ten identical plants and places them in ten closed environments that are identical except for the amount of carbon dioxide in the air. The researcher measures the amount of oxygen each plant produces to determine their photosynthetic activity.

What is the independent variable in this experiment?

a. The rate of photosynthesis.
b. The type of plant.
c. The amount of oxygen produced.
d. The amount of carbon dioxide in the air.

Answer 1

The independent variable in the experiment is the amount of carbon dioxide in the air (option d), as this is what the researcher is changing to measure its effect on photosynthesis.

Step-by-step explanation:

The independent variable in this experiment is d. The amount of carbon dioxide in the air. This is the factor that the researcher is intentionally varying to observe its effect on the rate of photosynthesis, as measured by the oxygen output of plants.

In the scientific method, the independent variable is the one that is manipulated by the researcher, and the dependent variable is the one that responds to the manipulation. In this experiment, different concentrations of carbon dioxide are introduced into the closed environments where the plants are placed.

The researcher is looking to see how these different levels of carbon dioxide affect the rate of photosynthesis, which is indirectly measured by the amount of oxygen produced by the plants. It is essential that other potential variables, such as light intensity, temperature, and water availability, are controlled for, ensuring that the observed effects are solely due to changes in carbon dioxide concentration.