Final answer:
The manipulated variable is the one that is altered by the experimenter to see its impact on the dependent variable. In the context provided by the options, it could be the amount of water, carbon dioxide, or the type of light received by the plants, depending on the focus of the experiment.
Step-by-step explanation:
The manipulated variable in a scientific investigation is the one that the experimenter varies to observe its effect on the dependent variable. The dependent variable, in this case, is the amount of oxygen each plant produces, which is the outcome being measured. Given the options provided:
- The amount of water each plant receives
- The amount of carbon dioxide each plant receives
- The type of light each plant receives
these are all potential manipulated variables. However, the correct answer depends on the specific context of the experiment, which is not provided in the question. In general, if the experiment is intended to measure the effect of, for instance, different watering regimes on oxygen production, then the amount of water would be the manipulated variable.
Controlled variables are factors in the experiment that are kept constant to ensure that any changes in the dependent variable are due to the manipulation of the independent variable. Examples of controlled variables might include the amount of soil, the size of the plant containers, and ensuring the plants receive the same amount of plant food.