Improving Experimental Validity in Photosynthesis Study

Very Hard Research Summaries Experimental Design

A well-controlled study was conducted to assess the impact of varying light wavelengths on the rate of photosynthesis in *Elodea* plants. In this experiment, scientists established four different groups of *Elodea* plants, each exposed to a specific light wavelength: red, blue, green, and white light. The rate of photosynthesis was quantified by measuring the volume of oxygen produced by each group over a defined period. The researchers found that plants exposed to red light exhibited the highest rates of photosynthesis, while those under green light showed the least. The researchers concluded that light wavelength significantly influences photosynthetic rates in *Elodea*.

Which of the following experimental designs could improve the validity of this study?

Introduce a fifth group using a combination of all light wavelengths.

Replicate the experiment in a controlled environment with more plant samples.

Randomly assign different light conditions to plants in a single aquarium.

Measure the plants' growth rates instead of oxygen production.

Hint

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