A biologist is conducting an experiment to determine how light affects the reproduction of Bacteria X. The biologist is trying to decide the best way to conduct his experiment in order to collect meaningful data.

Which of the following experiments would help him collect the best data?

The best way by which the biologist can conduct his experiment -in order to collect meaningful data- is place a Petri dish with Bacteria X in a lighted area and a Petri dish with the Bacteria X in a darkened area, and then observe the rate of reproduction over time.

Explanation:

Options for this question are:

A.  Place a Petri dish with Bacteria X in a lighted area and a Petri dish with the Bacteria X in a darkened area, and then observe the rate of reproduction over time.

B.  Place a Petri dish with Bacteria X in a lighted area and a Petri dish with Bacteria Y in a darkened area, and then observe the rate of reproduction over time.

C.  Place a Petri dish with Bacteria X in a sunny window and an identical Petri dish under a grow lamp.

D.  Place a Petri dish with Bacteria X in a moist, dark area and record the rate of reproduction over time.

The aim of the biologist is clearly to see how light influences the reproduction of bacteria X. In this case, the design of the experiment is simple, as he must separate his sample into two groups, exposing each group to controlled conditions, light and dark.

The stimulus, presence or absence of light, is the independent variable, while the rate of reproduction is its dependent variable.

If the biologist observes that bacteria X reproduce better in the illuminated area, it means that light is a factor that promotes reproduction in that bacteria, or that darkness negatively affects reproduction.

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Example of an experiment with bacteria link

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