Question

A student suggests that a certain species of bacteria grows better in the light than in the dark. The student has 10 culture plates on which to grow the bacteria. Which of the following would be the best experiment to test this idea? Question 3 options:

a. Grow 10 plates in the dark.
b. Grow 10 plates in the light.
c. Grow 5 plates in the dark and 5 plates in the light.
d. Grow 10 plates in the light, with extra water.

Answer 1

Answer:

c. Grow 5 plates in the dark and 5 plates in the light.

Explanation:

Growing the whole of the 10 plates in the light or in the dark will not give basis for comparison necessary for a controlled experiment.

The controlled variable is the light, hence, some of the culture plates should be grown in the light and others grown in the dark. Whatever difference noticed in the growth can then be attributed to the presence or absence of light.

The correct option is c.