A scientist observed that white mice that were fed seeds appeared to grow more than mice given leafy green and yellow vegetables. The scientist hypothesized that the protein in the seed was responsible for the growth. He designed an experiment to test his hypothesis. He divided 200 mice of the same age, size, health, and sex into two groups of 100 mice each. The mice were kept under identical conditions for fourteen days. One group
was given a diet low in protein. The other group was given a normal diet. The mass of each mouse was recorded daily for fourteen days.

1. Which group of mice served as a control?
2. What was the variable?
3. What effect of the protein diet was tested?
4. What other effects of a protein diet could have been tested?