To test the effect of hormones on plant growth, six potted plant seedlings of the same species were measured and then sprayed with auxin, a growth hormone. After four weeks of growth under ideal conditions, the plants were measured again. What should the investigator do to set up a proper control for this experiment?
Wash the auxin off three of the plants after two weeks.
Spray the same plants with different amounts of auxin.
Spray auxin on six plant seedlings of the same species and grow them in the dark for four weeks.
Grow another six plant seedlings of the same species under the same conditions, spraying them only with distilled water.
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The investigator should grow another six plant seedlings of the same species under the same conditions, spraying them only with distilled water. This will serve as a proper control to compare the growth of the plants sprayed with auxin to those that were not treated with the hormone.
1 answer