Uma wanted to test her hypothesis that fescue grass grows best under red light. Independent variables, such as size of fescue grass plants, soil type, number of plants, and length of exposure to light were kept identical for both the experimental and control groups. Uma exposed the experimental group to red, green, and blue light and the control group only to sunlight. She took daily measurements of plant height for the next three weeks.
During the second week, Uma noticed that 8 of the 10 plants that she had exposed to red light looked a little wilted. She increased the daily water amount for these 8 plants. At the end of the experiment, she concluded that fescue grass grows best under red light.
What is a possible flaw in Uma’s experiment?
A . keep track of plant growth under each treatment
B . plant all samples in the same type of soil
C . plant an equal number of plants under each treatment
D . monitor the plants in the control group
E . give equal amounts of water to all plants
Answer: E
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