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Difficulty: EasyFormulating and Modifying Hypotheses

A student proposes the following hypothesis:

*Hypothesis*: Plants grown under blue light will grow taller than plants grown under green light or red light.

To test this hypothesis, the student grows 33 identical pea plants under different wavelengths of light for 1414 days, keeping all other variables constant. The heights of the plants at the end of the experiment are shown in the table below:

Light ColorFinal Plant Height (cm\text{cm})
Blue1212
Green88
Red1515

Based on these results, which of the following statements best describes how the student should modify the hypothesis?

  1. Modify the hypothesis to state that plants grown under red light will grow taller than plants grown under blue light or green light.Answer
  2. B
    Modify the hypothesis to state that plants grown under green light will grow taller than plants grown under blue light or red light.
  3. C
    Modify the hypothesis to state that plants grown under blue light and green light will grow to the same height.
  4. D
    Retain the hypothesis as originally proposed because the plant grown under blue light grew taller than the plant grown under green light.

Answer

Modify the hypothesis to state that plants grown under red light will grow taller than plants grown under blue light or green light.
The experimental results demonstrate that the plant grown under red light achieved the greatest height (15 cm15\text{ cm}), followed by the plant grown under blue light (12 cm12\text{ cm}), and the plant grown under green light (8 cm8\text{ cm}). Because the original hypothesis predicted that blue light would yield the tallest plants, the finding that red light resulted in the tallest plants contradicts the prediction. Therefore, the hypothesis must be modified to reflect that red light produces the greatest height.

Step-by-Step Solution

1
Analyze the student's original hypothesis.
The hypothesis predicts that blue light results in the greatest plant height compared to green or red light.
To evaluate the hypothesis, we must first understand what it predicts.
2
Examine the experimental results in the table.
The final heights are: Red = 15 cm15\text{ cm}, Blue = 12 cm12\text{ cm}, Green = 8 cm8\text{ cm}.
This provides the actual data to compare against the prediction.
3
Compare the data to the hypothesis and determine the correct modification.
Since red light resulted in the tallest growth (15 cm15\text{ cm}, which is greater than blue light's 12 cm12\text{ cm}), the original hypothesis is incorrect. The hypothesis should be modified to state that red light leads to the tallest growth.
A scientific hypothesis must be updated when experimental evidence contradicts its initial prediction.

Key Concept

Evaluating and modifying a hypothesis based on experimental evidence.
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Topics

Formulating and Modifying Hypotheses

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