A biology student wanted to study the effect of fertilizer on the growth of tomato plants. He placed four of the same type of tomato plants into separate containers, each containing the same amount of soil. Each pot received a different watering solution, containing varying amounts of fertilizer.
The table below shows the average height of the plants by the end of one week.
Plant group | Fertilizer amount (g) | Avg height of plants (cm)
1 | 0 | 3.0
2 | 5 | 3.2
3 | 10 | 4.4
4 | 20 | 5.0
Which of the plant groups is the control group?
Plant group 1, which received 0 grams of fertilizer, is the control group.
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A class of biology students conducted an experiment on ants. Each group was randomly assigned 20 ants. Each ant was placed halfway between food located down a dark-colored path and food located down a bright-colored path.
Five of the groups find that the ants choose the bright path more often. Three groups find that the ants prefer the dark path and two groups find no preference among their ants.
A student who hypothesized that ants are attracted to bright colors found that this hypothesis was supported by his group's data.
How is the student’s conclusion an example of bias?
Choose 1 answer:
Choose 1 answer:
(Choice A) The students broke into multiple groups to perform the experiment, which skewed results.
A. The students broke into multiple groups to perform the experiment, which skewed results.
B The student disregarded the data that did not support the hypothesis.
C The sample size in the experiment was too small to yield valid results.
D The groups of students selected ants that were more likely to support their hypothesis.
B. The student disregarded the data that did not support the hypothesis.
A biology student wanted to study how the amount of light affects the growth of aquatic plants over the course of a week. She set up two tanks with four plants in each. Both tanks were identical in every way except for the amount of light provided.
What is one thing the student could do to improve the accuracy of her results?
A Increase the size of both tanks
B Grow the plants for a shorter length of time
C Use a greater number of plants
D Eliminate data that does not fit with her hypothesis
C. Use a greater number of plants.
An experiment to investigate the influence of music on plant growth is set up according to the design shown in the table. Each plant group contains 20 plants.
Plant group | Music type | Environment | Time music played (hrs/day)
1 | Classical | Bright windowsill | 2
2 | Jazz | Shady corner | 2
3 | rock | Dark closet | 2
4 | No music | Sunny outdoor space | N/A
Which statement explains how the experiment exhibits bias?
A The size of the sample is not large enough
B Time for all three trials is constant
C Plant growth cannot be measured directly
D Variables other than music may influence results
D. Variables other than music may influence results.
To determine which plant group is the control group in this experiment, we need to understand the purpose of a control group.
A control group is a group in an experiment that is not exposed to the independent variable (in this case, the fertilizer). It serves as a baseline for comparison to determine the actual effect of the independent variable.
In this experiment, the control group would be the plant group that did not receive any fertilizer. By comparing the growth of the plants that received different amounts of fertilizer to the control group, we can measure the impact of the fertilizer on the growth of the tomato plants.
Looking at the table, we can see that the plant group with a fertilizer amount of 0 grams has an average height of 3.0 cm. Therefore, plant group 1, with no fertilizer, is the control group in this experiment.