A student investigated the effect of root space on plant growth. The student grew two groups of plants of the same variety. Both groups received the same amount of water and sunlight and grew in the same type of soil. The plants in Group A were grown in cube-shaped containers that were 3 centimeters deep. The plants in Group B were grown in cube-shaped containers that were 10 centimeters deep. The table shows the student's observations
Week Plant Group A (Average Height, cm) Plant Group B (Average Height, cm)
1 2 3
2 3 6
3 5 8
4 7 10
5 8 14
6 10 18
What was the effect of root space on plant growth based on the student's investigation? Use the data from the table to support your answer. Explain how you would know whether this effect was likely due to environmental or genetic factors.
(2 points)
Short Answer Rubric (2 points)
Points Awarded Criteria
2
The answer is very clear.
The answer is fully supported by details.
There may be a few errors in grammar, usage, or mechanics. Errors do not interfere with meaning.
1
The answer is somewhat clear.
Details are weak or not related.
There are some errors in grammar, usage, and mechanics. Errors interfere with meaning.
0
The question is not answered.
Based on the student's investigation, it is clear that root space had a significant effect on plant growth. Group B plants, which had more root space with 10 centimeter deep containers, consistently grew taller than Group A plants, which had less root space with 3 centimeter deep containers. By the end of the six weeks, Group B plants were on average 8 centimeters taller than Group A plants.
To determine whether this effect was likely due to environmental or genetic factors, the student would need to conduct further experiments. One way to do this would be to repeat the experiment but this time switch the plants between the two groups mid-way through the growth period. If the plants from Group A then placed in Group B containers begin to grow taller than the plants originally from Group B, this would suggest that root space is the determining factor. On the other hand, if the plants continue to grow at the same rate regardless of the container they are in, this would indicate genetic factors play a larger role in plant growth. Additional experiments such as changing the type of soil or amount of sunlight could also help isolate the specific factors affecting plant growth in this investigation.