Question

evaluating arguments
another class received similar data in their investigation and found that it appears water enters plants through the roots and exits through the leaves when light shines on it. below are three students’ claims to answer the question “what happens to the water inside the plant?”

student explanations	how would you respond to this statement? what do you agree or disagree with? what ideas seem interesting to you? what have we discussed or explored in class that you could tell this student?
student b: the water molecules that go into the plant are used to make food molecules, and other chemical reactions in the plant form water molecules that come out of the leaves.
student c: some of the water molecules are used by the plant to make food molecules while some of the water molecules pass straight through the plant unchanged.
i	d	c	b	a
work is incomplete, plagiarized, or there are concerns about academic dishonesty.	there is a response for each student, but the answers do not make sense or thoroughly address the statement.	each student response has an answer that makes sense, but they are lacking detail or concepts/data from class.	some responses meet the criteria for an a.	all responses are

• thorough, address all parts of the student statement.
• use ideas and data explored during class. |

Explanation:

For Student A:

Disagree with this claim. While some water moves through the plant and exits via transpiration, plants use water for photosynthesis ($6\text{CO}_2 + 6\text{H}_2\text{O} \xrightarrow{\text{light energy}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$) and other cellular processes, so not all water molecules pass through unchanged.

For Student B:

Disagree with this claim. Most water that exits leaves is the same water taken up by roots (transpiration). The water produced in cellular respiration is a small amount and not the main water lost through leaves.

For Student C:

Agree with this claim. This matches class explorations: plants use some water for photosynthesis and other reactions, while most water moves through the plant (transpiration) and exits leaves unchanged.

Answer:

Response to Student A:

Disagree. Not all water passes through unchanged; plants use water for photosynthesis and other cellular functions, so only a portion of water exits leaves as the original molecules.

Response to Student B:

Disagree. The majority of water exiting leaves is the same water absorbed by roots (transpiration). Water produced by plant reactions is minimal and not the main water lost.

Response to Student C:

Agree. This aligns with plant physiology: some water is used to make food via photosynthesis, while most flows through the plant and exits leaves unchanged.