A student was conducting a scientific experiment with a plant. She cut out three 1-inch circles from construction paper and attached each circle to a different leaf of the plant. Finally, she set the plant in front of a sunny window with good air flow and left it there. She made sure that the plant was given enough water during her experiment. After 2 days, she removed one of the circles; after 4 days, she removed another circle; and at the end of the week, she removed the last circle.
Here are her results:
Day 2: slight mark where the paper covered the leaf; it is a lighter green than the rest of the leaf.
Day 4: yellow circle where the construction paper was.
Day 7: almost white circle where the paper covered the leaf.
Using your knowledge of photosynthesis, which answer choice explains her results the best?
(1 point)
Responses
The part of the leaves that were covered with paper didn't get any light. Without light, cellular respiration was unable to take place because the mitochondria within the leaf cells were unable to absorb the ATP energy needed for the chemical reaction.
The part of the leaves that were covered with paper didn't get any light. Without light, photosynthesis was unable to take place because the chlorophyll within the leaf cells were unable to absorb the sunlight energy needed for the chemical reaction.
The part of the leaves that were covered with paper didn't allow for water to be absorbed. Without water, photosynthesis was unable to take place because the phloem was not able to bring the needed water molecules to the roots.
The part of the leaves that were covered with paper didn't allow for gas exchange through the leaf's stomata. Without oxygen, photosynthesis was unable to take place because the needed reactant of oxygen was missing.
The best explanation for the student's results is:
The part of the leaves that were covered with paper didn't get any light. Without light, photosynthesis was unable to take place because the chlorophyll within the leaf cells were unable to absorb the sunlight energy needed for the chemical reaction.
The best explanation for the student's results is:
The part of the leaves that were covered with paper didn't get any light. Without light, photosynthesis was unable to take place because the chlorophyll within the leaf cells were unable to absorb the sunlight energy needed for the chemical reaction.
To find the best answer choice, we need to understand the results of the experiment and relate them to the process of photosynthesis.
The experiment involved covering parts of the leaves with construction paper for different durations of time. The results showed that after 2 days, there was a slight mark where the paper covered the leaf and the color of the leaf was slightly lighter in that area. After 4 days, a yellow circle formed where the paper was, and after 7 days, the circle became almost white.
From these observations, we can infer that the process being affected here is photosynthesis. Photosynthesis is the process by which plants convert sunlight, water, and carbon dioxide into glucose and oxygen, using chlorophyll in their leaves.
Now let's go through the answer choices:
1. The part of the leaves that were covered with paper didn't get any light. Without light, cellular respiration was unable to take place because the mitochondria within the leaf cells were unable to absorb the ATP energy needed for the chemical reaction.
- This choice mentions cellular respiration, which is not directly related to the results observed in the experiment. Therefore, this is not the best explanation.
2. The part of the leaves that were covered with paper didn't get any light. Without light, photosynthesis was unable to take place because the chlorophyll within the leaf cells were unable to absorb the sunlight energy needed for the chemical reaction.
- This choice aligns with the results of the experiment because the color changes observed in the covered areas indicate a lack of chlorophyll and, consequently, a lack of photosynthesis due to the absence of light. Therefore, this is a likely explanation.
3. The part of the leaves that were covered with paper didn't allow for water to be absorbed. Without water, photosynthesis was unable to take place because the phloem was not able to bring the needed water molecules to the roots.
- This choice mentions the phloem, which is responsible for transporting sugars, not water. Moreover, the experiment didn't involve covering the roots or affecting the water supply to the plant. Therefore, this is not the best explanation.
4. The part of the leaves that were covered with paper didn't allow for gas exchange through the leaf's stomata. Without oxygen, photosynthesis was unable to take place because the needed reactant of oxygen was missing.
- While gas exchange through stomata is important, it doesn't directly explain the observed changes in color in the covered areas. Therefore, this is not the best explanation.
Based on the observations and the knowledge of photosynthesis, the best explanation for the results is:
- The part of the leaves that were covered with paper didn't get any light. Without light, photosynthesis was unable to take place because the chlorophyll within the leaf cells were unable to absorb the sunlight energy needed for the chemical reaction.
Therefore, the best answer choice is (2) - The part of the leaves that were covered with paper didn't get any light. Without light, photosynthesis was unable to take place because the chlorophyll within the leaf cells were unable to absorb the sunlight energy needed for the chemical reaction.