A small molecule thought to inhibit an aspect of photosynthesis is administered to a weed within a controlled laboratory environment. All of the other plant's needs were met (water, appropriate lighting, etc). A negative control plant was also grown in the same conditions without the administration of the small molecule inhibitor. Both plants (the test plant and the negative control) exhibited oxygen production. However, the test plant did not absorb nearly as much carbon dioxide and ultimately died. Given this data answer the following questions. What portion of photosynthesis is being inhibited by the small molecule? Why? The best answer will address both the oxygen production and carbon dioxide utilization data. Predict what will happen to the levels of NADPH and ATP within the test plants stroma relative to the negative control.

Based on the provided data, it appears that the small molecule inhibitor is affecting the carbon fixation stage of photosynthesis. This stage involves the conversion of carbon dioxide (CO2) into organic compounds, specifically carbohydrates, through the Calvin cycle. The evidence for this conclusion comes from the observation that while both the test plant (administered with the inhibitor) and the negative control plant exhibited oxygen production, only the test plant showed reduced carbon dioxide uptake and ultimately died. This suggests that the inhibitor interferes with the ability of the plant to fix carbon dioxide into organic molecules.

The oxygen production observed in both plants indicates that the light-dependent reactions of photosynthesis, which produce oxygen as a byproduct, are not significantly affected by the inhibitor. This suggests that the inhibition occurs downstream of the light-dependent reactions, specifically in the Calvin cycle.

In the absence of efficient carbon fixation, the test plant would likely experience a decrease in the levels of NADPH and ATP within the stroma compared to the negative control. NADPH and ATP are products of the light-dependent reactions and are utilized in the Calvin cycle to drive the conversion of CO2 into carbohydrates. With reduced carbon dioxide fixation, there would be less demand for NADPH and ATP, leading to lower levels of these molecules in the stroma of the test plant compared to the negative control.

Furthermore, the decrease in carbohydrate production due to inhibited carbon fixation would negatively impact the overall metabolism and growth of the test plant, ultimately leading to its death. This scenario highlights the critical role of carbon fixation in sustaining plant growth and survival through the production of essential organic compounds.