Question

in a recent study, researchers grew rice in chambers with varying levels of carbon dioxide (co2) to simulate different atmospheric conditions. they found that as co2 levels increased, the nutritional content of the rice changed. specifically, the rice contained less protein, iron, and zinc, but contained more carbohydrates. one potential explanation for these findings is that, since co2 is an important input to photosynthesis, the elevated carbon dioxide levels could be spurring the plants to photosynthesize more rapidly. this in turn could lead to increased carbohydrate production at the expense of other nutrients like protein, iron, and zinc.
which finding from the study, if true, would most directly weaken the potential explanation?
choose 1 answer:
a rice plants consumed co2 at nearly identical rates, regardless of variations in atmospheric co2 levels.
b protein production suffered more in high - co2 conditions than zinc production did.
c rice plants grew more quickly overall in low - co2 conditions than in high - co2 conditions.
d carbohydrate production increased and then plateaued as atmospheric co2 levels increased.

Explanation:

The potential explanation is that elevated CO2 levels spur plants to photosynthesize more rapidly, increasing carbohydrate production at the expense of other nutrients. If rice plants consumed CO2 at nearly identical rates regardless of CO2 - level variations, it undermines the idea that higher CO2 levels cause more rapid photosynthesis. This directly weakens the proposed explanation.

Answer:

A. Rice plants consumed CO2 at nearly identical rates, regardless of variations in atmospheric CO2 levels.