Question

A researcher is interested in plants and nitrogen. She puts two groups of plants into identical soil that has been sterilized, so there are no living organisms in it. One group of plants is placed in a chamber with ordinary air, and the other group is placed in a chamber with air that has been enriched with nitrogen gas. What is the expected outcome regarding the growth rates of the two groups of plants?

A) True, the two groups of plants will grow at identical rates.
B) False, the group of plants exposed to nitrogen-enriched air will grow at a slower rate.
C) False, the group of plants exposed to nitrogen-enriched air will grow at a faster rate.
D) False, there is not enough information to determine the growth rates.

Answer 1

Plants cannot directly utilize nitrogen gas, instead relying on soil bacteria for nitrogen fixation. In sterilized soil without bacteria, the presence of nitrogen-enriched air is unlikely to affect plant growth rates, potentially leading to similar growth in both groups.

Step-by-step explanation:

The expected outcome regarding the growth rates of two groups of plants, where one is placed in ordinary air and the other in nitrogen-enriched air, is not as straightforward as it might seem. Although plants require nitrogen to grow, they cannot directly use nitrogen gas (N2). Most plants get the nitrogen they need from the soil in the form of nitrate ions or ammonium ions, which they can readily absorb through their roots. Plants rely on soil bacteria to convert nitrogen gas from the atmosphere into these more usable forms, a process known as nitrogen fixation. In a sterilized soil with no living organisms, this process cannot occur. Therefore, enriching the air with nitrogen gas would not necessarily increase the availability of nitrogen in a form that the plants could use. It is possible that the plants in both chambers would grow at similar rates if they are not able to utilize the atmospheric nitrogen.