Question

Which role do plants play in the nitrogen cycle?

O A. They take the nitrogen found in soil and turn it back into nitrogen
gas.
B. They break down wastes and return nitrogen compounds to soil.
C. They take up the usable forms of nitrogen found in soil.
D. They take up nitrogen gas directly from the atmosphere.

Answer 1

Plants absorb usable forms of nitrogen, such as nitrate and ammonium, which have been changed from atmospheric nitrogen by nitrogen-fixing bacteria. They use these compounds to build essential molecules for growth, contributing to the nitrogen cycle.

Step-by-step explanation:

Plants play a critical role in the nitrogen cycle by assimilating nitrogen. They cannot use nitrogen gas (N₂) directly due to its stable molecular triple bond. Instead, they absorb usable forms of nitrogen, such as nitrate (NO₃⁻) and ammonium (NH₄⁺), that have been fixed by nitrogen-fixing bacteria found in soil or on the roots of legumes. Once absorbed through the roots, plants use these compounds to synthesize proteins and nucleic acids necessary for their growth. As plants are consumed by animals or decompose after death, the nitrogen within them becomes available for other organisms or is converted back into nitrogen gas by decomposers, thus continuing the cycle.

Answer 2

C

Step-by-step explanation:

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