S) Which of the statements regarding the nitrogen cycle is true? a) Nitrogen fixation is the process atmospheric nitrogen is co usable forms. b) Denitrification occurs when a nitrogen containing compou in the soil. c) Atmospheric nitrogen is absorbed through the leaves of pl d) Animals obtain nitrogen through the process of cellular re

## Step 1<br />The nitrogen cycle is a process that involves the conversion of nitrogen in various forms through biological and physical means. This cycle includes several stages such as nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.<br /><br />## Step 2<br />Let's analyze each option:<br /><br />a) Nitrogen fixation is the process where atmospheric nitrogen (N2) is converted into ammonia (NH3) or related nitrogenous compounds in the soil. This process is carried out by certain bacteria and is essential for making nitrogen available to plants.<br /><br />b) Denitrification is the process by which nitrate (NO3-) in the soil is converted back into nitrogen gas (N2) or nitrous oxide (N2O), which is released into the atmosphere. This process completes the nitrogen cycle by returning nitrogen to the atmosphere.<br /><br />c) Plants do not absorb atmospheric nitrogen directly through their leaves. Instead, they absorb nitrogen compounds like nitrate or ammonia from the soil through their roots.<br /><br />d) Animals obtain nitrogen by consuming plants or other animals. The process of cellular respiration does not directly involve the acquisition of nitrogen; rather, it is a process of energy production from nutrients.<br /><br />## Step 3<br />Based on the above analysis, the correct statement regarding the nitrogen cycle is option a), which correctly describes nitrogen fixation.