Question

drag the tiles to the correct boxes to complete the pairs.

match each step in the nitrogen cycle to its description.

nitrogen fixation <-> bacteria convert nitrates into nitrogen gas
denitrification <-> bacteria break down waste products and return nitrogen to the soil
nitrification <-> plants and animals take in and use nitrogen compounds
ammonification <-> bacteria convert atmospheric nitrogen to ammonia
assimilation <-> bacteria convert ammonia to nitrites and nitrates

Explanation:

Analyze nitrogen fixation

Nitrogen fixation is the process where atmospheric nitrogen gas \(\text{N}_2\), which is relatively inert, is converted into ammonia \(\text{NH}_3\) or related nitrogenous compounds, primarily by specialized bacteria. Looking at the descriptions, "bacteria convert atmospheric nitrogen to ammonia" matches nitrogen fixation.

Analyze denitrification

Denitrification is the biological process of reducing nitrate \(\text{NO}_3^-\) and nitrite \(\text{NO}_2^-\) back into gaseous nitrogen forms, primarily diatomic nitrogen gas \(\text{N}_2\). Looking at the descriptions, "bacteria convert nitrates into nitrogen gas" matches denitrification.

Analyze nitrification

Nitrification is a two-step biological oxidation process where ammonia \(\text{NH}_3\) is first oxidized to nitrites \(\text{NO}_2^-\) and then further oxidized to nitrates \(\text{NO}_3^-\) by nitrifying bacteria. Looking at the descriptions, "bacteria convert ammonia to nitrites and nitrates" matches nitrification.

Analyze ammonification

Ammonification (or mineralization) occurs when decomposers (like bacteria and fungi) break down organic nitrogen from dead animal and plant waste products, converting it back into inorganic ammonia or ammonium in the soil. Looking at the descriptions, "bacteria break down waste products and return nitrogen to the soil" matches ammonification.

Analyze assimilation

Assimilation is the process by which plants and animals incorporate the nitrates and ammonia formed through nitrogen fixation and nitrification into their own organic molecules, such as proteins and nucleic acids. Looking at the descriptions, "plants and animals take in and use nitrogen compounds" matches assimilation.

Answer:

Step	Description
denitrification	bacteria convert nitrates into nitrogen gas
nitrification	bacteria convert ammonia to nitrites and nitrates
ammonification	bacteria break down waste products and return nitrogen to the soil
assimilation	plants and animals take in and use nitrogen compounds