Unit 3 - Ecosystem Interactions

Which nitrogen cycle process is occurring when plant roots absorb ammonium ions and nitrate ions for use in making molecules such as DNA, amino acids, and proteins?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

Which nitrogen cycle process is occurring when bacteria convert ammonium to nitrite and then into nitrate?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

Which nitrogen cycle process is occurring when nitrogen in plant or animal protein is converted to ammonium?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

What is the name of NH₃?

• ammonia

• ammonium

• nitrate

• nitrite

• nitrous oxide

Which of these nitrogen molecules would be present in the atmosphere?

• NH₃

• NH₄⁺

• NO₃^-

• N₂

Which of these nitrogen cycle processes converts atmospheric nitrogen to a soil form of nitrogen that is usable by plants?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

Which of these nitrogen cycle processes takes nitrogen from its largest reservoir?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

When deciduous trees shed their leaves, specialized soil bacterial will consume the leaf material for energy and, in the process, will return some of the leaf nitrogen to the soil. What nitrogen cycle process is taking place?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

What is the role of denitrifying bacteria

• change nitrate back into nitrogen gas

• change nitrogen gas into nitrate

• absorb carbon dioxide in the soil

• release oxygen gas into the atmosphere

What is the role of decomposing bacteria in the nitrogen cycle?

• change Nitrogen gas into Nitrate

• Return the nitrogen compounds to the soil

• Turn nitrogen into water

• Turn nitrate into nitrogen gas