Nitrogen Cycle

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 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

According to this diagram, plants use nitrogen to make _________________________

• carbohydrates

• cellulose

• proteins

• unsaturated fats

What % of the air is made of nitrogen?

• 21%

• 52%

• 61%

• 78%

True or False. The nitrogen in the atmosphere is in the right form for living things to use.

• True

• False

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

We need nitrogen to make

• proteins

• enzymes

• cells

• all of these