Systems and Cycles Evaluation

Besides bacteria, what converts some atmospheric nitrogen into nitrates that organisms can use?

• Sun

• Rain

• Thunder

• Lightening

Animals obtain the nitrogen they need directly from the

• soil in their habitat

• air they breathe

• plants they eat

• bacteria living within them

Plants and animals cannot use nitrogen directly from the air.

• True
• False

What converts nitrogen into a useable form for plants and animals?

• bacteria
• fungi
• rain

Process in which bacteria or lightening convert nitrogen gas into ammonia that can eventually be used by other living things is called

• nitrogen fixation

• ammonificaiton

• nitrification

• denitrification

The step in the nitrogen cycle where plants take up nitrate and use it to make biological molecules is:

• nitrification
• ammonification
• nitrogen fixation
• assimilation

The step in the nitrogen cycle where bacteria convert ammonia (NH₃) to nitrate (NO₃^-) is:

• nitrification
• ammonification
• nitrogen fixation
• assimilation

The process where some bacteria remove nitrate from the soil by converting it to nitrogen gas is:

• ammoniafication

• nitrogen fixation

• denitrification

• nitrification

What part of the nitrogen cycle deals with the conversion of nitrogen in waste products or dead organisms into ammonia?

• nitrification
• ammonification
• denitrification
• nitrogen fixation

Nitrogen is essential for living organisms to make:

• Lipids
• Carbohydrates
• Proteins
• Fats