The Nitrogen Cycle

Root Hair Cell

For plants to take up mineral ions, ions are moved into root hair cells, where they are in a higher concentration than in the soil.

Active transport occurs within the root so that the plant takes in even more of the ions that it needs from the soil.

Denitrifying bacteria convert nitrates into nitrogen gas that returns to the atmosphere.

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Multiple Choice

How is nitrogen "fixed" into a usable form for plants?

• Through action of bacteria only

• Through action of bacteria and lightning

• Through lightning only

• Through photosynthesis

Multiple Choice

How do animals get the nitrogen they need?

• From the air they breathe

• From the water they drink

• From the food they eat

• From the sun

Multiple Choice

Plants and animals cannot use nitrogen directly from the air.

• True

• False

Multiple Choice

What converts nitrogen gas into a usable form for plants and animals?

• bacteria

• fungi

• rain

• car exhaust

Multiple Choice

The process that changes atmospheric nitrogen gas into nitrogen compounds that are usable by living things is called

• nitrogen composition

• ammonia

• denitrification

• nitrogen fixation

Multiple Choice

What process occurs when dead plant and animal matter decomposes and nitrogen is released back into the atmosphere?

• Assimilation

• Fixation

• Ammonification

• Denitrification

Multiple Choice

The step of the nitrogen cycle that is in red is called...

• Denitrification

• Nitrification

• Nitrogen Fixation

• Ammonification

Multiple Choice

The step of the nitrogen cycle that is in red is called...

• Denitrification

• Nitrification

• Nitrogen Fixation

• Ammonification

Multiple Choice

The step of the nitrogen cycle that is in red is called...

• Denitrification

• Nitrification

• Nitrogen Fixation

• Ammonification