39 18.2 & 18.3 Quiz Nutrient Cycles and Populations

The conversion of atmospheric nitrogen into ammonia, a form of nitrogen plants can readily use, is called -

• denitrification.

• ammonification.

• nitrogen fixation.

• nitrification.

Answer explanation

The conversion of atmospheric nitrogen into ammonia is known as nitrogen fixation. This process allows plants to utilize nitrogen, which is essential for their growth.

Tags

NGSS.MS-LS2-3

To obtain the nitrogen they need, animals depend on many different microscopic ____________________ to convert nitrogen at all stages of the nitrogen cycle.

• protozoa

• bacteria

• worms

• insects

Answer explanation

Bacteria play a crucial role in the nitrogen cycle by converting nitrogen into forms that animals can use. They are essential for processes like nitrogen fixation and nitrification, making them the correct choice.

The atmosphere is made up of mostly nitrogen. The percentage of nitrogen in the atmosphere is approximately _____.

• 60%

• 78%

• 83%

• 51%

Answer explanation

The atmosphere is composed of approximately 78% nitrogen, making it the most abundant gas. The other options are incorrect as they do not accurately represent the nitrogen percentage in the atmosphere.

(a)   converts ammonia and ammonium into nitrite and nitrate.

Answer explanation

Nitrification is the process that converts ammonia and ammonium into nitrite and nitrate, making it essential for nitrogen cycling in ecosystems.

Tags

NGSS.MS-LS2-3

Select all answers below that are stages of the nitrogen cycle.

• Nitrogen fixation

• Diffusion

• Ammonification

• Nitrification

Answer explanation

The nitrogen cycle includes key stages such as nitrogen fixation, where atmospheric nitrogen is converted to usable forms, ammonification, which converts organic nitrogen to ammonia, and nitrification, which transforms ammonia into nitrates.

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

Answer explanation

Animals obtain nitrogen primarily from the food they eat, as proteins and nucleic acids in their diet contain nitrogen. They cannot directly use atmospheric nitrogen, making food the essential source.

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

• Assimilation

• Fixation

• Ammonification

• Denitrification

Answer explanation

Denitrification is the process where bacteria convert nitrogen compounds in dead plant and animal matter back into nitrogen gas, releasing it into the atmosphere. This is a key part of the nitrogen cycle.

A correct path that nitrogen could take would be

• air -> animals -> plants -> bacteria

• animals -> air -> bacteria -> plants

• bacteria -> air -> plants -> animals

• air -> bacteria -> plants -> animals

Answer explanation

The correct path for nitrogen is air -> bacteria -> plants -> animals. Nitrogen in the air is fixed by bacteria, then taken up by plants, and finally consumed by animals, completing the nitrogen cycle.

Tags

NGSS.MS-LS2-3

NGSS.MS-LS2-4

NGSS.MS-LS2-1

The diagram below shows the carbon cycle.

Press the hotspot for where you would find fossil fuels.

Tags

NGSS.MS-ESS3-1

NGSS.MS-ESS3-4

The diagram below shows the carbon cycle.

Press the hotspot for where you would find carbon dioxide.

Tags

NGSS.MS-LS2-3

NGSS.MS-LS1-6

NGSS.MS-ESS2-1