Carbon, Nitrogen, and Phosphorus Cycles

Front

What is the role of carbon in living things?

Back

Carbon is an essential element for all living things, found in living tissues, rocks, the atmosphere, and the ocean.

Front

What percentage of carbon participates in the carbon cycle?

Back

Less than 1% of the carbon found on earth participates in the carbon cycle.

Front

How do photosynthesizing organisms use carbon dioxide?

Back

They use carbon dioxide from the air or water to build organic molecules such as glucose.

Front

What are the three ways carbon can return to the air or water?

Back

Respiration, erosion, and combustion.

Front

What happens during respiration in the carbon cycle?

Back

All living organisms undergo cellular respiration, using oxygen to break down food, releasing CO2 as a byproduct.

Front

How does erosion contribute to the carbon cycle?

Back

Marine organisms use carbon to make shells; when they die, the calcium carbonate breaks down, forming CO2 that returns to the atmosphere.

Front

What is the role of combustion in the carbon cycle?

Back

Combustion or burning of fossil fuels releases carbon back into the atmosphere.

Front

What percentage of the atmosphere is nitrogen?

Back

Nitrogen makes up 78% of the atmosphere.

Front

Why can't most organisms use atmospheric nitrogen?

Back

Most organisms are unable to use nitrogen in its atmospheric form.

Front

What is nitrogen fixation?

Back

Bacteria combine nitrogen from the atmosphere with hydrogen to make ammonia (NH3) in the soil.