Carbon & Nitrogen Cycles

When humans burn fossil fuels, most of the carbon quickly enters the ___ as carbon dioxide.

• Water

• Sun

• Atmosphere

• Air

What does NOT produce carbon dioxide?

• Photosynthesis

• Animal respiration

• Burning fossil fuels

• Plants decaying

How do living organisms return carbon to the atmosphere in the carbon cycle?

• Respiration and photosynthesis

• Decomposition and respiration

• Respiration and nitrification

• Photosynthesis and transpiration

How does the carbon in grass become part of a lion?

• The lion eats the grass

• Carbon from the grass doesn't end up in a lion

• The carbon ends up in the lion's food chain

• The lion breathes in carbon given out by the plant

Which of the following removes carbon from the atmosphere?

• Combustion

• Photosynthesis

• Respiration

• Death

What is the process of converting nitrogen gas to a compound that plants can use?

• Nitrogen composition

• Nitrogen fixation

• Ammonia

• Denitrification

Which type of nutrient is rich in nitrogen?

• Protein

• Oxygen

• Carbohydrates

• Fats

Plants and animals cannot use nitrogen directly from the air.

• True

• False

The process of returning nitrogen to the atmosphere via bacterial action is called...

• Denitrification

• Precipitation

• Nitrogen fixation

• Nitrification

Lightning is involved in which part of the nitrogen cycle?

• Nitrification

• Decomposition

• Nitrogen fixation

• Denitrification