Biogeochemical Cycles

What is the most abundant gas in the atmosphere?

• hydrogen

• oxygen

• helium

• nitrogen

Which is NOT a process of the water cycle?

• precipitation

• freezing

• transpiration

• evaporation

Nitrogen that is not combined with other elements and found in the atmosphere as gas is _____.

• free nitrogen

• nitrogen compounds

• ammonia

• nitrates

Why do living things need nitrogen?

• To get energy

• To make amino acids

• To make proteins

• To make proteins AND amino acids

What happens during the process of denitrification?

• Nitrogen compounds turn into free nitrogen

• Free nitrogen turns into nitrogen compounds

How does carbon dioxide leave the atmosphere?

• Through transpiration

• Through photosynthesis

• Through factory emission

• Sunlight

Which process takes Carbon Dioxide from the air and converts it into a form of carbon used by living things?

• Precipitation

• Photosynthesis

• Respiration

• Bioremdiation

Respiration is the process by which ____________ is consumed and _______________ is produced.

• Carbon, Oxygen

• Oxygen, Carbon dioxide

• H20, oxygen

• Carbon, H2O

Carbon dioxide is added to the atmosphere by

• Burning fossil fuels

• Cellular respiration

• Decomposing organic matter

• All answers are correct

How much of the atmosphere is composed of nitrogen gas?

• 87%

• 38%

• 78%

• 21%