Nitrogen cycle

Which nitrogen cycle process is occurring when bacteria convert ammonium to nitrite and then into nitrate?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

Which of these nitrogen cycle processes converts atmospheric nitrogen to a soil form of nitrogen that is usable by plants?

• nitrogen fixation

• nitrification

• denitrification

• ammonification

• assimilation

How much of the atmosphere is composed of nitrogen gas?

• 87%
• 38%
• 78%
• 21%

Organisms that break down dead plants & animals and release nitrogen back into atmosphere...

• bacteria
• plants
• animals
• producers

Organisms that need nitrogen to survive

• only plants
• only animals
• only bacteria
• all living organisms

Plants and animals cannot use nitrogen directly from the air.

• True
• False

After plants and animals contain nitrogen, what puts it back into atmosphere and soil?

• decomposition
• precipitation
• condensation
• bacteria

Nitrification happens in the ______

• Air 
• Soil 
• Ground Water 
• Plants 

What is true about nutrients in the ecosystem (such as water, carbon, and nitrogen)?

• They are not affected by humans in the ecosystem.

• They cannot be recovered if they are lost in the ecosystem.

• They cycle through the ecosystem in different forms to support life.

• They are usually only found in one form in the ecosystem to support life.

What is the chemical equation for photosynthesis?

• Sun+water+co2=o2+sugar

• sun+photosynthesis

• O2+sugar=water+co2+energy