NITROGEN CYCLE REVIEW

Our atmosphere is _____  nitrogen gas.

• 78%

• 75%

• 80%

• 82%

Animals and plants cannot directly use all the nitrogen found in our __________

• Soil

• Atmosphere

• Rivers

• Oceans

.

Only special bacteria can directly use nitrogen in our atmosphere and “fix” it so other organisms can benefit. These bacteria are called _______________________bacteria.

• Nitrogen -fixing

• Photosynthetic

• Aerobic

• Anaerobic

Higher organisms use nitrogen to make their    _____________

• Bones

• Lipids

• protein

• Carbohydrates

Animal waste decay by the action of bacteria which create _____________ and ______________products rich in nitrogen, and useful for plants to use again.

• Carbon dioxide/oxygen

•  ammonia/nitrate

• Methane/sulfur

• Hydrogen/phosphorus

_______________ bacteria in the soil can break down the ammonia into the gaseous form of nitrogen, which is not available for use by plants or animals.

• denitrifying

• antropogensis

• fixation

• photosynthetic

In another part of the cycle, animals eat plants containing nitrogen, which is again returned to the soil by animal   ___________or decaying ______________and animals

• ammonia/nitrate

• hair/leaves

• nodules/legumes

• waste/plants

Observe the picture: Which part of the cycle shows how oxygen is returned into the atmosphere what's the name of these bacterias?

• Nitrifying bacterias

• Denitrifying bacteria

• Nitrogen fixing bacterias

• Gram positive bacterias.

select the letter that is described

waste and decay of organic matter

• A

• B

• C

• D

select the letter that is described

nitrogen fixed by bacteria in root nodules

 

• A

• B

• C

• D