8th Grade Chapter 18 Review

Organisms need nitrogen in order to...

• To breathe

• To obtain water for growth

• To build proteins & DNA

• To regulate temperature

Gas that makes up 78% of our atmosphere.

• Oxygen

• Nitrogen

• Hydrogen

• Carbon Dioxide

Based on the picture, what is the chemical formula for atmospheric nitrogen?

• N

• N₂

• NH₃

• NO₃

Plants and animals cannot use nitrogen directly from the air.

• True
• False

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

Bacteria fix nitrogen from the atmosphere into a form plants can use.

• True

• False

How nitrogen is "fixed" into useable form for plants...

• through action of bacteria only
• through lightning only
• through action of bacteria & lightning
• through photosynthesis

How do animals get the nitrogen they need?

• From the air they breathe

• From the water they drink

• From the food they eat

• From the sun

How does fertilizer affect the ecosystem?

• the bacteria reproduce quicker

• causes increase in rain, thereby increasing flooding of ponds and lakes

• create large algae blooms in the water

• cause the nitrogen fixing bacteria in the soil to be more productive

Organisms that need nitrogen to survive

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