11. The Nitrogen cycle

Why do organisms need nitrogen, and why can't they use the nitrogen in the atmosphere?

- All organisms need nitrogen to build proteins and nucleic acids.
- While nitrogen gas makes up about 78% of Earth's atmosphere, most organisms cannot use this atmospheric nitrogen directly to make proteins or amino acids.
- They need a different form of nitrogen that is not readily available in the air.

Where is nitrogen found, and how is it recycled in nature?

-Nitrogen is found in

• ammonia, (dead plants and animals,)

• and the wastes of living organisms (like urine and feces).
  - The nitrogen cycle, which recycles nitrogen, is made possible by different types of bacteria living in the soil.
  

what is the nitrogen cycle?

complex cycle with 5 important processes

how many steps are in the nitrogen cycle?

five

What is nitrogen fixation in the nitrogen cycle?

- Nitrogen fixation is the first step of the nitrogen cycle.
- It's the process where atmospheric nitrogen gas (N₂) is converted into ammonia (NH₃),
- making it usable by plants and other living things.

What is nitrification in the nitrogen cycle?

- Nitrification is the second step of the nitrogen cycle.
- In this process, bacteria in the soil convert ammonia (NH₃) into nitrates (NO₃⁻),
- which plants can absorb from the soil and use to grow.

What is assimilation in the nitrogen cycle?

how does nitrogen become part of plants and animals?

Assimilation is the third step in the process.

• It happens when plants take in nitrates and ammonium from the soil and use them to make proteins and important materials like nucleic acids.

• When animals eat these plants, they use the nitrogen to make their own proteins and nucleic acids.

• This is how nitrogen becomes part of both plants and animals.

What is ammonification in the nitrogen cycle?

turns what to what?

plants use it to make what?

this helps?

Ammonification is when

• 4th step

• bacteria in the soil break down nitrogen

• from animal waste. dead plants and animals,

• turning it into ammonia.

• Plants can then use some of this ammonia to make proteins and nucleic acids.

• This helps recycle nitrogen back into the soil.

What is denitrification in the nitrogen cycle?

- Denitrification is when certain bacteria change leftover nitrates back into nitrogen gas.
- This nitrogen gas is released into the air,
- finishing the nitrogen cycle.

What role does nitrogen fixing bacteria play in the nitrogen cycle?

• take nitrogen gas from the atmosphere

• turn it into ammonia,

• which plants can use.
  

the different types of bacteris in the nitrogen cycle (4)

- nitrogen fixing bacteria
- ammoifying bacteria
- nitrifying bactera
- denitryfing bacteria

What roles does ammonifying bacteria play in the nitrogen cycle?

they turn what to what?

• These bacteria break down dead plants and animals,

• turning the nitrogen in their bodies into ammonia.

What role does nitrifying bacteria play in the nitrogen cycle?

• change ammonia into nitrates,

• which plants can absorb from the soil.
  

What role does denitrifying bacteria play in the nitrogen cycle?

• These bacteria

• convert nitrates back into nitrogen gas,

• releasing it into the atmosphere.