Presentation is loading. Please wait.

Presentation is loading. Please wait.

The Nitrogen Cycle  All organisms need nitrogen to make proteins  Nitrogen gas makes up 78% of the atmosphere, but it cannot be used directly by most.

Similar presentations


Presentation on theme: "The Nitrogen Cycle  All organisms need nitrogen to make proteins  Nitrogen gas makes up 78% of the atmosphere, but it cannot be used directly by most."— Presentation transcript:

1 The Nitrogen Cycle  All organisms need nitrogen to make proteins  Nitrogen gas makes up 78% of the atmosphere, but it cannot be used directly by most organisms

2 Nitrogen Cycle  They get their nitrogen from substances such as ammonia that contain nitrogen.  Nitrogen fixation is the converting nitrogen gas into ammonia

3 Nitrogen-fixing  Bacteria perform this critical step  Without these bacteria, movement of nitrogen would stop almost completely.  Lightning is the only other natural nitrogen fixing process. It accounts for only about 1% of the world’s nitrogen fixation.

4 Nitrogen Fixation Bacteria  Plants called legumes (peas, bean and alfalfa) have nodules on their roots that contain nitrogen-fixing bacteria  NF bacteria supply usable nitrogen directly to the plants.  They also live freely in the soil and water  Most plants cannot use the ammonia these bacteria produce.

5 Nitrifying bacteria  Convert ammonia into nitrites and then nitrates, which plants absorb through their roots.  Animals get the nitrogen they need by eating plants or animals.  When animals digest protein, a by-product is ammonia.  Ammonia is toxic to animals and they get rid of it in their wastes.

6 Nitrogen Cycle  Bacteria and fungi in the soil break down the ammonia in wastes and dead organisms into nitrates and release them into the soil where they can be adsorbed by plants

7 Returning Nitrates to Nitrogen Gas  Denitrifying bacteria- in the soil convert nitrates back into nitrogen gas, which returns to the atmosphere

8  s07_int_nitrogen/ s07_int_nitrogen/


Download ppt "The Nitrogen Cycle  All organisms need nitrogen to make proteins  Nitrogen gas makes up 78% of the atmosphere, but it cannot be used directly by most."

Similar presentations


Ads by Google