Nitrogen Cycle

• Plants absorb these substances and convert them into proteins

  
• Primary consumers eat the plants and can make their own proteins, secondary consumers eat primary consumers and so on.

  
• Death and decay happens at each trophic level leading to stage one

  
• Denitrifying bacteria carry out denitrification: they convert nitrogen-containing substances into atmospheric nitrogen

  
• Nitrogen fixing bacteria provide usable nitrogen for plants, these may exist in the root nodules where they live in symbiosis with the plants (nitrogen fixation), or this can happen because of lightning, or microorganisms provide them through decomposition.

  
• Nitrifying bacteria convert nitrogen-containing substances into better nitrogen-containing substances for the plants (this is called nitrification)