AP BIOLOGY

Detailed explanation-1: -Denitrifying bacteria convert the nitrate back into nitrogen gas, which reenters the atmosphere. Nitrogen from runoff and fertilizers enters the ocean, where it enters marine food webs.

Detailed explanation-2: -Bacteria that convert atmospheric nitrogen into nitrogen compounds like ammonia are called nitrogen-fixing bacteria. These bacteria make nitrogen available for the plants. These are of 2 types, symbiotic nitrogen-fixing bacteria like Rhizobium and non-symbiotic nitrogen-fixing bacteria like Azotobacter.

Detailed explanation-3: -Nitrogen-fixing bacteria are prokaryotic microorganisms that are capable of transforming nitrogen gas from the atmosphere into “fixed nitrogen” compounds, such as ammonia, that are usable by plants.

Detailed explanation-4: -Denitrifying bacteria, also known as nitrate-reducing bacteria (NRB), refers to a group of bacteria that helps to convert nitrates or nitrites into nitrogen-containing gases. This conversion is crucial for the atmosphere. It completes the nitrogen cycle by recycling nitrogen into the atmosphere.

Detailed explanation-5: -The Rhizobium or Bradyrhizobium bacteria colonize the host plant’s root system and cause the roots to form nodules to house the bacteria (Figure 4). The bacteria then begin to fix the nitrogen required by the plant.