Nitrogen cycle

What role do bacteria play in the nitrogen cycle?

Bacteria convert atmospheric N2 to NH3 (ammonia) and nitrates (NO3-) that can be used by plants for nutrition. Denitrifying bacteria can convert nitrates to N2 released back into the atmosphere.

What effect does deforestation have on the nitrogen cycle?

Deforestation leads to nitrogen released and less nitrogen is being taken up by plants so this accelerates eutrophication (process of nitrogen entering the water).

What is eutrophication? This should be in your own words and easy to understand!

Fertilizers rich in nitrogen eventually make their way to water sources like lakes and rivers. When there is too much nitrogen in the water, algae begins to grow. Excess algae grow reduces oxygen levels in the water and kills organisms in the water.

How do humans negatively affect the nitrogen cycle?

Humans use fertilizers that have nitrogen in them leading to more nitrogen in the ground than there should be. Humans also cause deforestation, also leading to too much nitrogen in the ground because there are less plants to take up the nitrogen. NO2 is a byproduct of factories and is released into the atmosphere as pollution.

What are the biggest and smallest reservoirs for this substance?

Largest reservoir = atmosphere Smallest reservoir = biosphere

What is the role of legumes?

Legumes are plants with nodules that have bacteria in them that have the ability to change atmospheric nitrogen into usable nitrogen for plants.

Where is most of the nitrogen stored?

Most nitrogen is found in the atmosphere

What are denitrification and nitrification? What organisms do denitrification and nitrification?

Nitrification → nitrifying bacteria convert ammonium into usable nitrates Denitrification → denitrifying bacteria convert nitrates into atmospheric nitrogen.

Name different nitrogen fixing bacteria and indicate where they come into play in the steps of the nitrogen cycle.

Nitrification → nitrifying bacteria convert ammonium into usable nitrates Denitrification → denitrifying bacteria convert nitrates into atmospheric nitrogen. Bacteria convert atmospheric N2 to NH3 (ammonia) and nitrates (NO3-) that can be used by plants for nutrition. Denitrifying bacteria can convert nitrates to N2 released back into the atmosphere.

How does it get to the plants?

Nitrogen fixing bacteria convert N2 into ammonium and nitrifying bacteria convert it into nitrates that are taken up by plants. (This is called Nitrification)

What is nitrogen fixation? What organisms do nitrogen fixation?

Nitrogen-fixing bacteria transform atmospheric nitrogen into fixed nitrogen.

How does the nitrogen cycle produce acid rain?

One of the acids in acid rain is HNO3. This is formed when nitrogen is being released from factories as NO2 and this reacts with water to create acid rain.

What happens if there is too much nitrogen in lakes? What/where does this excess nitrogen come from?

Overgrowth of algae occurs (See #1). Excess nitrogen comes from chemical fertilizers that are washed into the water.

What is ammonification? What organisms do ammonification?

Plants and animals that die or emit waste produce organic nitrogen. Ammonification is when bacterial decomposers in the ground form ammonium from that organic nitrogen and make it available for other organisms.

Why does excess nitrogen fertilizer cause plant growth (research limiting & excess reagents)?

Plants/trees can only take up so much nitrogen in the fertilizer. When farmers put too much fertilizer not all of the nitrogen is being taken up leading to excess fertilizer in the ground.