Nitrogen and Phosphorus Cycles

True or False: Organisms can readily use nitrogen gas.

False - organisms cannot use nitrogen gas - the nitrogen has to be in a more usable form

NH3

ammonia

What nitrogen compound is toxic to plants?

ammonia

the process that happens as organisms are decomposed - releasing ammonia or ammonium ions back into the soil

ammonification

NH4+

ammonium

a nitrogen compound that only some plants can use

ammonium

process where plants use nitrogen to build proteins, DNA and chlorophyll

assimilation

process by which bacteria convert nitrate back into nitrogen gas

denitrification

what are 4 ways phosphorus is released back into the environment?

during decomposition, weathering of apatite rocks and bird droppings (guano), erosion, leaching

What happens to ammonia automatically in the soil as it reacts with water?

it converts into ammonium

NO3

nitrate

nitrogen compound that most plants use

nitrate

the two-part process by which bacteria convert ammonia into nitrite and then nitrate

nitrification

NO2

nitrite

process by which bacteria convert nitrogen gas into ammonia

nitrogen fixation

N2

nitrogen gas

PO4

phosphate salt

What are two things that make the phosphorus cycle different from the other cycles?

phosphorus is not found in a gaseous state and therefore the atmosphere doesn't play a role, it is the slowest cycle

how are phosphate salts absorbed and transferred?

plants take it in from the soil / water, animals eat the plants

What is the largest reservoir of nitrogen?

the atmosphere