Cycles

Question 1

nitrogen fixation

Answer 1

because atmospheric N2 cannot be used directly by plants it must first be converted into ammonia (NH3) by bacteria (rhizobium)

Question 2

ammonification

Answer 2

decomposers convert organic waste into ammonia

Question 3

nitrification

Answer 3

ammonia (NH3) is converted to nitrate ions (NO3-)

Question 4

assimilation

Answer 4

inorganic nitrogen is converted into organic molecules such as DNA/amino acids and proteins

Question 5

denitrification

Answer 5

bacteria convert nitrate (NO3-) and nitrite (NO2-) back into N2 gas

Question 6

phosphorus does not circulate as easily as nitrogen because

Answer 6

it does not exist as a gas, but is released by weathering of phosphate [PO4(3-)]n rocks

Question 7

how excess phosphorus is added back to aquatic ecosystems

Answer 7

runoff of animal wastes, fertilizer, discharge of sewage

Question 8

largest reservoirs of C

Answer 8

carbonate [CO3(2-)] rocks first, oceans second