The Nitrogen Cycle (pg 92-94)

The Nitrogen Cycle (pg 92-94) • All organisms need ________________________________ • Amino acids are the ________________________________ __________ which are critically important ______________ ____________________________________ in living things Sources of Nitrogen: • Nitrogen is the most _______________________________ _______________________________________________ • N2 gas is unavailable to most organisms b/c it is difficult___ _______________________________________________ _______________________________________________ __ • Nitrogen cycle: the movement of________________________ _______________________________________________ _______________________________________________ ______

~In order for nitrogen to be useful to organisms, nitrogen gas must _______________________________________________ __________________________________________________ ~ Nitrogen Fixation: • First Step in the Nitrogen Cycle is Nitrogen Fixation: Nitrogen from nitrogen gas is “fixed” or combined with _______________________________________________ • Some bacteria are capable of _________________________ and they produce __________________________________ _______________________________________________ _ • Nitrogen fixing bacteria can be found on the roots of plants. This is a _______________________________ in which both organisms benefit. Therefore this is an example of ___________________. • Excess ammonia produces by bacteria moves into ________ __________, where it dissolves in ____________________ _______________________________________________

• Non-biological nitrogen fixation by____________________ __________________________ also makes atmospheric nitrogen available for plants. Nitrification: • Most plants require a combination of _________________ _____ (NH4+) ______________________ (NO3-) for optimal growth • Nitrate is a highly soluble form_______________________ _______________________________________________ • Nitrate is produced ________________________________ _______________________________________________. • Nitrification: the process that _______________________ _______________________________________________. NH4+ (ammonium)  NO2- (nitrification by nitrifying bacteria)  NO3- (nitrate)

• Nitrate is taken up by plants through their ______________. • Plants use nitrate to synthesis (build) the ________________

______________________________________, as well as the _____________________ that are then linked together to form proteins ~How do consumers obtain their Nitrogen? ___________________________________________________ ___________________________________________________ __ Decomposition and Denitrification: • when organism die, ________________________________ • Nitrogen compounds and proteins are broken down by ___________________ into the simpler _______________ and ____________________. • These dissolve in _____________ in the_____________ or other water sources and are once again ________________ _______________________________________________ • Denitrification: when special bacteria convert____________ _______________________________________________ _______________________________________________ __

~Why do we aerate our lawns? What does aerobic mean? (look up in glossary)? ~ ___________________________________________________ ___________________________________________________ ___________________________________________________ ___________________________________________________ ___________________________________________________ ___________________________________________________ ______

~Do Check Your Understanding 4.3, Q’s 117~