C2-3 Nitrogen Cycle Flashcards
Organisms cannot exist without ___ (3) which all are organic molecules that contain nitrogen
amino acids
peptides
proteins
is therefore an extremely important nutrient for living things
nitrogen
nitrogen makes up about ____ of the air around us
78%
plants cannot use __, the stable two-atom form most common in air, but bacteria can.
N2
Bacteria can fix nitrogen, or combine gaseous N2 with hydrogen to make ____ and ____
ammonia (NH3) and ammonium (NH4+)
other bacteria then combine ammonia with oxygen to form
nitrite (NO2-)
Another group of bacteria convert nitrites to
nitrate (NO3-) which green plants can absorb and use.
Plant cells reduce nitrate to ____
ammonium (NH4) which is used to build amino acids that become the building blocks for peptides and proteins
____________ and their associated bacteria add nitrogen to the soil which is beneficial farming practices that take practical advantage of this relationship
legumes
the most obvious path of nitrogen re-entry is
death of organisms
these decompose dead organisms, releasing ammonia and ammonium ions
fungi and bacteria
this is especially high in nitrogen because it contains the detoxified wastes of protein metabolism
urine
all living organisms that are decomposed are
replenishing soil fertility
denitirying bacteria break down nitrates (NO3-) into
N2 and nitrous oxide (N2O)
occurs mainly in waterlogged soils that have low oxygen availability and a large amount of decomposable organic matter
denitrification
