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Science 10
Name __________________________
Carbon and Nitrogen Cycle Reviews
The Carbon Cycle
1.
Complete the paragraph:
The two basic life processes involved in the carbon cycle are ____________________ and
____________________. Both plants and animals perform ____________________, but only plants carry on
____________________.
During photosynthesis, green plants take ____________________ and ____________________from
the atmosphere. Using the energy from the ____________________, water molecules break down and the
hydrogen atoms from the water combine with the CO2 to form ____________________ (C6H12O6). The oxygen
from the water molecules is given off into the ____________________. The carbohydrates made during
photosynthesis help make other organic compounds (compounds with carbon in them). Plant-eating animals use
these organic compounds to grow, move, reproduce and perform other life activities. These animals, in turn, are
eaten by other animals who use the same compounds.
During cellular respiration, ________________ and ______________ are reactants. As a result,
____________________ is given off into the atmosphere. When plants and animals die the organic compounds in
them break down. Fossil fuels also give off ____________________ into the atmosphere when they are burned.
2.
Complete the table below by choosing true or false:
Type of Organism
Cellular
Respiration
Photosynthesis
Takes in
CO2
Takes in O2
Gives off
CO2
Gives off O2
Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Decomposer
3.
On a separate piece of paper, sketch a diagram of the carbon cycle and label the following (Some labels may be
used more then once):

Producers
Consumers
Decomposers

Dead organisms/waste
Photosynthesis
Cellular respiration

Oxygen
Carbon dioxide
The Nitrogen Cycle
4.
Complete the paragraph:
____________________% of the atmosphere is nitrogen. The nitrogen cycle involves green plants,
animals and several kinds of bacteria. Nitrogen gas, which is unusable by most living organisms, is fixed during the
process of ____________________ by bacteria called ____________________. (In aquatic environments, this
bacteria is called ____________________). This process turns the nitrogen gas into ____________________.
Plant roots then absorb this from the soil (or water) and use them to make ____________________ and
________________. Animals get proteins by eating other animals or plants. Animals do not use all the proteins;
some are broken down and released as waste, which contains nitrogen in the form of ____________________.
Then, ____________________ bacteria in the soil or water break down these compounds even further and make
them into ____________________ to be usable by plants again. Bacteria also break down dead organisms.
Nitrogen from a decaying organism’s protein combines with hydrogen to form ____________________. This
form of nitrogen is actually poisonous to most plants and animals. Since it cannot be absorbed by plants,
____________________ bacteria convert it into ____________________, a useable form of nitrogen for
plants. Sometimes, though, these nitrates are turned back into ____________________ and released into the
atmosphere to complete the cycle. This is called ____________________ and it is carried out by
____________________ bacteria.
5.
6.
List the three main processes in the Nitrogen Cycle.
a)
_____________________________________________________________
b)
_____________________________________________________________
c)
_____________________________________________________________
On a separate piece of paper, draw and label the nitrogen cycle using the following terms (Terms can be used
more than once):

Nitrogen gas, ammonium and nitrates

Nitrogen fixation and nitrogen fixing bacteria (Rhizobium and cyanobacteria)

Denitrification and dentrifying bacteria

Nitrification and nitrifying bacteria

Producers, consumers and decomposers