

Carbon is the basis for life on Earth.
99.9% of all organisms on the planet to
carbon based life.
 This means that all of those organisms require
carbon to survive


Is there carbon in sugar?
Is there carbon in CO2 ?


The Earth has only a fixed amount of carbon.
Carbon is the ultimate form of recycling.

How do plants use carbon?
 Photosynthesis –
▪ Takes CO2 from atmosphere and combine with water

Animals are the non-photosynthetic
creature
 Cannot create their own food
 Break down sugar and starches through a
process of metabolism
 What does an animal get from metabolizing?
 Energy
 H2O
 CO2
 CO2 goes back to the atmosphere to use again.

Decomposers are involved in the carbon
cycle
 Break down organic materials
▪ Dead plants and animals
▪ Feces
 Produces gasses
▪ CO2 and Methane
Carbon atoms
may return to the
pool of carbon
dioxide in
the air and water
in three ways.
1. Respiration.
2. Combustion.
3. Erosion.
p. 352
Step 1

PLANTS USE CARBON FROM
THE AIR (CO2) & WATER &
ENERGY FROM SUNLIGHT
STEP 2

ANIMALS EAT PLANTS (sugar
for energy) & BREATH IN O2 &
breath out CARBON DIOXIDE
GAS
Step 3

PLANTS USE CARBON
DIOXIDE & ANIMALS DIE &
DECOMPOSE & nutrients are
returned to the soil.
Composition of the Atmosphere
The atmosphere is primarily composed of
Nitrogen (N2, 78%)
Oxygen (O2, 21%)
Argon (Ar, 1%).
A myriad of other very influential components
are also present which include
water (H2O, 0 - 7%),
"greenhouse" gases or Ozone
(O3, 0 - 0.01%)
Carbon Dioxide (CO2, 0.01-0.1%)

What is Nitrogen?

Where is Nitrogen?
 An element just like
 There are huge amounts
carbon
 All creatures need
Nitrogen to survive
of Nitrogen in the
atmosphere!
 Most plants and animals
cannot use it.
 It must be fixed (put in a
biologically useful
compound)
 After its fixed it can be
used.

Atmosphere

Soil
 Most abundant N source
 nitrates in soil can be
 Cannot be used by
used by plants
 Can be converted into
nitrate compounds by
bacteria, algae, &
evening lighting.
 Once in soil nitrogen
becomes biologically
accessible.
animals and plants

Plants are the main
users of nitrogen in
soil.

They take in nitrates
through their root
systems.

Once in the plant it
helps the plant survive.

Once the plants have
converted the nitrogen
the element can be
returned to the soil or
be taken in by animals
Herbivores eat plants
and convert many of
the amino acids into
new proteins
 Omnivores eat both
plants and animals into
new proteins.


The nitrogen
compounds are only
borrowed

Nitrogen atoms are
returned to the soil in
feces and dead animals

Once in the soil the
process happens again!
Nitrogen Cycle: Bacteria carry out many of the important
steps in the nitrogen cycle, including the conversion of
atmospheric nitrogen into a usable form, ammonia. p. 353
http://www.nicksnowden.net/images/Nutrient_Cycles/nitrogen_cycle_cartoon.gif