Cycles

Cycle: sequence of a recurring events

Carbon Cycle

Carbon is the chemical backbone

of life on Earth

Carbohydrates: C, H, O

Short term energy source, plant cell walls

Lipids : C, H, O

Long term energy storage, cell membranes

Proteins: C, H, O, N

Enzymes, Structure, Movement, Hormones

Nucleic Acids: C, H, O, N, P

GeneticMaterials

CO2 in the atmosphere

Carbon cycle

Plant

respiration

Industrial

combustion

Animal

respiration

CO2

Carbon
Dioxide

(CO₂)

CO2

Fossils and
fossil fuels

Decomposition

Photosynthesis

Glucose
(C₆H₁₂O₆)

CO2

Consumers

Plants

Carbon

ABSORB carbon

from the

atmosphere

RELEASE

carbon into the

atmosphere

Decomposers

RELEASE

carbon into the

atmosphere

Fossil Fuels

RELEASE

carbon into the

atmosphere

Nitrogen Cycle

Nitrogen is essential for protein synthesis and

DNA production

Proteins: C, H, O, N

Enzymes, Structure, Movement, Hormones

Nucleic Acids: C, H, O, N, P

GeneticMaterials

N in the atmosphere is unusable

Nitrogen Cycle

Decomposition

Lightning
can fix
Nitrogen

Nitrogen fixing bacteria

Unused Nitrogen

Bacteria “Un Fixes” Nitrogen