Oxygen Cycle

• Colourless, odourless, tasteless gas

• Oxidation – process of uniting/of causing a substance to unite with oxygen

• Carl Wilhelm Schele– Swedish chemist

– Discovered O2 1772

Required

• All living things use oxygen OR

• Depend on organisms that use oxygen in some way

Biological Importance

• Need it to breathe

• Need it for decomposition of organic waste

• Water can dissolve oxygen – supports aquatic life

• Use oxygen to break down simple sugar release energy

• Done through respiration/fermentation

• Animals mainly use respiration

Respiration

• Breaks apart simple food molecules release energy

• Occurs inside cells

Cycle

Simple sugar - Glucose

• Molecule most living things use for energy

• Break down food into smaller molecules during digestion. One of which is Glucose.

• Leaves intestines blood stream every cell in body

Respiration in Cells

• Oxygen used to split glucose apart releasing energy, water, carbon dioxide

Today

• East’s atmosphere – 21%

• Lithosphere 99.5%

• Hydrosphere 46.6%

• Biosphere 0.01%

Photosynthesis

• Plants – take in CO2, H2O make food

• Food: glucose

• Plants pull carbon off CO2 and use oxygen in glucose. (They do not need oxygen for this. Get it from H2O.)

Release oxygen into atmosphere

* Other organisms use the free oxygen for respiration

Photosynthesis and Cellular Respiration

Chemical Relation

• Photosynthesis – uses CO2 O2

• Cellular respiration – uses O2 CO2

Aquatic environment

• Happens on land, in water

• Algae, aquatic plants produce food underwater through photosynthesis

• They are present 20% in atmosphere

• Other aquatic organisms use the dissolved oxygen these plants release into the water.

Human Impact

• Destroying natural areas, forested areas eith many plants replacing with buildings, parking lots, lawns etc

• Fewer plants less O2, more CO2

• Disturbs balance of natural cycle

Need to do

• Stop destroying, promote re-growth of natural areas (forests)

• Burn less (fossil fuels, forest fires etc)

Summary

• O2

• Atomic #8

• Uses – oxidation reactions for respiratory functions – humans, animals, plant, some bacterias etc

• Sources – photolysis, photosynthesis

• Reservoir – bio-/atmos-/litho- sphere