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Tree of Life
Transcript of Tree of Life
Photosynthesis means "light-production" using light to produce substances
The Rise of Photoautotrophs
First prokaryotes were chemoautotrophs
How Energy is Obtained
Autotrophs are self-nourishing
They create their own energy
Plants, Archaebacteria, and many Protists are autotrophs
Heterotrophs are nourished by others
They obtain energy by consuming other organisms
Animals, Fungi, many Protists, and most Eubacteria are heterotrophs
Chemoautotrophs extract energy and carbon from simple, inorganic compounds
The first prokaryotes did not have the enzymes for complicated metabolic reactions
Today's Archaebacteria are chemoautotrophs
Photoautotrophs use photosynthesis to produce energy
They make sugars and other compounds using sunlight and Carbon Dioxide
Plants and Protists like algae are photoautotrophs
They lacked enzymes for complicated metabolic reactions, so they had to extract energy from inorganic compounds, like methane and hydrogen sulfide
The early atmosphere contained these gases but little free oxygen
The First Autotrophs
Some organisms evolved light-sensitive molecules, and became the first photoautotrophs
They then gained the ability to split water molecules apart as a source of electrons for their reactions
This leads to the release of oxygen into the atmosphere
The oxygen reacts with metals, producing free radicals, which are toxic to cells
Prokaryotes that could not neutralize these free radicals died off or were limited to only anaerobic environments
Prokaryotes that could neutralize these free radicals had an advantage, and filled the spaces the other cells left
The ozone protected organisms from deadly UV radiation, and allowed them to come out of the deep ocean and other dark places
Humans can get in the way of photosynthesis, such as with pollution, deforestation, and other issues.
Pigments are used to absorb light
Chlorophyll is the main pigment in most plants
It reflects green and thus leaves look green
It best absorbs red and violet light
Carbon dioxide is absorbed
Oxygen is produced
Cycle of gases
Oxygen from photosynthesis builds up in the atmosphere
The oxygen forms ozone, which blocks harmful UV radiation from the sun
Why are we just standing here?
This protection allows advanced organisms to evolve and survive
Photosynthesis produces sugars and other organic compounds that feed these advanced organisms, the heterotrophs