Water and Life

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Water and Life
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Setting the stage for the evolution of advanced
forms of life
Radius of the earth
Circumference of the earth
Total water on earth
readily available fresh water
Age of the earth
Waters appearance on the earth
3 sources of earths water
Water is an essential precursor to life.
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Water and Life
The most abundant substance in living systems

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New born baby     77 Grown-up man      65
Grown-up woman 58 The elderly            
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Human body 65 Plants 80 Fruits and
Vegetables 70-80
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22 73 79
Heart 77 Lungs 80 Kidneys 80 Brain 85
same salinity as the ocean
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Average person has about 50 quarts of body water
A loss of just 5 percent of the body's total
water will cause the mouth to go dry, the surface
of the skin to shrink, and may even cause
hallucinations
A loss of more than 12 - 15 percent total body
fluid would be fatal. The longest anyone has
ever survived without water is _____
Water Loss
15 percent of human water loss is through the act
of respiration
20 percent is lost through perspiration
65 percent is lost by excretion
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Water and Life
Water is an ideal medium for life processes.
1. retains heat, moderates temperature 2.
excellent solvent transports nutrients, life
compounds 4. Participates in biochemical
reactions
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Water and Lifes Beginnings
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Commonality in all living things

• Organisms consist of similar
• organic (carbon-rich) compounds.

• To grow and develop, organisms must
• assemble complex carbon compounds
• from external sources of carbon.

• Assembling complex carbon compounds
• requires energy and water.

• Metabolism and reproduction are controlled
• by proteins. Protein synthesis requires
  reaction
• with water.

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Liquid Water
3.35 3.5 bya
4.4 bya
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The Earliest Organisms
Anaerobic live in low oxygen environments
Autotrophic produce complex organic compounds
from simple inorganic molecules and an
external source of energy.
Energy Sources
Light photoautotroph chemical reactions
chemoautotroph
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Photoautotroph
A photoautotroph is an organism that produces
complex organic compounds from simple inorganic
molecules using energy from light.
energy
light
6CO2 6H2O C6H12O6 6O2
complex organic compound
simple inorganic molecule
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Chemoautotroph
A chemoautotroph is an organism that produces
complex organic compounds from simple inorganic
molecules using energy from chemical reactions
6CO2  6H2O  3H2S ? C6H12O6  3H2SO4
complex organic compound
simple inorganic molecule
Energy?
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Energy is obtained from chemical reactions.
When atoms exchange electrons during certain
reactions, energy can be generated.
6CO2  6H2O  3H2S ? C6H12O6  3H2SO4
Sulfur is the electron donor Carbon is the
electron acceptor
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Earliest Organisms
Chemoautotrophs
Embedded in the lava are numerous tubular
structures left behind by ancient microbes
3.5 bya
tubes contain carbon that represents organic
material left behind by the early organisms.
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Photoautotrophs
Cyanobacteria
(Blue-green algae)
2.5 3.0 bya
bacterial fossils 3 bya
Photosynthetic
Fix atmospheric carbon dioxide into complex
organic compounds.
light
6CO2 6H2O C6H12O6 6O2
(Simplified)
- removed carbon dioxide - added oxygen to the
atmosphere
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Stromatolites
the oldest macroscopic evidence of life on Earth,
at least 2.5 billion years old
Calcium Carbonate Cyanobacteria colonies
turfs
Colonies of Cyanobacteria
Produced billions of tons of oxygen
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In the absence of oxygen, iron is easily
dissolved in water
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When oxygen is present it quickly combines with
iron to form compounds that are not easily
dissolved in water.
Photosynthesis produces oxygen
CO2 H2O C6H12O6 O2
Dissolved iron oxygen solid iron
sinks
Approximately 1.8 bya
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Banded Iron Formations
photosynthesis
CO2 H2O C6H12O6 O2
4 Fe2 3O2 2Fe2O3
Dissolved in oceans
solid
20 times the oxygen of the atmosphere
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Oxygen in the Atmosphere/Oceans
emergence of complex cells and multi-cellular
organisms
All of these organisms lived in the oceans.
Why?
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500 million years
Higher Oxygen Levels
Ozone Layer
Terrestrial Life
The ozone layer screens out harmful UV radiation
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Carboniferous Period
About 350 million years ago
First land plants 480 mya.
Primitive bark-bearing trees
the age of swamps and coal"
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245 mya 65 mya
Age of Reptiles
Warm Wet Productive
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Subsequent Timeline
Mammals 65 million years ago
Primates 30 million years ago
Pre-humans 5 million years ago
Homo sapiens 200,000 years ago
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Liquid water 3.5 4.4 bya Earliest
organisms 3.5 bya Cyanobacteria 3.0 3.5
bya Stromolites 2.5 bya Iron Formations 2.0
bya Atmospheric O2 increase 1.5
bya Complex/multicells 1.0 bya Ozone Layer 400
mya Carboniferous 350 mya Reptiles 245
mya Mammals 65 mya