Description:In one corner of the Solar System, life abounds. From the frozen lakes in
Antarctica to the boiling ocean-floor springs of the Pacific, planet Earth is
teeming with life. But these diverse locations all share some common
ground. They all contain the essential ingredients needed to create life.
http://www.bbc.co.uk/science/space/life/beginnings/index.shtml
Ingredients:1) Liquid water
2) Chemical building blocks like carbon, oxygen, hydrogen and nitrogen
3) An energy source
Directions:1) Liquid water
Biologists studying primitive organisms all agree on one thing. Liquid water
is absolutely essential for life to evolve and survive. The search for life on
other worlds is a search for places where water can exist in liquid form. But
why is water so precious?
* For life to evolve, simple chemicals must combine to form more
complex ones. Many chemicals dissolve in water allowing them to mix
together and react
* Liquid water is the right temperature for chemical reactions to happen
* Many chemicals have parts which are attracted to water and parts
which are repelled by it. These forces also help reactions happen
2) Chemical building blocks
Carbon
Carbon is important because of its ability to form long chain-like molecules.
Carbon chains form the backbone of organic molecules.
Hydrogen and oxygen
Hydrogen and oxygen can both bond with carbon in lots of different ways.
These two elements make up water molecules. So if water is present,
hydrogen and oxygen will already be there.
Nitrogen
Like hydrogen and oxygen, nitrogen can also combine with carbon in lots
of different ways. Large molecules made from carbon, hydrogen, oxygen
and nitrogen also tend to be very stable.
Other elements
Sulphur, phosphorus, sodium, potassium, magnesium, calcium,
manganese, iron, cobalt, copper and zinc are all needed for life as we
know it on Earth.
3) An energy source
All chemical reactions need an energy source to drive them.
On Earth, most primitive animals and plants get their energy by absorbing
ultra-violet light from the Sun. This is called 'photosynthesis'.
Humans and other animals get their energy by eating plants, or other
animals. So all animals ultimately rely on energy from the Sun to live.
Stage 2: combining these ingredients to make life
Life finds a way
Until recently, it was thought that life couldn't exist anywhere that was
shaded from the Sun's light. However, scientists have recently discovered
organisms living deep beneath the ocean. These organisms absorb energy
directly from chemicals in the water around them.
Three moons in our Solar System (Europa, Callisto and Titan) may all
harbor deep underground oceans. Could they also harbour extraterrestrial
life?
