Life On EarthL.O: To be able to explain and evaluate the theories of how life evolved on earth

Friday, April 21, 2023

LifeHow is it that life on Earth began?

Life on earth began with the help of aliens. A group of scientist aliens were travelling in the movable laboratory. The aliens were trying to bottle all of the stars to stop all of the light in the universe. The bottles were made of blue glass so when the aliens captured the stars a green glow was given off. The aliens were scared of the colour green so quickly threw the bottles overboard. The bottles landed on earth where it was revealed that the green colour was actually the first life form!

Theories about lifeThere are various theories about the origins of life on Earth. However, there is little evidence to support these theories and, at the moment, there is no definitive answer.

This is because scientists are unsure about the conditions available on the early Earth. There is also little information about early life forms.

Get into a group of 3You will be given a theory to try an explain on poster paper using pictures and no more than 10 words.

The theories are:

Creationism

Panspermia

Cozmozoan

Steady state

Miller-Urey

You will be given a sheet of information and 10 minutes to create your poster

Now pick a speaker for your group.The rest of the group are information collectors.Decide two topics to collect each from:CreationismPanspermiaCozmozoanSteady state Miller-Urey

Teach the rest of the group the theories then come to an agreement about which is the most likely and why.

Life TheoriesSome religions discuss the theory of creation. They believe

the world and all the living things on Earth were created by a supernatural or divine being at a particular time in the past

The story is told in the book of Genesis in the Old Testament of the Bible. This theory of creation is believed by Jewish and Christian people who take the Bible literally

Other religions have their own beliefs about creation – the Muslim creation story is similar in many ways to the Old Testament with Nabi Adam and Stina Houwa replacing Adam and Eve in the Garden of Eden

Life Theories In traditional African cultures, there are various beliefs

about the origin of life – some peoples believe that humans originated from a cave in the Earth. Other peoples believe that humans originated from elements in nature, such as reeds in water

The cosmozoan theory states that life originated from outer space – the ancient Greeks, Chinese and Egyptians believed that life arose many times out of non-living matter (known as the spontaneous generation theory)

Another theory, the steady state theory, is that the Earth has no origin and that it has always been able to support life which has remained unchanged throughout time (this theory has largely been disproved)

What were conditions like on earth before life?

Early EarthThe early Earth was very different to the one we know today –

it was hotter and the atmosphere consisted mostly of carbon dioxide, with other gases such as ammonia and methane

There are two possible origins for these molecules: -They were produced by the conditions on Earth at the

time, or They came from somewhere else, such as another planet in

our solar system or further out in space

Early EarthOver many millions of years these molecules joined with

other molecules, becoming gradually more complex and dependent on each other

The process of evolution by natural selection eventually led to all of the different living things that we see on Earth today

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Life formation

Miller Urey ExperimentThey used a sealed and sterile glass flask with the gases ammonia, methane, hydrogen and water vapour inside – they then passed electrical sparks (simulating lightning) through the gases for a week…

Miller Urey ExperimentWhen they analysed the mixture they found many carbon

compounds had formed inside the flask (from the methane gas)

Some of these compounds were found to be amino acids (used to make proteins)

This suggests the first life forms may have been bacteria able to utilise the methane and ammonia to live

Could biological material have appeared from somewhere else?A meteorite?Deep under oceans?Near volcanic vents?

However they appeared it is most likely that a primordial soup formed.

(6 mark) Discuss the theories and evidence of how life appeared on earth