Transcript GCSE Results - Noadswood School

Earth
Noadswood Science, 2014
Tuesday, July 21, 2015
Earth
 To know the structure of the Earth
Structure
 What is the structure of the Earth like?
Structure
 The Earth is almost a sphere, consisting of four main layers…
 Crust – relatively thin and rocky
 Mantle – has the properties of a solid, but can flow very
slowly
 Outer core – made from liquid nickel and iron
 Inner core – made from solid nickel and iron
Earth Structure
 The Earth and its layers…
A thin crust – 10-100km thick
A mantle – has the properties of a solid
but it can also flow
A core – made of molten nickel and iron.
Outer part is liquid and inner part is solid
Life on Earth
 How is it that life on Earth began?
Early Earth
 The 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 Earth
 Over 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
Life
 Sometime between about 4.1 billion years ago when the Earth’s
crust began to solidify, and 3.5 billion years ago life began
 Most biologists subscribe to the hypothesis that life developed
on Earth from non-living materials that became ordered into
molecular aggregates – these eventually became capable to selfreplication and metabolism
 In the ancient environment the origin of life was evidently
possible (conditions were very different, with more intense
lightning; volcanic activity; meteorite bombardment; and UV
radiation)
Miller-Urey Experiment
 We know the type of molecules that make up living organisms –
to make these amino acids are needed which then form proteins
 Most amino acids contain carbon, hydrogen, nitrogen and
oxygen
 Two scientists, Miller and Urey, took
this basic building blocks and tried to
recreate the formation of amino
acids (they successfully produced 22
different amino acids)
Miller-Urey Experiment
 The experiment provided
evidence that it was possible to
make the molecules of early life
from gases that may have been
in our early atmosphere…