life on earth topic 2 evidence for the origin of life n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Life on Earth Topic 2 : Evidence for the origin of life PowerPoint Presentation
Download Presentation
Life on Earth Topic 2 : Evidence for the origin of life

Loading in 2 Seconds...

play fullscreen
1 / 24

Life on Earth Topic 2 : Evidence for the origin of life - PowerPoint PPT Presentation


  • 163 Views
  • Uploaded on

Life on Earth Topic 2 : Evidence for the origin of life. Part of the Evolution of Australian Biota Module Biology in Focus, Preliminary Course Glenda Childrawi and Stephanie Hollis. DOT POINT.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Life on Earth Topic 2 : Evidence for the origin of life' - selena


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
life on earth topic 2 evidence for the origin of life

Life on EarthTopic 2: Evidence for the origin of life

Part of the Evolution of Australian Biota Module

Biology in Focus, Preliminary Course

Glenda Childrawi and Stephanie Hollis

dot point
DOT POINT
  • Identify the relationship between the conditions on early Earth and the origin of organic molecules
introduction
Introduction

The approximate age of the Earth, based on geologic, magnetic, radiographic and palaeontological studies, is 4.5 billion years. During the Hadean eon (4.5-3.8bya) was the formation of the Earth.

activistpost.com

introduction1
Introduction

4 billion years ago the Earth was a very different place than it is today. The sun was only 70% of its present strength, Earth was spinning much faster and day was only 18 hours long and there was no free oxygen in the atmosphere How was anything to survive on such an inhospitable planet?

introduction2
Introduction

We know Earth transformed from a gaseous cloud into a solid body. The heavier molten elements, like iron, sank down to become the core. The lighter elements, like silica, rose to the surface and formed the crust.

But how did we get our atmosphere?

flickrhivemind.net

introduction3
Introduction

Intense heat and pressure, due to the extreme forces of gravity, below the surface cause the material to remain in a molten state. We know that hot material rises (think of boiling water), and so does this molten material in the centre of the Earth.

physics.arizona.edu

introduction4
Introduction

Once this molten material reaches the surface we get volcanoes! These amazing geologic features not only bring to the surface fresh minerals and rock, they also bring gases trapped within the material.

It was these gases that formed the original atmosphere of our planet.

en.wikipedia.org

early earth s atmosphere
Early Earth’s Atmosphere

The process of volcanoes releasing gases into our atmosphere is called outgassing and included:

  • Water (H₂O)
  • Methane (CH₄)
  • Ammonia (NH₃)
  • Hydrogen (H₂)
  • Nitrogen (N₂)
  • Carbon Dioxide (CO₂)

geology.com

early earth s atmosphere1
Early Earth’s Atmosphere

The atmosphere was anoxic meaning it had no free Oxygen (O₂) as all the oxygen was bound within other compounds such as water and carbon dioxide. This meant that there was no ozone (O₃) layer exposing the Earth’s surface to ultraviolet radiation.

howitworksdaily.com

early earth s atmosphere2
Early Earth’s Atmosphere

Most of the hydrogen gas escaped into space, as happens today, whereas the other gases accumulated and remained in the atmosphere.

telegraph.co.uk

forming the first o rganic m olecules
Forming the First Organic Molecules

Early Earth provided an environment in which the production of organic carbon-containing molecules could have happened fairly easy. The energy for driving these reactions could have come from a number of sources which include:

  • Sun (ultraviolet radiation)
  • Lightning
  • Hot springs
  • Volcanoes
  • Radioactivity in the crust
  • Meteorite impacts

environment.nationalgeographic.com

forming the first o rganic m olecules1
Forming the First Organic Molecules

In Early stages of Earth’s formation, organic molecules would have most likely formed in the lower atmosphere or at the Earth’s surface. We’ll look at the stages of change thought to occur in the early Earth.

spaceprime.com

forming the first o rganic m olecules2
Forming the First Organic Molecules

Dense clouds formed in the steamy atmosphere. These clouds were formed of water from meteorites and hydrated minerals. These clouds then formed a reflective shield from the suns penetrating heat

scientificamerican.com

forming the first o rganic m olecules3
Forming the First Organic Molecules

About 500 million years later, meteorite impacts declined due to this protective layer and the friction caused on entry. The Earth cooled and the temperature fell below 1000C, forming a stable rocky crust.

amp.wpcamr.org

forming the first o rganic m olecules4
Forming the First Organic Molecules

The release of gases from volcanoes increased air pressure in the atmosphere. When the temperatures cooled, this assisted in causing the immense clouds of water vapour to condense into liquid and fall as rain.

zdnet.com

forming the first o rganic m olecules5
Forming the First Organic Molecules

Rain would have washed organic molecules into lakes and ponds rich in dissolved minerals. This created an environment for reactions to occur which produced new organic molecules and compounds.

forming the first o rganic m olecules6
Forming the First Organic Molecules

Carbon Dioxide dissolves readily in water to form carbonic acid (H₂CO₃). It would have been flushed out of the atmosphere by rain and into the oceans where it reacted with calcium to form calcium carbonate (CaCO₃)

carbon-based-ghg.blogspot.com

forming the first o rganic m olecules7
Forming the First Organic Molecules

At first, the rain evaporated as it fell on the hot rock surface but the evaporation gradually cooled the crust until water could accumulate in the lower regions of the Earth’s surface forming oceans. The first rives were created where the water, dissolving and transporting minerals along the way, eventually ran back into the oceans.

ibn-tv.com

forming the first o rganic m olecules8
Forming the First Organic Molecules

The dissipation of heat into space cooled the Earth, causing crust fragments to become numerous enough to form a first thin, solid cover.

norblog.typepad.com

forming the first o rganic m olecules9
Forming the First Organic Molecules

Over the next 3.5 billion years, the amount of carbon dioxide in the atmosphere was reduced as it became incorporated in rocks (limestone). The main gas remaining in the Earth’s atmosphere was nitrogen.

onorbit.com

forming the first o rganic m olecules10
Forming the First Organic Molecules

The composition of Earth’s atmosphere today is somewhat different to that proposed on early Earth. Today it consists of 78.1% nitrogen, 20.9% oxygen and 1% trace elements such as carbon dioxide, water vapour, methane, hydrogen and ozone.

redorbit.com

forming the first o rganic m olecules11
Forming the First Organic Molecules

There is much known about the composition and conditions of Early Earth, however there are a lot of unanswered questions. Scientists continue to search for more evidence reflecting the conditions of early Earth that may have existed when life began.

futurity.org

forming the first o rganic m olecules12
Forming the First Organic Molecules

If these conditions are known, then we may perhaps discover more about the building blocks from which life began….

scribd.com

h omework
Homework

None again!