Study Notes Life On Earth
8.4 Life On Earth
Students Learn About
1. Analysis of the oldest sedimentary rocks provides evidence for the origin of life
• Identify the relationship between the conditions on early
Earth and the origin of organic molecules Notes
THE AGE OF THE EARTH
- based on geological, magnetic, radiographic and paleontological studies: aged 4.5 billion years - Hadean eon: formation of earth from gaseous cloud to solid body. Heavy molten iron sank down and became the core, lighter rock came to surface = crust
- As a result of the high temperatures at the centre of the Earth and due to volcanic activity, there as an emission of gases, or out-gassing, of volatile molecules, such as water (H2O), methane (CH4), ammonia (NH3), hydrogen (H2), nitrogen (N2), and carbon dioxide (CO2).
- Environment was anoxic (no free oxygen) = no ozone layer, earth exposed to high solar radiation (UV)
- Early Earth = atmosphere of water vapour, hydrogen, methane and ammonia making production of organic carbon-containing easier.
- energy for driving these reactions could have come from a number of sources, in particular the sun. Ultraviolet light would easily have reached the Earth’s surface because no ozone layer existed. Other sources include: lightning, hot springs and volcanoes, radioactivity in the crust, and impact from meteorites.
- Organic molecules most likely formed in lower atmosphere or earth’s surface
STAGES OF EARTH’S DEVELOPMENT
- Dense clouds of water formed in the atmosphere, which reflects the sun’s heat
- Earth cooled sufficiently to allow for the formation of a rocky crust.
- Volcanic gas eruptions increased the air pressure, forming clouds which allowed for the water vapour to condense and fall as rain.
- Water would have absorbed a lot of the carbon dioxide present in the atmosphere due to solubility. - The cooling process by the rain continued until the Earth was cool enough to allow for the formation of rivers and oceans.
- Heat was dissipated into space, causing a more
Students Learn About
1. Analysis of the oldest sedimentary rocks provides evidence for the origin of life
• Identify the relationship between the conditions on early
Earth and the origin of organic molecules Notes
THE AGE OF THE EARTH
- based on geological, magnetic, radiographic and paleontological studies: aged 4.5 billion years - Hadean eon: formation of earth from gaseous cloud to solid body. Heavy molten iron sank down and became the core, lighter rock came to surface = crust
- As a result of the high temperatures at the centre of the Earth and due to volcanic activity, there as an emission of gases, or out-gassing, of volatile molecules, such as water (H2O), methane (CH4), ammonia (NH3), hydrogen (H2), nitrogen (N2), and carbon dioxide (CO2).
- Environment was anoxic (no free oxygen) = no ozone layer, earth exposed to high solar radiation (UV)
- Early Earth = atmosphere of water vapour, hydrogen, methane and ammonia making production of organic carbon-containing easier.
- energy for driving these reactions could have come from a number of sources, in particular the sun. Ultraviolet light would easily have reached the Earth’s surface because no ozone layer existed. Other sources include: lightning, hot springs and volcanoes, radioactivity in the crust, and impact from meteorites.
- Organic molecules most likely formed in lower atmosphere or earth’s surface
STAGES OF EARTH’S DEVELOPMENT
- Dense clouds of water formed in the atmosphere, which reflects the sun’s heat
- Earth cooled sufficiently to allow for the formation of a rocky crust.
- Volcanic gas eruptions increased the air pressure, forming clouds which allowed for the water vapour to condense and fall as rain.
- Water would have absorbed a lot of the carbon dioxide present in the atmosphere due to solubility. - The cooling process by the rain continued until the Earth was cool enough to allow for the formation of rivers and oceans.
- Heat was dissipated into space, causing a more