Biology Notes: Life on Earth
LIFE ON EARTH REVISION
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.
- Formation of the organic molecule was the first event in the evolution of life. - The molecules provided a building block for cell formation and the food for the earliest life. - Present day life’s atmosphere contains: - Oxygen - Water - Carbon dioxide - Protection from harmful rays from space such as ultraviolet light. - Early earth had an atmosphere containing little free: - Nitrogen - Oxygen - Carbon dioxide - Instead it had - Methane - Ammonia - Water vapour - hydrogen - Those conditions mean that concentrations of organic molecules could have built up on early earth. - First major stage in evolution was formation of organic molecules - Molecules could have formed here in the condition of early earth or they could have come from sources beyond the earth (the cosmos)
- Discuss the implications of the existence of organic molecules in the cosmos for the origin of life on earth.
- Meteorites and comets have been studied to try to add evidence to ideas about the first organic molecules may have risen. - 74 amino acids found in meteorites - The existence of organic molecules means that the same processes could have occurred on primitive earth. - For example an asteroid or anywhere simple compound like methane, ammonia, hydrogen and water and a reducing atmosphere exist. - General agreement that only under very specific conditions could the original molecules exist and therefore the possibility that they could be formed in to complex molecules and eventually primitive cells.
- Describe two scientific theories of the chemicals of life and discuss their significance in understanding the origin of life.
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.
- Formation of the organic molecule was the first event in the evolution of life. - The molecules provided a building block for cell formation and the food for the earliest life. - Present day life’s atmosphere contains: - Oxygen - Water - Carbon dioxide - Protection from harmful rays from space such as ultraviolet light. - Early earth had an atmosphere containing little free: - Nitrogen - Oxygen - Carbon dioxide - Instead it had - Methane - Ammonia - Water vapour - hydrogen - Those conditions mean that concentrations of organic molecules could have built up on early earth. - First major stage in evolution was formation of organic molecules - Molecules could have formed here in the condition of early earth or they could have come from sources beyond the earth (the cosmos)
- Discuss the implications of the existence of organic molecules in the cosmos for the origin of life on earth.
- Meteorites and comets have been studied to try to add evidence to ideas about the first organic molecules may have risen. - 74 amino acids found in meteorites - The existence of organic molecules means that the same processes could have occurred on primitive earth. - For example an asteroid or anywhere simple compound like methane, ammonia, hydrogen and water and a reducing atmosphere exist. - General agreement that only under very specific conditions could the original molecules exist and therefore the possibility that they could be formed in to complex molecules and eventually primitive cells.
- Describe two scientific theories of the chemicals of life and discuss their significance in understanding the origin of life.