Life on Earth Study Notes
Life on Earth
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.
- Conditions of early Earth: Massive oceans existed
Only small landmasses above the surface of the water
No ozone layer
Large amounts of radiation reached the Earth
No free oxygen in the air Large amounts of volcanic activity; heat, ash, dust and gases into atmosphere
Violent electric storms common
Atmosphere contained some water vapour (H2O), hydrogen (H2), hydrogen cyanide (HCN), a lot of carbon dioxide (CO2), nitrogen (N2), possibly ammonia (NH3) and methane (CH4).
- The chemicals of life are contained within the following basic organic compounds: water, carbohydrates, lipids, proteins, and nucleic acids.
- These compounds are made up of hydrogen (H), oxygen (O), carbon (C), nitrogen
(N) and some other common elements.
- The elements needed to create the basic organic compounds were already present in the atmosphere; i.e., H, O, C and N were already there.
- The lack of an ozone layer, the frequent violent electric storms, and the volcanic activity of early Earth could have provided the energy for molecules to be formed.
Discuss the implications of the existence of organic molecules in the cosmos for the origin of life on Earth.
For life to have originated, the following events need to have happened:
The required chemicals need to have been formed These chemicals need to have come together in a self-replicating body This body would need to have a form of protection for its contents
It had to be able to use an energy source to replicate itself
- The first step needed for life to be formed would be that the organic molecules needed for life would have to be present
- These organic molecules could have been formed here on Earth, or been sent to Earth from outer space (the cosmos)
Describe two scientific theories
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.
- Conditions of early Earth: Massive oceans existed
Only small landmasses above the surface of the water
No ozone layer
Large amounts of radiation reached the Earth
No free oxygen in the air Large amounts of volcanic activity; heat, ash, dust and gases into atmosphere
Violent electric storms common
Atmosphere contained some water vapour (H2O), hydrogen (H2), hydrogen cyanide (HCN), a lot of carbon dioxide (CO2), nitrogen (N2), possibly ammonia (NH3) and methane (CH4).
- The chemicals of life are contained within the following basic organic compounds: water, carbohydrates, lipids, proteins, and nucleic acids.
- These compounds are made up of hydrogen (H), oxygen (O), carbon (C), nitrogen
(N) and some other common elements.
- The elements needed to create the basic organic compounds were already present in the atmosphere; i.e., H, O, C and N were already there.
- The lack of an ozone layer, the frequent violent electric storms, and the volcanic activity of early Earth could have provided the energy for molecules to be formed.
Discuss the implications of the existence of organic molecules in the cosmos for the origin of life on Earth.
For life to have originated, the following events need to have happened:
The required chemicals need to have been formed These chemicals need to have come together in a self-replicating body This body would need to have a form of protection for its contents
It had to be able to use an energy source to replicate itself
- The first step needed for life to be formed would be that the organic molecules needed for life would have to be present
- These organic molecules could have been formed here on Earth, or been sent to Earth from outer space (the cosmos)
Describe two scientific theories