Life On Earth Flashcards
Formation of the earth
An atmosphere of primordial gases covers the cooling, molten rock. These gases are eventually stripped away by the solar wind (high energy particles ejected from the Sun).
The hardening crust exhales gases such as CO2, N2 through volcanoes. Icy comets also bombard the surface.
Volcanic activity adds carbon dioxide, carbon monoxide, nitrogen, water vapour, ammonia, methane, etc to the atmosphere.
Addition of oxygen by early form of life.
An atmosphere of primordial gases covers the cooling, molten rock. These gases are eventually stripped away by the solar wind (high energy particles ejected from the Sun).
How?
The Earth’s protective magnetic field was not stable, allowing for the high energy, charged particles, to strip the gases from the atmosphere.
The hardening crust exhales gases such as CO2, N2 through volcanoes. Icy comets also bombard the surface.
How?
The very hot molten rock is a very reactive environment, the by-product of which is the exhaled gases.
Volcanic activity adds carbon dioxide, carbon monoxide, nitrogen, water vapour, ammonia, methane, etc to the atmosphere.
What about Oxygen?
Oxygen was part of the primitive atmosphere, but did not dominate because it is a reactive element, and was consumed by chemical reactions as fast as it was added.
Addition of oxygen by early form of life.
How?
A strange form of early life called Archaea took hold in the extremely hot, hydrogen sulfide rich seas near active undersea volcanoes.
They lived off of the hydrogen sulfide and exhaled sulfur, carbohydrates, and water.
Addition of oxygen by early form of life.
How?
Microbacteria called cyanobacteria formed large scale structures called stromatolites. These bacteria consumed are capable of photosynthesis – they make their own food from sunlight and CO2.
This process, acting over millions of years, enriched our atmosphere with oxygen and paved the way for the biosphere of today.
Addition of oxygen by early forms of life.
Archaea
3.8 Billion year old fossils
They still exist today near active undersea volcanoes.
Some extremophile species love the heat! They like to live in boiling water, like the geysers of Yellowstone Park, and inside volcanoes. They like the heat so much that it has earned the nickname “thermophile”, which means “loving heat”, and it would probably freeze to death at ordinary room temperature.
Addition of oxygen by early forms of life.
Cyanobacteria
3.8 Billion year old fossils
These organisms made their own food through photosynthesis.
These bacteria are present in the chloroplasts of all green plants and are the reason why plants are able to do photosynthesis!
