Increase In Oxygen Levels Flashcards
How did the first organisms gain energy?
Through chemosynthesis
What is chemosynthesis?
The formation of organic compounds without the need for sunlight
What was the earth’s atmosphere like when it first formed?
Its oxygen levels were very low
What are Cyanobacteria?
Early life forms that used heat energy from the sun to form organic compounds
They were anaerobic
What does anaerobic mean?
Able to form organic compounds without the need for oxygen
What does aerobic mean?
Organisms that produce their own food using oxygen
What happened to cause oxygen levels in the atmosphere to rise?
Different types of bacteria arose
What did these different types of bacteria do?
They produced food through photosynthesis
Why was it advantageous for these bacteria to perform photosynthesis?
There was a lot of carbon dioxide in the atmosphere
Photosynthesis made use of this
When did these oxygen-producing organisms appear?
Around 3.5-2.5 billion years ago
What did the rise in atmospheric oxygen cause?
The appearance of aerobic organisms
What did the arrival of aerobic organisms cause?
An increase in the variety of life forms on earth
