The Start of Life On Earth Flashcards
What was primitive Earth like?
Volcanoes, rocky, warm – but held water.
Oparin’s Hypothesis
Hypothesis on how life on Earth appeared: through reactions that made simple compounds gradually more complex. Lightning (electricity) gave electrons to the compounds which made them bigger and more complex.
Simple compounds (Hydrogen, water, Ammonia, Methane, gas) -> More Complex Compounds -> Amino Acids -> Purins (building block between amino acids and RNA) -> RNA (can grow on its own) -> DNA (code for proteins) -> Proteins (building block for organisms) -> Life.
How did we get oxygen on Earth?
The first cells produced chloroplasts which contained chlorophyll, which allowed them to photosynthesize. The cells released O2, but also O3 – Ozone. An Ozone layer was formed around the earth which kept the oxygen from flying out and away.
When did the first multicellular organisms appear?
600 million years ago.
What were the first multicellular organisms?
Invertebrates (sponges, snails, jellyfish).
These did not really require any bones because there was barely any predation happening, so there was no need for extra protection.
What happened as more animals evolved? (From the first multicellular organisms.)
Food chain developed. To escape the danger, animals adapted to be able to live on land and the first amphibians appeared.
What happened as more reptiles populated the earth?
More animals meant more predation, so other animals had to evolve to be able to survive. This resulted in bigger reptiles – dinosaurs.
What were the consequences of the Meteorite?
The meteorite caused dinosaurs to go extinct. It created a great layer of dust on the ozone layer, which prevented the sun from properly reaching the earth, which resulted in plants dying and the animals had nothing to eat.
The small reptiles that survived evolved wings that allowed them to fly above the inhospitable ground. These were the first birds, basically.
Fewer large animals meant less predation, and this allowed smaller mammals to evolve.
A mutation in the hip bone of a monkey species was inherited, and this is how the first humanoid evolved. (Monkey -> Humanoid (monkey-like; walks on two legs) -> Human.)
