History of Life

Evo Bio Exam 2

How old is the earth? What is the center of the earth like now, and why?

• 4.6 billion years ago

• molten lava in the middle

• solid metal ball mostly iron and nickel

Why was there no water on earth when it first formed? What were the early oceans like?

• very hot b/c planet was getting hit with random rocks and fire

• cool enough for some of the water in the atmosphere to cool down and become liquid

• soup of chemicals like oxygen and nitrogen

What was the first life on earth most likely like? Why don’t we know for sure?

• collection of chemicals surrounded by a membrane

• some chemicals developed into amino acids and eventually RNA

  • protobionts

• dna, prokaryotes, dont know for sure bc they dont fossilize well

What was the first genetic material? Why do you think it was not DNA? Why did DNA take over as the primary genetic material?

• RNA

• Mutation then DNA then replication?

• RNA is simpler

• DNA is more stable but needs complex proteins

• DNA is more chemically stable and less prone to mutations

When did the first living cells arise?

• Prokaryotes: 3.9-3.5 billion years ago during Archaeon Eon

The first living cells where most like what organisms that are alive today?

• Extremophiles? Bacteria or archaea that live in harsh environments

What is an Eon? What are the three Eons? What are Eons broken up into?

• Phanerozoic, Proterozoic, Archaean

• Breaks up into eras, periods, and epochs

• Eon is the largest division of geological time

What was the oxygen revolution (also called “great oxygenation event” or “oxygen catastrophe”)? What organism lead to this event? Why was it such a big deal?

• Cyanobacteria produced oxygen; photosynthesis

• Alot of prokaryotes died bc they lived without oxygen

• Mass extinction

What is endosymbiosis? How was it involved in the evolution of eukaryotes?

• Eukaryotes: all plants and animals

• Endosymbiosis: one prokaryote parasitized another prokaryotes and began living together

  • Mitochondria and chloroplasts

• Result: single celled organisms with organelles

What happened during the Cambrian explosion? Why was it important for animal evolution?

• 535 million years ago

• Diversity of all animal life on Earth exploded

• Creatures used minerals and seawater to build skeletons and shells

• Claws, defensive plates

• Evolutionary arms race between predator and prey

• Organisms became complex

When did plants, animals, and fungi start colonizing land? Why did they do this, and why was it important?

• Ordovician Period

• 500 million years ago

• Prolly did this as a way to escape predation

• Arthropods, tetrapod's

What events resulted in what we call fossil fuels? What type of organisms are responsible for fossil fuels?

• Carboniferous Period

• 359-299 million years ago

• Forests were so dense and so widespread that they made all our fossil fuels

• Released a lot of oxygen that the atmosphere contained around 35% oxygen

• Started to cool the planet b/c there wasn’t enough carbon dioxide to maintain temps that the jungles needed to survive

• System crashed and all the carbon sunk into swamps and got locked into rocks

• Huge amounts of organic matter died and were buried under sediment before they could decay

What is a mass extinction event? Why is it hard to determine the cause(s) for mass extinction events?

• 252 million years ago

• Permian-Triassic Extinction Event

• 96% of all marine species and 70% of terrestrial vertebrates died

• Only known mass extinction of insects

• Rlly significant

• Hard to determine the reason bc all the evidence has been wiped out maybe by an asteroid

• Whole bunch of volcanoes erupted + methane released from sea floor + gas explosions + climate change + sea level change + ocean salinity changes

Why are extinction events often followed by the evolution of new groups of organisms?

• Not much competition for resources so they evolved to fill an available niche

• Leaves behind empty ecological niches

What is a niche?

• Combination of living and non-living resources used to survive

• Specific role an organisms plays in its environment

Did mammals exist at the same time as dinosaurs?

• Yes but they were small and lowk everywhere

What is coevolution and how is it relevant to understanding the history of life on earth?

• Angiosperms appeared and flying insects evolved with them so the plants were everywhere

• When two or more species reciprocally affect each other's evolution

Why did the dinosaur extinction lead to mammals becoming dominant on land?

Took over because they fill the available niche

What is the Anthropocene? How are humans currently effecting life on earth?

• Anthropocene: a proposed new geological approach defined by the significant impact of humans on Earth

• Currently causing more extinction "Sixth mass extinction" through habitat destruction, climate change, and pollution