17.2-Earth's Early History

how did Earth become a spherical planet?

pieces of rocks together, collisions melt fragments into spheres

what formed the planet’s core?

densest rock debris

what caused the core to become hot?

radiaoctive decay

what was earth’s early atmosphere mostly comprised of?

hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water

when did earth’s surface cool enough to allow for a solid lithosphere?

about 4 billino years ago?

when was earth’s surface cool enough for water to remain liquid?

about 3.8 billion years ago

the earliest oceans contained…

iron

how might’ve organic molecules formed as proven by miller and urey’s experiments?

simpler compounds were fused together by lightning storms

what are proteinoid microspheres?

cell-like structure with permeable membranes

apart from permeable membrane, microspheres can also…

store and release energy

first life was based off what type of genetic material?

RNA

what are microfossils?

microscopic fossils

when did the first photosynthetic bacteria become common?

about 2.2 billion years ago

how did oxygen affect the oceans?

it caused iron to rust and cleared the oceans up

what does the endosymbiotic theory state?

that the mitochondria and chloroplast were once bacteria that became symbiotic to another organism

what are the three types of evidence for endosymbiotic theory?

similarities in genetics, similarities in anatomy/structure, and similarities in reproduction