chapter 15- bio112

the divisions from largest to smallest

Eon → Era → Period → Epoch

how old is the earth

4.6 billion yrs ago

Precambrian supereon (pre-game) is made up of what eons?

Hadean eon

Archean eon

Proterozoic eon

Haden Eon

earth forms 3.6 bya, its hot, molten, hellish place with no life

Archean Eon

Earth cools, ocean form and Life begin around 3.6 bya. Simple, single-celled bacteria.

Proterozoic Eon

oxygen builds up in the atmosphere. more complex singled celled life. first multicell life appears, like Ediacaran’s (soft-bodied, weird-looking organisms)

the eras of the Phanerozoic Eon (the main event/visible life)

Past Mammals Chat

Paleozoic

Mesozoic

Cenozoic

Paleozoic nickname is

ancient life

Mesozoic nickname

age of reptiles

Cenozoic nickname

age of mammals

Paleozoic key event & first appearance

Explosion of life?! first fish, first plants on land, first insects, first amphibians, first reptiles

Mesozoic key event & first appearance

Dinosaurs rule! First mammals (tiny), first birds, first flowering plants

Cenozoic key event & first appearance

Mammals take over! Grass spreads, and mammals diversify into all shapes and sizes (whales, bats, elephants, humans)

what ended each era in the phanerozoic eon

P- mass extinction

M- asteroid impact

C- we’re still in it

when did life arise?

first evidence of life is from 3.6 bya

Miller-Urey Experiment

recreated the gases they thought were in Earth’s early atmosphere and zapped it with electricity, resulting in organic molecules ~ which shows that the building blocks of life could have formed naturally on early Earth

RNA world hypothesis

the idea that before DNA, the world was dominated by RNA

what two crucial things can RNA do?

1. store genetic info

2. act as an enzyme to speed up chemical reactions

This means it could have self-replicated, kicking off evolution by natural selection

how did early life change earth?

Early photosynthetic bacteria started pumping out oxygen. This was a disaster for most early life (it was poisonous to them!), but it eventually led to an oxygen-rich atmosphere, allowing for more complex, energy-hungry life to evolve.

Endosymbiosis Theory

how eukaryotic cells (cells with nuclei, like ours) got their mitochondria and chloroplasts.

The story of endosymbiosis theory

A large, simple cell swallowed a small, oxygen-breathing bacterium. Instead of digesting it, they formed a partnership! The bacterium got protection, and the big cell got extra energy. This happened again with a photosynthetic bacterium, which became the chloroplast in plants.

hominin

The group of species that includes humans and all our extinct ancestors after our evolutionary line split from the chimpanzee line. (We are the human branch of the great ape family tree).

how does diet show up in fossils

Look at teeth and skulls. Big, flat molars and heavy jaw muscles = tough plant diet (like nuts). Sharper canines = more meat.

how does locomotion show up in fossils

The biggest clue for human ancestors is bipedalism (walking on two legs). Key evidence includes: The position of the foramen magnum (the hole where the spine connects to the skull). In upright walkers, it's centered underneath the skull.

The shape of the pelvis and knee joints.

The foot structure (no opposable big toe).

true or false are we identical to chimps

true we are

n which period did fish, including those with bony skeletons, become dominant, earning it the nickname "Age of Fishes"?

Devonian