25.3 first single celled and O2 revolution

Question 1

first evidence of life

Answer 1

stromatolites

Question 2

what are stromatolites

Answer 2

layered rocks that form when prokaryotes bind thin films of sediment together

Question 3

what are cyanobacteria

Answer 3

oxygen releasing photosynthetic bacteria

Question 4

how did oxygen reach the atmosphere?

Answer 4

1- cyanobacteria makes it during photosynthesis (the water splitting step)
2- at first, it just dissolved until it could react with dissolved iron and water and become iron oxide
3- iron oxide is pressed into rock layers as bands of red
4- after all the iron had been reacted with, the oceans saturated with O2 and it started to gas out of it
5- 2.7 bya, rocks show that terrestrial iron rocks started to rust meaning O2 had reached the atmosphere

Question 5

what happened in the oxygen revolution

Answer 5

1- O2 increased a lot which is bad for prokaryotes b/c it can attack chemical bonds, inhibit enzymes, and damage cells
2- prokaryotes died and survivors grew adaptations like cellular respiration