History of Life (Chp.29)

Question 1

the earth is

Answer 1

4.6 bilion years old

Question 2

earliest life forms are from about

Answer 2

4 billion years ago

Question 3

geologic time scale

Answer 3

described when events occurred throughout history of earth

Question 4

preccambrian eon takes up

Answer 4

over 80% of earths history and is much larger than Phanerozoic

Question 5

precambrian eon (4 billion years)

Answer 5

-first cell evolved 4 billion years ago
-most likely from chemical evolution
-cells multiplied and diversified in oceans and eating molecules

Question 6

the ocean was filled with prokaryotes

Answer 6

-2.7 billion years ago

Question 7

photosynthetic cyanobacteria

Answer 7

-made their own food and releasted oxygen
-prokaryotes
as they multiplied oxygen built up in the atmosphere, this oxygen was posionous to many prokaryotes and caused a mass extinction

Question 8

stromatolites

Answer 8

fossil formations of cyanobacteria which dates back to the precambrain time period

Question 9

first eukaryotic cells occurred

Answer 9

2.5 billion years ago
this increased the complexity of life

Question 10

1.5 billion years ago

Answer 10

mulicellularity evolved and organisms with much bigger sizes emerged

Question 11

ex. of first multicellular organisms

Answer 11

red and brown algae in oceans

Question 12

1.2 billion years ago

Answer 12

sexual reproduction first occurred

Question 13

sexual reproduction

Answer 13

increased the rate of evolution

Question 14

600 million years ago

Answer 14

first animals evolved as sponges at bottom of oceanp

Question 15

paleozoic era (540-245 mya)

Answer 15

Cambrian explosion
first fish evolved
plants colonized land and diversified
amphibians arose
reptiles evolved

Question 16

cambrian explosion

Answer 16

explosion of new kinds of organisms

Question 17

trilobites

Answer 17

became abundant
small ocean invertebrates

Question 18

oxygen atmospher made by

Answer 18

cyanobacteria and algae formed a thin ozone layer

Question 19

ozone layer

Answer 19

protects land from ultraviolet rays

Question 20

permian explosion

Answer 20

heated the whole earth