The Tree of Life and The History of Life Cont.

Question 1

Radiometric dating

Answer 1

uses the decay of radioactive isotopes in fossils as a “clock” to date them

Question 2

What are the four hypothesized processes that lead to the origin of life?

Answer 2

1. The abiotic synthesis of small organic molcules (amino acids, bases).
2. Abiotic synthesis of these small organic molecules into macromolecules.
3. Packing of macromolecules into “protocells”.
4. The origin of self-replicating molecules.

Question 3

What is the order of key events in the history of life in the last 4.5 billion years?

Answer 3

Origin of the Solar System and Earth, Prokaryotes, Atmospheric oxygen, Single-celled eukaryotes, Multicellular eukaryotes, Animals, Colonization of land, and Humans

Question 4

Cambrian explosion

Answer 4

many present-day animal groups appear suddenly as fossils formed 535-525 million years ago in the Cambrian period; possible causes: increased oxygen, increased genetic complexity of organisms, climate change

Question 5

What were the first forms of life and first animals to colonize land?

Answer 5

First forms of life: fungi and plants

First animals: Arthropods followed by vertebrates

Question 6

Continental drift

Answer 6

movement of tectonic plants on the surface of the earth; reconfigures landmasses of earth throughout geological history and cause extinction of animals

Question 7

Extinction

Answer 7

occurs when habitats and environments change in a way that is unfavorable for the organisms living there; natural feature of life-no species lasts forever

Question 7

How many mass extinctions have there been?

Answer 7

5

Question 8

Adaptive radiations

Answer 8

periods of rapid formation of new species whose adaptions allow them to fill diff. ecological roles

Question 9

What were the ancestors of primates?

Answer 9

rodent-like ancestors that lived an arboreal lifestyle (similar to squirrels) around 65 MYA

Question 10

Hominins

Answer 10

clade that includes modern and extinct humans, arose 5.5 MYA; key diff. from other primates: smaller canine teeth, bipedalism, loss of grasping feet, larger brain, tool making/use

Question 11

Given that evolutionary processes can act by chance (genetic drift) or by natural selection. True or False: Evolution is a “linear”, goal-oriented, sequence of events.

Answer 11

False

Question 12

Fossils

Answer 12

impressions of prehistoric organism preserved in petrified form or as a mold or cast in rock

Question 13

Protocell

Answer 13

early, simple precursors to cellular organisms

Question 14

Stromatolites

Answer 14

a calcareous mound built up of layers of lime-secreting cyanobacteria and trapped sediment, found in Precambrian rocks as the earlies known fossils, and still being formed in lagoons in Australasia

Question 15

Endosymbiosis

Answer 15

symbiosis in which one of the symbiotic organism lives inside the other; reason why mitochondria and chloroplasts are in eukaryotes)