chapter 17 - the history of life on earth

Question 1

define strata

Answer 1

layers of rocks that record the history of earth

Question 2

define fossils

Answer 2

the preserved remains of ancient organisms

Question 3

what do fossils tell us?

Answer 3

the morphology (body form) of organisms and where they used to live

Question 4

what is radiometric dating used for?

Answer 4

determining the actual age of rocks (using radioisotopes)

Question 5

define a half-life

Answer 5

the time it takes for half of a radioisotope to decay & change to another element

Question 6

how is carbon dating used?

Answer 6

the ratio of unstable/stable isotopes is compared to the initial conditions of what is being observed

Question 7

how is the time of death of fossils estimated?

Answer 7

by observing the radioactivity of the extracted carbon

Question 8

can radioisotope dating be used for sedimentary rocks?

Answer 8

no

Question 9

dating rocks that are >50,000 years old require isotope dating of what kind of rocks?

Answer 9

igneous rocks (rocks made from cooled lava)

Question 10

absolute dates of organisms can be determined by:

Answer 10

tree rings, radiometric dating, and paleomagnetic dating

Question 11

define continental drift

Answer 11

the movement of earth’s tectonic plates

Question 12

what happens when plates are pushed together/shift sideways?

Answer 12

forms mountain ranges & valleys

Question 13

what happens when plates are pushed apart?

Answer 13

forms ocean basins

Question 14

the position, size, and connection among continents influence:

Answer 14

ocean circulation patters, sea level, and climate

Question 15

what happens when sea levels drop?

Answer 15

mass extinction of marine life

Question 16

historical biogeography interprets the distribution of organisms by:

Answer 16

observing the historical distribution of land/marine environments and phylogenetic relationships

Question 17

current distributions of organisms are a product of:

Answer 17

vicariance, dispersal, speciation, and extinction

Question 18

biodiversity of oceanic islands originates from:

Answer 18

long-distance dispersal of colonizing species

Question 19

when did earth’s oxygen levels incresase?

Answer 19

when bacteria evolved to use H2O for H+ ions for photosynthesis and produced O2 as a waste product

Question 20

the increase of O2 levels resulted in:

Answer 20

larger/more complex cells, eukaryotes to evolve, and multicellular organisms to evolve