Chapter 17 | History of Life

Question 1

layers of rock

Answer 1

strata

Question 2

where are the oldest layers of rock found?

Answer 2

at the bottom towards the core of the earth

Question 3

where are the youngest layers of rock found?

Answer 3

at the top towards the surface of the earth

Question 4

without doing calculations or carbon dating, how can you qualitatively determine the relative ages of rock?

Answer 4

compare their height layers to one another if possible

Question 5

preserved remains of ancient organisms

Answer 5

fossils

Question 6

what can fossils tell us about organisms?

Answer 6

(1) body form or structure
(2) where they lived
(3) how they lived

Question 7

what can fossils tell us about rocks?

Answer 7

(1) age of the rock
(2) stratum of the rock

Question 8

fossils of modern organism are more likely to be found

Answer 8

in more recent strata/rock layers

Question 9

fossils of historic organisms are more likely to be found

Answer 9

in older strata/rock layers

Question 10

what can be used to determine the actual age of rocks?

Answer 10

radioisotopes

Question 11

what is unique about radioisotopes that allow us to determine the age of rocks?

Answer 11

they decay at a constant rate, which can help pinpoint where the rock is time-wise

Question 12

time interval over which 50% of a remaining radioisotope decays, changing into another element

Answer 12

half-life

Question 13

how is an event dated in regards to radiometric dating?

Answer 13

the ratio of unstable and stable isotopes are compared to the initial conditions

Question 14

what is the ratio of Carbon-14 to Carbon-12 in a living organism?

Answer 14

its constant

Question 15

why is the ratio of C-14 to C-12 constant in living organisms?

Answer 15

there is a constant cycle of carbon dioxide flowing in and out of their systems through respiration & energy consumption

Question 16

what does C-14 decay to when an organism dies?

Answer 16

Nitrogen-14

Question 17

why can’t sedimentary rocks be dated using radioactive isotopes?

Answer 17

the materials that make up sedimentary rocks may have existed on earth before becoming a rock, thus could be inaccurate

Question 18

what does dating rocks older than 50,000 years require?

Answer 18

estimating isotope concentrations in igneous rocks

Question 19

how are igneous rocks formed?

Answer 19

when molten material cools and hardens

Question 20

which radioisotope relationship is used for most ancient igneous rocks?

Answer 20

Potassium-40 decaying to Argon-40

Question 21

how can absolute dates be determined?

Answer 21

(1) tree rings
(2) radiometric dating
(3) paleomagnetic dating

Question 22

the earth’s crust

Answer 22

the lithosphere

Question 23

what is the lithosphere comprised of?

Answer 23

solid plates

Question 24

what do the solid plates that make up the lithosphere float on?

Answer 24

a fluid layer of liquid rock or magma

Question 25

what causes the plates of the lithosphere to move?

Answer 25

pressure from the heat within the earth’s core that causes the magma to circulate in convection currents

Question 26

the movement of plates

Answer 26

continental drift

Question 27

what happens when the plates are pushed together?

Answer 27

they either move sideways past one another or one is pushed underneath the other

Question 28

what types of earth structures are formed from continental drifts?

Answer 28

(1) mountain ranges
(2) deep rift valleys
(3) trenches
(4) ocean basins

Question 29

the geological separation of a population as a result of a emerging land barrier

Answer 29

vicariance

Question 30

study of how past geological and environmental events have influenced the distribution and diversity of species on earth

Answer 30

historical biogeography

Question 31

current distributions of organism are a product of

Answer 31

(1) vicariance
(2) dispersal
(3) speciation
(4) extinction

Question 32

how are oceanic islands formed?

Answer 32

by volcanism from the oceanic crust

Question 33

where does the biodiversity on oceanic islands come from?

Answer 33

long-distance dispersal of colonizing species

Question 34

describe the molecular clock hypothesis

Answer 34

rates of molecule change are constant enough to predict timing of evolutionary divergence

Question 35

how is a molecular clock calibrated?

Answer 35

independent data such as:
(1) fossil record
(2) known divergence
(3) biogeographic dates

Question 36

the early earth’s atmosphere likely lacked

Answer 36

free oxygen

Question 37

how did O2 increase in the atmosphere?

Answer 37

when certain bacteria evolved the ability to use water as a source of H+ ions in photosynthesis

Question 38

how did anaerobic prokaryotes react to the initial appearance of O2?

Answer 38

it was poisonous to them

Question 39

what is the advantage of utilizing O2 for organisms?

Answer 39

aerobic metabolism is faster and more energy can be harvested

Question 40

when the partial pressure O2 is raised, what happened to the Drosophila?

Answer 40

they evolved larger body sizes over a few generations