Topic 9

Question 1

What six features do organisms need to be considered alive?

Answer 1

i) Organization
ii) Metabolism
iii) Response to stimuli
iv) Homeostasis
v) Adaptation
vi) Reproduction

Question 2

What term describes the maintenance of some internal chemical and/or thermal consistency relative to variation outside of the entity?

Answer 2

Homeostasis

Question 3

Are viruses alive?

Answer 3

No

Question 4

What components of life do viruses lack?

Answer 4

Metabolism, homeostasis and cannot reproduce without a host cell

Question 5

What three large eons is the geologic record divided into?

Answer 5

i) Archaean
ii) Proterozoic
iii) Phanerozoic

Question 6

What three eras is the Phanerozoic eon divided into?

Answer 6

i) Paleozoic
ii) Mesozoic
iii) Cenozoic

Question 7

What is a preserved remnant/evidence of organisms that lived in the past?

Answer 7

Fossil

Question 8

Why is the fossil record biased and incomplete?

Answer 8

i) Requires burial in sediment
ii) Probability of an organism getting fossilized is low
iii) Few organisms are fossilized and discovered

Question 9

What increases the probability of an organism becoming fossilized?

Answer 9

i) existed for a long time
ii) abundant and widespread
iii) hard-bodied
iv) aquatic
v) inshore marine
vi) decomposing organisms absent

Question 10

What is a cast fossil?

Answer 10

A cast forms when minerals fill space in sediment where the organism decayed after having been buried

Question 11

What type of fossil have had their tissues replaced by minerals?

Answer 11

Replacement (petrified) fossils

Question 12

What is a trace fossil?

Answer 12

Fossils that record evidence of behaviour (tracks, burrows, feces, etc.)

Question 13

What type of fossil has original organic material retained (carbon films, amber, tar or peat, permafrost)?

Answer 13

Preserved fossil

Question 14

What is relative dating of fossils?

Answer 14

The sedimentary strata reveal the relative ages of fossils (indicates which fossil came first, second, etc.)

Question 15

What is a downside of relative dating fossils?

Answer 15

i) Does not indicate how long ago the fossil was created

ii) Gaps are created by erosion or major land movements

Question 16

What is absolute dating (radiometric dating)?

Answer 16

Using radioactive decay of specific isotopes of elements in fossils or rocks

Question 17

What term describes 50% of atoms in a given amount of radioactive substance that has decayed?

Answer 17

Half-life

Question 18

What is plate tectonics theory?

Answer 18

Earth’s crust is composed of plates floating on the Earth’s mantle that move slowly through the process of continental drift

Question 19

What is continental drift?

Answer 19

Oceanic and continental plates can collide, separate, or slide past each other and their interactions cause the formation of mountains and islands

Question 20

What were the three effects of Pangaea?

Answer 20

i) Deepening of ocean basins
ii) Reduction in shallow water habitat
iii) Colder and drier climate inland

Question 21

What are three consequences of continental drift?

Answer 21

i) Changes to the environment and climate
ii) Opportunities for the diversification of life via allopatric speciation
iii) Mass extinctions

Question 22

How many mass extinctions have occurred and what are the two main extinctions?

Answer 22

Five

Permian and Cretaceous

Question 23

What is the Permian mass extinction?

Answer 23

Defines the boundary between Paleozoic and Mesozoic eras 251 million years ago that occurred rapidly and had the extinction of about 60% of all families and 96% of marine animal species

Question 24

What are the two hypothesized causes of the Permian mass extinction?

Answer 24

i) Catastrophic environmental change, such as large meteorite impacts and increased volcanism
ii) Gradual environmental changes including sea-level change, oceanic anoxic events (O2 depletion) and changes in ocean circulation due to climate change

Question 25

What is the Cretaceous mass extinction (dinosaurs)?

Answer 25

Occurred 65.5 million years ago that separated Mesozoic from Cenozoic in which 20% of all families went extinct including 50% of marine species

Question 26

What is a hypothesized cause of the Cretaceous mass extinction?

Answer 26

Presence of iridium in sedimentary rock suggests a massive meteorite impact about 65 million years ago

Question 27

What are three consequences of mass extinctions?

Answer 27

i) can take a long time for diversity to recover
ii) changes the types of organisms found in communities
iii) lineages with advantageous features can be lost

Question 28

What term describes the evolution of diversely adapted species from a common ancestor?

Answer 28

Adaptive radiation

Question 29

What are three things adaptive radiation may follow?

Answer 29

i) Mass extinctions
ii) Evolution of novel characteristics
iii) Colonization of new regions

Question 30

What are the four steps that may have produced very simple cells as the origin of life?

Answer 30

i) Abiotic synthesis of small organic molecules
ii) Joining of small molecules into macromolecules
iii) Packing of molecules into protocells (micells)
iv) Origin of self-replicating molecules

Question 31

How did the abiotic synthesis of small organic molecules occur?

Answer 31

Thought to have formed in the early atmosphere (water vapour, ammonia and methane, reducing environment, frequent lightning) but now thought to have been synthesized near volcanoes or deep-sea vents (strongly reducing conditions)
Amino acids have also been found in meteorites

Question 32

How did the abiotic synthesis of macromolecules occur?

Answer 32

Small organic molecules polymerize when they are concentrated on hot sand, clay or rock

Question 33

How did protocells form?

Answer 33

Organic molecules can spontaneously form hollow vesicles with a lipid bilayer and experiments show vesicles form faster in the presence of volcanic clay

Question 34

How did self-replicating molecules form?

Answer 34

Via natural selection that produced self-replicating RNA molecules that stored genetic information

Question 35

What is the oldest fossil evidence of life? (3.5 bya)

Answer 35

Prokaryotes

Question 36

What describes organisms without DNA contained in a nucleus and without membrane-bound organelles?

Answer 36

Prokaryotes

Question 37

What are the two domains of prokaryotes?

Answer 37

i) Bacteria

ii) Archaea

Question 38

What are the oldest known fossils?

Answer 38

Stromatolites

Question 39

What are stromatolites?

Answer 39

Rocks formed by the accumulation of sedimentary layers on bacterial mats

Question 40

What organism used the sun’s energy to fix CO2 and produced )2 as a by-product?

Answer 40

Cyanobacteria

Question 41

What is the oxygen revolution?

Answer 41

The accumulation of O2 was toxic to most early prokaryotes but some groups survived by using anaerobic respiration to harvest energy