Lecture 6 Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

4 requirements for life

A
  1. metabolism
  2. response to stimuli
  3. homeostasis
  4. reproduction with potential for error
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

are viruses alive?

A

no, lack metabolism and homeostasis, cannot reproduce without host cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

fossil

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

strata

A

distinct layers in rock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

why is our understanding of the diversity and distribution of past life is biased and incomplete?

A

fossils more likely to form if hard, aquatic, inshore, and decomposing organisms absent after death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

3 types of fossils

A
  1. trace fossils (evidence of behaviour)
  2. cast (minerals fill space in sediment where organism decayed)
  3. petrified (tissues replaced by minerals)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

ichnology

A

study of trace fossils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

sub-fossil

A

high % organic material (thin carbon film, amber, tar, peat, frozen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

relative dating

A

done via sedimentary stratigraphy, can’t tell how long ago fossil was created but can tell which fossil came 1st, 2nd, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

index/indicator fossils

A

help to read incomplete or scrambled layers, existed for a brief time with wide geographic distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

geologic time scale

A

created based on the appearance and disappearance of major taxa, major events correlated with changes in eon, era, period or epoch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

radiometric dating

A

measurement of radioactive isotopes in fossils or rocks to determine absolute dates for geologic time scale

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Carbon 12

A

common, 6 neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Carbon 14

A

8 neutrons, decays to N-14

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

half-life

A

when 50% of atoms in a given amount of radioactive substance have decayed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

carbon dating

A

when organism dies, C-12 stays but C-14 decays - increasing ratio of C-12:C-14 in fossils allows fossils to be dated

17
Q

half-life of carbon

A

5730 years, carbon dating only good for young fossils up to 75 000 years old

18
Q

half-life of uranium

A

4.5 billion years, better for older fossils

19
Q

continental drift

A

relative locations of land masses have changed over time, fossils provided first evidence

20
Q

Pangaea

A

first supercontinent

21
Q

Gondwana

A

Australia, Antarctica, and South America, same genus of fossil plant found

22
Q

2 mass extinctions

A
  1. End-Permian

2. End-Cretacious

23
Q

End-Permian

A

245 MYA, 60% of families and 90% of marine species extinct, formation of Pangaea

24
Q

End-Cretacious

A

65 MYA, at Cretaceous-Paleogene boundary, 20% of families including non-avian dinosaurs and ammonites extinct, climate change or asteroid strike

25
Q

planet formed

A

4.6 BYA, bombarded by large chunks of rocks until 3.9 BYA

26
Q

oldest fossil evidence of life

A

3.5 BYA, hypothesized to have existed up to 3.9 BYA - single-celled prokaryotes

27
Q

prokaryotes

A

lack membrane-bound organelles, DNA not contained in nucleus, only type of fossil evidence for 1.5 BYA

28
Q

stromatolites

A

where many of the oldest prokaryotic fossils are found, many species of prokaryotes living together on substrate, sediments accumulate, grow up through sediment, creates banded rock

29
Q

cyanobacteria aka blue-green algae

A

oxygen began accumulating 2.7 BYA when photosynthetic cyanobacteria started using sun’s energy to split water into hydrogen & oxygen

30
Q

banded iron rock

A

first oxygen released through photosynthesis probably reacted with dissolved iron in oceans to create iron oxide, iron oxide precipitated out

31
Q

early 02

A

toxic to early life, attacks chemical bonds

32
Q

obligate anaerobes

A

descendants of species that could survive only in very little 02, present in rotting oxygen-free substrates and guts of animals

33
Q

spontaneous generation

A

until 1800’s, how we thought that microbes arose

34
Q

Louis Pasteur’s beef broth experiment

A

broth spoiled only if bacterial spores could drop from the air, disproved spontaneous generation

35
Q

how early cell-like structures may have arisen

A

free-floating amino acids created, and spontaneous formation of hollow lipid vesicles

36
Q

Montmorillonite

A

volcanic clay 4 BYA that vesicles form faster in

37
Q

Where did life originate?

A

original: shallow water bodies
now: hot, mineral-rich deep-sea vents

38
Q

panspermia hypothesis

A

first prokaryotes came from space, supported by nanobes in meteorite

39
Q

most important condition for life to arise

A

free non-toxic water