Brief history of life on Earth, Lecture 3

Question 1

Three domains of life

Answer 1

Bacteria, eukaryotes, archaea

Question 2

Six kingdoms

Answer 2

1. Archeabacteria
2. Eubacteria
3. Protists
4. fungi
5. plantae
6. animalia

Question 3

Archaaebacteria

six kindgoms of life

Answer 3

Prokaryotes that lack a peptido-glycan cell wall, eg: extreme halophiles, thermophiles and methanogens.

Question 4

Eubacteria

six kindgoms of life

Answer 4

Prokaryotes with a peptidoglycan cell wall, eg: cyanobacteria, soil bacteria, nitrogen-fixing bacteria and pathogenic bacteria

Question 5

Protists

six kindgoms of life

Answer 5

Eukaryotic, primarily unicellular organisms, heterotrophic or photosynthetic organisms

Question 6

Fungi

six kindgoms of life

Answer 6

Heterotrophic, eukaryotic, chitin cell walls, mostly multicellular, usually non-motile

Question 7

Plantae

six kindgoms of life

Answer 7

eukaryotic, multicellular, photosynthetic, non-motile

Question 8

Animalia

six kindgoms of life

Answer 8

Eukaryotic, heterotrophic, multicellular, motile

Question 9

Early Earth

Answer 9

4.5 billion years old

Question 10

Characteristics of early earth

Answer 10

hostile, hot environment

reducing atmosphere - enabled formation of carbon rich compounds

Question 11

When did life begin?

Answer 11

3.8 billion years ago

Question 12

Earliest fossils

Answer 12

• are of prokaryotes, 3.5 billion years ago,
• simple structure, no nucleus and few internal structures
• dominant between 3.5-2 billion years ago

Question 13

Stromatolites

Answer 13

precambrian ‘colonies’ of cyanobacteria

Question 14

Photosynthesis

Answer 14

oxygen production

Question 15

Which two main evolutionary branches do prokaryotes comprise?

Answer 15

bacteria and archaea

Question 16

Which groups are included in the archaea?

3

Answer 16

methane producers, thermophiles and halophiles

these are found in very hostile anaerobic environments

Question 17

When did cyanobacteria evolve?

Answer 17

around 3.5 billion years ago

Question 18

Cyanobacteria

Answer 18

oxygen generating photosynthetic algae

Question 19

Role of cyanobacteria in early earth?

Answer 19

raised atmosphere oxygen levels
enabled the ozone layer to form
protected the earth from UV radiation

Question 20

Characteristics of eukaryotes

Answer 20

nucleus, chloroplasts, mitochondria

Question 21

The origin of eukaryotes

5

Answer 21

• ancestral prokaryote
• infoldings of plasma membrane
• engulfing of aerobic heterotrophic prokaryote
• engulfing of photosynthetic prokaryote
• endosymbiotic relationships between bacteria

Question 22

Multicellular eukaryotes

6

Answer 22

• evolved from single-celled eukaryotes living in association with each other
• development of specialised cells
• most are aerobic
• sexual reproduction was generally well developed
• the fusion of gametes enabled genetic recombination
• sex generates variation, enabling faster evolution

Question 23

When was there an explosion in eukaryotic diversity?

Answer 23

at the end of the ice age, early cambrian period, about 570 million years ago

Question 24

When was land colonised by plants, animals and fungi?

Answer 24

about 500 million years ago

Question 25

When were most of the orders of modern mammals, inc. the primates, established?

Answer 25

50-60 MYA

Question 26

When did the human lineage diverge from other primates?

Answer 26

5 - 6.5 mya

Question 27

Which events shape evolution?

Answer 27

mass extinctions

Question 28

Impact of extinction events | 4

Answer 28

- create 'ecological space' - removes organisms occupying some niches - the survivors descendants could evolve into those spaces with fewer constraints - adaptive radiation may occur after mass extinctions or when new opportunities arise, eg: new islands

Question 29

Adaptive radiation meaning

Answer 29

A process in which organisms diversify rapidly from an ancestral species into a multitude of new forms

Question 30

When does adaptive radiation often occur?w

Answer 30

when a change in the environment makes new resources available

Question 31

Example of adaptive radiation Dawin's finches 5

Answer 31

1. ancestral finches arrive on island 2. lack of small birds so no competition for food etc. 3. finches diverged to occupy different habitats 4. some evolved into different species 5. finches with different beaks and feeding habits