lecture 11

Question 1

following anaerobes were _______ with

Answer 1

• photoautotrophs

- oxygenic photosynthesis

Question 2

the key innovation made by photoautorophs was

The advantage of this was

Answer 2

• use of H20 as the electron donor (oxygenic photosynthesis)

- water was very plentiful

Question 3

called oxygen photosynthesis because

Answer 3

oxygen was a by-product of this new synthesis

Question 4

stromatolites formed by

Answer 4

photosynthetic bacteria grows in mound that are everntually covered by debris

• as the bacteria get covered they die while new bacteria gorw on top of the debris
• occurs again and again produceding fossilized layered rock able to preserve

Question 5

number of backteria in shark bay

Answer 5

3 billion cyanobacteri/m^2 of mat

Question 6

stromatolites reach what height

Answer 6

1.5 meters high, up to ~10m

Question 7

modern stromatolites generally found where

Answer 7

in hot or hyper-saline environments where they are free from grazing and burrowing animlas

Question 8

cyanobaceria are the likely the first life form to _____

But they are not likely the first ______

Answer 8

produce hard parts that can crystlalize

life forms

Question 9

once oxygen photosynthesis started with advent of cyanobacteria _______
this resulted in ________
____________ precipatated to the sediments leaving banded iron formations
by 2 billion years ago, the ferrous iron within the oceans had largely __________

Answer 9

• O2 accumulated in the atmosphere and waters of the ancient seas
• the oxidation of ferrous iron to ferric iron in these surface waters
• ferric iron with O2 attached,
• precipitated to the ocean floors

Question 10

Evarly biodiversity on earth consisted of ______

Answer 10

prokaryotes

Question 11

cyanobacteria has occupied the earth for ______

and was the _____ life form for more than _______

Answer 11

at least 3.5 billion years
dominant
-1.5 billion years

Question 12

build up in O2 in the atmosphere had three significant affects

Answer 12

1. A rapid expansion in the diversity of aerobic microorganisms, with a concurrent reduction in anaerobic prokaryotes
2. The first ice age (known as a snowball earth)
3. providing the atmosphere needed for the next major evolutionary step… origin of eukaryotes

Question 13

The great oxygenation event

Answer 13

2. 2 BYA, major extinction event (not in the 5
   - when the iron on earth had absorbed much of the O2, it could hold the remainder remained in the atmosphere
   - free oxygen toxic to anaerobes and wiped a lot of them out

Question 14

free oxygen reacted with ______
Causing it to ______
And trigger ______
And so anaerobic organisms ______

Answer 14

• atmospheric methane( a greehouse gas)
• greatly reduce in concentration
• a glaciation possibly the longest snowball Earth episode in the Earth’s history
• began to evolve, taking advantage of the newly available O2

Question 15

archae and bacteria developed from
archaea have genes similar to
Eukaryote branched from

Answer 15

• a common ancestor
• both bacteria and eukaryotes
• archaens millions of years ago

Question 16

evolution of eukaryotic life is based on

Answer 16

endosymbiosis

Question 17

endosymbiosis

Answer 17

one species(the endosymbiont) living within another species(the host)

Question 18

development of organelles known to be from

Answer 18

the plasma membrane

Question 19

heterotrophic cells acquired chlorplasts by ____
and mitchondria by ______
whereas normally the engulfed cell would _______

Answer 19

• incorporating cyanobacteria as the endosymbiont,
• other symbionts
• be digested

Question 20

Soft organisms are not associated with ________

So it would be very unlikely for them to ______

Answer 20

sediment/rock

be preserved

Question 21

currently oceans have low levels of ________

due to it being locked up in ________

Answer 21

• iron in solution

- sediments following oxidation

Question 22

There is currently ____x more oxygen stored in _____

than is present in the _________ as a result of _____

Answer 22

• 20
• BIFS
• atmosphere
• billions of year of oxygen production by photosynthesis

Question 23

The principle source of iron in steel production is

Answer 23

The iron locked up in bifs

Question 24

addition of the energy source of the cell(__________)

are thought to have occurred via

Answer 24

• mitochrondria and chloroplasts

- failed phagocytosis

Question 25

Host cell for cyanobacteria and mitochondria provide

Answer 25

Nitrogen and Phosphorus, and shelter(membrane)

Question 26

cyanobacterium and mitochondria provide

Answer 26

energy for the cell

Question 27

obligate mutualistic relationship

Answer 27

two organisms becoming one

Question 28

Evidence for endosymbiosys theory(2)

Answer 28

• Eukaryotic chloroplasts has cyanobacterial properties

- actual cyanobacteria occurs within the cells of many organisms today

Question 29

cyanobacterial properties of eukaryotic chloroplasts (3)

Answer 29

• remnant dna in chloroplast are similar to cyanobacterial DNA in that its circular and and lacking histones
• ribosomes in chloroplast as similar to cyanobacterial ribosomes in that they’re small(unlike the larger type found in eukaryotes)
• nucleotide sequences of DNA and ribosomal RNA are similar between chloroplasts and Cyanobacteria

Question 30

Histones

Answer 30

proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes

Question 31

Theory of secondary endosymbiosis - _______
explains how _______
these ideas are __________

Answer 31

• eukaryote engulfing another eukaryote
• other algae obtained chloroplasts
• more complex, often unresolved

Question 32

Evidence for theory of secondary endosymbiosis

Answer 32

• more than two envelopes around the chloroplasts of some algae
• small nuclei and eukaryotic sized ribsomes outside two inner chloroplast envelopes but inside chloroplast

Question 33

The rise of eukaryotic multicellular organisms and larger eukaryotes directly linked to _______
- this is due to ________
- large cells have a significantly harder time _______
larger cells need a higher level of ________

Answer 33

• rise in O2 levels
• the effect of size on surface to volume ratios and O2 ability to diffuse into aerobic cells
• diffusing O2 into their center than harder cells
• O2 to develop and thrive

Question 34

Theories for multicellular evolution

Answer 34

cells found eachother and aggregated to form colonies

- cells remained attached after cell division

Question 35

Advantages of being multicellular

Answer 35

• increase protection form the environment(less surface area exposed)
• division of labour(due to specialization)

Question 36

Disadvantages to being multicellular

Answer 36

The larger you get the more you must specialize(most of your cells can communicate with environment)