Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIO239 Microbiology And The Cycles Of Life > L1 Origins Of Life > Flashcards

L1 Origins Of Life Flashcards

1
Q

What are the 6 essential elements

A

Carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus

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

What are 3 fundamental conditions for life on earth

A

Essential elements,
Continual source of energy,
Temperature allowing liquid water to

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

What are two continual sources of energy

A

Solar or geothermal

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

What are the conditions where no life would exist

A

150C and 1atm

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

When was the earth formed

A

4.5 billion years ago

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

At what period was the earth formed

A

Hadean eon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How were the elements up to iron formed

A

Sun released hydrogen
Heating hydrogen formed helium and other elements up to iron

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

How were elements greater than iron formed

A

Supernova

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

What geological events bring new elements to an environment

A

Meteor strikes

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

What are the charges of the crust and core

A

Crust highly oxidised, core very reduced

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

What is the earths core made of

A

Iron

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

What is the crust made of

A

Silicon dioxide
Also carbonates and nitrates

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

Could life have existed before it evolved to what is is today? And how?

A

Life could have existed and been destroyed by repeated meteor bombardment and then only exist in deep rock

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

What was the early atmosphere made up of

A

Most carbon dioxide, similar to Mars

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

What would have happened if carbon dioxide had been continued to be released by all life

A

Earth would of continued to warm and life could not of existed

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

The atmosphere absorbs light and converts it to…

A

Heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Example of a planet where there is too much carbon dioxide

A

Venus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Example of a planet where there is too little carbon dioxide

A

Mars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What could have early microbial action caused

A

The ice age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What may have reversed the ice age

A

Evolution of methanogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is light driven carbon dioxide fixation

A

Photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When did photosynthesis evolve

A

At leat 3.4 billion years ago

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What was the trend when the atmosphere was oxygenated

A

Would’ve fluctuated with a general upwards trend

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why did oxygen conditions fluctuate

A

It was too toxic to most life at the time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why can earth be referred to as a closed biosphere
Everything currently here is what can be used, nothing more
26
How are products linked by metabolism between living organisms
Products from one type of metabolism are linked to other biological processes Products released by one are used by another - food, biomass etc
27
How long ago did life evolve
3.8 million years
28
What is the name of the time period where life evolved
Achaean eon
29
How was life able to develop
As stable oceans formed
30
Why is water so important for life
Remains liquid over wide temperature range Is a universal solvent Allows membranes to form
31
What are 4 evidences for the evolution of life 3.8MYA
Fossils Isotopes ratios Biosignatures Oxidation state
32
What two things can be used as fossils
Stromatolites and microfossils
33
Where are stromatolites found today
Shark Bay, Australia
34
What condition of Shark Bay allows stromatolites to survive and why
High saline pools = no predation
35
How is the structure of stromatolites formed
Mucilage traps calcium carbonate, cementing biofilm and creating structure Sediment-trapped mucilage forms rocks over time
36
From how long ago do stromatolites show evidence of life
3.4BYA - Archaean period
37
How do stromatolites fail to show evidence of life
Cannot see cells in fossils
38
How far back can microfossils be dated
2 BYA
39
What makes fossils form
Minerals precipitate
40
What are the advantages of using microfossils
Cell forms are visible and measurable
41
What else could have formed microfossils
Abiotic factors
42
Why do microfossils not appear before 2 BYA
Archaean rock was not compatible as it is metamorphic which is modified by temperature and pressure which destroys the fossils Only sedimentary rock forms these kinds of fossils
43
Give an example of enzymes selecting isotopes
Carbon dioxide fixing RubisCo prefers carbon-12 over carbon-13
44
What happens to the carbon in cells
Converted to calcium carbonate
45
How can the difference in C12 and C13 be measured
(C13 / C12 (of experimental rock) - C131 / C12 (of standard rock)) Divided by (C13 / C12 (standard rock)) All timesed by 1000
46
What other element can be used to show enzymes selecting isotopes and how far does this date back
Sulphur 34 and 32 From 3.5 MYA
47
Advantages of using isotope ratios
Highly reproducible, provide physical measure Strong evidence for dating earliest life Can be used to calibrate phylogenetic trees
48
Disadvantages of using isotope ratios
Only tells us life existed, not what it looked like or what it did Cannot guarantee they are not produced abiotically - can’t prove a negative
49
What will the amount of C-13 be in a biological source
Depleted
50
What would a minus value for the difference in carbon isotopes show
Minus value indicates a depletion of C-13 compared to C-12
51
What type of ion is soluble
Crustal ferrous (Fe2+)
52
What is an oxidised ferric ion Is it soluble
Fe 3+ Insoluble
53
How can iron ions show varying oxygen concentrations
Layers of Fe3+ in sedimentart rock show alternating oxic and anoxic conditions Grey layers of silicon oxide and red layers of ferric oxides
54
What are 3 possible sources of energy in early Archaean oceans
Oxidised forms of iron, nitrogen or sulphur interacting with hydrogen and driven by light reactions Light-driven ion pumps creating gradients across memebranes Metahnogenesis (2H2 + CO2 -> Ch4 + H2O)
55
What are the 3 models proposed for crearting life from energy
Prebiotic soup Metabolist model RNA world model
56
Who came up with the prebiotic soup model What experiment was carried out
Oparin and Miller Common compounds (hydrogen, water, methane) put under heat and pressure forms biomolecules like gylcine. Eventually develops proto-cells but this is large leap
57
What is the assumption of Oparin and Millers simulation and is it true
No oxygen present Some evidence oxygen was present and could’ve reacted with N, Fe, S in prescence of UV light
58
What are arguments against Oparin and Millers experiment
Big leap from amino acids to functional proteins and cell formation Elements may have been too dilute in ancient oceans - shallow coastal pools, or intertidal surfaces seem a more likely source for these reactions
59
How was the early cell membrane formed Which theory does this stem from
Micelle shaken to form a bilayer Formed from amphipathic fatty acid glycerol esters Metabolists model
60
How was each amino acid formed Which of the 3 theories does this stem from
From a component of the TCA cycle and 2 dinucleotides - went on to form basis of genetic code Metabolists model
61
What is the nutrient cycle in the metabolist model
Self-sustaining carbon dioxide based metabolism similar to citric acid (TCA) cycle which was catalysed by metal sulphides
62
What does the RNA world model account for that is not covered in other models
The production of macromolecules that encode complex information
63
Why is it RNA model and not DNA
RNA uses uracil which is produced earlier than thymine (DNA)
64
How did adenine form in the RNA world model
From NH3 and carbon dioxide in ancient oceans

BIO239 Microbiology And The Cycles Of Life (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions