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Life in the Cosmos > 8-13 > Flashcards

8-13 Flashcards

1
Q

privide an outlife of life on earth time line

A

first 2 billion years - we know nothing
next 2 b, life was microscopic microbes, rarely larger than 1mm or 2-3 cells
following 600 m years to presentm explosion of large and complex organisms - cambrian explosion

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2
Q

what was the cambrian explosion

A

explsion of life
545 million years ago
development of life in 5-10 m years in short time frame
led to most animal groups development that we know today

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3
Q

What does intermezzo mean

A

diversity and complexity

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4
Q

what does morph mean in evolution

A

the incormpoation of a modular construction of standardised units to form a dynamic range of sizes

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5
Q

What are the levels of organisation

A

Cell
tissue
organ
organ system
organism

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6
Q

What are the 3 domains of life

A

Eukaroyta
Bacteria
Archea

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7
Q

What are prokaryotes

A

Bacteria and Archaea
- 2 domians of single cell organisms
- they are cell without a nuclei and consist of a long strand of DNA with several thousend genes

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8
Q

How many species live on earth todat

A

10 million

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9
Q

what are eukaryotes

A

multi celled organisms have a nucleeous, seperated by a membrane
DNA held within the nucleus
Eurkaryotes can store more infomration in their genetic material

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10
Q

Morphological evoltuion allowed…

A

Allowed increase in size and therefore complexity
More complexity means more diversity

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11
Q

What are the mechanisms for evolutionary processes

A
  1. random passive tendancy t evolve through an overall increase in variance
  2. non random, active, process that bisas evolution towards increased size of comeplexity
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12
Q

What evidnce is there from the fosil period

A

multi-celular life evoved independantly many times
life forms with new body parts or morphology (higher comeplxity) arise from early multi-cellular organsisms
New life forms lead to periods of rapid diversification

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13
Q

What are cyanobacteria

A
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14
Q

What are stromatolites

A

rock based structures built by microbes (single celled cyanobactria) know as blue-green algae — sharks bay

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15
Q

what are trilobites

A

one of the oldest know fossil groups - 500 m yrs old
they roamed the oceans for 270 million years

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16
Q

What is life made from - gimme the ingrediants

A

83 stable elements - 4 (H, O, C, N) weigh 95% of all living matter

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17
Q

What is the utillity of hydrogen and oxygen

A

follows from the large amount of water that make living oganisms

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18
Q

what is the utillity of carbon

A

has good abillity to bond with other carbon atoms - creating chains and bonds with other atoms

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19
Q

what is the utility of nitrogen and oxygen

A

capable of forming bonds with carbon that are robust but not unbreakable — a combination of carbon, oxygen and nitrogen bonds can exist

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20
Q

What are expremopiles

A

microorganisms that thrive in extreme envrionments (from HUman perspective)
Many of them could not survice in moderate condictions

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21
Q

What are the categories of extreame environment

A

PHysical
Geogchemical
Biological

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22
Q

What is the atmoushphic pressure at sea level

A

100,000 Pa or 1.01 bar

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23
Q

What are some environmental limiting

A

Temp, radiationn, salinity, pH, desiccation, pressure, oxygen

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24
Q

What are thermophiles

A

50-80 degress

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25
Q

what are mesophiles

A

15-50 degrees

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26
Q

What are psychrophiles

A

less than 15 degrees

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27
Q

What are tardigraades

A

water bears
they show crypotbosis
they disiccatie as environment dries
they shrivel into a tun and wait for mositure to return
1150 species discovered since 1773
only grow to 1mm
they have 4 pairs of each limbs

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28
Q

What is extreame

A

a distance from the median for that ecosystem variable

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29
Q

Why is temprature important for enzymes

A

They have optimal ranges for energy - too cold = frozen, too hot = protein and nucleic acids break down

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30
Q

What is the highest temprature surviving domian of life -

A

archeae

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31
Q

What is sulfolobus acidocaldrius

A

survives with average pH of 3 and temp of 80 dgerees

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32
Q

How deep is the marian trench and what is the pressure there

A

10994 (6 way)
pressure of 1086 bars - more than 1000 x that of sea level

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33
Q

What is the challenge of pressure on life

A

cell membranes are compressed - decreases mebranve fluidity and prevents many chemical reactions

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34
Q

How does pressure change in the atmoussphere

A

10km above SL, 1/4th pressure

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35
Q

What role did oxygen play in early life ?

A

it was an anaerobic environment - photosinthisis oxygen increased in the atmpoushphere

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36
Q

What role does oxygen play in life today

A

key element to sustain life - photosinthisis and respiration

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37
Q

How does oxygen damage things

A

Oxidation = to nucleic acids, priotiens and lipids

(some things have evolved to have antioxidents)

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38
Q

What is the environment on mars

A

Surface temp - 210 K
Atms pressure - 0.007 bars
Atms make up - 95% Co2
Gravity - 38%
It also has high solar raditation levels

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39
Q

What is the environment on Venus

A

Surface temp - 737 K
Atms pressure - 92 bars
Atms make up - 96% Co2 +suphuric acid clouds
Gravity - 88%

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40
Q

What are the key requirements for life

A

Carbon
Liquid water
energy soruce

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41
Q

WHat is the traditional view of forming life

A

spontanrous formation of complex molecules from atmouspheric gasses - abiogensis
These molecules accumlate in pools of water under the action of some soild catalyst – life started in this primordial soup

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42
Q

Where has the theory of some little warm pond shifted to

A

around the areas where there are undersea colcanic vents

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43
Q

What was the miller-urey experiment

A

1950s
they took molecules they belived to represent major components of the earlyths warlu atmousphere and put them in a closed system
They use:
- Methan
Ammonia
Hydrogen
Water
They ran elecrical curent through the system

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44
Q

What were the results of the Miller Urey experiment

A

at the end of the week, 10-15% of carbon was now an organic compound
2% of the carbon had formed some amino acids to make protiens
It showed that the organic compounds could be made easily under conditions in early earth

45
Q

Why was carbon importantg

A

can form with many other atoms
can dissolve in water

46
Q

Why is silicon not an altertive to carbon

A

its bonds are too weak
interacts with too few elements
only form single bonds
;ess mpbile
1000x more abundant on earth, but life is still carbon based

47
Q

Why is water important in life

A

living systems need a medium to discolve and for chemical reactions to take place
it is a stable temprature
alternative is ammonia but only liquid when less than -30 degrees

48
Q

What are some sources of energy

A

Light - 20-30% weaker than today
impacting sub atomic particles
shock waves
geothermal heat
eruptions of lava
radioactiviuty
thunder and lightning
ocean surf

49
Q

What is panspermia

A

idea that life floats about in the interstellar medium and occasionally comes to rest on a planet
space is hazardous though
the building blocks of life could exist in space and then form part of the early atmpushephere

50
Q

What are some differnt types of Panspermia

A

Basic - bacterial spores
Radio - propegated by raditaion of stars
Ballistic - cells escape a planet from an impact
Modern - comets
Pesudo - comeplex organic coumpounds from space
Directed 0 intelligent life sent by aliens

51
Q

What are some more radical theories of Pansperia

A

viruses and DNA can survive in space and abiogenesis happened close to the galactic cnetrer before paspemia caried life through the glaxcy

52
Q

What are problems with the alterntive theories of begininngs of life (Hoyle-Whckramasinghe)

A

opposed idea that life began in a warm soup
There was a sociological preblem between biologists and astologers as the two disiplines never meet

53
Q

What if Hoyle and Wichramasinghe are correctg

A

bactria could be around interstellar clouds that collapse to form stars and planets
comets could preseve lifeforms and scatter tham to other planets
supported by e.coli data

54
Q

how could comets contain life

A

Theybhave frozen water, dust and other substances
anaerobic bacteria dont need oxygen to grow
they shower viable material onto planets like earth

55
Q

what life was there in Hale-Bopp

A

infrared raditaion emmited by small particles in the coma of HB

56
Q

What is the rate of arrival of material on earth

A

100 tons per day
may bring new bugs which could interact with terestial life or kill it

57
Q

whaqt role does UV radtion play in preventing life from traversing the solar system

A

only 0.1% of bacterial spores survived 2,500 yrs of UV starlight - if coated with 1 micron of dust or soot, they would be shieled

58
Q

Why is a TV camara important to finfing extreame survival in space

A

it had stretococcus mitis on it after 2 years in space because someone had sneezed on it before it went up and it survived
We now know that vacum is not a fatal problem for bacteria

59
Q

What is in the space inbetween stars

A

around one H atom per cubic meter
they are heated by UV radiation so move very fast and bonds are hard to make

60
Q

What are GMCs

A

Giant molecular clouds (hard to make) - they are the sites of star and planet formation

61
Q

How large and how long do GMCs last for

A

150 ly across, 10 -100 million years

62
Q

How to GMCs help facillitatet life

A

they contain grafite dust to shield UV light and acts as a catylist

we cannot recreate them becase we cant get the desnity low enough or wait millions of yearsWh

63
Q

What are most of the molecules in GMCs

A

hydrogen
CO

64
Q

How are molecules detected

A

MASEERS
Microwave amplification by stimulated emission of radiation
Like lasters

65
Q

How are moelcules detercted from earth

A

ALMA telescope - atacama large milimiter array - very high and dry location - observes in mm and sub-mm wavelengths

66
Q

When have molecules been found in space

A

OH in 1963
Ammonia in 1968
CH20 in 1969

67
Q

What are the four types of organic molecules that combine to build cells and their parts

A

carbohydrates
protiens
lipids
necleic acids

68
Q

What is the amino acid glycine

A

formed from a reaction between acetic acid and ammonia

69
Q

What is Glycoaldehyde

A

a simple sugar that forms one of the subunits of nucleic acid

70
Q

What was the murchison meteroite and why was it imporant

A

landed in 1969
weighted over 100kg
one of the most studied meteorites
7 billion yrs old
(oldest on earth)
had common amino acids like glycine, alanine, glutamic
Equal amount of L and D types of amino acids

71
Q

What is chirality

A

mirror symmetry
amino acids exist in two forms, mirroring each other in L and D types - all life on earth uses L types - D types can be produced in labs

72
Q

How do we define a habitable planet

A

Liquids - medium for molecules to dissolve and chemical reactions take place
Suitable Star - energy
Atmoushphere - sheilfds radiation, temp, chemicals
Gravity - keep atmoushpehre bound to planet
Jupiter - protector from asteroids and comets
Moon - tidal and climate

73
Q

What are the chemical elements required for life

A

Carbon
H
O
N
Mg
Ca
Cl

74
Q

What would happen if the temprature is too high in planrt

A

the mositure wil evapourate into space or create a greenhouse effect –

venus - runaway GHE - the surface as dried up and riased temps to 460 degrees

75
Q

What happens if the temprature is too low in a planet

A

too little solar heat can lead to permanent ice age
snowball earth scenario - aldedo of the earth inensifies coolding

76
Q

what is the snowball earth

A

scenario where ice formations leafd to albedo and mroe cooling after solar radiation is reflected back into space

77
Q

what is the circumsetllar habitale zone

A

the areas around a star which can support liquid water - 273-373

78
Q

Why do the moon and mars not have enoguh gravity to support life on earth

A

moon - not massive enough to hold atmpusphere - onlu 1/6th of earths
Mars - 62% lower gravity than on earth - only a thin layer of CO2 provides little insulation. solar wind is stripping away martian atmpouhssphere

79
Q

Where are tghe heavy elemetns found

A

Heavy elements are found in all population-I type stars (younger, second generation) but not in enough quantity in older population II stars
the older stars are found in the centre of our galaxy - they are unlikley to have rocky planets and so are likley devoiud of any life

80
Q

How was the first atmoushphere formed

A

outgassing of gases trapped in the interior of the early earth

81
Q

How large is the milky way

A

80,000 ly across

82
Q

what is the milky way buldge made from

A

old stars, gas, dust

83
Q

what does the MW disk contain

A

young stars, gas and dust - concentrated in spiral arms

84
Q

what does the halo in the milky way conatin

A

old stars and clusters of old stars, dark matter

85
Q

what is andomeda

A

our sister galaxy
2.5 million yr away

86
Q

What is eccentrcity and why is it important

A

one feature of our solar system is that it is less elliptical than others of similar size and shape
The prevents plunges into the inner galaxy where radiation and super novae are commin

87
Q

What is co-rotation

A

where the angular speed of the galaxy spiral meets that of the stars within

88
Q

What is metallicity

A

the abundanmce of other elements apart from hydrogen and helium

89
Q

how does metallicity vary in different stars

A

less than 0.1% in old stras
more than 2% in young stars in the galactic disk
a high volumne of metals is important for the creation of rocky planets §

90
Q

How many exoplanets have been found with a metallity of less than 20% solar

A

7 exoplanets, all gas giants

91
Q

What would happen if metallicity is too high ?

A

terresrial planets would be larger with stronger gravity, richer in volitile compounds
they would probably be covered in water
thought to be bad for weather

92
Q

what is a parsec (pc)

A

3.261 light years

1 kiloparsec = 3261 ly

93
Q

How does the metrallicity of the gas in the mily way vary

A

at the suns location, (8kpc) from the centre, the metallicity is falling at 17% per kpc

94
Q

Summerise the trade offs in galstaic planet survival in thr galaxcy

A

too far - supply of materials is too poor
too close - inner regions have high supernovae - likley to be exposed to radiation

95
Q

What is the GHZ

A

galactic habitable zone

96
Q

What are active galactic nuclei

A

Areas at the centre of some galaxcies that is brighter than can be explained

97
Q

what on our planet defends particle radiation

A

planets magenetic field

98
Q

what on our planet screens out electromegnetic radiation

A

ozone layer

99
Q

What is the killer radius of a SN

A

100 ly

100
Q

where do most supernovae take place

A

60% of the suns distace from the cenrrew

101
Q

how oftern do SN happen

A

6 in past 1000 years
1 per 40 +- 10 year in normal galaxcies

102
Q

What are gamma-ray bursts

A

most powerful explosions observed in distant ga;axies since the big bang - they could sterlise earth in one shot

Would remove the ozone layer and allow SOlar UV to reach the earth

Gamma rays pass thoguh humans and ionise things, causing tissue damage and DNA

103
Q

How habitable are globular clusters

A

low metallicity

104
Q

How habitable are Nebulae

A

newly formed giant stars with strong winds ould evaportae protoplanets

105
Q

How habitable are Nebulae Trifid Nebula

A

Ionised gas hazad affecting the atmoushphere

106
Q

How habitable are massive young stars

A

lots of UV and short livesx

107
Q

How habitable are galactic centre

A

intense radiation and unstabel orbits

108
Q

How habitable are supernova remnants (cygnuslooop)

A

debris from stellar explosions

109
Q
A

Life in the Cosmos (3 decks)

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