Life in the Cosmos

Question 1

All chemical elements except from hydrogen, helium and lithium were formed by what?

Answer 1

Nucleosynthesis in the cores of previous generations of stars and ejected into supernova

Question 2

Where does star and planet formation take place?

Answer 2

Molecular clouds

Question 3

3 steps of protoplanet formation

Answer 3

1. Condensation into dust molecules
2. Accretion into planetesimals
3. Coalescence into protoplanets.

Question 4

First Earth Area

Answer 4

Hadean Era

Question 5

What was earth like during the Hadean Era

Answer 5

Hot, volcanic and under constant bombardment by meteorites/ planetesimals

Question 6

Atmosphere in the Hadean Era

Answer 6

Mainly N2, CO2, H2O, CH4, H2

Question 7

What era were the first ambiguous signs of life?

Answer 7

Archean Era

Question 8

What is life on earth based on?

Answer 8

Proteins and amino acids

Question 9

Where have amino acids been detected?

Answer 9

Space, meteorites

Question 10

What experiment have amino acids been formed in

Answer 10

Miller-Urey

Question 11

What is outgassing?

Answer 11

Heating and melting of the earths surface drove volatile gases into the atmosphere.

Question 12

What was the Hadean atmosphere rich in?

Answer 12

CO2

Question 13

What did the Hadean CO2 rich atmosphere cause?

Answer 13

Greenhouse effect

Question 14

How did CO2 leave earths atmosphere?

Answer 14

Mainly precipitated out,
Some was returned to atmosphere by plate tectonics

Question 15

How did the fraction of oxygen in Earths atmosphere start to rise?

Answer 15

Oxygen is produced by photosynthesising organisms

Question 16

Increase in oxygen conc. marks the start of what era?

Answer 16

Proterozoic era

Question 17

What is the Pre-Cambrian Era made up of?

Answer 17

Archaean Aeon and Proterozoic Aeon

Question 18

What does the Pre-Cambrian Era constitute?

Answer 18

The vast majority of the time for which life has existed on Earth

Question 19

Why is oxygen a better element for us to have in our atmosphere?

Answer 19

Its much more reactive than CO2, easier for living organisms to extract energy using aerobic reactions than anaerobic

Question 20

What is ozone?

Answer 20

A form of oxygen that protects life on earth by screening out the suns UV radiation

Question 21

What was the Cambrian Explosion?

Answer 21

Huge growth in the number and variety of multi-cellular creaturesW

Question 22

When was the Cambrian Explosion?

Answer 22

540 Million Years ago

Question 23

Factors for the growth of diversity?

Answer 23

Oxygen, Genetic complexity, absence of predators

Question 24

What is the geological year

Answer 24

Representation of the development of life by imagining the lifetime of the Earth compressed into a single year.

Question 25

What is the K-Pg extinction?

Answer 25

The extinction that killed the dinosaurs

Question 26

What do scientists think the K-Pg extinction was caused by?

Answer 26

Impact of a 10 km meteorite

Question 27

Evidence for the K-Pg extinction being caused by a large meteorite?

Answer 27

Large crater of the right age, and a high iridium abundance at the K-Pg boundary, consistent with that found in meteorite material

Question 28

Fossil record provides evidence for how many mass extinctions?

Answer 28

20

Question 29

Which events have a much higher probability of occuring than large, energetic events

Answer 29

Small, less energetic events

Question 30

The bigger an impacting meteorite, the bigger the ______

Answer 30

BANG

Question 31

Do meteorites always leave a crater?

Answer 31

No not always

Question 32

If a meteorite doesnt leave a crater, can it still cause damage?

Answer 32

Yes - considerable amounts of damage

Question 33

What was the Tunguska airburst?

Answer 33

A meterorite or comet exploded in the earths atmosphere, about 8 km above the ground

Question 34

How does an explosion above the ground happen?

Answer 34

Rapid heating due to friction with molecules in the atmosphere

Question 35

Effects of the Tunguska airburst

Answer 35

1. Shock wave flattened a 2000 km area 2. Forest fires that burned for weeks 3. Ash and debris sent to atmosphere, carried around the world m

Question 36

When did the most extreme extinction occur?

Answer 36

Between the Permian and Triassic Eras

Question 37

What percentage of organisms were lost in the Permian-Triassic extinction?

Answer 37

90% of ocean species 70% of all land vertebrate species

Question 38

What is life defined as?

Answer 38

A material system which as the ability to self-replicate, mutate and evolve in response to changing environments

Question 39

What must a system do in terms of energy and raw materials to repair itself?

Answer 39

Must be able to draw energy and process raw materials to repair itself.

Question 40

What are optimal conditions

Answer 40

Conditions we would look for to maximise our chances of finding extra-terrestrial life

Question 41

Carbon forms bonds with itself, creating _____ bonds

Answer 41

Covalent

Question 42

Are carbon-carbon covalent bonds strong?

Answer 42

Yes, take a lot of energy to break therefore can withstand high levels of heat.

Question 43

Where does carbon place in terms of how abundant it is in the universe?

Answer 43

4th most abundant element in the universe

Question 44

Why is carbon such a succesful element?

Answer 44

Forms a greater variety of chemical compounds than any other element, Has the greatest ability of any element to bond with itself, can form long chain molecules that encode information

Question 45

Why is silicon not as likely to be the basis of alien life than carbon?

Answer 45

Bonds arent as strong Cant form double bonds Silicon more likely to bond with oxygen into a small molecule than form long chain molecules

Question 46

What is a deep-sea smoker?

Answer 46

Deep sea geothermal which is expelling extremely hot mineral rich water from within the Earths Crust.

Question 47

What element were the ecosystems found around deep sea-smokers based on

Answer 47

Sulphur

Question 48

What word describes bacterial colonies that live around the deep sea smokers and metabolise sulphur compounds?

Answer 48

Anaerobic

Question 49

When colonies live deep down in the sea with no sunlight, where do they get energy from?

Answer 49

Sulphur chemistry

Question 50

Where do many scientists believe life orginated?

Answer 50

Deep sea smokers, due to chemical reactions in the mineral-rich waters.

Question 51

What factors make up the overall environment of a planet?

Answer 51

Temperature, mass, age and atmospheric composition

Question 52

What are the compounds that if present are hopeful signs of life?

Answer 52

Water, oxygen and carbon

Question 53

What other conditions are necessary to protect life?

Answer 53

Protection from radiation, Moderate and stable temperatures, atmospheric recycling mechanisms

Question 54

What is the electromagnetic spectrum?

Answer 54

A continuous spectrum of energy-carrying waves of electric and magnetic fields

Question 55

The shorter the wavelength, ...

Answer 55

The greater the energy

Question 56

Is short or long wavelength radiation more dangerous?

Answer 56

Short

Question 57

Why are shorter wavelengths more dangerous?

Answer 57

They have enough energy to break bonds in carbon chemistry

Question 58

How are we (carbon life) protected from radiation?

Answer 58

Ozone layer

Question 59

For liquid water to survive on a planetary surface, the planet must lie within the _______

Answer 59

Habitable Zone

Question 60

What is the habitable zone?

Answer 60

The range in distance from the central star in which water can exist as a solid

Question 61

What happens if a planet is too close to its central star?

Answer 61

It will recieve a lot of heat radiation, overheating. Water will evaporate.

Question 62

If planet lies outside of habitable zone?

Answer 62

Planet too cold, water will freeze.

Question 63

What makes Venus and Mars interesting candidates for the search of extra-terrestrial life?

Answer 63

They are both very near the edge of the habitable.

Question 64

A star hotter than ours will have a more _____ zone

Answer 64

Distant

Question 65

A star cooler than ours will have a _____ zone

Answer 65

Closer