Chapter 9

Question 1

Astrobiology

Answer 1

The study of the origin, evolution, distribution, and future of life in the universe including extraterrestrial life and life on Earth.

Question 2

Solar Habitable Zone

Answer 2

Hypothetical distance around a star that would support life as we know it.
Liquid water exists on a planet.
Can change over the lifetime of a star.

Question 3

Galactic Habitable Zone

Answer 3

Too close to the center of the galaxy is dangerous due to supernovae and gamma ray bursts.
Too far out and there’s not enough heavier matter like carbon.

Question 4

Liquids i the Solar System

Answer 4

Mars used to have a lot of liquid water and still has a little.
Europa, a moon of Jupiter, is also thought to contain liquid water.
Titan, a moon of Saturn, contains surface liquid methane and ethane.

Question 5

Mars

Answer 5

Liquid water in past.
Possible liquid water now.
Thin atmosphere.
Surface unprotected from solar radiation.
Geologically dead.
Mars has disputed amounts of methane that can have a geological or biological origin.

Question 6

Europa

Answer 6

Composed of rock.
Covered in ice, with possible liquid water underneath.
Has oxygen in its atmosphere.
Has strong tidal forces.

Question 7

Titan

Answer 7

Dense atmosphere.
Liquid on surface.
Wind and rain.
Its methane cycle is like our water cycle.
Protected from solar wind by Saturn.
Has complex organic molecules.

Question 8

Panspermia

Answer 8

Hypothesis that life exists throughout the universe.

Life is dispersed by asteroids and meteors.

Question 9

Interplanetary vs Interstellar

Answer 9

Interplanetary is between planets in a solar system.

Interstellar is between stars.

Question 10

Interplanetary Transfer

Answer 10

A large object hits a planet and knocks rocks off into space.
Microorganisms can float off the earth and be carried by stellar winds.

Question 11

Evidence for Interplanetary Transfer

Answer 11

Rocks from Mars and the Moon are on Earth.
Meteorites have been found on Mars and the Moon.
Computer simulations predict a large impact on Earth would eject debris as far as Saturn.
Life from Earth is on Mars.

Question 12

Interstellar Transfer

Answer 12

Just like interplanetary but a lot longer.

Driven by solar winds and gravity.

Question 13

Meteoric Travel

Answer 13

The insides of meteorites don’t get that hot.

Landing on a planet is easier than getting off a planet.

Question 14

Desiccation

Answer 14

Drying out fragments DNA.

A space hazard.

Question 15

Ultraviolet light

Answer 15

Fragments and damages DNA.

A space hazard.

Question 16

Radiation

Answer 16

Fragments and damages DNA.

A space hazard.

Question 17

Cosmic Rays

Answer 17

Fast moving particles fragment and damage DNA.

A space hazard.

Question 18

Radiation and DNA

Answer 18

High frequency radiation or fast moving particles can knock electrons off of atoms.

Question 19

Direct Route vs Indirect Route

Answer 19

Direct: Electrons can be stripped off DNA.

Indirect: Electrons can be removed form another molecule to create a free radical that then damages DNA.

Question 20

Radiation

Answer 20

Can break the backbone causing single or double stranded breaks.
Radiation can break the hydrogen bonds between the bases.
Radiation can damage the bases and change them chemically.

Question 21

Extremophiles

Answer 21

An organism that thrives in conditions that would kill most life on Earth.

Archea, bacteria, animals, insects, worms.

Question 22

Waterbears

Answer 22

An 8 legged animal.
Can live without water for 10 years.
Can survive at extreme temperatures and pressures.
Can survive the vacuum of space.
Can survive 1000 times as much radiation as other animals.

Question 23

Deinococcus Radiodurans

Answer 23

Most radiation resistant organism known.
Can survive toxic environments.
Can survive desiccation.
Doesn’t make spores.
Instead of hiding in a spore it can repair its DNA from fragments.
Has multiple copies of its genome to serve as templates.
DNA repair helps it survive desiccation.

Question 24

Exaptation

Answer 24

When a trait that evolved for one function becomes useful for another.
Ex. Feathers evolved for heat regulation later became useful for sexual displays and still later became useful for flight.

Question 25

Spores

Answer 25

Made by bacteria, fungi, plants, algae, and protozoans.
Like a seed but smaller and tougher.
Can remain dormant for millions of years.
Resistant to radiation.

Question 26

Bacterial Endospores

Answer 26

DNA and protein surrounded by a protein coat.
Not a true spore as it’s not produced by reproduction.
It’s a place for the bacteria to hide when times are tough.
When time are good the spore spore germinates.
Don’t need foo.
Can survive high temperatures, extreme freezing, ultraviolet radiation, desiccation, and chemical disinfectants.
Contains internal proteins that protect DNA from UV damage.
Have been isolated form inside rock.
Have been germinated after 25-40 million years.

Question 27

Abiogenesis

Answer 27

The study of how life could evolve form inorganic matter.

Describes how life could have arose on Earth.