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any life that originates from outside Earth
Evidence of how biology may be common in the universe
- -Organic molecules form naturally everywhere
- -Life appeared early
studying conditions that began and support life on earth, looking for other places with these conditions, and looking for evidence of life in other places.
What were the two types of thinkers in ancient Greece?
Believed in extraterrestrial life?
- the earth and sky are made of invisible atoms (4 kinds – earth, air, water, fire)
- ET life: maybe
Believed in extraterrestrial life?
- the 4 elements (maybe atoms, maybe not) make up the earth and the 5th element (quitessence) makes up the sky
- ET life: NO
Who put Aristotelian ideas into Christian thought?
When did Europeans begin to forget Greek ideas?
early middle ages 500-1000 AD
What was Atomism equated to and what did it cause?
Atheism; caused it to go into decline
How are Atomists and Aristotelians wrong?
- -not 4 elements
- -Earth isn't that special
- -not enough evidence
What makes evidence good?
- -can be proven scientifically
- -consistency in testing
- -credible source
- -testable, measurable
- -mathematically explainable
- -physical, tangible
scientifically, a well-sustained explanation of some aspect of the natural world (like a model, but more thoroughly tested)
Can everything be proven scienifically:
NO (new info comes in all the time)
a back-and-forth motion in stars
the sun and stars orbit the earth
was supposed to predict positions of planets, but the planets were never in their spots
facts and statistics collected together; often used as evidence
The Big Bang
moment when everything started in the universe, not an explosion, and nothing existed before it
What did Edwin Hubble and Humanson do?
used a large telescope to discover all galaxies are moving apart
Hubble and Humanson's discoveries:
- -farther away= moving faster
- -Galaxies are not expanding
- -some nearby exceptions are moving closer because of gravity
- -the universe itself is expanding, meaning it was closer together in the past and must have been one point at one time
When were the lightest 3 elements made?
within first 3 seconds of Big Bang
How were the 3 lightest elements made?
as soon as the universe expanded and cooled enough, protons, neutrons, and electrons combined to make these elements
Where are elements 2-26 made?
in the center of stars by fusion (byproduct is light)
Where are elements heavier than iron made?
made in supernova when they explode
previous generation stars die and give some contents back to space to form more stars
What is light?
sometimes described as an electromagnetic wave or as particles called photons
Is light important for measuring the conditions of a planet?
When light behaves as a particle:
- -called a photon
- -has no mass
- -only thing in universe to travel at the speed of light
- -photons have different energies
What are the light intesity names from left to right?
- 1) Gamma
- 2) X-ray
- 3) Ultraviolet
- 4) visible
- 5) Infrared
- 6) microwave
- 7) Radio
How is visible light different from invisible light?
How does one see different types of light?
using a different telescope for the specific kind of light
- -high energy radiation
- -used in medicine to tell ho dense something is
Infrared light (IR)
objects that are warm or hot emit IR ratiation (heat waves); the hotter the object, the more heat waves it emits
What different types of light can tell us:
- -how far away things are in space
- -what elements are emitted
- -how hot the place is (temp. and radiation)
- -density of planet
- -speed the objects are apporaching or receding
- -how fast they spin
How can we learn about temp. from light?
- more heat= more light emitted
- more heat= more high energy light emitted
What is radioactivity?
the nuclei of some isotopes spontaneously break apart, relasing particles, energy, and daughter isotopes
What is radioactivity also called?
fission or radioactive decay
Is radiation the same as radioactivity?
What does high-energy ratiation/particles do to DNA?
it breaks the DNA strands
Does background ratiation hurt us too?
it does penetrate DNA, but our bodies can repair it quickly
How does radiometric dating work?
rocks and fossils get less radioactive over time; this is what is used to tell the ages
time it takes for an element to decay to exactly half of the origional sample
Why is the earth still warm?
- -differentiation (dense stuff sinks to the bottom)
flowy, gooey part between crust and mantle
Earth's layers from inside to outside:
- 1) inner core (solid metal)
- 2) outer core (liquid)
- 3) mantle (solid)
- 4) crust
What creates Earth's magnetic field?
the core's convection cells
How does the Earth's core create magnetic fields?
the core convection moving around the charged particles creates a magnetic field that shields the atmosphere
How does the magnetic field protect us on Earth?
it prevents solar wind from stripping away the atmosphere
What two conditions are needed for water?
- -correct temperature
- -correct pressure (needed for liquid form)
What drives plate tectonics?
convection in the aesthenosphere
How does CO2 enter and leave the earth's atmosphere?
What effect do greenhouse gases have on Earth's temperature?
the more greenhouse gases, the hotter Earth gets
What is the most abundant greenhouse gas?
water vapor (H2O)
6 classifications of life:
- complex and organized
- grows and develops
- taking and using energy
- responds to environment
- evolution and adaptation
All living things have:
cells, DNA, protein
Main elements of cells:
sulfur, carbon, hydrogen, nitrogen, oxygen, phosphorus (SCHNOPs)
What is the most common element in the universe?
What are the major molecules?
- -Nucleic Acid
workhorses of cells; enzymes, antibodies, hormones
fats, oils, cholesterol; long term energy storage, cell structure, and hormones
DNA and RNA; info storage and transfer
sugar and polysaccharides; short-term energy storage
Why is carbon a better element for life than others?
- -very abundant
- -can bond up to 4 other elements at a time
- -very strong bonds
- -can make double bonds with itself
What does RNA need to make DNA?
What major molecule determines how we look and how we function?
Earth life needs 3 things:
- -source of carbon and other raw materials
- -source of energy
- -water (liquids)
"life arising from non-life"
What are some problems with abiogenesis?
- -biologists use this model knowing it's incomplete
- -not all steps are reproducible in the lab
Where did life most likely begin?
Five steps in development of life:
- 1) molecular building blocks form
- 2) RNA becomes self-replicating
- 3) pre-cells arise
- 4) true cells with RNA genomes appear
- 5) modern cells with DNA genomes evolve
Which came first: DNA or RNA?
RNA came first and may have assembled itself by sticking to rock or clay or assembled in icy water
Can nucleic acids be made in the lab?
What does RNA need to replicate itself?
Which is better: DNA or RNA?
DNA; stonger, copies more reliable, encode more.
What are comets?
icy asteroids that were formed in the colder regions of the solar nebulas
What is a comet's tail?
ice being subliminated to gas by the sun's heat
meteor that hit the ground
What causes meteor showers?
residue from comets
What was the K-T impact?
the huge meteorite that hit the earth 65 mil. years ago and caused the extiction of the dinosaurs by climate change
5 major mass extinctions:
- Impacts: 2
- Volcanism and global warming: 1
- Poisoning: 1
- Sea level change: 1
8 pieces of evolution:
- body hair
- extra ribs
- male nipples
- third eyelid
- wisdom teeth
What was the appendix for?
ancestors needed extra organ to digest tough veggies
What were the wisdom teeth for?
ancestors had bigger mouths and used them for grinding tough plants
What was the tailbone for?
ancestors had tails and the modern tailbone is several tiny fused bones