Origin Of Life And Evolution Notes Flashcards
What are fossils?
Any evidence an organism once lived
What can scientists determine by looking at fossils?
What ancient climate they lived in and the behavior of organisms
What layer of rock do fossils form in?
Sedimentary
What are the two types of fossils? Briefly describe each one.
- cast-space filled in with minerals like a dinosaur bone
* mold-like print
Are younger fossils found closer to or farther from the surface?
Younger fossils are found closer to the surface, while older fossils are found farther from it.
What are the two types of dating? Briefly describe each one.
- relative-can only tell which one is younger/older
- radiometric-uses carbon and sophisticated machines to determine age (carbon 14-radioactive isotopes that decay or break down over time)
How many mass extinctions (where almost everything died off) were there, according to the fossil records?
Five mass extinctions
Spontaneous generation
People once thought things appeared or were formed from the air and not from other living things.
When did the earth form?
About 4.6 billion years ago
What did Francesco Redi prove and how did he prove it?
Francesco Redi disproved spontaneous generation trough his meat-in-a-jar experiment. But, he couldn’t explain where microorganisms came from, so he said there was a “vital force” that made them appear.
What is biogenesis?
Some scientists thought living organisms MUST come from other living organisms.
What experiment did Louis Pasteur perform?
He did a broth experiment where he boiled some broth in two flasks, then closed one of them off.
What did Louis Pasteur find out from his experiment?
He found out that if there was no air or no way for bacteria to get in, then the broth stays good. But, if the bacteria can get in, then the broth goes bad. He determined living things come from other living things.
What was Earth’s atmosphere originally made of (billions of years ago)?
Water vapor, methane, and ammonia.
Who believed that life came from the oceans?
Alexander Oparin
Who did experiments with Earth’s original atmospheric stuff and added electricity?
Stanley Miller and Harold Urey
What did Miller and Urey get?
Things needed for life like amino acids, sugars, and organic compounds (made of carbon…)
Who heated the amino acid solutions?
Sidney fox
What did Fox call what formed?
Protocells-they’re like regular cells, but they don’t carry out all of the processes living things need to do.
What are prokaryotes?
The first real living cells, most of which were anaerobic (didn’t need oxygen to survive).
By what process did prokaryotes get energy?
Fermentation (not respiration because they didn’t need oxygen)
Were prokaryotes heterotrophs?
Yes, because they had to “get” their own food.
What formed after a couple of hundred million years that could make their own food?
Autotrophs
What did autotrophs put into the atmosphere?
Oxygen
What were the first autotrophs called and where could they live?
Archaebacteria, and they could live in got sulfur springs & deep sea ocean vents.
What happened after autotrophs appeared?
They produced lightning, storms with lots of oxygen lead to ozone.
What does ozone do?
Protect us from harmful solar and cosmic rays.
What did Charles Darwin do?
He proposed the theory of evolution.
What is evolution?
Change in a species over time.
What did Charles Darwin sail on and where did he sail to?
Charles Darwin sailed in the HMS Beagle to the Galapagos Islands off the coast of South America.
What did Charles Darwin find?
That the animals an plants on the Galápagos Islands were very similar to those on the mainland of South America.
What did Darwin mostly look at? What did he find?
Finches. He found that each of the fourteen species was almost the same as the next save for their beak shape.
What did the different beak shape of the finches indicate?
That they all ate different things.
What did Charles Darwin do after studying the finches?
He proposed natural selection; he said that organisms born with the best traits are adapted to survive and reproduce.
What were Darwin’s main ideas for natural selection?
- With natural selection, there is overproduction of offspring, so at least some will survive.
- Also more chances for random mutations
- There is competition between them for the same resources. Some survive, while others do not.
- Natural selection also leads to variation between individuals and between different species, and some of this is heritable.
- Therefore, species can adapt to changing conditions to ensure survival.
- Darwin states that species alive today are descended modification from ancestral species, this links all organisms on Earth. (Ex: bacterial resistance to antibiotics)
What other kind of selection did Darwin say there was?
Artificial selection, in which humans will actually interfere with nature and pick the best traits (like in dog breeding).
What book did Darwin publish?
On The Origin of Species By Natural Selection, on all of his research.
What did Jean baptiste lamark believe about evolution?
He believed that traits were acquired during an organism’s lifetime and then passed on to the offspring.
What is mimicry?
When one organism copies another (ex: viceroy and monarch).
What is camouflage?
When an organism blends in with its surroundings (ex: chameleon).
What is an analogous structure?
Structures that do the same thing on different species, but look very different from one another (ex: bird wing and butterfly wing).
What is a vestigial structure?
A structure that remains in an organism, although it is unused (ex: appendix in humans).
What is embryological development?
When organisms look very similar in the early stages of life when they are embryos.
What are biochemical comparisons?
We can look at amino acid sequences and look at the difference in the proteins of an organism.
One could look at DNA and RNA, and see that all organisms “native” to Earth that we know of have all the same bases (A, T, C, G) and see when a species might have diverged from the common ancestor.
On what does natural selection act?
An organism’s phenotype, NOT their genotype.
Do populations evolve or just individuals?
Populations!
Within a population, you need to see:
The entire gene pool
What is the allelic frequency?
The percent of a gene in the gene pool.
What is the only mechanism to add new genetic variations to a gene pool?
Mutations. This is why they’re so important.
What is genetic equilibrium?
Nothing is changing, so the species isn’t evolving.
What is genetic drift?
Allele frequencies are changing at random, so evolution is happening.
Where is there a greater chance of inheriting a recessive allele?
In small populations.
What is the greatest factor influencing gene pool?
Natural selection
Stabilizing selection
Selects the “average joe” in the population (ex: the medium of bunch)
Directional selection
Selects one extreme (ex: biggest or smallest of bunch)
Disruptive or diversifying selection
Selects BOTH extremes (ex: the smallest AND the largest)
What is speciation?
The evolution of a new species.
Geographic isolation
Happens when a natural barrier separates a species so they evolve differently (ex: mountains separate squirrels, who grow up with different traits)
Reproductive isolation
Happens when two populations of the same species become so different (mostly due to geographic isolation) that they cannot breed together anymore (ex: when a species becomes a polyploid [extra set of chromosomes]. Fastest form of speciation).
Gradualism
Species gradually gets new adaptions–long time (Darwin’s idea).
Punctuated equilibrium
Speciation occurs quickly, then there is a long period of time where nothing happens.
Adaptive radiation
One species evolves into many species that occupy different niches (roles in environment).
Divergent evolution
Species were once similar, diverged into totally different species over time.
Convergent evolution
Species are not related at all, but get similar characteristics to live in their environment (ex: Dolphins and fish both have fins or flippers)
Coevolution
A species evolves r aide another species evolves. They are usually dependent on each other in some way.
