Intro to evolution Flashcards
Fact vs. Theory
Facts can be observed and measured, theories seek to explain facts.
List and explain the 3 theories about the origin of life
Creationism- all species of organisms were
individually created, exactly as they exist today. Based on creationist stories, the Earth is between 4 000-
10 000 years old.
Panspermia/ cosmozoan- Life may not have originated on Earth but may have “arrived” here from space via an asteroid, meteor, or other
extraterrestrial intervention
Directed panspermia -
intentionally colonized by
extraterrestrial life
Accidental panspermia - life
arrived by random chance
Abiogenesis- Life evolved from abiotic (non-living) macromolecules coming together in a unique fashion until the “unit” was cell-like. It took another billion years for that “unit” to evolve all of the defining characteristics of life and become a cell.
What are the problems with the three theories of evolution?
Creationism- science suggests the Earth is in fact 4.5 BILLION YEARS OLD. Religious beliefs are based on FAITH and not TESTABLE. Not supported by facts, observations, OR experiments.
Panspermia/ cosmozoan- doesn’t really answer the question. Not currently testable.
Abiogenesis- impossible to imagine this timeline.humans prefer to feel special, unique, and different.
List the steps of abiogenesis
(each took 1 million years)
- Non-living synthesis of simple
organic molecules, e.g. sugars and
amino acids
- Assembly of these organic molecules
into polymers - Formation of polymers that can
self-replicate (enabling inheritance) - Formation of membranes to package
the organic molecules
Explain the Miller-Urey experiment
- Simulation of early Earth conditions
- Water (early ocean) was ently boiled to mimic exaporation
- Added methane, hydrogen, and ammonia to the “atmosphere”, which are simple gasses that scientists believed to be abundant on the early Earth
- Sparks simulated lightning
- After one week, complex molecules, including amino acids had formed
- Showed that biomolecules can form under early Earth conditions
Explain Redi’s experiment
Explain Pasteur’s experiement
List the general timeline of life
Life began 3.5 BYA. After 1 bollion years, nuclei were formed. After another 0.5 billion years. there was an explosion of diversity.
What are stromatolites?
Layered microbial rock created by cyanobacteria. Fossils of the first life on Earth.
Explain radiocarbon dating
Look at the ratio of carbon 12 to carbon 14. Carbon 14 is unstable, so when an organism dies the carbon 14 in it starts to disappear. Using the half-life of carbon 14 reveals how many thousands of years have passed since the animal died. Note that c-14 is only good until 50,000 years ago.
What are the three different mechanisms by which changes in DNA can occur?
Mutations, environmental factors, epigenetics
Where did life originate?
What are variations and adaptations?
Variations: changes in DNA that lead to structural, functional,
or physiological differences between individuals within a
population. Think genetic diversity!
Adaptations: if over time, these variations make the species
MORE successful at mating, reproducing and keeping their
young alive so they can reproduce in their particular
environment, then the variations become adaptations that are
passed down to future generations.
**NOTE: not all variations become adaptations.
What are Darwin’s observations?
1 - Individuals within a species vary in many ways.
survive and pass on their variations. (envt. cannot support larger pop)
What are Darwin’s inferences?
1 - Members of the same species compete with each other for
survival.
to survive and pass their favorable variations to their offspring.
Survival is not random.
offspring to succeeding generations, the favourable variations
will become more common. (This is “natural selection”).
