Bio 1202 Exams With Correct Questions And Answers

Basics of evolution
- What’s happening to the genetic makeup of a population over time?
o Evolution is not a linear process
o It is the change in generations over time
- Changes are driven by selective pressure
o Different form one population to another
o Can be different within one population’s time
- Evolution occurs for different generations at different rates
- Society typically depicts evolution as such
o ABCD
- However, it looks more along the lines of
o A
o B C
o D E F G

 “Species F” could go instinct, any of them could
 Because of selective pressure
 During some time periods, large numbers of species could go
extinct because of a large amount of selective pressure (mass
extinctions)
Darwin’s work
- Darwin saw this pattern of evolution
- This was not a common belief of the time
o People were put to death for speaking of “evolution” and “biology” in
these ways
o People mainly believed in creationism
 Creationism says that all the organisms that are here were
created in the way they are now and will never change
 they will remain constant
 once it comes into existence, that’s the way it will forever
be
 some also believed that organisms will slightly change over
time, but it would look more like this
 ABCD
 A1
 A2  B2
 People accepted this because although some change is
occurring, it is mostly creation of another organism
- It is irrefutable that the genetic makeup organisms have slowly changed
over time as the world around has changed
- Why was this controversial?
o They had taught creationism for so long
o It was society’s dogma at the time

, o People (mainly biologist/scientist) at the time did not want to accept
that they were wrong
- Also competed with other hypotheses at the time
o Darwin’s view on evolution was not the only
o Lamarck had a view as well
 Followed more of the linear idea
Lamarck’s Work
- Believed the change/evolution was driven by the organism itself striving to
become better and fit with nature better
o Rather than nature effecting the organism
- Scientists liked this idea of thinking because they liked the idea that each
organism was striving to be the best it could be
o Man was the most evolved
o Man was the highest and above all the other organisms
- Very accepted view
- However, there is no internal force that drives evolution
o External forces drive it
- Ex:
o It’s like saying a father who loses a finger due to an accident, will give
birth to children without that same finger
- Only very slightly true
o Genetic changes that occur in the cells can be passed onto offspring
o However, it would not be something like a finger being lost
- Some genetic changes make the future offspring more adapt
o Good change = more likely to be passed on
- Some genetic changes make no difference
o It’s still change, but makes no difference
o May get passed on, may not
- Some genetic change is bad
o Weeds out these organisms if it affects the organism’s ability to
reproduce
o However (speaking for humans) if it only lowers the organism’s life, it
will not likely affect that specific chain of organisms
 Humans get their reproduction done earlier on in life
Catastrophism and Uniformitarianism (a.k.a gradualism)
- Ideas came from geology
- Gradualism
o The gradual and slow changes happen over very, very long periods of
time
o However, over a long enough period of time, it amounts to a big
change
- Big changes can be produced, just over long periods of time
- Flip side  Catastrophism

, o Huge changes that happen all at once
 Volcanic eruptions
 Tidal waves
- Goes hand in hand with evolution
o Mutations
o Happens one nucleotide at a time
o Slow mutations through nucleotides that are passed down through
generation after generation will result in a big change  gradualism
- Gradualism can also have evolution repercussions
Natural Selection
- The pressure of nature which decides who’s going to be successful and who
isn’t
- Basically, mother nature putting a cap on an organism’s population’s growth
o Causes it to stabilize
- The organisms who do not start to stabilize outrun their resources and their
population crashes
o Forces them to either start over again, or go extinct
- Human population is reaching that point
o We have found ways to sidestep the natural selective ways
o Medicine
o Kill off predators
o Etc.
 However, we can’t do that forever
 We do not know if our population will crash or stabilize
 You cannot grow as a population completely unchecked forever
Evidence of evolution
- We go back to look for:
o Were there catastrophic changes in DNA?
o Are there point mutations that accumulate over time that occur in a
change in genes of a population?
o What was the selective pressure of the time?
- This has no bearing for what will happen in the future
- We can study evolution in a backwards view, not in a forward’s view
o we do not know what genetic changes are coming
o or what natural selective changes will occur
- evolution will never be a predictive science
- fossil evidence is evidence of evolution
o however, fossil evidence is only as good as what you can find
o most environments are not conducive to producing fossils
o there must be very specific conditions met to preserve a bone
 and then it must survive that preservation
o there is a finite amount
o only a snapshot of existence at the time

, Other lines of evidence:
Comparative anatomy
- What does this fossil look like compared to this other fossil?
- What does this living thing look like compared to this living thing?
o Picking organisms that seem to represent their population the
greatest
- Quantify differences that amount to anatomical differences
o How big
o How long
o How many teeth
o How many limbs
o Etc.
o All quantifiable, more statistical approach to the evolution

Convergent evolution
- Structures that are remarkably similar in two different organisms that the
population has evolved into due to similar selective pressure
o Flying squirrels and sugar gliders
o Different organisms
o No where near related
o Similar structures to avoid predators
- Structures have evolved in populations to allow populations to survive better
o Forming traits (more aerodynamic bodies to avoid predators) that
allows them to survive
o Might affect two difference lineages due to two different populations
having the same issue
- Allows us to look outside of just the anatomical traits to see why that
organism has evolved
- Must look at all different sources to study evolution
- Flip side: homologous structures
Homologous structures
- Two structures that might look very and different and do very different
things, but upon close studying it can be discovered that they may have
come from similar origin
- A dolphin's flipper, a bird's wing, a cat's leg, and a human arm are
considered homologous structures
Vestigial structures
- Some anatomical structures will evolve out of existence
o Whales have a pelvis where its hind legs use to attach
 The pelvis serves no real purpose
 However, remnants are still there
o We have an appendix, remnants of our ancestral origins