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BIOL 100 Exam 2 - Questions & Solutions
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BIOL 100 Exam 2 - Questions & SolutionsDistinguish between a theory and a hypothesis. ✔️Ans - hypothesis - an
educated guess; must be testable and must be falsifiable
theory - a scientific explanation, supported by evidence gathered over time
A hypothesis is a guess that can be proven wrong but a theory is proven to be
true by scientific evidence.
Identify and explain the mechanisms of evolution. ✔️Ans - random
evolution:
- mutation - a change in the DNA sequence of an organism
- genetic drift - the random loss of alleles from a population and is most
effective in small populations
- gene flow - the movement of alleles from one population to the other
adaptation:
- natural selection - the process by which those traits that increase fitness
become more common in a population over generations
Describe how the mechanisms of evolution influence genetic variation of a
population. ✔️Ans - Populations are constantly under the influence of the
4 mechanisms of evolution.
They change the genetic makeup of organisms by either random chance or by
adaptation.
These mechanisms influence variation because there is no perfect way that an
organism can or will change.
Explain the difference between random and adaptive mechanisms of
evolution. ✔️Ans - random:
adaptive:
- depends on many environmental factors
- depends on other genes in individual
- depends on others in population
,Provide and discuss examples for the evidence of evolution. ✔️Ans -
*Homology - similarity in structure due to common ancestry
Evidence for evolution can be found from diverse disciplines such as
comparative anatomy, embryology, intermediate fossils, and experiments.
How do organisms that cannot physically move undergo gene flow/migration?
✔️Ans - organisms can exchange genetic information through movement
gammies and spores
Which mechanism(s) *increase* variation in a population? ✔️Ans -
mutation and gene flow/migration
Which mechanism(s) *decrease* variation in a population? ✔️Ans -
genetic drift (bottleneck effect and founder effect)
How are a hypothesis and a theory different? ✔️Ans - A hypothesis is
narrow while a theory is broad.
Define gene pool. ✔️Ans - the total collection of alleles in a population
What is a gene pool? ✔️Ans - It refers to the total number of genes of
every individual in a population.
A large gene pool indicates high genetic diversity, increased chances of
biological fitness, and survival.
Can different populations of the same organism have different gene pools?
Why or why not? ✔️Ans - Yes, different populations of the same organism
can have different gene pools.
Different populations of the same organism can be under different selection
pressures depending on a variety of conditions. Physical location, for example,
may cause different allele frequencies between the two populations.
For evolution to occur, what must happen to a population's gene pool?
✔️Ans - the frequency of alleles in a population's gene pool must change.
, Will a change in allele frequencies always result in a beneficial evolutionary
change for the population? ✔️Ans - A change in allele frequencies does
not mean that a beneficial evolutionary change has happened.
There may be shifts in allele frequencies that are neither beneficial nor
harmful.
Does evolution and natural selection create perfect organisms? ✔️Ans -
No, environments are constantly changing which are constantly changing
traits
*natural selection is mindless, not goal oriented
Natural selection ✔️Ans - How allele frequencies change: individuals with
favorable alleles reproduce preferentially, increasing the frequency of these
alleles
Adaptive or nonadaptive?: adaptive
Its effect on genetic diversity: decreases - unfavorable alleles are eliminated
from the population
Mutation ✔️Ans - How allele frequencies change: new alleles are created
randomly
Adaptive or nonadaptive?: nonadaptive
Its effect on genetic diversity: increases - new alleles are introduced into the
population
Genetic drift ✔️Ans - How allele frequencies change: allele frequencies
change due to change events
Adaptive or nonadaptive?: nonadaptive
Its effect on genetic diversity: decreases - alleles are eliminated from the
population
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