bio 182 exam 2 180 questions and correct answers l
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BIO 182 Exam 2 180 Questions And Correct Answers Latest Update
2024
1. How many modes of selection are 3
there?
2. What are the modes of selection? Stabilizing selection, directional
selection, and disruptive selection
3. Stabilizing Selection The mean of the trait remains sim-
ilar over time but the standard de-
viation decreases
4. Directional Selection The mean phenotype shifts in a
particular direction
5. Disruptive Selection The standard deviation of the trait
increases as individuals with the
mean value disappear.
6. Stabilizing Selection Explained The stronger the selective pres-
sure against extreme phenotypes,
,BIO 182 Exam 2 180 Questions And Correct Answers Latest Update
2024
the narrower the distribution of
phenotypes will be in future gener-
ations. In the end, the size of the
standard deviation will reflect both
the strength of selection against
extremes and the frequency of
mutations creating new variation.
Thus, when we observe a wide
range of phenotypes in a popula-
tion, we might infer weak selective
pressure against the extremes.
7. Directional Selection Explained The population's environment
changes. The mean phenotype in
the population may no longer be
the phenotype that reproduces the
most. Over time, we should expect
the mean phenotype to shift high-
er or lower, depending on the di-
rection of selective pressure. Once
the mean phenotype catches up to
the change in the environment, sta-
bilizing selection will resume. The
environment must change slowly
enough for the population to per-
sist. If the environment changes
too quickly, no members of the
population will be able to repro-
duce, leading to extinction.
8. Disruptive Selection Explained A population can occupy an en-
vironment in which individuals
with extreme phenotypes repro-
duce more than individuals with the
mean phenotype.
This mode of selection occurs
when several distinct strategies
confer greater reproductive suc-
cess than other strategies do. Can
, BIO 182 Exam 2 180 Questions And Correct Answers Latest Update
2024
produce new species when in-
dividuals choose to mate only
with similar-looking individuals.
This non-random mating prevents
recombination from restoring inter-
mediate phenotypes.
9. Evolution by Natural Selection Heritable variation leads to differ-
ential reproductive success
10. Selection and Fitness
11. Directional Selection Equation y=bx+c
y=relative fitness
x= trait value
b= strength of selection
c=parameter
12. True or False? If the slope of the rela- False, it would increase the value
tionship between the phenotype and of the trait over time
fitness is positive, natural selection
would decrease the phenotype over
generations.
13. Stabilizing Selection Equation y=ax^2+bx+c
y=relative fitness
x= trait value
a/b= strength of selection
c= parameter
14. True or False? If the parameter for the True, depends on how large the
squared term is negative, natural se- parameter is for the squared term
lection will likely stabilize the pheno-
type at an intermediate value.
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