BIO 345 EXAM 2 QUESTIONS AND ANSWERS
Genetically identical twins have different personalities and grow to different heights -
Answers -Explained by environmental differences
E. coli cells exhibit different growth rates when cultured in the lab under the same
temperature, light, and food - Answers -Explained by genetic differences
Cancer risk is determined by genetic mutations, and environmental effects play a small
role - Answers -Nature vs. Nurture
Cancer risk is determined by how environmental factors mediate the effect of genetic
mutations by activating different combinations of genes - Answers -Nature and Nurture
Directional selection - Answers -No or minimal change in variance of trait distribution
stabilizing selection - Answers -decrease in trait distribution variance
disruptive selection - Answers -increase in trait distribution variance
Consider a new, hypothetical scenario where you observed the Darwin's finch,
Geospiza difficilis, before and after a drought. Now imagine that you looked at the
offspring of the survivors. Using this data, what are Δz, h2, and S? - Answers -Delta(z)
= 0; h2 = 0; and S = -0.5 mm
Mutations causing persistence of the lactase enzyme after infanthood explain much but
not all of human phenotypic variation in lactose tolerance. Some gut bacteria also
produce a lactase enzyme, which helps people digest lactose and improves their
tolerance. What is the reaction norm for lactose tolerance given the environmental
difference of absence/presence of bacteria in this case? - Answers -B - Linear increase
(diagonal up from left to right)
Certain mutations cause a crossvein in the wing of Drosophila to fail to develop if the fly
is subjected to heat shock in the pupal stage. Conrad Waddington bred a population in
which individuals subjected to high temps failed to develop the crossvein. After further
selection, the population lacked the crossvein even without heat shock, and this
condition was heritable. Match the reaction norms for 1) the wildtype genotype with the
crossvein and no plasticity, 2) Waddington's artificially bred genotype that reacted to
heat, and 3) the final mutant genotype after genetic assimilation - Answers -A -
diagonal down from left to right - Waddington's artificial
B- strait no slope from cold to hot Present crossvein - wildtype crossover
C- strait no slope absent crossvein - After genetic assimilation
, Does the figure show Gene X Environment Interaction? Why? Choose all correct
answers below. - Answers -Yes, because the montane and lowland genotypes show
different slopes AND Yes, because there is non-linearity in the reaction norms
Why does the evidence from Beldade's artificial selection experiments and data from
other species support adaptation rather than constraints for B. anynana's reaction
norm? - Answers -Hypothesis B, because genetic variation does exist allowing
evolution in the reaction norm but the norm remains stable in the wild
Which of these options best matches the pattern we expect from a selective sweep?
(Hint: think about what happens to heterozygosity in each case.) - Answers -B - from
dispersed to entirely homogenous
DN/DS - Answers -
Calculate the growth rate (R) of Species B based on the life history table below.
Remember that x is the age, lx is the chance of surviving to age x, and mx is the
average number of offspring produced at age x. Enter your answer as a decimal in the
format "#.#" - Answers -2.4
Calculate the growth rate (R) of a mutant in Species B based on the life history table
below. Remember that x is the age, lx is the chance of surviving to age x, and mx is the
average number of offspring produced at age x. Enter your answer as a decimal in the
format "#.#". - Answers -2.7
Which situation(s) would represent a trade-off between survival and reproduction?
Select all that apply. - Answers -ALL:
- Mating activity and egg production reduce the longevity of both sexes
- Survival to greater age comes at the expense of early reproduction
- Human parents have less sleep and higher rates of disease infection than
nonreproductive individuals
- Producing more offspring results in smaller offspring
True or False: Option B is the better life history table under r selection in terms of
population growth rate. - Answers -False
If individuals reproduce asexually and always have two offspring, population growth will
be Exponential (2^x) .
If individuals reproduce sexually and always have two offspring, population growth will
be Constant (c) .
Based on the answers to a) and b), the asexual reproductive type will be more fit than
the sexual type. - Answers -- Exponential (2^x)
- Constant (c)
- More fit than
Genetically identical twins have different personalities and grow to different heights -
Answers -Explained by environmental differences
E. coli cells exhibit different growth rates when cultured in the lab under the same
temperature, light, and food - Answers -Explained by genetic differences
Cancer risk is determined by genetic mutations, and environmental effects play a small
role - Answers -Nature vs. Nurture
Cancer risk is determined by how environmental factors mediate the effect of genetic
mutations by activating different combinations of genes - Answers -Nature and Nurture
Directional selection - Answers -No or minimal change in variance of trait distribution
stabilizing selection - Answers -decrease in trait distribution variance
disruptive selection - Answers -increase in trait distribution variance
Consider a new, hypothetical scenario where you observed the Darwin's finch,
Geospiza difficilis, before and after a drought. Now imagine that you looked at the
offspring of the survivors. Using this data, what are Δz, h2, and S? - Answers -Delta(z)
= 0; h2 = 0; and S = -0.5 mm
Mutations causing persistence of the lactase enzyme after infanthood explain much but
not all of human phenotypic variation in lactose tolerance. Some gut bacteria also
produce a lactase enzyme, which helps people digest lactose and improves their
tolerance. What is the reaction norm for lactose tolerance given the environmental
difference of absence/presence of bacteria in this case? - Answers -B - Linear increase
(diagonal up from left to right)
Certain mutations cause a crossvein in the wing of Drosophila to fail to develop if the fly
is subjected to heat shock in the pupal stage. Conrad Waddington bred a population in
which individuals subjected to high temps failed to develop the crossvein. After further
selection, the population lacked the crossvein even without heat shock, and this
condition was heritable. Match the reaction norms for 1) the wildtype genotype with the
crossvein and no plasticity, 2) Waddington's artificially bred genotype that reacted to
heat, and 3) the final mutant genotype after genetic assimilation - Answers -A -
diagonal down from left to right - Waddington's artificial
B- strait no slope from cold to hot Present crossvein - wildtype crossover
C- strait no slope absent crossvein - After genetic assimilation
, Does the figure show Gene X Environment Interaction? Why? Choose all correct
answers below. - Answers -Yes, because the montane and lowland genotypes show
different slopes AND Yes, because there is non-linearity in the reaction norms
Why does the evidence from Beldade's artificial selection experiments and data from
other species support adaptation rather than constraints for B. anynana's reaction
norm? - Answers -Hypothesis B, because genetic variation does exist allowing
evolution in the reaction norm but the norm remains stable in the wild
Which of these options best matches the pattern we expect from a selective sweep?
(Hint: think about what happens to heterozygosity in each case.) - Answers -B - from
dispersed to entirely homogenous
DN/DS - Answers -
Calculate the growth rate (R) of Species B based on the life history table below.
Remember that x is the age, lx is the chance of surviving to age x, and mx is the
average number of offspring produced at age x. Enter your answer as a decimal in the
format "#.#" - Answers -2.4
Calculate the growth rate (R) of a mutant in Species B based on the life history table
below. Remember that x is the age, lx is the chance of surviving to age x, and mx is the
average number of offspring produced at age x. Enter your answer as a decimal in the
format "#.#". - Answers -2.7
Which situation(s) would represent a trade-off between survival and reproduction?
Select all that apply. - Answers -ALL:
- Mating activity and egg production reduce the longevity of both sexes
- Survival to greater age comes at the expense of early reproduction
- Human parents have less sleep and higher rates of disease infection than
nonreproductive individuals
- Producing more offspring results in smaller offspring
True or False: Option B is the better life history table under r selection in terms of
population growth rate. - Answers -False
If individuals reproduce asexually and always have two offspring, population growth will
be Exponential (2^x) .
If individuals reproduce sexually and always have two offspring, population growth will
be Constant (c) .
Based on the answers to a) and b), the asexual reproductive type will be more fit than
the sexual type. - Answers -- Exponential (2^x)
- Constant (c)
- More fit than
