Question 1

In southwestern Arizona,the melanocortin 1 receptor mutation-bearing mice (dark hair)are commonly found in:
A)rocky lava outcrops.
B)stream beds.
C)sandy desert regions.
D)mixed rodent populations.
E)high mountain regions.

Accepted Answer

The melanocortin 1 receptor mutation-bearing mice, which have dark hair, are commonly found in rocky lava outcrops in southwestern Arizona. This is because the dark fur provides camouflage against the dark rocks, offering protection from predators.

Question 2

Assume that the following amino acid sequences were obtained for a highly conserved gene,gene X,in eukaryotes.Using this information,determine the most probable ancestral amino acid sequence.

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Question 3

What is meant by the phrase,"The force of selection is myopic."?

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Question 4

Define the molecular clock.

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Question 5

Some of the most striking and best understood examples of morphological divergence are found in:
A)populations of antibiotic resistant bacteria.
B)virology.
C)animal body-color patterns.
D)mouse eye-color mutants.
E)blood-type examples in mammals.

Accepted Answer

Animal body-color patterns are a classic example of morphological divergence, as different populations of animals may have evolved unique coloration patterns based on their environment, predators, and other selective pressures. This can lead to striking differences in appearance, even among closely related species.

Answer: D 
 Mouse eye-color mutants are another well-studied example of morphological divergence, as different strains of laboratory mice have been selectively bred for specific eye color traits. This has allowed researchers to investigate the genetic and developmental mechanisms underlying these morphological changes in detail.

Note: While antibiotic-resistant bacteria and blood types in mammals are important examples of evolution and adaptation, they are not necessarily examples of morphological divergence specifically. Virology is also an important field, but not directly relevant to the question of morphological divergence.

Question 6

How will pleiotropy affect selection at particular loci?

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Question 7

Organophosphate resistance in the sheep blowfly (Luciliacuprina)is an example of:
A)the toxicity of insecticides.
B)the generation of neutral mutations over time.
C)a lethal frameshift mutation.
D)cumulative selection.
E)evolutionary selection of a single amino acid change in a protein.

Accepted Answer

Organophosphate resistance in the sheep blowfly is an example of evolutionary selection of a single amino acid change in a protein. Specifically, a mutation in the acetylcholinesterase enzyme pathway results in a change in a single amino acid that allows the blowfly to break down the insecticide more effectively, leading to resistance. This is an example of adaptive evolution through natural selection.

Question 8

Describe how a population can shift adaptive peaks.Be clear about what mechanisms can accomplish this transition.

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Question 9

A strawberry breeder wants to increase the yield of strawberry plants.To do so,he selects the two highest-yielding plants from a segregating population and uses them as parents that he hopes will produce higher yielding offspring.How would you use Darwin's evolutionary theory to explain the following results?
a)The breeder was able to obtain a better-yielding offspring.
b)The breeder was unable to obtain a better-yielding offspring.

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Question 10

An adaptive walk of beta-lactamase in response to selective pressure exerted by cefotaxime likely involved:
A)the random generation of five changes that provide microbial resistance to the antibiotic.
B)sequential changes in single amino acids that each provided an incremental level of resistance to the antibiotic.
C)increased genetic change induced by selective pressure exerted by the antibiotic.
D)one clear beneficial change and several non-impactful changes in the gene.
E)major shifts in the metabolic pathways in the microbe under selection.

Accepted Answer

An adaptive walk involves sequential changes in a gene, with each change providing an incremental level of adaptation to the selective pressure. Therefore, option B is the best choice since it suggests that the beta-lactamase changes via small incremental changes in single amino acids to adapt to selective pressure exerted by cefotaxime. Option A suggests changes generated randomly, and option C is vague as it does not explain the specific mechanisms of the genetic changes induced by the antibiotic. Option D suggests a clear beneficial effect but with several non-impactful changes, which is not representative of an adaptive walk. Option E suggests a shift in the metabolic pathway, which is not relevant to the adaptation of the beta-lactamase gene to antibiotic pressure.

Question 11

In E.coli,the mutation of beta-lactamase in response to cefotaxime exposure involved five changes in the gene sequence,which can be accomplished through __________ different orderings.
A)16
B)32
C)64
D)120
E)240

Accepted Answer

The number of different orderings for five changes can be calculated using the formula for permutations, which is n! (n factorial), where n is the number of items to arrange. For 5 changes, it's 5! = 5 x 4 x 3 x 2 x 1 = 120.

Question 12

The rate of change is not identical for all genes.The following graph shows the rate of change of four hypothetical human proteins (A-D).Use this graph to answer the following questions.
  
 a)Which of the proteins is changing at the fastest rate?
b)Which protein is most conserved?
c)Which evolutionary force (drift,selection,or migration)plays the biggest role in causing the observed difference in the rate of change between proteins A-D?
d)If you do Southern hybridization to determine if the genes encoding each of these human proteins (A-D)also exist in rice,which would give the strongest hybridization signal? Justify your answer.
e)If you were going to use one of the proteins to build a phylogenetic tree of various mammalian species (which diverged during the last 50 million years),which protein sequence would be most useful? Justify your answer.
f)If you were going to use one of the proteins to build a phylogenetic tree of various plant species (which diverged during the past 500 million years),which protein sequence would be most useful? Justify your answer.
g)If you were going to use one of the proteins to build a phylogenetic tree of a mixture of plant and animal species (which diverged 1200 million years ago),which protein sequence would be most useful? Justify your answer.

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Question 13

Darwin's theory of evolution was developed around three central principles: the principle of variation,the principle of heredity,and the principle of selection.Define each of these principles,and explain their role in evolution.

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Question 14

Inherited blindness in some cavefish arose through:
A)an individual mutant fish that displayed reproductive success.
B)atrophy of the eye when unused in darkness.
C)viral infection of the optic nerve.
D)a defect in gene splicing.
E)separate incidences of inactivating mutation in the Oca2 gene.

Accepted Answer

Inherited blindness in some cavefish is due to separate incidences of inactivating mutation in the Oca2 gene. This has been observed in multiple populations of different cavefish species, indicating convergent evolution of this trait.

Question 15

In fruit flies,mutations in cis-acting regulatory sequences are associated with:
A)abnormal functioning of operator sequences.
B)body form/color variations.
C)changes in fruit fly behavior.
D)changes in reproductive fitness.
E)an alteration of DNA replication.

Accepted Answer

Cis-acting regulatory sequences control the expression of genes that can lead to variations in body form and color in fruit flies.

Question 16

An excess of nonsynonymous fixed mutations between species is likely due to:
A)natural selection.
B)random genetic drift.
C)a catastrophic event.
D)inbreeding.
E)immigration.

Accepted Answer

An excess of nonsynonymous fixed mutations between species suggests that natural selection is at play. This is because nonsynonymous mutations affect the amino acid sequence of a protein, and if these mutations are fixed in a species it suggests that they provide some selective advantage for that species compared to its ancestor. Random genetic drift would not necessarily result in an excess of nonsynonymous mutations, and neither would catastrophic events, inbreeding, or immigration.

Question 17

Wichman and colleagues examined adaptive walks using:
A)antibiotic selection on bacteriophage populations.
B)bacteriophage infection of mutation-bearing bacteria.
C)a bacteriophage and two different host cell types.
D)mutagenic compounds delivered to rapidly dividing phage virions.
E)None of the answer options are correct.

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A)antibiotic...

Question 18

An orchid breeder is interested in increasing the number of stems and the length of stems that can be produced by an orchid plant.She finds a segregating population that contains a wide range of both stem number (ranging from 2 to15 stems per plant)and stem length (ranging from 2 to 7 inches in length).She selected plants from this population that either had the most stems per plant or the longest stems per plant (shown as filled regions in the diagrams below).She then interbred the plants with the most stems (or the longest stems)and grew the resulting populations of orchids.Following an additional round of selection and breeding,the breeder drew graphs to look at the distribution of plants in each generation.Shown below are graphs representing the distribution of plants in each generation in terms of stem number and stem length (in inches).For each trait,determine whether or not the trait is heritable.Justify your answers.

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Question 19

The melanocortin 1 receptor protein displays four amino acid substitutions between dark- and light-colored populations of pocket mice.In dark mice,these unique amino acids cause the receptor to:
A)fold inappropriately in the cell membrane.
B)incorrectly identify ligand.
C)be non-functional in regulating gene expression.
D)be internalized and degraded.
E)be constitutively active.

Accepted Answer

These unique amino acids in dark mice cause the melanocortin 1 receptor to be constitutively active, which means it is always turned on, leading to the production of dark pigments in these mice.

Question 20

Can behaviors be the product of selection,even when their heritability is either very low or zero? Justify your answer.

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Quiz 20: Evolution of Genes and Traits

In southwestern Arizona,the melanocortin 1 receptor mutation-bearing mice (dark hair) are commonly found in:

Assume that the following amino acid sequences were obtained for a highly conserved gene,gene X,in eukaryotes.Using this information,determine the most probable ancestral amino acid sequence.

What is meant by the phrase,"The force of selection is myopic."?

Define the molecular clock.

Some of the most striking and best understood examples of morphological divergence are found in:

How will pleiotropy affect selection at particular loci?

Organophosphate resistance in the sheep blowfly (Luciliacuprina) is an example of:

Describe how a population can shift adaptive peaks.Be clear about what mechanisms can accomplish this transition.

An adaptive walk of beta-lactamase in response to selective pressure exerted by cefotaxime likely involved:

In E.coli,the mutation of beta-lactamase in response to cefotaxime exposure involved five changes in the gene sequence,which can be accomplished through __________ different orderings.

Darwin's theory of evolution was developed around three central principles: the principle of variation,the principle of heredity,and the principle of selection.Define each of these principles,and explain their role in evolution.

Inherited blindness in some cavefish arose through:

In fruit flies,mutations in cis-acting regulatory sequences are associated with:

An excess of nonsynonymous fixed mutations between species is likely due to:

Wichman and colleagues examined adaptive walks using:

The melanocortin 1 receptor protein displays four amino acid substitutions between dark- and light-colored populations of pocket mice.In dark mice,these unique amino acids cause the receptor to:

Can behaviors be the product of selection,even when their heritability is either very low or zero? Justify your answer.