Genetics and Evolution - Biology
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A species of bird has an allele for black feathers and an allele for blue feathers. Which of the following scenarios would violate the necessary conditions for Hardy-Weinberg equilibrium in a population of this species?
A species of bird has an allele for black feathers and an allele for blue feathers. Which of the following scenarios would violate the necessary conditions for Hardy-Weinberg equilibrium in a population of this species?
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If a population is in Hardy-Weinberg equilibrium, there is no evolution taking place in the population. One of the violations of Hardy-Weinberg equilibrium is selective mating. If birds prefer to mate with others that are similarly colored, then Hardy-Weinberg equilibrium is violated and the gene pool in the population is changing.
Hardy-Weinberg requires no migration, random mating, large population size, no natural selection, and no mutation.
If a population is in Hardy-Weinberg equilibrium, there is no evolution taking place in the population. One of the violations of Hardy-Weinberg equilibrium is selective mating. If birds prefer to mate with others that are similarly colored, then Hardy-Weinberg equilibrium is violated and the gene pool in the population is changing.
Hardy-Weinberg requires no migration, random mating, large population size, no natural selection, and no mutation.
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Which of the following is NOT a requirement for Hardy-Weinberg equilibrium?
Which of the following is NOT a requirement for Hardy-Weinberg equilibrium?
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Hardy-Weinberg equilibrium has a set of conditions that must be met in order for the population to have unchanging gene pool frequencies. There must be random mating, no mutation, no migration, no natural selection, and a large sample size.
It is not necessary for the population to be at carrying capacity. The population can grow or shrink while maintaining the gene pool.
Hardy-Weinberg equilibrium has a set of conditions that must be met in order for the population to have unchanging gene pool frequencies. There must be random mating, no mutation, no migration, no natural selection, and a large sample size.
It is not necessary for the population to be at carrying capacity. The population can grow or shrink while maintaining the gene pool.
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Which of the following is not one of the major causes of evolutionary change as outlined by Hardy-Weinberg equilibrium?
Which of the following is not one of the major causes of evolutionary change as outlined by Hardy-Weinberg equilibrium?
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The Hardy-Weinberg principle is a mathematical model proposing that, under certain conditions, the allele frequencies and genotype frequencies in a sexually reporoducing population will remain constant over generations. For this principle to hold true, evolution must essentially be stopped. The conditions to maintain the Hardy-Weinberg equilibrium are: no mutation, no gene flow, large population size, random mating, and no natural selection.
The Hardy-Weinberg equilibrium can be disrupted by deviations from any of its five main underlying conditions. Therefore mutation, gene flow, small population, nonrandom mating, and natural selection will disrupt the equilibrium.
Differentiation is the process whereby relatively unspecialized cells become specialized into particular tissue types. This is a standard process in organismal development, and is generally unrelated to evolutionary principles.
The Hardy-Weinberg principle is a mathematical model proposing that, under certain conditions, the allele frequencies and genotype frequencies in a sexually reporoducing population will remain constant over generations. For this principle to hold true, evolution must essentially be stopped. The conditions to maintain the Hardy-Weinberg equilibrium are: no mutation, no gene flow, large population size, random mating, and no natural selection.
The Hardy-Weinberg equilibrium can be disrupted by deviations from any of its five main underlying conditions. Therefore mutation, gene flow, small population, nonrandom mating, and natural selection will disrupt the equilibrium.
Differentiation is the process whereby relatively unspecialized cells become specialized into particular tissue types. This is a standard process in organismal development, and is generally unrelated to evolutionary principles.
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Which of the following is NOT one of the assumptions made by Hardy and Weinberg regarding Hardy-Weinberg equilibrium?
Which of the following is NOT one of the assumptions made by Hardy and Weinberg regarding Hardy-Weinberg equilibrium?
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All of the answer choices are assumptions made when considering Hardy-Weinberg equilibrium. Thus, the model is not very realistic in nature, since these conditions are rarely met. Also, no natural selection is assumed to occur.
All of the answer choices are assumptions made when considering Hardy-Weinberg equilibrium. Thus, the model is not very realistic in nature, since these conditions are rarely met. Also, no natural selection is assumed to occur.
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A lake contains a population of twelve bluegill fish, 8 with red spots and 4 with no red spots. The fish are healthy and strong, all exactly the same except for the coloring. Fishermen visit the lake, and catch 7 fish with red spots and 1 fish with no red spots, leaving 1 with red spots and 3 without red spots remaining in the lake. This change in the population is an example of .
A lake contains a population of twelve bluegill fish, 8 with red spots and 4 with no red spots. The fish are healthy and strong, all exactly the same except for the coloring. Fishermen visit the lake, and catch 7 fish with red spots and 1 fish with no red spots, leaving 1 with red spots and 3 without red spots remaining in the lake. This change in the population is an example of .
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All the factors listed are factors that can change the genetic equilibrium of a population. Genetic drift is a random change in the frequency of alleles, as in this question—at first, there were more red-spotted fish than spotless fish (a 2:1 ratio), but once the random fishing took place, there were fewer red-spotted fish than spotless fish (a 1:3 ratio). This selection by chance is genetic drift.
Gene flow is the movement of alleles into or out of a population, generally due to patterns of migration.
Migration is the physical departure or arrival of organisms between different populations or geographical locations.
Natural selection is the increased prevalence of "favorable" traits and genes, and the decline in prevalence of "unfavorable" traits and genes.
Mutation is a genetic alteration that results in a new DNA sequence. Mutation is responsible for the creation of new alleles, traits, and phenotypes.
All the factors listed are factors that can change the genetic equilibrium of a population. Genetic drift is a random change in the frequency of alleles, as in this question—at first, there were more red-spotted fish than spotless fish (a 2:1 ratio), but once the random fishing took place, there were fewer red-spotted fish than spotless fish (a 1:3 ratio). This selection by chance is genetic drift.
Gene flow is the movement of alleles into or out of a population, generally due to patterns of migration.
Migration is the physical departure or arrival of organisms between different populations or geographical locations.
Natural selection is the increased prevalence of "favorable" traits and genes, and the decline in prevalence of "unfavorable" traits and genes.
Mutation is a genetic alteration that results in a new DNA sequence. Mutation is responsible for the creation of new alleles, traits, and phenotypes.
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Which of the following is not an application of the assumptions underlying Hardy-Weinberg equilibrium?
Which of the following is not an application of the assumptions underlying Hardy-Weinberg equilibrium?
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For Hardy-Weinberg equilibrium to be in effect, five conditions must be met:
1. Large Population
2. Isolated populations (no immigration or emigration)
3. No spontaneous mutations
4. Mating is random
5. No natural selection
For Hardy-Weinberg equilibrium to be in effect, five conditions must be met:
1. Large Population
2. Isolated populations (no immigration or emigration)
3. No spontaneous mutations
4. Mating is random
5. No natural selection
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Which of these factors would not contribute to Hardy-Weinberg equilibrium?
Which of these factors would not contribute to Hardy-Weinberg equilibrium?
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Hardy-Weinberg equilibrium describes no change in genotypic frequencies over multiple generations. This is not likely to be seen in nature due to multiple factors, but it can be a useful theory for scientists. Hardy-Weinberg equilibrium requires no immigration or emigration, a large population, random mating, and no spontaneous mutations (all of which are virtually unavoidable in nature). Natural selection would violate these conditions.
Hardy-Weinberg equilibrium describes no change in genotypic frequencies over multiple generations. This is not likely to be seen in nature due to multiple factors, but it can be a useful theory for scientists. Hardy-Weinberg equilibrium requires no immigration or emigration, a large population, random mating, and no spontaneous mutations (all of which are virtually unavoidable in nature). Natural selection would violate these conditions.
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If all Hardy-Weinberg conditions are met, what will be the result?
If all Hardy-Weinberg conditions are met, what will be the result?
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Hardy-Weinberg equilibrium describes no change in the genotypic frequencies of a population. After one generation, assuming random mating, a closed system, a large population, and no random mutations, the genotypic frequencies of the population will not change.
Hardy-Weinberg equilibrium describes no change in the genotypic frequencies of a population. After one generation, assuming random mating, a closed system, a large population, and no random mutations, the genotypic frequencies of the population will not change.
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Consider a population in Hardy-Weinberg equilibrium. A gene in the population has two alleles. The gene pool shows a distribution of 80% of the dominant allele and 20% the recessive allele.
What percentage of the population is heterozygous for the trait?
Consider a population in Hardy-Weinberg equilibrium. A gene in the population has two alleles. The gene pool shows a distribution of 80% of the dominant allele and 20% the recessive allele.
What percentage of the population is heterozygous for the trait?
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Since the population is in Hardy-Weinberg equilibrium, we can use the following equation to determine the genotypic frequencies for the allele in question:
In this equation, 
represents the frequency of the dominant allele and 
represents the frequency of the recessive allele. The 
portion of the expression represents the frequency of heterozygotes in the population. Using the allelic frequencies given in the question, we can calculate the percentage of heterozygous individuals.
32% of the population is heterozygous for the trait.
Since the population is in Hardy-Weinberg equilibrium, we can use the following equation to determine the genotypic frequencies for the allele in question:
In this equation,
32% of the population is heterozygous for the trait.
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For a particular gene, the allele 
is dominant to the allele 
. If in a population the allele frequency for 
is 0.85, what is the frequency of individuals that are heterozygotes? Assume Hardy-Weinberg equilibrium conditions are met.
For a particular gene, the allele
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There are two equations for Hardy-Weinberg equilibrium:
Using the first equation, we can substitute in 0.85 for 
and solve to get 
.
We can then use the second equation to find the frequencies of each genotype.
= frequency of 
genotype
= frequency of 
genotype
(Why do we multiply by 2? Because we must count both 
and 
as heterozygotes.)
= frequency of 
genotype
Thus we get 
.
There are two equations for Hardy-Weinberg equilibrium:
Using the first equation, we can substitute in 0.85 for
We can then use the second equation to find the frequencies of each genotype.
(Why do we multiply by 2? Because we must count both
Thus we get
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In a population of rabbits, the dominant B allele produces brown fur and the recessive b allele produces white fur. There are 544 brown rabbits and 306 white rabbits in the population.
How many of the brown rabbits would you expect to be homozygous dominant (BB)?
In a population of rabbits, the dominant B allele produces brown fur and the recessive b allele produces white fur. There are 544 brown rabbits and 306 white rabbits in the population.
How many of the brown rabbits would you expect to be homozygous dominant (BB)?
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In the Hardy-Weinberg equation, the value of the term 
is the percentage of homozygous dominant (BB) individuals in a population. Thus, to answer this question we will need to solve for 
.
With the information we are given, we can calculate 
, which is the percentage of the population that is homozygous recessive (bb). We know the total number of homozygous recessive rabbits (306 white rabbits) and the total number of rabbits in the population (306 + 544 = 850). We can thus divide the number of white rabbits by the population total to find 
:
36% of the population is homozygous recessive. We then take the square root of 
to find 
:
This value tells us that 60% of all the alleles in the population are recessive (b).
The Hardy-Weinberg equation is based off the idea that the total number of alleles in a population is the sum of the dominant and recessive alleles, as shown by this equation:
We can use this equation to solve for 
using 
:
This value tells us that 40% of all the alleles in the population are dominant (B).
We can now square to obtain . Recall that this will be the frequency of homozygous dominant individuals in the population:
The result is 16%, meaning 16% of the rabbits in the population are homozygous dominant. We can then multiply 16% by the total population to find the number of rabbits who are homozygous dominant:
Thus, 136 homozygous dominant rabbits would be expected in this population.
In the Hardy-Weinberg equation, the value of the term
With the information we are given, we can calculate
36% of the population is homozygous recessive. We then take the square root of
This value tells us that 60% of all the alleles in the population are recessive (b).
The Hardy-Weinberg equation is based off the idea that the total number of alleles in a population is the sum of the dominant and recessive alleles, as shown by this equation:
We can use this equation to solve for
This value tells us that 40% of all the alleles in the population are dominant (B).
We can now square
The result is 16%, meaning 16% of the rabbits in the population are homozygous dominant. We can then multiply 16% by the total population to find the number of rabbits who are homozygous dominant:
Thus, 136 homozygous dominant rabbits would be expected in this population.
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A population of frogs, which is at equilibrium, carries a dominant allele for black spots (B) and a recessive allele for no spots (b). 76 frogs have no spots, and 399 frogs have black spots.
How many of the frogs are heterozygous (Bb) for the black spot trait?
A population of frogs, which is at equilibrium, carries a dominant allele for black spots (B) and a recessive allele for no spots (b). 76 frogs have no spots, and 399 frogs have black spots.
How many of the frogs are heterozygous (Bb) for the black spot trait?
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In the Hardy-Weinberg equation, the value of the term 
is the percentage of heterozygous (Bb) individuals in a population. Thus, to answer this question we will need to solve for 
.
With the information we are given, we can calculate , which is the percentage of the population that is homozygous recessive (bb). We know the total number of homozygous recessive rabbits (76 without spots) and the total number of rabbits in the population (76+ 399= 475). We can thus divide the number of frogs without spots by the population total to find :
16% of the population is homozygous recessive. We then take the square root of to find :
This value tells us that 40% of all the alleles in the population are recessive (b).
The Hardy-Weinberg equation is based off the idea that the total number of alleles in a population is the sum of the dominant and recessive alleles, as shown by this equation:
We can use this equation to solve for using :
This value tells us that 60% of all the alleles in the population are dominant (B).
Now that we have 
and , we can calculate 
. Recall that this will be the frequency of heterozygous individuals in the population:
The result is 48%, meaning 48% of the frogs in the population are heterozygous. We can then multiply 48% by the total population to find the number of frogs who are heterozygous::
Thus, 228 heterozygous frogs would be expected in this population.
In the Hardy-Weinberg equation, the value of the term
With the information we are given, we can calculate
16% of the population is homozygous recessive. We then take the square root of
This value tells us that 40% of all the alleles in the population are recessive (b).
The Hardy-Weinberg equation is based off the idea that the total number of alleles in a population is the sum of the dominant and recessive alleles, as shown by this equation:
We can use this equation to solve for
This value tells us that 60% of all the alleles in the population are dominant (B).
Now that we have
The result is 48%, meaning 48% of the frogs in the population are heterozygous. We can then multiply 48% by the total population to find the number of frogs who are heterozygous::
Thus, 228 heterozygous frogs would be expected in this population.
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In an isolated population of ants in the Amazon rainforest, color is determined by a single gene. Ants that are homozygous dominant (BB) and heterozygous (Bb) for this gene are black, but ants that are homozygous recessive (bb) for this gene are brown.
If the phenotype frequencies are 0.75 black and 0.25 brown, what are the allele frequencies within this population?
In an isolated population of ants in the Amazon rainforest, color is determined by a single gene. Ants that are homozygous dominant (BB) and heterozygous (Bb) for this gene are black, but ants that are homozygous recessive (bb) for this gene are brown.
If the phenotype frequencies are 0.75 black and 0.25 brown, what are the allele frequencies within this population?
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We can use the Hardy-Weinberg equations to solve this question:
We know that the black allele (B) is dominant and the brown allele (b) is recessive.
Using these two equations, we know that 0.25 are homozygous recessive (brown). This value will be equal to 
.
We can then solve as follows:
Therefore, we know that the frequency of each allele is equal to 0.5.
We can use the Hardy-Weinberg equations to solve this question:
We know that the black allele (B) is dominant and the brown allele (b) is recessive.
Using these two equations, we know that 0.25 are homozygous recessive (brown). This value will be equal to
We can then solve as follows:
Therefore, we know that the frequency of each allele is equal to 0.5.
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If p=0.3 and q=0.7, what will be the final genotypic frequencies of a population be under Hardy-Weinberg equilibrium?
If p=0.3 and q=0.7, what will be the final genotypic frequencies of a population be under Hardy-Weinberg equilibrium?
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Recall that under Hardy-Weinberg conditions, the allele frequencies remain constant. The formulas for Hardy-Weinberg equilibrium are:
and
Here, 
is the frequency of the homozygous dominant genotype, 
is the frequency of the heterozygous genotype, and 
is the frequency of the homozygous recessive genotype. Since we have all the variables we need, and we want to find the genotypic frequencies (not the phenotypic) we plug into the second equation.
Be sure to check to make sure these frequencies add up to 1.
Recall that under Hardy-Weinberg conditions, the allele frequencies remain constant. The formulas for Hardy-Weinberg equilibrium are:
and
Here,
Be sure to check to make sure these frequencies add up to 1.
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If p=0.9 and q=0.1 what will be the final genotypic frequencies of a population be under Hardy-Weinberg equilibrium?
If p=0.9 and q=0.1 what will be the final genotypic frequencies of a population be under Hardy-Weinberg equilibrium?
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Recall that under Hardy-Weinberg conditions, the allele frequencies remain constant. The formulas for Hardy-Weinberg equilibrium are:
and
Here, 
is the frequency of the homozygous dominant genotype, 
is the frequency of the heterozygous genotype, and 
is the frequency of the homozygous recessive genotype. Since we have all the variables we need, and we want to find the genotypic frequencies (not the phenotypic) we plug into the second equation.
Be sure to check to make sure these frequencies add up to 1.
Recall that under Hardy-Weinberg conditions, the allele frequencies remain constant. The formulas for Hardy-Weinberg equilibrium are:
and
Here,
Be sure to check to make sure these frequencies add up to 1.
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Tail length in a population of aardvarks is determined by one gene, where L=long tails and l=short tails. If the frequency of L in the population is 0.4, determine the expected frequencies of each possible genotype: homozygous dominant (LL), heterozygous (Ll), and homozygous recessive (ll).
Tail length in a population of aardvarks is determined by one gene, where L=long tails and l=short tails. If the frequency of L in the population is 0.4, determine the expected frequencies of each possible genotype: homozygous dominant (LL), heterozygous (Ll), and homozygous recessive (ll).
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To begin, we must know that we are working with the Hardy-Weinberg equations:
We can designate the dominant allele (L) as 
and the recessive allele (l) as 
.
Since the frequency of L was given (0.4) we know the the frequency of l must be:
Now we have both allele frequencies and can plug them into the equation:
So for 
, LL (homozygous dominant), is equal to 0.16
for 
, Ll (heterozygous), is equal to 0.48
for 
, ll (homozygous recessive), is equal to 0.36
To begin, we must know that we are working with the Hardy-Weinberg equations:
We can designate the dominant allele (L) as
Since the frequency of L was given (0.4) we know the the frequency of l must be:
Now we have both allele frequencies and can plug them into the equation:
So for
for
for
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Which of the following is an example of co-evolution?
Which of the following is an example of co-evolution?
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Co-evolution is defined as a change of two or more species in close association with one another. Co-evolution is most common with mutualistic relationships, in which both species gain benefit. Such evolution can result in symbiotic relationships, in which the organisms depend on one another for survival. For example, bees make honey from flowers and flowers are pollinated by bees. Neither species can survive without the other.
Parasitism, commensalism, and predator-prey relationships can also demonstrate co-evolution, as one species develops defenses and the other develops offensive traits.
Co-evolution is defined as a change of two or more species in close association with one another. Co-evolution is most common with mutualistic relationships, in which both species gain benefit. Such evolution can result in symbiotic relationships, in which the organisms depend on one another for survival. For example, bees make honey from flowers and flowers are pollinated by bees. Neither species can survive without the other.
Parasitism, commensalism, and predator-prey relationships can also demonstrate co-evolution, as one species develops defenses and the other develops offensive traits.
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Which of the following statements is true for genetic drift in a large population?
Which of the following statements is true for genetic drift in a large population?
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Genetic drift can be defined as changes in allele frequencies in a population caused by random events or chance. Large populations are capable of retaining fairly stable allele frequencies, thereby maintaining a small degree of genetic drift.
In contrast, in a small population, either losing the alleles of a single individual or an over-contribution by a single individual in reproduction can significantly change the frequency of alleles within the population. This could eventually lead to the loss of alleles from the population.
Genetic drift can be defined as changes in allele frequencies in a population caused by random events or chance. Large populations are capable of retaining fairly stable allele frequencies, thereby maintaining a small degree of genetic drift.
In contrast, in a small population, either losing the alleles of a single individual or an over-contribution by a single individual in reproduction can significantly change the frequency of alleles within the population. This could eventually lead to the loss of alleles from the population.
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Which of the following describes the endosymbiotic theory?
Which of the following describes the endosymbiotic theory?
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The endosymbotic theory describes the evolution of eukaryotic cells from prokaryotes. Small independent organisms were engulfed by larger ones; both were prokaryotic and unicellular. This engulfment benefited both organisms, and the genes that promoted this engulfment were selected for. Over a long time, eukaryotic cells evolved with many membrane-bound organelles, each with their own specific structure.
The endosymbotic theory describes the evolution of eukaryotic cells from prokaryotes. Small independent organisms were engulfed by larger ones; both were prokaryotic and unicellular. This engulfment benefited both organisms, and the genes that promoted this engulfment were selected for. Over a long time, eukaryotic cells evolved with many membrane-bound organelles, each with their own specific structure.
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Which of the following is not an example of evolution?
Which of the following is not an example of evolution?
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Evolution must occur over many generations and a long time scale. Changes within the life of an individual do not constitute evolution. Thus, a tadpole becoming a frog is not evolution.
Evolution must occur over many generations and a long time scale. Changes within the life of an individual do not constitute evolution. Thus, a tadpole becoming a frog is not evolution.
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