Question 1

A process that prevents the production of much higher amounts of protein in females than in males is known as
A) X inactivation.
B) imprinting.
C) crossing over.
D) linkage.

Accepted Answer

X inactivation is a process that occurs in females, where one of the two X chromosomes is randomly inactivated in each cell to prevent the overproduction of protein from the extra X chromosome. This ensures that males and females produce a similar amount of protein from the X chromosome. Imprinting, crossing over, and linkage do not have a direct effect on the production of protein in males and females.

Question 2

A characteristic that results from genes on the X chromosome that are not duplicated on the Y chromosomes is referred to as being
A) recessive.
B) mutated.
C) an SNP.
D) sex-linked.

Accepted Answer

A characteristic that results from genes on the X chromosome that are not duplicated on the Y chromosome is referred to as being sex-linked. This is because these genes are found exclusively on the sex chromosomes, and their expression is influenced by an individual's sex. The Y chromosome does not carry these genes, so males (who have one X and one Y chromosome) may express different traits than females (who have two copies of the X chromosome).

Question 3

The Minnesota Study of Twins Reared Apart found support for which of the following conclusions?
A) Identical twins are very similar to each other on a number of traits, regardless of whether the correlation for any particular trait was high or low.
B) Identical twins raised together are very similar to each other on a number of traits, but identical twins raised apart are not.
C) Identical twins are very similar on traits that are highly correlated, like fingerprint ridges, but not similar to each other on traits that are not highly correlated, like nonreligious social attitudes.
D) Identical twins are no more similar to each other on highly correlated traits than fraternal twins and non-twin siblings.

Accepted Answer

The Minnesota Study of Twins Reared Apart found support for the conclusion that identical twins are very similar to each other on a number of traits, regardless of whether the correlation for any particular trait was high or low. This suggests a strong genetic influence on these traits.

Question 4

Amber and Rachel are identical twins who were raised together, and Nicole and Kayla are identical twins who were adopted by different families at birth. Based on the findings of the Minnesota Study of Twins Reared Apart, what can we expect to see as these girls grow up?
A) Amber and Rachel will be have more similar nonreligious social attitudes than Nicole and Kayla.
B) Amber and Rachel will show about the same similarities in their nonreligious social attitudes as Nicole and Kayla.
C) Amber and Rachel will show less similarity in their nonreligious social attitudes than Nicole and Kayla.
D) None of the twins will share any substantial similarities in nonreligious social attitudes with her twin.

Accepted Answer

The Minnesota Study of Twins Reared Apart found that genetics play a significant role in shaping personality characteristics and attitudes. Therefore, since Amber and Rachel are identical twins raised together, they are likely to have more similar nonreligious social attitudes than Nicole and Kayla, who were raised in different families.

Question 5

Calico cats have splotches of colors of fur arrayed on them, with the color being determined by different alleles of an X chromosome gene. Calico cats
A) can be male or female.
B) are almost always male, because the calico condition is sex-linked.
C) are always female, because the calico condition results from x-inactivation.
D) are the result of spontaneous mutations that do not affect the sex chromosomes.

Accepted Answer

The calico condition is the result of x-inactivation, which only occurs in females. Therefore, calico cats are always female.

Question 6

Two important processes that produce lasting but reversible changes in gene expression are histone modification and __________.
A) imprinting
B) crossing-over
C) x-linked gene mapping suppression
D) DNA methylation

Accepted Answer

Histone modification and DNA methylation are both important processes that can produce lasting but reversible changes in gene expression. Histone modification involves the addition or removal of specific chemical groups to histone proteins, which can affect the accessibility of the DNA to the transcriptional machinery. DNA methylation involves the addition of a methyl group to cytosine residues in DNA, which can also change the accessibility of the DNA and affect gene expression. Imprinting, crossing-over, and x-linked gene mapping suppression are not processes that directly affect gene expression through histone or DNA modifications.

Question 7

_________ of the genes found on the X chromosome are duplicated on the Y chromosome.
A) All
B) None
C) Most
D) Some

Accepted Answer

Some of the genes found on the X chromosome are duplicated on the Y chromosome, but not all. The Y chromosome is much smaller than the X chromosome and carries only a fraction of the genes found on the X chromosome.

Question 8

When variations in a single base are responsible for the difference between two alleles, the resulting condition is known as
A) X inactivation.
B) an imprinted gene.
C) a SNP.
D) a mutation.

Accepted Answer

Single nucleotide polymorphisms (SNPs) are variations in a single base that can cause the difference between two alleles. X inactivation and imprinting involve epigenetic alterations and affect groups of genes, not just single nucleotides. Mutations can also cause differences between alleles, but this term is more general and can include larger changes in the DNA sequence beyond a single nucleotide.

Question 9

Red-green color deficiency is due to a recessive gene on the X chromosome. Women can be carriers or have color deficienty, and men are either color deficient or not. If an unaffected male and a female who is a carrier have children, what is your prediction as to the color deficiency status of their children?
A) Half of the couple's daughters, but none of their sons, are likely to have red-green color deficiency.
B) Half of the couple's sons, but none of their daughters, are likely to have red-green color deficiency.
C) None of the couple's children are likely to have red-green color deficiency.
D) All of the couple's children are likely to have red-green color deficiency.

Accepted Answer

Since the gene for red-green color deficiency is on the X chromosome, and the mother is a carrier (XcX), while the father is unaffected (XY), their sons (XY) have a 50% chance of inheriting the X chromosome with the deficiency from their mother, leading to color deficiency. Daughters (XX) would receive a normal X chromosome from their father, making them carriers if they inherit the affected X from their mother, but they would not express the deficiency themselves.

Question 10

Extreme skewing in x-inactivation has been linked with which of the following characteristics in offspring?
A) hemophilia
B) colorblindness
C) Alzheimer's disease
D) autoimmune diseases

Accepted Answer

Extreme skewing in X-inactivation has been linked to autoimmune diseases. X-inactivation is a process by which one of the copies of the X chromosome present in female mammals is inactivated. The skewing of this process can lead to an imbalance in gene expression, which has been associated with the development of autoimmune diseases.

Question 11

A mutation of a person's DNA
A) always has negative outcomes.
B) always has positive outcomes.
C) can have positive, negative, or neutral outcomes.
D) has neither positive nor negative outcomes, because they are always recessive.

Accepted Answer

Mutations can have various outcomes, including positive, negative, or neutral effects on an individual's traits or health. It depends on the specific gene that is affected by the mutation and the severity of the change. Therefore, option C is the best choice.

Question 12

Research has shown that a person's height is about 81 percent heritable, whereas his or her BMI is about 59 percent heritable. Which of the following is the most accurate interpretation of these findings?
A) The variability we see in a population's height is more influenced by genetic factors than the variability we see in the population's weight.
B) Environmental factors account for only 19 percent of a person's height and 41 percent of a person's BMI.
C) We cannot make any conclusions about genetic contributions to either height or weight.
D) Knowing the relative genetic contributions to traits such as height or weight does not allow us to compare these two unrelated characteristics of people.

Accepted Answer

The most accurate interpretation of these findings is that the variability we see in a population's height is more influenced by genetic factors than the variability we see in the population's weight. This is because the heritability estimate for height is 81%, compared to 59% for BMI. This means that genetic factors explain a larger portion of the variation in height than in BMI.

Question 13

In their study of the heritability of autistic traits among Dutch teens, Rosa Hoekstra and her colleagues were careful to choose participants from a variety of backgrounds and circumstances. Why is careful sampling especially important to studies of heritability?
A) The effects of genetics are most obvious in populations that exclude extreme environmental conditions, such as affluent or very poor families.
B) Environmental influences are magnified in extreme environmental conditions, such as among affluent or very poor families.
C) Extremes of environmental conditions, such as affluent or very poor families, tend to magnify the influence of genetics.
D) These precautions are really not relevant, because heritability cannot be assessed experimentally.

Accepted Answer

Careful sampling is important in heritability studies because extreme environmental conditions can magnify the influence of genetics. Therefore, it is important to include participants from various backgrounds and circumstances to avoid biases in the study results.

Question 14

Different versions of the APOE gene are correlated with the development of
A) hemophilia.
B) color deficiency.
C) breast cancer.
D) Alzheimer's disease.

Accepted Answer

Different versions of the APOE gene are associated with an increased risk of developing Alzheimer's disease. Specifically, the APOE ε4 allele is the strongest genetic risk factor for late-onset Alzheimer's disease.

Question 15

Kyle plants a group of seeds in a pot of enriched soil and provides all the seeds with identical temperature, lighting, and water. When his plants are mature, he notices that they are quite different in height. Which of the following is the best conclusion Kyle could draw from his observations?
A) The differences in the height of his plants are due to equal contributions of environmental and genetic variables.
B) Holding the plants' environment constant has magnified the influence of genetic differences on the height of the plants.
C) Genetic variables are more influential than environmental variables in determining the height of Kyle's plants.
D) Kyle lacks sufficient information to draw any scientific conclusions from his observations.

Accepted Answer

Since Kyle provided identical environmental conditions for all seeds, any observed differences in height must be due to differences in their DNA. Holding the environment constant has thus magnified the influence of genetic differences on plant growth. This suggests that genetic variables are more influential than environmental variables in this case.

Question 16

Compared with non-twin siblings, fraternal twins
A) experience the same level of genetic and environmental influence.
B) have more genes in common.
C) have fewer environmental influences in common.
D) have more environmental influences in common.

Accepted Answer

Fraternal twins share about 50% of their genetic material, just like non-twin siblings. However, they do share more environmental influences in common, such as pre-natal environment, early childhood experiences, and shared family and upbringing.

Question 17

The presence of a recessive allele can
A) only be expressed when paired with a matching allele.
B) influence a genotype but not a phenotype.
C) influence the phenotype of female children but not male children.
D) influence a phenotype when it occurs in chromosome pairs or on the X chromosome of a male.

Accepted Answer

The answer of  The presence of a recessive allele can
A)...

Question 18

Tom's father has hemophilia, but Tom does not have the disease. What are the chances that Tom's children will have hemophilia?
A) Tom's sons will almost certainly have it because Tom will have inherited the recessive gene from this father.
B) Tom's daughters may be carriers, but his sons will not have the gene.
C) All of Tom's children will be carriers, but it will not be expressed until they have children.
D) None of Tom's children will be carriers or have the illness because his X gene came from his mother, who is not a carrier.

Accepted Answer

Tom's father has hemophilia, which is a sex-linked recessive trait. This means that the gene for hemophilia is located on the X chromosome. Tom inherited one X chromosome from his father and one X chromosome from his mother. Since Tom does not have hemophilia, he must have inherited the dominant allele for normal blood clotting from his mother. This means that Tom's genotype is X^H Y, where X^H represents the dominant allele for normal blood clotting and Y represents the Y chromosome.Tom's children will inherit one X chromosome from Tom and one X chromosome from their mother. If Tom's children are male, they will inherit the Y chromosome from Tom and will not have hemophilia. If Tom's children are female, they will inherit one X chromosome from Tom and one X chromosome from their mother. If Tom's children inherit the X chromosome with the hemophilia allele from their mother, they will be carriers for hemophilia. However, they will not have hemophilia because they will also inherit the dominant allele for normal blood clotting from Tom.

Question 19

Queen Victoria of England had a son, Leopold, and a great-grandson, Tsarevich Alexei Nikolaevich Romanov of Russia, both of whom had hemophilia. We can conclude that
A) Queen Victoria must have had hemophilia, too.
B) Queen Victoria was a carrier for hemophilia.
C) Queen Victoria's husband, Prince Albert, must have been a carrier.
D) Leopold and Tsarevich Alexei probably developed hemophilia due to a spontaneous mutation, because their female relatives did not have the condition.

Accepted Answer

Queen Victoria was not affected by hemophilia, but she was a carrier for the disease. This means that she carried the gene for hemophilia on one of her two X chromosomes, which she passed on to her son Leopold, and potentially to other descendants. Hemophilia is a sex-linked recessive genetic disorder, meaning that it primarily affects males who inherit the defective X chromosome from their mother. It is unlikely that Prince Albert was a carrier, as the hemophilia gene was not present in his family tree. The likelihood of spontaneous mutation is also low, as hemophilia is a rare disorder with a low mutation rate.

Question 20

In the Minnesota Study of Twins Reared Apart, identical twins were found to be
A) very similar in all characteristics studied, regardless of whether they were raised together or apart.
B) similar in some characteristics studied, but not all, regardless of whether they were raised together or apart.
C) similar in all characteristics studied only if they were raised together.
D) similar in some characteristics studied, but not all, only if they were raised together.

Accepted Answer

The Minnesota Study of Twins Reared Apart found that identical twins were similar in some characteristics, such as intelligence and personality, regardless of whether they were raised together or apart, indicating a genetic influence. However, they were not identical in all characteristics, showing the role of environment as well.

Quiz 5: Genetics and the Development of the Human Brain

A process that prevents the production of much higher amounts of protein in females than in males is known as

A characteristic that results from genes on the X chromosome that are not duplicated on the Y chromosomes is referred to as being

The Minnesota Study of Twins Reared Apart found support for which of the following conclusions?

Amber and Rachel are identical twins who were raised together, and Nicole and Kayla are identical twins who were adopted by different families at birth. Based on the findings of the Minnesota Study of Twins Reared Apart, what can we expect to see as these girls grow up?

Calico cats have splotches of colors of fur arrayed on them, with the color being determined by different alleles of an X chromosome gene. Calico cats

Two important processes that produce lasting but reversible changes in gene expression are histone modification and __________.

_________ of the genes found on the X chromosome are duplicated on the Y chromosome.

When variations in a single base are responsible for the difference between two alleles, the resulting condition is known as

Extreme skewing in x-inactivation has been linked with which of the following characteristics in offspring?

A mutation of a person's DNA

Research has shown that a person's height is about 81 percent heritable, whereas his or her BMI is about 59 percent heritable. Which of the following is the most accurate interpretation of these findings?

In their study of the heritability of autistic traits among Dutch teens, Rosa Hoekstra and her colleagues were careful to choose participants from a variety of backgrounds and circumstances. Why is careful sampling especially important to studies of heritability?

Different versions of the APOE gene are correlated with the development of

Kyle plants a group of seeds in a pot of enriched soil and provides all the seeds with identical temperature, lighting, and water. When his plants are mature, he notices that they are quite different in height. Which of the following is the best conclusion Kyle could draw from his observations?

Compared with non-twin siblings, fraternal twins

The presence of a recessive allele can

Tom's father has hemophilia, but Tom does not have the disease. What are the chances that Tom's children will have hemophilia?

Queen Victoria of England had a son, Leopold, and a great-grandson, Tsarevich Alexei Nikolaevich Romanov of Russia, both of whom had hemophilia. We can conclude that

In the Minnesota Study of Twins Reared Apart, identical twins were found to be