Question 1

Red-green color blindness is inherited as a sex-linked recessive trait.The gene is found on the X chromosome.How can a man with normal color vision father a daughter who is red-green color-blind?
A) The woman with whom he mates is red-green color-blind.
B) The man is heterozygous for red-green color blindness.
C) He can't (unless there is a mutation).
D) The man's mother carries an allele for red-green color blindness, and the expression of the trait skipped a generation.

Accepted Answer

A man with normal color vision cannot pass on the red-green color blindness allele to his daughter unless there is a mutation, because he would only pass on a normal X chromosome.

Question 2

Many human traits,such as our performance on intelligence tests or our susceptibility to heart disease,are ______.
A) determined only by our genes
B) influenced by both genes and the environment
C) determined by genes in some people and by the environment in other people
D) not affected by our genes

Accepted Answer

Most human traits are influenced by both genetic and environmental factors. While genetics can predispose individuals to certain traits or conditions, environmental factors can also play a significant role in the expression of those traits. This is known as the nature vs. nurture debate, which suggests that both nature (genes) and nurture (environmental factors) contribute to the development of human traits.

Question 3

An individual with (naturally)curly hair and an individual with (naturally)straight hair mate; all of their offspring have (naturally)wavy hair. What is the relationship between the alleles for hair texture?
A) pleiotropy
B) incomplete dominance
C) wavy hair is dominant to both straight and curly hair
D) codominance

Accepted Answer

This is an example of incomplete dominance, where neither allele is dominant over the other and the phenotype of the heterozygous offspring falls in between that of the homozygous dominant and homozygous recessive parents. In this case, the curly allele and straight allele are not dominant over each other, resulting in wavy-haired offspring.

Question 4

What is the key to the recognition of codominance?
A) The phenotype of the heterozygote falls between the phenotypes of the homozygotes.
B) The trait exhibits a continuous distribution.
C) The alleles affect more than one trait.
D) The heterozygote expresses the phenotype of both homozygotes.

Accepted Answer

Codominance occurs when the heterozygote expresses the phenotype of both homozygotes. This means that both alleles are fully expressed and neither is dominant or recessive over the other.

Question 5

In humans,the inheritance of ______ is best explained as being polygenic.
A) cystic fibrosis
B) height
C) blood type
D) sickle-cell disease

Accepted Answer

Height is controlled by multiple genes and is therefore polygenic.

Question 6

Hypophosphatemia (vitamin D-resistant rickets)is inherited as an sex-linked dominant trait.The relevant gene is found on the X chromosome.What is the expected outcome of a cross between a homozygous recessive woman and a man with hypophosphatemia?
A) All of their daughters and none of their sons exhibit hypophosphatemia.
B) Fifty percent of their daughters and fifty percent of their sons exhibit hypophosphatemia.
C) All of their sons and none of their daughters exhibit hypophosphatemia.
D) Twenty-five percent of their offspring exhibit hypophosphatemia.

Accepted Answer

In a cross between a homozygous recessive woman (xx) and a man with hypophosphatemia (X^H Y), all daughters (X^H x) will inherit the dominant X-linked trait from their father, while none of the sons (xY) will inherit it, as they receive their X chromosome from their mother.

Question 7

______ genes violate Mendel's principle of independent assortment.
A) Codominant
B) Linked
C) Recessive
D) Pleiotropic

Accepted Answer

Linked genes violate Mendel's principle of independent assortment because they are located on the same chromosome and are usually inherited together as a unit, rather than sorting independently during meiosis.

Question 8

Linked genes are usually
A) found on the X chromosome.
B) found on the Y chromosome.
C) codominant.
D) located close together on a chromosome.

Accepted Answer

Linked genes are located close together on a chromosome, which means that they are inherited together more frequently than would be expected by chance. This is because the farther apart two genes are on a chromosome, the more likely they are to be separated by crossing over during meiosis. Linked genes do not have to be located on sex chromosomes and are not codominant.

Question 9

An individual with the blood group genotype L^MLN has the phenotype MN. What is the relationship between the L^M and L^N alleles? A) codominance B) pleiotropy C) L^N is dominant D) incomplete dominance

Accepted Answer

The MN blood group system exhibits codominance, which means both alleles are expressed equally in the phenotype. Therefore, the L^M and L^N alleles are both expressed and contribute to the MN phenotype.

Question 10

What is the basis of Mendel's laws?
A) the behavior of chromosomes during prophase I of meiosis only
B) the behavior of chromosomes during mitotic anaphase
C) the behavior of chromosomes during prophase I and prophase II of meiosis
D) the behavior of chromosomes during metaphase I and anaphase I of meiosis

Accepted Answer

Mendel's laws are based on the behavior of chromosomes during metaphase I and anaphase I of meiosis. This is where the separation and assortment of homologous chromosomes occurs, which is the basis for Mendel's law of segregation and law of independent assortment.

Question 11

A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring.What is the recombination frequency of the two gene pairs?
A) 6%
B) 3%
C) 30%
D) 1.5%

Accepted Answer

Recombination frequency is calculated by dividing the number of recombinant offspring by the total number of offspring and multiplying by 100. Therefore, the recombination frequency in this case is (30/1000)*100 = 3%.

Question 12

Achondroplasia is a form of dwarfism caused by a dominant allele.The homozygous dominant genotype causes death,so individuals who have this condition are all heterozygotes.If a person with achondroplasia mates with a person who does not have achondroplasia,what percentage of their children would be expected to have achondroplasia?
A) 0%
B) 50%
C) 75%
D) 100%

Accepted Answer

Since achondroplasia is caused by a dominant allele and the homozygous dominant genotype causes death, all individuals with achondroplasia are heterozygotes. When a person with achondroplasia mates with a person who does not have achondroplasia, there is a 50% chance that each child will inherit the dominant allele and have achondroplasia, and a 50% chance that each child will inherit the recessive allele and not have achondroplasia.

Question 13

The recombination frequency between gene B and gene C is 11%. The recombination frequency between gene B and gene D is 5%. The recombination frequency between gene C and gene D is 15%. What would be the arrangement of these genes on a linkage map?
A) CDB
B) DBC
C) BCD
D) More information is needed.

Accepted Answer

The answer of The recombination frequency between gene B and...

Question 14

Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome.A man with three nostrils has a daughter who has a son with a man who has only two nostrils.What is the probability that the three-nostriled man's grandson has three nostrils?
A) 0%
B) 25%
C) 50%
D) 100%

Accepted Answer

The answer of Assume that having three nostrils is inherited...

Question 15

An individual with (naturally)curly hair and an individual with (naturally)straight hair mate; all of their offspring have (naturally)wavy hair. If an individual with wavy hair mates with an individual with straight hair,what is the probability that their child will have curly hair?
A) 0%
B) 25%
C) 50%
D) 75%

Accepted Answer

The answer of An individual with (naturally)curly hair and an...

Question 16

Marfan syndrome is the result of inheriting a single allele. Individuals with Marfan syndrome are tall and long-limbed,and have both cardiovascular and eye defects. The inheritance of Marfan syndrome is an example of ______.
A) codominance
B) a recessive disorder
C) pleiotropy
D) incomplete dominance

Accepted Answer

Marfan syndrome is an example of pleiotropy because the single allele affects multiple traits, including height, limb length, cardiovascular system, and eyes. It is not an example of codominance or incomplete dominance because there is no blending or equal expression of alleles. It is also not a recessive disorder because inheriting only one allele is enough to cause the syndrome.

Question 17

What is the best explanation for a BbCc × bbcc cross producing offspring in a 5:5:1:1 phenotypic ratio?
A) linked genes
B) polygenic inheritance
C) incomplete dominance
D) codominance

Accepted Answer

The answer of What is the best explanation for a...

Question 18

What is the key to the recognition of a trait whose expression is determined by the effects of two or more genes (polygenic inheritance)?
A) A mating between a homozygous and a heterozygous individual produces more than the expected number of offspring expressing the dominant trait.
B) All of the alleles of the gene for that trait are equally expressed.
C) Pleiotropy occurs.
D) The trait varies along a continuum in the population.

Accepted Answer

Polygenic inheritance results in the trait varying along a continuum in the population, rather than being a discrete trait with only two possible expressions. This is due to the combined effects of multiple genes, each contributing to the overall expression of the trait. Therefore, the key to recognizing a trait that is determined by the effects of two or more genes is to observe variation in the trait within the population. A and B are not correct because they do not reflect the variability that is characteristic of polygenic inheritance. Pleiotropy is a phenomenon in which a single gene affects multiple traits, so C is also incorrect in this context.

Question 19

What is the key to the recognition of incomplete dominance?
A) The phenotype of the heterozygote falls between the phenotypes of the homozygotes.
B) The trait exhibits a continuous distribution.
C) The alleles affect more than one trait.
D) The heterozygote expresses the phenotype of both homozygotes.

Accepted Answer

In incomplete dominance, the phenotype of the heterozygote falls between the phenotypes of the homozygotes. This means that the heterozygote expresses an intermediate phenotype that is not the same as either homozygote. This is the key feature of incomplete dominance and distinguishes it from other types of inheritance patterns.

Question 20

Which of the following techniques is used to collect fetal cells during pregnancy for genetic testing?
A) testcross
B) dihybrid cross
C) amniocentesis
D) pedigree analysis

Accepted Answer

Amniocentesis is a procedure in which a small amount of amniotic fluid is removed from the sac surrounding the fetus. The fluid contains fetal cells that can be used for genetic testing. Testcross, dihybrid cross, and pedigree analysis are not used to collect fetal cells during pregnancy for genetic testing.

Quiz 9: Patterns of Inheritance

Red-green color blindness is inherited as a sex-linked recessive trait.The gene is found on the X chromosome.How can a man with normal color vision father a daughter who is red-green color-blind?

Many human traits,such as our performance on intelligence tests or our susceptibility to heart disease,are ______.

An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. What is the relationship between the alleles for hair texture?

What is the key to the recognition of codominance?

In humans,the inheritance of ______ is best explained as being polygenic.

Hypophosphatemia (vitamin D-resistant rickets) is inherited as an sex-linked dominant trait.The relevant gene is found on the X chromosome.What is the expected outcome of a cross between a homozygous recessive woman and a man with hypophosphatemia?

______ genes violate Mendel's principle of independent assortment.

Linked genes are usually

An individual with the blood group genotype L^MLN has the phenotype MN. What is the relationship between the L^M and L^N alleles?

What is the basis of Mendel's laws?

A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring.What is the recombination frequency of the two gene pairs?

The recombination frequency between gene B and gene C is 11%. The recombination frequency between gene B and gene D is 5%. The recombination frequency between gene C and gene D is 15%. What would be the arrangement of these genes on a linkage map?

Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome.A man with three nostrils has a daughter who has a son with a man who has only two nostrils.What is the probability that the three-nostriled man's grandson has three nostrils?

An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. If an individual with wavy hair mates with an individual with straight hair,what is the probability that their child will have curly hair?

Marfan syndrome is the result of inheriting a single allele. Individuals with Marfan syndrome are tall and long-limbed,and have both cardiovascular and eye defects. The inheritance of Marfan syndrome is an example of ______.

What is the best explanation for a BbCc × bbcc cross producing offspring in a 5:5:1:1 phenotypic ratio?

What is the key to the recognition of a trait whose expression is determined by the effects of two or more genes (polygenic inheritance) ?

What is the key to the recognition of incomplete dominance?

Which of the following techniques is used to collect fetal cells during pregnancy for genetic testing?