Question 1

In humans,the presence or absence of dimples is a trait controlled by a single gene.What is the genotype of an individual who is heterozygous for dimples?
A) DD
B) Dd
C) dd
D) DI

Accepted Answer

Dimples are controlled by a single gene with two alleles: D (dominant) and d (recessive). A heterozygous individual has one copy of each allele, represented as Dd. The dominant allele (D) results in the presence of dimples, while the recessive allele (d) results in their absence. Therefore, an individual who is heterozygous for dimples (Dd) will have dimples.

Question 2

Which of these crosses will produce only heterozygous offspring?
A) AA × aa
B) AA × Aa
C) Aa × Aa
D) Aa × aa

Accepted Answer

A

Question 3

Attached earlobes are recessive to free earlobes.What is the probability of having a child with attached earlobes when an individual with attached earlobes mates with an individual heterozygous for free earlobes?
A) 0%
B) 25%
C) 50%
D) 75%

Accepted Answer

C

Question 4

An individual who is homozygous ________.
A) expresses the dominant trait
B) carries two different alleles for a gene
C) carries two copies of the same allele for a gene
D) expresses the recessive trait

Accepted Answer

An individual who is homozygous carries two copies of the same allele for a gene. This means that they have two identical forms of the gene, whether dominant or recessive, and will express the corresponding phenotype.

Question 5

Round seeds (R)are dominant to wrinkled seeds (r),and yellow seeds (Y)are dominant to green seeds (y).What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual?
A) 1:2:1
B) 9:3:3:1
C) 3:1
D) 1:1:1:1

Accepted Answer

The answer of Round seeds (R)are dominant to wrinkled seeds...

Question 6

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds.The F₁ plants have yellow seeds.What is the expected phenotypic ratio of seed color of the offspring of an F₁ × F₁ cross?
A) 1:2:1
B) 2:1
C) 3:1
D) 9:3:3:1

Accepted Answer

When a purebred yellow-seeded plant is crossed with a purebred green-seeded plant, the resulting F₁ generation all have yellow seeds because yellow seed color is dominant over green. When two of these F₁ plants are crossed, the expected phenotypic ratio of seed color in their offspring is 3:1, with three plants having yellow seeds and one plant having green seeds. This is because the F₁ plants are heterozygous for seed color (Yy), and when they are crossed, there is a 1:2:1 genotypic ratio of YY, Yy, and yy offspring. The YY and Yy offspring both have yellow seeds, while the yy offspring has green seeds. Therefore, the expected ratio of yellow-seeded plants to green-seeded plants in the offspring of an F₁ × F₁ cross is 3:1.

Question 7

A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would produce a(n)________.
A) purebred variety
B) hybrid
C) P generation
D) F₂ generation

Accepted Answer

A mating between two purebred plants with different traits (purple-flowered and white-flowered) would produce a hybrid offspring, as they would inherit one allele for each trait from each parent.

Question 8

Alleles are described as ________.
A) homologous chromosomes
B) environmental factors that affect gene expression
C) alternate versions of a gene
D) alternate phenotypes

Accepted Answer

Alleles are alternate versions of a gene that occur at the same locus on homologous chromosomes. They can code for different traits and can result in alternate phenotypes. Environmental factors do not qualify as alleles, and homologous chromosomes are not the same as alleles.

Question 9

The best definition of a purebred plant is one that ________.
A) cannot be cross-fertilized
B) self-fertilizes to produce offspring identical to the parent
C) produces sterile offspring when cross-fertilized
D) self-fertilizes to produce hybrid offspring

Accepted Answer

A purebred plant is one that is homozygous for all traits, meaning it has the same alleles for each gene. These plants are often self-fertilized to ensure that their offspring have the same genotype as them. Therefore, choice B, which states that a purebred plant self-fertilizes to produce offspring identical to the parent, is the correct definition. The other choices do not accurately describe what a purebred plant is.

Question 10

The ________ is most commonly found in nature.
A) recessive trait
B) wild-type trait
C) parental type
D) dominant trait

Accepted Answer

The wild-type trait is the most common in nature because it is the trait found in the majority of organisms that have not undergone any genetic mutations. The other options (recessive trait, parental type, dominant trait) may also be found in nature but are not necessarily the most common.

Question 11

What data or test would you seek to determine whether or not a trait is sex linked?
A) karyotype
B) pedigree
C) DNA sequence
D) blood test

Accepted Answer

A pedigree would be the best choice to determine whether or not a trait is sex linked. Sex-linked traits are inherited differently between males and females, and a pedigree can show the pattern of inheritance and help to determine if the trait is linked to the X or Y chromosome. Karyotype and DNA sequence tests can provide information about the individual's genetic makeup but may not necessarily reveal whether a trait is sex-linked. A blood test would also not be specific enough for determining whether a trait is sex-linked.

Question 12

Mendel crossed purebred purple-flowered plants with purebred white-flowered plants,and all of the resulting offspring produced purple flowers.The offspring are all ________,and the allele for purple flowers is ________.
A) heterozygotes... recessive
B) heterozygotes... dominant
C) homozygotes... recessive
D) homozygotes... dominant

Accepted Answer

When all of the resulting offspring from a cross between a purebred dominant trait and a purebred recessive trait show the dominant trait, the offspring must be heterozygotes for the dominant trait. Therefore, the allele for purple flowers must be dominant.

Question 13

According to Mendel's law of segregation,________.
A) two alleles segregate into each gamete
B) more gametes carrying the dominant allele are produced than gametes carrying the recessive allele
C) gametes have one allele copy for each gene
D) gametes are diploid

Accepted Answer

The answer of According to Mendel's law of segregation,________.
A) two...

Question 14

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds.The seeds of all of the offspring are yellow.Why?
A) The yellow allele is recessive to the green allele.
B) All of the offspring are homozygous yellow.
C) The yellow allele is dominant to the green allele.
D) The alleles are codominant.

Accepted Answer

The fact that all the offspring have yellow seeds indicates that the yellow allele is dominant to the green allele. If the yellow allele was recessive, then some offspring would have had green seeds. If the alleles were codominant, then the offspring would have had a mix of yellow and green seeds. The fact that all offspring are yellow indicates that they are either homozygous dominant (YY) or heterozygous (Yy) for the yellow allele.

Question 15

An individual with the genotype AaBb produces four different gametes in equal proportions.This is a demonstration of ________.
A) the chromosomal theory of inheritance
B) Mendel's law of independent assortment
C) linkage
D) Mendel's principle of segregation

Accepted Answer

Mendel's law of independent assortment states that during gamete formation, the segregation of one allele for a particular gene does not influence the segregation of another allele for a different gene. Therefore, the production of four different gametes in equal proportions is a demonstration of independent assortment of the two different genes.

Question 16

A couple has two female children.What is the probability that their next child will be male?
A) 25%
B) 50%
C) 33%
D) 67%

Accepted Answer

The probability of having a male child is always 50% regardless of the gender of the previous child. The gender of the previous children does not affect the gender of the future children, as each child is an independent event. Therefore, the probability of having a male child is not influenced by the gender of the previous children, and it remains at 50%.

Question 17

In humans,free earlobes (E)are dominant to attached earlobes (e)and the presence of freckles (F)is dominant to the absence of freckles (f).If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles,what is the probability of having a child with attached earlobes and freckles?
A) 0%
B) 25%
C) 50%
D) 100%

Accepted Answer

The answer of In humans,free earlobes (E)are dominant to attached...

Question 18

To determine the phenotype of an individual who expresses a dominant trait,you would cross that individual with an individual who ________.
A) expresses the dominant trait
B) is homozygous recessive for that trait
C) is homozygous dominant for that trait
D) is heterozygous for that trait

Accepted Answer

In order to determine the phenotype of an individual who expresses a dominant trait, you need to cross that individual with an individual who is homozygous recessive for that trait. This will allow you to determine if the individual expressing the dominant trait is homozygous dominant or heterozygous, based on the phenotype of their offspring. If the offspring all exhibit the dominant trait, then the individual expressing the trait must be homozygous dominant. If some offspring express the recessive trait, then the individual expressing the dominant trait must be heterozygous. Crossing with an individual who expresses the dominant trait or is homozygous dominant would not give you this information, as both individuals would always produce offspring with the dominant trait.

Question 19

What name is given to the specific location of a gene on a chromosome?
A) locus
B) phenotype
C) genotype
D) allele

Accepted Answer

The specific location of a gene on a chromosome is known as a locus.

Question 20

Attached earlobes are recessive to free earlobes.What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?
A) 2:1
B) 1:1
C) 1:2:1
D) 3:1

Accepted Answer

The answer of Attached earlobes are recessive to free earlobes.What...

Quiz 9: Patterns of Inheritance

In humans,the presence or absence of dimples is a trait controlled by a single gene.What is the genotype of an individual who is heterozygous for dimples?

Which of these crosses will produce only heterozygous offspring?

Attached earlobes are recessive to free earlobes.What is the probability of having a child with attached earlobes when an individual with attached earlobes mates with an individual heterozygous for free earlobes?

An individual who is homozygous ________.

Round seeds (R) are dominant to wrinkled seeds (r) ,and yellow seeds (Y) are dominant to green seeds (y) .What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual?

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds.The F₁ plants have yellow seeds.What is the expected phenotypic ratio of seed color of the offspring of an F₁ × F₁ cross?

A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would produce a(n) ________.

Alleles are described as ________.

The best definition of a purebred plant is one that ________.

The ________ is most commonly found in nature.

What data or test would you seek to determine whether or not a trait is sex linked?

Mendel crossed purebred purple-flowered plants with purebred white-flowered plants,and all of the resulting offspring produced purple flowers.The offspring are all ,and the allele for purple flowers is .

According to Mendel's law of segregation,________.

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds.The seeds of all of the offspring are yellow.Why?

An individual with the genotype AaBb produces four different gametes in equal proportions.This is a demonstration of ________.

A couple has two female children.What is the probability that their next child will be male?

To determine the phenotype of an individual who expresses a dominant trait,you would cross that individual with an individual who ________.

What name is given to the specific location of a gene on a chromosome?

Attached earlobes are recessive to free earlobes.What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?