Question 1

In the Bombay phenotype,a gene in the recessive condition blocks the expression of A and B red blood cell antigens.Thus,all A,B,and AB genotypes are expressed as the O phenotype.This is an example of
A) complete dominance.
B) epistasis.
C) incomplete dominance.
D) co-dominance.
E) pleiotropy.

Accepted Answer

In the Bombay phenotype, the recessive gene blocks the expression of A and B antigens, which is an example of epistasis. This is because the expression of the A and B antigens is dependent on the expression of another gene. In this case, the recessive gene blocks the expression of the gene responsible for A and B antigen production. This results in the O phenotype regardless of the A, B, or AB genotype.

Question 2

Achondroplasia
Achondroplasia is an autosomal dominant disorder,however homozygous dominant individuals do not have achondroplasia - they either die before birth or very shortly thereafter.The homozygous recessive condition is normal.A dwarf couple decide to have children.Use this information to answer the following question(s).
-In the example above,what is probability that the couple will have a child with achondroplasia?
A) 0
B) 1/4
C) 1/3
D) 2/3
E) 1/2

Accepted Answer

Since both parents have achondroplasia, they are heterozygous (Aa). The possible genotypes for their children are AA, Aa, and aa. The AA genotype is lethal, so only Aa (achondroplasia) and aa (normal) are viable. Out of the viable offspring, 2/3 will have achondroplasia (Aa).

Question 3

A bell-shaped curve of phenotypic variation is indicative of
A) environmental effects on phenotypes.
B) incomplete dominance.
C) multiple alleles.
D) epistasis.
E) more than one of these.

Accepted Answer

A bell-shaped curve of phenotypic variation is indicative of multiple factors influencing the phenotype, including both genetic and environmental factors. Incomplete dominance, multiple alleles, and epistasis can also contribute to variation in phenotype, but none of these explanations solely account for a bell-shaped curve of variation.

Question 4

Syndrome means
A) an abnormal number of chromosomes.
B) a simple genetic disease.
C) a collection of associated symptoms.
D) a recessive disorder.
E) a genetic disorder involving base-pair substitutions.

Accepted Answer

Syndrome refers to a collection of associated symptoms that frequently occur together, but may not have a specific underlying genetic cause. Examples include Down syndrome, Turner syndrome, and Marfan syndrome. Options A, B, D, and E refer to specific genetic conditions or abnormalities and do not encompass the full meaning of syndrome.

Question 5

Most human traits show continuous variation.This is most likely the result of
A) pleiotropy.
B) incomplete dominance.
C) epistasis.
D) environmental effects.
E) all of these.

Accepted Answer

Continuous variation is most likely the result of all of these factors. Pleiotropy is the phenomenon of a single gene affecting multiple traits. Incomplete dominance is the phenomenon of a heterozygote having a phenotype that is intermediate between the two homozygotes. Epistasis is the phenomenon of one gene affecting the expression of another gene. Environmental effects can also contribute to continuous variation.

Question 6

Six fingers on one hand would be classified as
A) a genetic disorder.
B) a disease.
C) a syndrome.
D) a genetic abnormality.
E) an illness.

Accepted Answer

Six fingers on one hand is a genetic abnormality, which means it is a variation from the normal genetic makeup.

Question 7

Achondroplasia
Achondroplasia is an autosomal dominant disorder,however homozygous dominant individuals do not have achondroplasia - they either die before birth or very shortly thereafter.The homozygous recessive condition is normal.A dwarf couple decide to have children.Use this information to answer the following question(s).
-In the example above,what is the probability that this couple will have a normal child?
A) 0
B) 1/4
C) 1/3
D) 2/3
E) 1/2

Accepted Answer

Since both parents have the autosomal dominant disorder achondroplasia, they are heterozygous (Aa) and there is a 25% chance they will pass on the recessive allele to their offspring, resulting in a normal child (aa). Therefore, the probability of having a normal child is 1/4 or 25%, which corresponds to choice C.

Question 8

Which of the following is NOT associated with Marfan syndrome?
A) skin lacking elasticity
B) loose joints
C) weakened aorta
D) short stature
E) mutated fibrillin gene

Accepted Answer

Short stature is not associated with Marfan syndrome. People with Marfan syndrome are typically tall with long limbs.

Question 9

In a pedigree chart,a male who does NOT demonstrate the trait being studied is represented by
A) a darkened square.
B) a darkened diamond.
C) a clear circle.
D) a clear square.
E) a darkened circle.

Accepted Answer

In a pedigree chart, a clear square represents a male who does not demonstrate the trait being studied. A darkened square represents a male who does demonstrate the trait. A darkened diamond is used for individuals of unknown gender who demonstrate the trait. A clear circle represents a female who does not demonstrate the trait, while a darkened circle represents a female who does demonstrate the trait.

Question 10

Human eye color is an example of a trait that
A) varies according to the geographical area.
B) varies periodically.
C) varies according to humidity.
D) varies continuously.
E) varies according to seasons.

Accepted Answer

Human eye color varies continuously from light blue to dark brown. It is not determined by geographical area, humidity, or seasons. While there may be some variation in eye color within populations due to genetic differences, it is not periodic in nature.

Question 11

In cows,certain coat colors are co-dominant.For example red is dominant; white is recessive; roan (red and white)is co-dominant.If a roan bull is crossed with a white cow what will be the expected coat colors of the calves?
A) all roan
B) half roan and half white
C) half red and half white
D) 3/4 roan and 1/4 white
E) 1/2 roan, 1/4 red, 1/4 white

Accepted Answer

When a roan bull is crossed with a white cow, the possible gametes of the bull are R or W, and the gametes of the cow are both W. The offspring will inherit one allele from each parent, so all of them will be heterozygous Roan (RW genotype), which is a blend of red and white. Therefore, the expected coat colors of the calves will be half roan and half white.

Question 12

In a pedigree chart,a female showing the specific trait being studied is indicated by a
A) clear square.
B) darkened square.
C) clear circle.
D) darkened diamond.
E) darkened circle.

Accepted Answer

In pedigree charts, females are represented by circles and males by squares. A darkened shape indicates that the individual exhibits the specific trait being studied. Therefore, a darkened circle represents a female showing the specific trait.

Question 13

What tool do geneticists use to study the genetics of families through generations?
A) Punnett squares
B) pedigrees
C) karyotypes
D) DNA profiles
E) fossil analyses

Accepted Answer

Geneticists use pedigrees to study the genetics of families through generations. Pedigrees are diagrams that show the inheritance patterns of certain traits or diseases within a family. They can be used to determine if a trait is inherited in a dominant or recessive manner, and to track the transmission of genetic disorders over multiple generations.

Question 14

Siamese cats have enzymes that code for dark fur color but are only active in cooler temperatures.Thus,the tips of a Siamese cat's ears,feet,and tail are dark but not the warmer regions of its body core.This is an example of
A) pleiotropy.
B) environmental effects.
C) epistasis.
D) incomplete dominance.
E) co-dominance.

Accepted Answer

The different fur color in different regions of the Siamese cat's body is due to the effect of temperature on enzyme activity. This is an example of an environmental effect, where the phenotype is affected by external factors such as temperature, rather than being solely determined by genetics. The other options, pleiotropy, epistasis, incomplete dominance, and co-dominance, refer to genetic mechanisms of inheritance and do not apply to this example.

Question 15

The switching between asexual and sexual reproduction by water fleas is controlled by
A) epistasis.
B) pleiotropy.
C) incomplete dominance.
D) codominant inheritance.
E) environmental effects.

Accepted Answer

The switching between asexual and sexual reproduction in water fleas is controlled by environmental factors, such as changes in temperature, photoperiod, and food availability. These factors can trigger the production of a different type of egg or embryo, which leads to either asexual or sexual reproduction. Genetic factors such as epistasis, pleiotropy, incomplete dominance, and codominant inheritance do not play a significant role in the switching between asexual and sexual reproduction in water fleas.

Question 16

PKU is a human disease in which the affected individual is unable to metabolize the amino acid,phenylalanine.Symptoms of this disease include mental retardation,a lack of pigmentation,and black urine.PKU is an example of
A) epistasis.
B) pleiotropy.
C) incomplete dominance.
D) co-dominance.
E) complete dominance.

Accepted Answer

PKU is an example of pleiotropy because it is caused by a mutation in a single gene, but it affects multiple traits, including mental retardation, lack of pigmentation, and abnormal urine color.

Question 17

Humans have an MN gene that codes for a red blood cell antigen.The gene has two alleles,M and N.When the two alleles are inherited together,MN,both are expressed.This is an example of
A) codominance.
B) incomplete dominance.
C) complete dominance.
D) X-linked inheritance.
E) base-pair substitution.

Accepted Answer

Codominance occurs when both alleles in a heterozygous individual are expressed equally and fully, resulting in a phenotype that displays characteristics of both alleles. In this case, individuals with the MN genotype express both the M and N antigens on their red blood cells, indicating codominance. Incomplete dominance would result in a blending of the traits, while complete dominance would result in only one allele being expressed. X-linked inheritance would involve genes located on the X chromosome, and base-pair substitution refers to a type of mutation, which is not applicable in this scenario.

Question 18

The methylation and demethylation of regions of DNA triggered by changes in the environment and resulting in phenotypic changes are an example of
A) pleiotropy.
B) environmental effects.
C) epistasis
D) epigenesis.
E) more than one of these.

Accepted Answer

The answer of The methylation and demethylation of regions of...

Question 19

Which of the following would be the LEAST satisfactory organism for genetic research?
A) humans
B) bacteria
C) mice
D) fruit flies
E) pea plants

Accepted Answer

The answer of Which of the following would be the...

Question 20

In humans,hair texture is an incompletly dominant trait.Curly hair is the homozygous dominant trait; smooth hair is homozgous recessive; wavy hair is heterozygous.If two wavy haired individuals have children what is the expected phenotype ratio?
A) 1:2:1
B) 3:1
C) 4:0
D) 1:1
E) 1:0

Accepted Answer

The answer of In humans,hair texture is an incompletly dominant...

Quiz 9: Patterns of Inheritance

In the Bombay phenotype,a gene in the recessive condition blocks the expression of A and B red blood cell antigens.Thus,all A,B,and AB genotypes are expressed as the O phenotype.This is an example of

A bell-shaped curve of phenotypic variation is indicative of

Syndrome means

Most human traits show continuous variation.This is most likely the result of

Six fingers on one hand would be classified as

Which of the following is NOT associated with Marfan syndrome?

In a pedigree chart,a male who does NOT demonstrate the trait being studied is represented by

Human eye color is an example of a trait that

In cows,certain coat colors are co-dominant.For example red is dominant; white is recessive; roan (red and white) is co-dominant.If a roan bull is crossed with a white cow what will be the expected coat colors of the calves?

In a pedigree chart,a female showing the specific trait being studied is indicated by a

What tool do geneticists use to study the genetics of families through generations?

Siamese cats have enzymes that code for dark fur color but are only active in cooler temperatures.Thus,the tips of a Siamese cat's ears,feet,and tail are dark but not the warmer regions of its body core.This is an example of

The switching between asexual and sexual reproduction by water fleas is controlled by

PKU is a human disease in which the affected individual is unable to metabolize the amino acid,phenylalanine.Symptoms of this disease include mental retardation,a lack of pigmentation,and black urine.PKU is an example of

Humans have an MN gene that codes for a red blood cell antigen.The gene has two alleles,M and N.When the two alleles are inherited together,MN,both are expressed.This is an example of

The methylation and demethylation of regions of DNA triggered by changes in the environment and resulting in phenotypic changes are an example of

Which of the following would be the LEAST satisfactory organism for genetic research?

In humans,hair texture is an incompletly dominant trait.Curly hair is the homozygous dominant trait; smooth hair is homozgous recessive; wavy hair is heterozygous.If two wavy haired individuals have children what is the expected phenotype ratio?