Chapter 19: Genetics

Variations of homologous genes that result in differences in structure and function are: A: Alleles B: Autosomes C: Dominant D: Linked E: Loci

A: Alleles

If one possesses one allele for blood group A antigen and one allele for blood group B, he will have type AB blood, distinctly different from both A and B. This type of inheritance is called ________. A: Codominance B: Complete dominance C: Polygenic D: Incomplete dominance

A: Codominance

The law of segregation states that: A: genes separate from each other during gamete formation so that each sperm and egg receive only one allele from each pair. B: different alleles for the same gene occupy unique loci on sister chromatids C: when different alleles for the same trait come together, one allele will be recessive to another. D: when two identical alleles come together, complete dominance occurs in terms of phenotype. E: genes for different traits assort independently of each other during the formation of egg and sperm.

A: Genes separate from each other during gamete formation so that each sperm and egg receive only one allele from each pair.

If both alleles of a particular gene are identical, the person is said to be A: Homozygous B: Heterozygous C: Genotypic D: Phenotypic E: An identical twin

A: Homozygous

Which of the following could be detected by examination of a karyotype? A: Trisomy 21 B: Hemophilia C: Huntington disease D: Sickle cell anemia

A: Trisomy 21 (Trisomy 21 would be obvious from a karyotype. There would three copies of the #21 chromosome, instead of the normal two copies.)

Which of the following genotypes results in a female phenotype? A: X B: XY C: XYY D: XXY E: Both X and XXY

A: X

When a heterozygous genotype results in a phenotype that is intermediate between the two homozygous conditions, this type of inheritance is referred to as A: incomplete dominance B: codominance C: polygenic D: complete dominance

A: incomplete dominance

In polygenic inheritance: A: multiple alleles and genes contribute to a phenotype. B: all individuals in the population are initially heterozygous for a particular trait. C: all traits are expressed as incomplete dominance. D: the environment has no influence in phenotype expression. E: the genotype makeup of individuals in a population is the only factor influencing phenotypes.

A: multiple alleles and genes contribute to a phenotype.

The inheritance of phenotypic traits that depend on many genes is called ________. A: polygenic inheritance B: codominant inheritance C: dominant inheritance D: incomplete inheritance

A: polygenic inheritance

The Punnett Square is a useful tool for: A: predicting the ratios of possible genotypes of a particular combination of alleles. B: predicting the level of crossing over that will occur during meiosis. C: determining which genes or traits assort independently during gamete formation. D: calculating how many mutations occur during DNA replication. E: determining the rate of segregation of alleles.

A: predicting the ratios of possible genotypes of a particular combination of alleles.

Given the information below, answer the following question, assuming complete dominance. "In humans, the ability to roll the tongue is a dominant trait; the inability to roll the tongue is a recessive trait." If two individuals heterozygous for this trait have a child, what is the chance that the child will not be able to roll his tongue? A: 0% B: 25% C: 50% D: 75% E: 100%

B: 25%

Tay-Sachs disease is inherited as an autosomal recessive disease. A couple has learned that they are both heterozygous carriers of the Tay-Sachs recessive gene. What is the probability that they will have a child with Tay-Sachs disease? A: 0% B: 25% C: 50% D: 100%

B: 25%

If a piece of chromosome breaks off during mitosis or meiosis and does not reattach, the event is called A: Non-dysplasia B: A deletion C: Non-disjunction D: Dysplasia E: A translocation

B: A deletion

Given the information below, answer the following question. "The color of the four-o'clock flower is as follows: homozygous dominantred homozygous recessivewhite" The flower color in this plant is inherited by incomplete dominance. If a flower homozygous dominant for flower color is crossed with a white flower, the color of the offspring flowers will be expected to be A: All red B: All pink C: All white D: 50% white and 50% pink E: 50& white and 50% red

B: All pink

An individual who possesses two different alleles for a particular gene is referred to as: A: X-linked B: Heterozygous C: Polygenic D: Homozygous

B: Heterozygous

When a piece of chromosome breaks off and reattaches at another site on the same or another chromosome, this is called A: Nondisjunction B: Translocation C: Recombination D: Nontranslation E: A deletion

B: Translocation

Hemophilia is an X-linked recessive disorder. A daughter can be afflicted with hemophilia if she inherits ________. A: an Xh allele from her father only B: an Xh allele from her father and her mother C: an Xh allele from her mother only. D: two normal X chromosomes; hemophilia usually arises spontaneously

B: an Xh allele from her father and her mother

Which of the following demonstrates incomplete dominant inheritance? A: cystic fibrosis B: familial hypercholesterolemia C: Down syndrome D: Huntington disease

B: familial hypercholesterolemia (This is a good example of incomplete dominance, because the heterozygous individual has a blood cholesterol level intermediate between that of the homozygous dominant and the homozygous recessive.)

PKU is an inherited disease that causes serious mental retardation shortly after birth. PKU ________. A: cannot be treated B: is a homozygous recessive condition in which individuals accumulate too much of the amino acid phenylalanine C: cannot be detected D: is more prevalent than cystic fibrosis

B: is a homozygous recessive condition in which individuals accumulate too much of the amino acid phenylalanine

A phenotypic trait is considered sex-linked when A: the phenotype is polygenic for both sexes. B: the genes for the phenotype occur on X or Y chromosomes. C: the phenotype only occurs in females. D: a trait only occurs in males. E: the phenotype is only expressed after sexual intercourse.

B: the genes for the phenotype occur on X or Y chromosomes.

Cystic fibrosis is a genetic disorder that results from the inheritance of two recessive alleles. What is the chance that a child will inherit the disorder if one parent is heterozygous for this gene and one parent has cystic fibrosis? A: 0% B: 25% C: 50% D: 75% E: 100%

C: 50%

Given the information below, answer the following question, assuming complete dominance. "In humans, widow's peak is a dominant trait, and a straight hairline is a recessive trait." If an individual homozygous dominant for widow's peak has a child with an individual heterozygous for widow's peak, what is the chance that the child will have a homozygous dominant genotype? A: 0% B: 25% C: 50% D: 75% E: 100%

C: 50%

Red-green color blindness is an X-linked recessive disorder. Assume that mom is a carrier and dad is color blind. What is the chance that their son will inherit red-green color blindness? A: 0% B: 25% C: 50% D: 75% E: 100%

C: 50%

If a female inherits and expresses an X-linked recessive disorder, what must be true about her parents? A: Her mother has the disease. B: Neither parent has the disease. C: Her father has the disease. D: Both parents must have the disease.

C: Her father has the disease.

Failure of sister chromatids to separate properly is called A: Crossing-over B: segregation C: Nondisjunction D: Hemophilia E: Translocation

C: Nondisjunction

A recessive allele associated with chromosome 15 causes an enzyme deficiency disease called A: Edwards syndrome B: Patau syndrome C: Tay-Sachs D: Turner syndrome E: PKU

C: Tay-Sachs

The trend toward increased height and weight due to improved nutrition in certain human populations is an example of the effect of ________ on phenotypes. A: Genetic disorders B: Polygenic inheritance C: The environment D: Gene linkage E: Codominance

C: The environment

What could be said of the genes for two different traits that always appear together? A: They are different alleles of the same gene. B: They must be on the X chromosome. C: These are "linked genes" on the same chromosome. D: They are the same genes.

C: These are "linked genes" on the same chromosome.

Genes located on the same chromosome are not always inherited together because of the process of ________, which occurs during meiosis; this process "reshuffles" the genes.

Crossing-over

An individual with the genotype XXY would have ________ chromosomes and phenotypically would be a ________. A: 46; male B: 47; female C: 46; female D: 47; male

D: 47; male

Which of the following conditions is caused by trisomy 21 A: cystic fibrosis B: Tay Sachs disease C: PKU (phenylketonuria) D: Down syndrome

D: Downs Syndrome

An example of a genotype is: A: Long fingers B: Blood type AB C: Brown hair color D: Homozygous dominant E: Attached earlobes

D: Homozygous dominant

The offspring resulting from a cross between a nearly white horse (cc) and a chestnut-colored horse (CC) are of an intermediate color (between white and chestnut). Which of the following patterns of inheritance best explains this? A: Codominance B: Polygenic Inheritance C: Sex-linked D: Incomplete Dominance E: Complete Dominance

D: Incomplete Dominance

Which of the following is true regarding Klinefelter syndrome? A: due to nondisjunction of chromosomes after fertilization B: XYY Genotype C: Female phenotype D: Sterility and shows mild mental impairment E: Trisomy 18 genotype

D: Sterility and shows mild mental impairment

Which of the following does NOT apply to the sex chromosomes X and Y? A: The nonhomologous pair is thought to have evolved from a homologous pair 250 million years ago. B: They look different and carry different genes. C: They are included in an organism's karyotype. D: They are autosomes.

D: They are autosomes.

A person born with Edward's syndrome have a genotypic condition identified as A: XO B: Non-disjunction C: Trisomy 21 D: Trisomy 18 E: XXY

D: Trisomy 18

Which of the following syndromes results in an individual with a nearly normal female phenotype and a tendency to develop mild mental retardation? A Turner Syndrome: B: Double-Y Syndrome C: Trisomy-Y Syndrome D: Trisomy-X Syndrome E: Klinefelter Syndrome

D: Trisomy-X Syndrome

In 2008 the U.S. Congress passed GINA, an act that prevents insurance companies from A: raising the rates of insurance premiums or denying coverage to people who have a pre-diagnosed health condition. B: denying insurance coverage to any U.S. citizen. C: requiring genetic testing be performed for potential policy holders with a family history of certain types of genetic disorders. D: increasing insurance costs for healthy individuals based on the results of genetic testing. E: refusing to pay for genetic screening of a fetus of a couple considered high risk for certain types of genetic diseases.

D: increasing insurance costs for healthy individuals based on the results of genetic testing.

Polygenic traits display phenotypes that A: are most commonly reflective of the heterozygous condition. B: often are lethal to second generation of children. C: are masked by a codominance condition. D: represent a continuous range within the population. E: usually express the dominate condition in greater than 75% of the population.

D: represent a continuous range within the population.

Alterations in chormosome number can occur with any chromosome, but most alterations are not seen in human populations because A: most are corrected during the first mitotic event in the fertilized egg. B: the phenotype of homozygous recessive. C: the genotype still represents a normal condition. D: they are lethal during fetal development. E: the phenotype is expressed in a continuous range in a given population and thus does not stand out.

D: they are lethal during fetal development.

A couple has a daughter who is color-blind. The mother is not color-blind, but the father is. What is the genotype of the mother for this trait? A: Two recessive alleles B: 3 dominant alleles C: One abnormal Y chromosome and one normal X chromosome D: 2 dominant alleles E: 1 dominant allele and 1 recessive allele

E: 1 dominant allele and 1 recessive allele

A couple is planning to have a child. The female is a carrier for hemophilia; the male does not have hemophilia. What is the chance that a female child will never develop hemophilia? A: 0% B: 25% C: 33% D: 50% E: 100%

E: 100%

Given the information below, answer the following question, assuming complete dominance. "In humans, the ability to roll the tongue is a dominant trait; the inability to roll the tongue is a recessive trait." If an individual homozygous dominant for this trait has a child with a person who cannot roll his tongue, what is the chance that the child will have a heterozygous genotype? A: 0% B: 25% C: 50% D: 75% E: 100%

E: 100%

Given the information below, answer the following question, assuming complete dominance. "In humans, widow's peak is a dominant trait, and a straight hairline is a recessive trait." If an individual homozygous dominant for widow's peak has a child with an individual heterozygous for widow's peak, what is the chance that the child will have a widow's peak? A: 0% B: 25% C: 50% D: 75% E: 100%

E: 100%

Which of the following human traits is an example of codominance? A: Sickle-cell anemia B: Human height C: Variation in eye color D: AB blood type E: Both sickle-cell anemia and AB blood type

E: Both sickle-cell anemia and AB blood type

Which of the following genetic disorders is caused by the inheritance of a dominant-lethal allele? A: Klinefelter syndrome B: muscular dystrophy C: hemophilia D: Down syndrome E: Huntington's disease

E: Huntington's disease

Cystic fibrosis is the most common fatal genetic disease in North America and results in what type of allele located on chromosome 7? A: Dominant B: Heterozygous C: Polygenic D: Homozygous E: Recessive

E: Recessive

What is the significance of crossing-over, independent assortment, and random fertilization? A: an increase in the number of daughter cells produced by mitosis, thus providing a mechanism for rapidly repairing injured tissues B: an increase in the number of gametes produced by an individual, thereby increasing the chance that fertilization will occur C: a decrease in the amount of time it takes to produce gametes D: a decrease in the genetic complexity of living systems, making it more likely that a species will survive E: an increase in the genetic diversity of gametes and zygotes

E: an increase in the genetic diversity of gametes and zygotes

Which of the following is true regarding an individual who has inherited one sickle-cell gene and one normal gene for hemoglobin? A: will produce only abnormal hemoglobin B: has the homozygous recessive genotype for this trait C: will most likely die before the age of 10 from complications associated with abnormal white blood cells D: will develop sickle-cell anemia E: is more likely to resist malaria than an individual with two normal genes for hemoglobin

E: is more likely to resist malaria than an individual with two normal genes for hemoglobin

An individual who inherits three copies of chromosome 18 will develop __________ syndrome

Edwards

True or False? A recessive trait can only be inherited through complete dominance if both parents are heterozygous for the trait.

False

True or False? Cystic fibrosis is caused by the inheritance of a single dominant lethal allele.

False

True or False? Dominant alleles are always more common in a population than recessive alleles.

False

True or False? Each person has two identical or nearly identical copies, called loci, of most genes.

False

True or False? Gregor Mendel's law of segregation and law of independent assortment apply to the genetics of peas but not to the genetics of humans.

False

True or False? Individuals with Klinefelter's syndrome (XXY) are phenotypically female, because they have two X chromosomes.

False

True or False? Linked genes are not influenced by crossing-over during meiosis.

False

True or False? Women cannot inherit X-linked traits such as hemophilia and red-green color blindness.

False

________ refers to the analysis of an individual's genetic material to determine predisposition to a particular health condition.

Genetic Testing

If the two alleles of a particular gene pair are the same, the individual is ________ for that gene.

Homozygous

In ________, the phenotype of the heterozygous genotype is an intermediate between the phenotype of either homozygous genotype.

Incomplete dominance

A display of an individual's chromosomes is known as a ________.

Karyotype

Failure of homologous chromosomes or sister chromatids to separate properly is called ________.

Nondisjunction

The inheritance of a trait that is determined by many genes acting together is ________ inheritance.

Polygenic

According to Mendel's law of ________, genes of a gene pair separate from one another during the formation of gametes.

Segregation

The process by which a piece of a chromosome breaks off and then attaches to another chromosome is ________.

Translocation

True or False? A Punnett square can be used to determine possible genotypes of offspring as well as possible genotypic and phenotypic ratios of the offspring given a particular combination of alleles.

True

True or False? A deletion occurs when a piece of chromosome breaks off and is lost.

True

True or False? A pedigree chart is a tool used to follow the inheritance pattern of a trait through many generations.

True

True or False? Human height, eye color, and hair color are examples of traits determined by polygenic inheritance.

True

True or False? If alleles for the same gene are different in the same person, that individual is genotypically heterozygous

True

True or False? In incomplete dominance, the phenotype of the heterozygous genotype is intermediate between the phenotype of either homozygous genotype.

True

True or False? In the human male, genotype and phenotype associated with the genes on the X chromosome are determined by the one X chromosome he inherits from his mother.

True

True or False? Polygenic inheritance depends on gene products from multiple genes.

True

True or False? The Y chromosome contains a gene that leads to the development of testes and testosterone in a developing embryo.

True

During embryological development, if a certain gene on the ________ chromosome is activated during the sixth or seventh week of development, the embryo will develop into a male.

Y