chapter 16

Roberts Syndrome extremely rare genetic disorder that is characterized by mild to severe prenatal retardation or disruption of cell division, leading to malformation of the bones in the skull, face, arms, and legs. Shown below is a pedigree for a family with Robert's Syndrome. Consider couple II-C and II-D. What is the probability that their next two children will have Robert's Syndrome? 1/4 1/2 1/8 1/16 1/32

1/16

Type 1 fucosidosis is a rare human disease. Patients cannot hydrolyze the disaccharide fucose, and as a result have severe neurological decline and die by age 6. The disease is due to a defect in the gene that encodes the lysosomal enzyme that breaks down fucose (α-1-fucosidase), and is inherited in an autosomal recessive manner. Jane and John have a child who has Type 1 fucosidosis. What is the probability that their next child will also have the disease? No chance 1/4 1/2 3/4 4/4 or 100%

1/4

Nearsightedness is dominant to normal vision and hazel eyes are dominant to blue eyes. A nearsighted woman with hazel eyes who is heterozygous for both traits marries a man with normal vision and hazel eyes. His genotype for eye color is the same as his wife's. Their three children all have blue eyes and normal vision. What is the probability that their next child will have blue eyes and be nearsighted? 1/4 1/2 3/8 1/8 5/8

1/8

For mechanisms of sex determination, which of the following is incorrectly paired? X-Y, cow X-O, grasshopper ZZ-ZW, bluebird 1n-2n, pea plant high temperature-low temperature, alligator

1n-2n, pea plant

Consider the human population. With regards to the ABO blood groups there are _____ alleles, ____ possible genotypes, and _____ possible phenotypes. 3, 4, 6 2, 4, 6 2, 3, 4 2, 6, 4 3, 6, 4

3, 6, 4

A couple has five sons. What is the probability that their next child will be a girl? 0% 25% 50% 75% 100%

50%

Anury is the absence or abbreviation of the tail in sheep (and also other animals). It is inherited in an autosomal dominant fashion. A ram with anury is mated to a ewe with a normal tail. The ram's father had anury, his mother did not. What is the probability that the ram and ewe will produce a lamb with anury? (ram = male; ewe = female) 25% 50% 75% 100% No chance

50%

In Hodags (mythical creatures of Wisconsin), brown fur (B) is dominant over gray fur (b) and long horns (H) are dominant over short horns (h). Two true-breeding hodags, one with brown fur and long horns and the other with gray fur and short horns mate and produce an F1. Two F1 individuals are mated. What proportion of the offspring will exhibit a phenotypic combination that is different from the P generation? Assume the genes for fur color and horn length are on different chromosomes. 1/2 9/16 3/16 6/16 1/16

6/16

What is the distribution of phenotypes from a cross of purple dwarf pea plants that are heterozygous for flower color and plant height? (Purple is dominant to white; tall is dominant to dwarf.) 63 purple dwarf; 28 purple tall; 27 white dwarf; 7 white tall 132 purple dwarf; 138 white tall 54 purple dwarf; 6 white tall 100% purple dwarf 27 purple dwarf; 28 purple tall; 31 white dwarf; 29 white tall

63 purple dwarf; 28 purple tall; 27 white dwarf; 7 white tall

A male is heterozygous for the trait that produces freckles on the skin, and he has freckles. If he marries a woman who is also heterozygous for freckles, ______ percent of their children will be freckled and __________ percent of their children will be heterozygous. 100%, 100% 75%, 50% 75%, 25% 50%, 50% 100%, 75%

75%, 50%

Type 1 fucosidosis is a rare human disease. Patients cannot hydrolyze the disaccharide fucose, and as a result have severe neurological decline and die by age 6. The disease is due to a defect in the gene that encodes the lysosomal enzyme that breaks down fucose (α-1-fucosidase), and is inherited in an autosomal recessive manner. Jane and John have a child who has Type 1 fucosidosis. What is the probability that their next two children will NOT have the disease? None (all of their children will have the disease) 1/2 3/4 1/8 9/16

9/16

Hemophilia is a sex-linked recessive condition that results in deficient blood clotting. The disease causes excessive bleeding which occurs spontaneously or upon slight injury. In dogs (as in humans) hemophilia is caused by a defect in a gene on the X chromosome. What will be the results of mating between a normal, non-carrier female dog and a male dog with hemophilia? All female offspring will be normal and half the male offspring will have hemophilia. Half the male offspring will be normal and half will have hemophilia; all females will be carriers. All the female offspring will be normal and all male offspring will be carriers. Half the female offspring will have hemophilia and half will be carriers, all male offspring will be normal. All of the offspring will be normal, but all females will be carriers.

All of the offspring will be normal, but all females will be carriers.

In wolves, gray coat color (G) is dominant to black (g) and brown eyes (B) are dominant to blue (b). The genes that control these traits are located on different chromosomes. The alpha male of the pack has the dominant phenotype for both traits and is heterozygous for both traits. The alpha female has brown eyes and a black coat; she is heterozygous for eye color. Which option represents gametes that would be made by the alpha female? B, b, and g Bg and bg Bb and gg BG, Bg, bG, bg None of these

Bg and bg

How can you determine the genotype of a plant showing the dominant phenotype of red color? The phenotype reflects the genotype, so the plant must be homozygous for the trait. Cross the red plant with a white plant to see if any white plants appear. Cross the red plant with other red plants to see if any white plants appear. Cross the red plant with a white plant to see how many red plants appear. Cross the red plant with another red plant, and then cross the F1 population with each other to see if any white plants appear.

Cross the red plant with a white plant to see if any white plants appear.

A locus encodes different genes in different individuals of the same species. True False

False

Offspring receive both the alleles for a given trait from one parent. True False

False

The law of independent assortment states that the two alleles of the same gene will segregate from each other during gamete formation. True False

False

The sex of all animals is determined by chromosomes. True False

False

What personal characteristics and events in Gregor Mendel's life significantly contributed to his ultimate contribution to the study of inheritance? His training in physics and mathematics at the University of Vienna. He failed his physics exam. He failed his natural history exam. He got his teaching license at the age of 21. He got a job as a substitute teacher and enjoyed it.

His training in physics and mathematics at the University of Vienna.

Hemophilia A is an X-linked recessive genetic condition. In humans it is due to a mutation in the F8 gene, which encodes a protein called coagulation factor VII. Coagulation factors are proteins important in blood clotting. Individuals with hemophilia, when injured, bleed longer than a normal, healthy individual; the inability to normally clot blood can be life threatening. Hemophilia is much more common in males than in females. Which of the following does NOT explain why this is so? A female with one defective allele makes enough normal coagulation factor VII to clot blood and will not have hemophilia A Males are hemizygous for the F8 gene, so they will have hemophilia A if they have one defective allele Females have to receive a defective allele from both their mother and their father to get hemophilia A Males have to receive a defective allele only from their father to get hemophilia A

Males have to receive a defective allele only from their father to get hemophilia A

What features of meiosis allow for independent assortment of chromosomes? Random alignment of homologous sister chromatids on the metaphase plate Separation of sister chromatids Reduction of chromosome number from diploid to haploid Both the separation of sister chromatids and the reduction of chromosome number from diploid to haploid

Random alignment of homologous sister chromatids on the metaphase plate

Which of the following inheritance patterns is matched with an inaccurate molecular basis? Incomplete dominance: The protein produced by a wild-type allele affects the phenotype in a concentration-dependent manner. Codominance: Two proteins are produced in heterozygotes. Sex-influenced: Hormones alter the expression of proteins encoded by dominant and recessive alleles. X-linked: Hemizygotes with the recessive allele do not make a functional protein, but heterozygotes do. Simple Mendelian inheritance: The protein produced by a single allele cannot produce the dominant phenotype.

Simple Mendelian inheritance: The protein produced by a single allele cannot produce the dominant phenotype.

An individual with an SRY gene is a male mammal. True False

True

If you were to examine a typical population at a single locus, you would find more copies of the wild-type allele than any other allele. True False

True

In insects, as in humans, the presence of a Y chromosome determines maleness. True False

True

An X-linked gene is a gene that encodes traits seen only in females. a gene on the X chromosome. a gene found on any chromosome; they are X-shaped when they are metaphase chromosomes. a gene that is turned on (makes protein) only when the female hormone estrogen is present. a gene on the X chromosome that encodes traits seen only in females.

a gene on the X chromosome.

The two-factor crosses performed by Mendel support the observation that alleles for a given trait are distributed randomly among an individual's gametes independent of the alleles for other traits. traits that are encoded by genes on different chromosomes are never found within the same gamete. the F1 generation can display phenotypes in combinations different from those seen in the P generation. the F2 generation will only display phenotypes in the same combinations as the P generation. self-fertilization of the F1 generation will produce 100% heterozygous plants at both loci.

alleles for a given trait are distributed randomly among an individual's gametes independent of the alleles for other traits.

Roberts Syndrome is an extremely rare genetic disorder that is characterized by mild to severe prenatal retardation or disruption of cell division, leading to malformation of the bones in the skull, face, arms, and legs. Shown below is a pedigree for a family with Robert's Syndrome. Based on this pedigree Roberts Syndrome is inherited as a(n) ___________ trait? autosomal dominant autosomal recessive sex-linked dominant sex-linked recessive random

autosomal recessive

A person who is homozygous for a mutation of the phenylalanine hydroxylase gene can lead a normal life if the environment is controlled. cannot give blood. will always develop mental retardation in early infancy. will require phenylalanine supplements throughout life. Two statements are correct. They can lead a normal life if the environment is controlled by taking phenylalanine supplements.

can lead a normal life if the environment is controlled.

In Thomas Hunt Morgan's experiments, males had white eyes but females did not. What cross could you perform with his flies to obtain white-eyed females? cross the F1 offspring to each other cross an F1 female to a white-eyed male cross an F2 female with an F1 male cross an F2 female with a white-eyed male crossing either the F1 or F2 females with a white-eyed male will produce some white-eyed females

crossing either the F1 or F2 females with a white-eyed male will produce some white-eyed females

A woman comes to your genetic counseling center because she knows that Huntington disease occurs in members of her family. Her paternal grandfather was afflicted, but so far her father shows no symptoms. Her two great-great grandmothers on her father's side were healthy well into their 90s, and one of her great-great grandfathers died of unknown causes at 45. Testing for Huntington disease is extremely expensive, but she is concerned that she may fall victim to this disease and wants to plan her life accordingly. After examining her pedigree you advise her to get tested because there is no possibility that she is homozygous. not get tested because only males in her family get the disease. get tested because her father could be a carrier. not get tested because her father is only a carrier and it is very unlikely her mother is a carrier. not get tested because her 40-year-old father shows no symptoms.

get tested because her father could be a carrier.

In mammals, males are ________ and females are _______ for their sex chromosomes. heterozygous, homozygous hemizygous, homozygous homozygous, heterozygous hemizygous, heterozygous heterozygous, hemizygous

hemizygous, homozygous

If a pink snapdragon is self-fertilized, the offspring are red, pink, or white. What type of inheritance pattern does flower color exhibit in this example? codominance incomplete dominance dominance incomplete recessive recessive

incomplete dominance

Imagine that horn color in Hodags (folkloric creatures of Wisconsin) is controlled by a single gene. You mate a Hodag homozygous for a bright orange horns (COCO) with a Hodag homozygous for ivory horns (CICI). Numerous offspring are produced, all with pale orange horns. This pattern of inheritance of horn color can best be described as codominance. recombination. incomplete dominance. complete dominance. environmental effects on phenotype.

incomplete dominance.

The color of petunia flower can be changed from red to blue by altering the pH of the soil. This is an example of norm of reaction. the environment influencing the genotype. codominance. incomplete dominance. range of inheritance.

norm of reaction.

When a single-gene mutation can have phenotypic effects at multiple stages of development, it is pleiotropic. incompletely dominant. recessive. causing a disease. codominant.

pleiotropic.

A white cow was mated with a red cow, and they had an offspring who was roan - the calf had an even mixture of white hairs and red hairs covering her body. What is the most likely explanation of the inheritance of the roan coat? red is dominant and white is recessive red and white are codominant incomplete dominance X-linked dominance pleiotropy

red and white are codominant

Color blindness is a recessive X-linked trait. A normal couple has a color-blind child. Who else in this family is probably color blind? the child's maternal grandfather the child's maternal grandmother the child's paternal grandfather the child's paternal grandmother the child's maternal grandmother or grandfather

the child's maternal grandfather

In codominance, the two alleles affect the phenotype in separate, distinguishable ways the heterozygote exhibits the phenotypes of both parents equally the heterozygote is an intermediate phenotype between the parental phenotypes there are always more than two alleles for a given character in a population

the two alleles affect the phenotype in separate, distinguishable ways

In codominance, the two alleles affect the phenotype in separate, distinguishable ways the heterozygote exhibits the phenotypes of both parents equally the heterozygote is an intermediate phenotype between the parental phenotypes there are always more than two alleles for a given character in a population

the two alleles affect the phenotype in separate, distinguishable ways

A woman visits her doctor's office complaining of pattern baldness. Her mother and father do not have pattern baldness, but her brother does. The doctor is concerned that she may have the serious condition of __, and he immediately orders blood tests to check her ________ levels. tumor of the adrenal gland, 5-dihydrotestosterone tumor of the reproductive system, testosterone skin cancer, 2,5 alpha-reductase tumor of the adrenal gland, estradiol tumor of the reproductive system, 5-dihydrotestosterone

tumor of the adrenal gland, 5-dihydrotestosterone

Polydactyly is a dominant trait that results in extra fingers and toes in humans. A man with polydactyly marries a woman with 10 fingers and toes. They have a child that has a normal number of digits. The phenotype of the man's father is unknown, but his mother has a normal phenotype. What are the genotypes of the married couple? (D = polydactyl allele; d = wild type allele) woman Dd, man dd woman DD, man dd woman dd, man DD woman dd, man Dd woman DD, man Dd or dd

woman dd, man Dd

The probability of obtaining a dominant phenotype from self-fertilization of a heterozygous individual is 25% 50% 75% 100%

75%

In wolves, gray coat color (G) is dominant to black (g) and brown eyes (B) are dominant to blue (b). The genes that control these traits are located on different chromosomes. The alpha male of the pack has the dominant phenotype for both traits and is heterozygous for both traits. The alpha female has brown eyes and a black coat; she is heterozygous for eye color. The alpha male and the alpha female mate. What proportion of their offspring will have the same phenotype as the mother? 1/16 3/16 3/8 1/2 None

3/8

A homologous pair of mitotic chromosomes will possess _______ alleles for each locus. 2 4 8 1 50% of the

4

An organism that is heterozygous for two traits can produce a maximum of _______ different gametes for these traits. 2 4 2; if they are on the same chromosome 4; only if they are on different chromosomes 8

4

A man with pattern baldness and a woman who has no baldness have a son who develops pattern baldness. Their son has a daughter who also develops pattern baldness. They determine that her expression of this trait is not a symptom of a medical condition. If her mother does not have pattern baldness, the daughter's genotype is ________ and her mother's genotype is ________. BB, bb BB, Bb bb, BB Bb, Bb bb, Bb

BB, Bb

Eyelash length is an inherited trait. In the human population, there is an eyelash length gene. There are two possible variants of this gene - an allele for long eyelashes (> 1cm) and an allele for short eyelashes (1 cm or less). The allele for long eyelashes is dominant (L) and the allele for short eyelashes is recessive (l). An individual who is heterozygous for eyelash length would produce which of the following gametes? All gametes would have the l allele. All gametes would have the L allele. Half of the gametes would have the L allele and half of the gametes would have the l allele. The proportion of gametes receiving each allele would be random; the process of meiosis is very disorganized and chromosomes are not separated in an ordered fashion. None of the gametes would have the eyelash gene; gametes do not have eyelashes.

Half of the gametes would have the L allele and half of the gametes would have the l allele.

What is a testcross? Any genetics cross you do in a lab or an abbey garden Any genetics cross you see on an exam A cross between two organisms of different species A cross between an organism of unknown genotype with a homozygous recessive individual A cross between two true-breeding individual (such as we see in the P generation)

A cross between an organism of unknown genotype with a homozygous recessive individual

Only fathers can pass on pattern baldness to their sons. True False

False

Eyelash length is an inherited trait. In the human population, there is an eyelash length gene. There are two possible variants of this gene - an allele for long eyelashes (> 1cm) and an allele for short eyelashes (1 cm or less). The allele for long eyelashes is dominant (L) and the allele for short eyelashes is recessive (l). An individual who is heterozygous for eyelash length would have which of the following phenotypes? ll LL Ll Long eyelashes Short eyelashes

Long eyelashes

The probability of a couple having either a boy or a girl is ½. However, many families have more boys than girls and VICE VERSA. Why is the observed ratio of boys to girls in typical families different than the predicted ratio? There is a large random sampling error due to the small size of families. There is a small random sampling error due to the small size of families. Humans are more heterozygous than is predicted by random sampling. The sex of each child is determined independently. Two of the answers are correct. There is a large random sampling error due to the small size of human families and the sex of each child is determined independently.

Two of the answers are correct. There is a large random sampling error due to the small size of human families and the sex of each child is determined independently.

An organism has one Z chromosome and one W chromosome. That organism is a female bird. a male bird. a female insect. a male insect.

a female bird.