Bio Ch 7
In pea plants, the allele for purple flower color is dominant to the allele for white flower color. If you were to perform a test-cross to determine the genotype of a purple-flowered plant, you would expect the percentage of purple-flowered progeny to be _________ if the plant is homozygous and _____________ if the plant is heterozygous. Answers: 50%; 25% 50%; 100% 100%; 25% 75%; 75% 100%; 50%
100%; 50%
16. Gray hair in voles (H) is dominant to brown hair (h). Short claws (C) are dominant to long claws (c). What is the probability that the offspring of the cross HhCc × HHccwill have gray hair and long claws? 50 percent 56.25 percent 37.5 percent 0 percent 25 percent
A
19. In pea plants, the allele for purple flower color is dominant to the allele for white flower color. If you were to perform a testcross to determine the genotype of a purple-flowered plant, you would expect the percentage of purple-flowered progeny to be _________ if the plant is homozygous and _____________ if the plant is heterozygous. 100 percent; 50 percent 50 percent; 25 percent 50 percent; 100 percent 75 percent; 75 percent 100 percent; 25 percent
A
20. Which of the following statements is TRUE regarding pedigree analysis? Darkened shapes always represent individuals with the trait being traced. The length of the vertical lines is dependent on the relatedness coefficient between two individuals. White shapes always represent heterozygous individuals. Squares represent females, whereas circles represent males. Horizontal lines connect siblings.
A
25. A situation in which the heterozygote offspring of two homozygotes show a phenotype intermediate between those of the parents is called incomplete dominance. multiple allelism. a single-gene trait. a testcross. heterozygote superiority.
A
26. In snapdragons, flower color is inherited as a trait with incomplete dominance. There is an allele, CW, that produces no pigment, and an allele, CR, that produces red pigment. A plant with the CWCR genotype will produce _________________ flowers. pink red white two kinds of no
A
32. Which term refers to the genetic control of continuously varying traits such as height? polygenic codominant incomplete dominance multi-allelic pleiotropic
A
36. Sex-linked traits often are expressed in different frequencies in males and females. occur in females but not males. are coded for by genes on the autosomes. are coded for by genes on the Y chromosome only. occur in males but not females
A
43. Phenotypes are generally a product of the genotype in combination with the environment. multiple alleles at the same gene locus. the genotype. the environment. two or more genes in combination with each other.
A
5. Which of the following did Gregor Mendel never see? a chromosome a hybrid a pea an F2 generation a stamen
A
50. When crossing over occurs, _______________ genes usually stay together. linked sex-linked pleiotropic independently assorting multi-allelic
A
8. If a true-breeding blue-flowered plant was crossed with a true-breeding white-flowered plant, what phenotypic ratio would we observe in the progeny resulting from this cross? Assume the white-flowered trait is completely dominant. 100 percent white 100 percent light blue 100 percent blue 75 percent blue, 25 percent white Not enough information is provided to answer this question.
A
Virtually everyone with ________ has a parent who exhibits the same trait. a cleft chin freckles color-blindness sickle-cell disease phenylketonuria
A
Which of the following statements about dominant traits is CORRECT? None of the above answer choices is correct. They are observed one-quarter as frequently as heterozygous traits. They are observed more frequently than recessive traits. They increase in frequency over evolutionary time. They are observed less frequently than recessive traits.
A
13. How can two pea plants that have different genotypes for seed color be identical in phenotype? Genotype has no relation to phenotype. One of the two plants could be homozygous for the dominant allele, while the other could be heterozygous. One of the two plants could be homozygous for the dominant allele, while the other could be homozygous for the recessive allele. Seed color in pea plants is not genetically determined. One of the two plants could be homozygous for the recessive allele, while the other could be heterozygous.
B
18. The testcross is a cross of an individual whose genotype for a trait is not known with an individual who is homozygous recessive for the trait. All of the above answer choices are correct. makes it possible to determine the genotype of an individual of unknown genotype who exhibits the dominant version of a trait. Both the first and second answer choices are correct. sometimes requires the production of multiple offspring in order to reveal the genotype of an individual whose genotype is unknown.
B
21. In humans, X-linked traits All of the above answer choices are correct. occur on the X-chromosome. are passed from fathers to their sons. are more common than autosomal traits. occur more frequently in females.
B
22. Autosomal recessive traits are exhibited only in the offspring of two heterozygous parents. can skip generations. occur in one-quarter of all offspring. occur more frequently in females than males. All of the above answer choices are correct.
B
24. In snapdragons, there is an allele for flower color, CW, that produces no pigment. A plant with the genotype CWCW will produce _____________ flowers. purple white no red pink
B
27. The offspring from each cross done in Mendel's pea experiments always looked like one of the two parental varieties because many different genes interacted to produce the F1 phenotype. one allele showed complete dominance over the other. many different genes interacted to produce the parental phenotype. each allele affected phenotypic expression. the traits blended together because of crossing over in meiosis.
B
28. If two individuals who are heterozygous for the sickle-cell disease mate, their offspring will have the sickle-cell disease. have a one-quarter chance of being a sickle-cell-free homozygote. None of the above answer choices is correct. all have the genotype HbSHbA. all be heterozygous for the sickle-cell disease.
B
33. The SRY gene protect humans from somatic respiratory yeasts. causes fetal gonads to develop as testes shortly after fertilization. causes fetal gonads to develop as ovaries shortly after fertilization. causes circular red blood cells to resist malaria. causes sickle-shaped red blood cells to resist malaria.
B
37. Is it possible for a woman to have an X-linked recessive trait? If it is, how can this occur? Yes, a woman can have an X-linked recessive trait if both her father has the trait and her mother is heterozygous for the trait. Both the second and third answer choices are correct. Yes, a woman can have an X-linked recessive trait if her mother is homozygous for the trait. Yes, a woman can have an X-linked recessive trait if both her father has the trait and her mother is homozygous for the trait. No, women cannot have X-linked recessive traits because they are all recessive and women have two X chromosomes.
B
46. How many unique haploid gametic genotypes could be produced through independent assortment by an organism with the diploid genotype AABbCCDdEe? 4 8 1 16 2
B
7. In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for white flowers are crossed, in the offspring all of the flowers will be purple. all of the flowers will be white. one-quarter of the flowers will be purple and three-quarters will be white. three-quarters of the flowers will be purple and one-quarter will be white. half of the flowers will be purple and half will be white.
B
Is it possible for a woman to have a X-linked recessive trait? If it is, how can this occur? Answers: No, women cannot have X-linked recessive traits because they are all recessive and women have two X chromosomes. Yes, a woman can have an X-linked recessive trait if both her father has the trait and her mother is homozygous for the trait. Yes, a woman can have an X-linked recessive trait if both her father has the trait and her mother is heterozygous for the trait. Yes, a woman can have an X-linked recessive trait if her mother is homozygous for the trait. Both b) and c) are correct.
Both b) and c) are correct.
29. The ABO blood type system in humans is a system that contains ________ alleles that produce __________ different phenotypes. three; six three; three three; four four; three four; four
C
30. Some genes, such as the human ABO blood groups, have more than two alleles. For these genes some individuals can be triply heterozygous. natural selection cannot alter the allele frequencies. individuals can only possess two alleles. a greater proportion of the individuals must be heterozygous than homozygous. normal dominance relationships are not possible.
C
35. Most, if not all, genes are heterozygous. sex-linked. pleiotropic. codominant. multi-allelic.
C
39. Modern research on male-pattern baldness has confirmed that a single maternally inherited allele is the sole contributor of male-pattern baldness. it is caused by clogged hair follicles and toxic hair care products. it is a trait passed down to men from their mothers. balding men commonly share a DNA sequence on their Y chromosome. genes on chromosome 20 cause male-pattern baldness.
C
40. The failure of a seedling to turn green if grown in the dark is an example of incomplete dominance. continuous variation. interaction between genotype and environment. interaction between codominant alleles. pleiotropy.
C
42. Phenylketonuria (PKU) is a disease characterized by the buildup of phenylalanine. The enzyme phenylalanine hydroxylase, which catalyzes the conversion of _________ to __________, is mutated and non-functional. None of the above answer choices is correct. phenylalanine; arginine phenylalanine; tyrosine tyrosine; phenylalanine arginine; phenylalanine
C
6. A diploid individual with two identical alleles for a particular gene is said to be heterozygous for every gene. sex-linked dominant. homozygous for that gene. heterozygous for that gene. homozygous for every gene.
C
14. A true-breeding red rose is repeatedly mated with a true-breeding white rose, and all of their offspring are red. If two of these red offspring are mated, what percentage of their offspring will be red? 60 percent 50 percent 100 percent 75 percent 25 percent
D
15. In pea plants, tall stem length is dominant to short, and round seed shape is dominant to wrinkled seed shape. If a plant that is homozygous for tall stem and homozygous for wrinkled seeds is allowed to self-fertilize, what proportion of the offspring will have wrinkled seeds and a tall stem? 3/16 9/16 1/2 All of the offspring will have wrinkled seeds and a tall stem. None of the offspring will have wrinkled seeds and a tall stem.
D
31. Mary, who has type O blood, is expecting a child with her husband, who has type B blood. Mary's husband's father has type A blood. What is the probability that the child will have type O blood? 75 percent 0 percent 25 percent 50 percent 100 percent
D
34. The impact of a single gene on more than one characteristic is called polygenic inheritance. codominance. incomplete dominance. pleiotropy. epistasis.
D
38. All genetically normal humans have Two pairs of 22 autosomes, a Y chromosome, and an X chromosome. 46 autosomes. 8 toes. 44 autosomes. 23 chromosomes.
D
41. Phenylketonuria is a genetic disorder that causes the inability to convert tyrosine to phenylalanine. the buildup of tyrosine in the system. too many copies of phenylalanine to be added to protein chains. the inability to convert phenylalanine to tyrosine. too few copies of tyrosine to be added to protein chains.
D
44. When genetically based traits are inherited independently from each other, this is known as polygenism. multi-allelism. linkage. Mendel's law of independent assortment. pleitropy.
D
47. The MOST IMPORTANT reason that Mendel's law of independent assortment is NOT universally true is that genes are made of DNA. some genes are sex-linked. genes are almost always pleiotropic. genes are carried on chromosomes. half of your genes are inherited from your mother and half from your father.
D
48. We say that genes are linked when they contain multiple alleles. are responsible for producing the same protein. assort independently. are located near each other on a single chromosome. produce a balanced polymorphism.
D
Cystic fibrosis, which is usually lethal before reproductive ages, is a homozygous recessive disease. Why do cases continue to arise, even though people with the disease rarely live to reproduce? Cystic fibrosis is a multifactorial disorder, and is probably controlled by the action of many genes. Mosquitoes can transfer the disease from person to person. Individuals can pass on the alleles in non-genetic ways, including through the sharing of needles. The harmful allele can reside in heterozygous individuals with few to no negative effects. People continue to make unhealthy lifestyle choices.
D
12. Albinism (lack of skin and hair pigmentation) is caused by a recessive autosomal allele. A woman and man, both normally pigmented, have an albino child together. For this trait, what is the genotype of the albino child? It is unknown because not enough information is provided. It is homozygous dominant. It is heterozygous. It depends on the sex of the child. It is homozygous recessive.
E
17. In certain plants, red flowers are dominant to white flowers. If a heterozygous plant is crossed with a homozygous red-flowered plant, what is the probability that the offspring will be white-flowered? 100 percent 25 percent 50 percent It depends on whether the traits are linked. 0 percent
E
23. Assuming that a particular disorder is caused by an allele of a single gene, what feature of a pedigree would allow one to conclude that the disorder was caused by a dominant allele? Two unaffected parents have an unaffected child. All of the descendants of a particular affected person are also affected. Two unaffected parents have an affected child. An affected mother only has affected sons. Two affected parents have an unaffected child.
E
45. Mendel's law of independent assortment states that the alleles at one locus separate independently of those at other loci. This law does not apply to genes that influence the same character. to autosomal genes. if recombination between the two loci occurs. to identical twins. to genes located close together on the same chromosome.
E
49. Genes that are _____________ do not assort independently, but they may recombine by crossing over. epistatic polygenic pleiotropic continuously variable linked
E
How can an individual whose parents did not have the "fish odor syndrome" trait inherit that trait? If each parent were a silent carrier of the "fish odor syndrome," then their offspring would have a 100-percent chance of having the syndrome. Under the circumstances outlined above, the "fish odor syndrome" cannot be inherited. The "fish odor syndrome" trait is inherited extra-genetically If each parent were a silent carrier of the "fish odor syndrome," then their offspring would have a 50-percent chance of having the syndrome. If each parent were a silent carrier of the "fish odor syndrome," then their offspring would have a 25-percent chance of having the syndrome.
E
In genetics, the separation of alleles or homologous chromosomes during meiosis so that the haploid daughter cells have one allele or the other, but never both, is also referred to as Mendel's first law. All of the above answer choices are correct. segregation. random genetic drift. Both the first and second answer choices are correct.
E
Most genes come in alternative forms called gametes. recessives. dominants. chromosomes. alleles.
E
Which of the following is a single-gene trait? height blue eyes All of the above answer choices are correct. brown hair the widow's peak hairline
E
Which of the following was NOT true of Gregor Mendel? Answers: His primary research system was the pea plant. He was an Austrian monk. He lived in the 19th century. He understood basic concepts about DNA replication. He developed the first theory about how traits are inherited.
He understood basic concepts about DNA replication.
Jay has type O blood, and his brother Alon has type AB blood. What are the genotypes of these boys' parents? Answers: IAi and IBi ii and IBi IAIA and IBi IAi and IBIB ii and ii
IAi and IBi
Virtually everyone with __________________ has a parent that exhibits the same trait. Answers: a cleft chin freckles color-blindness phenylketonuria sickle-cell disease
Selected Answer: a cleft chin
If a true-breeding, blue-flowered plant was crossed with a true-breeding white-flowered plant, what phenotypic ratio would we observe in the progeny resulting from this cross? Assume the white-flowered trait is completely dominant. Answers: 75% blue, 25% white 100% blue 100% light blue 100% white There is not enough information to answer this question.
Selected Answer: 100% white
All genetically normal humans have: Answers: eight toes. 46 autosomes. 44 autosomes. Two pairs of 22 autosomes, a Y chromosome, and an X chromosome. 23 chromosomes.
Selected Answer: 44 autosomes.
A male with an X-linked recessive disorder mates with a female that is a carrier for this same X-linked recessive disorder. Which of the following is the correct expected frequency of this disorder in their children? Answers: 50% frequency in both the sons and the daughters 50% frequency in the sons 100% frequency in the daughters 100% frequency in the sons 50% frequency in the daughters
Selected Answer: 50% frequency in both the sons and the daughters
A true-breeding red rose is repeatedly mated with a true-breeding white rose, and all of their offspring are red. If two of these red offspring are mated, what percentage of their offspring will be red? Answers: 60% 100% 25% 50% 75%
Selected Answer: 75%
In genetics, the separation of alleles or homologous chromosomes during meiosis so that the haploid daughter cells have one allele or the other but never both is also referred to as: Answers: Mendel's first law. segregation. random genetic drift. Both a) and b) are correct. All of the above are correct.
Selected Answer: Both a) and b) are correct.
Which of the following statements is true regarding pedigree analysis? Answers: Squares represent females, while circles represent males. Horizontal lines connect siblings. Darkened shapes always represent individuals with the trait being traced. The length of the vertical lines is dependent on the relatedness coefficient between two individuals. White shapes always represent heterozygous individuals.
Selected Answer: Darkened shapes always represent individuals with the trait being traced.
Which of the following pairings, indicated by letters referring to blood type phenotypes, CANNOT produce a child with type B blood? Answers: O x O O x AB B x O A x B All of the above could produce a child with type B blood.
Selected Answer: O x O
Assuming that a particular disorder is caused by an allele of a single gene, what feature of a pedigree would allow one to conclude that the disorder was caused by a dominant allele? Answers: Two unaffected parents have an affected child. Two affected parents have an unaffected child. Two unaffected parents have an unaffected child. An affected mother only has affected sons. All of the descendants of a particular affected person are also affected.
Selected Answer: Two affected parents have an unaffected child.
The test-cross: Answers: makes it possible to determine the genotype of an individual of unknown genotype who exhibits the dominant version of a trait. is a cross of an individual whose genotype for a trait is not known with an individual homozygous-recessive for the trait. sometimes requires the production of multiple offspring in order to reveal the genotype of an individual whose genotype is unknown. a) and b) are both correct. a), b), and c) are correct.
Selected Answer: a) b) and c) are both correct.
The law of segregation states that: Answers: the transmission of genetic diseases within families is always recessive. the number of chromosomes in a cell is always divisible by 2. an allele on one chromosome will always segregate from an allele on a different chromosome. each of two alleles for a given trait segregate into different gametes. gametes cannot be separate and equal
Selected Answer: each of two alleles for a given trait segregate into different gametes.
A diploid individual with two identical alleles for a particular gene is said to be: Answers: homozygous for that gene. homozygous for every gene. heterozygous for every gene. sex-linked dominant. heterozygous for that gene.
Selected Answer: homozygous for that gene.
Albinism (lack of skin and hair pigmentation) is caused by a recessive autosomal allele. A woman and man, both normally pigmented, have an albino child together. For this trait, what is the genotype of the albino child? Answers: It depends on the sex of the child. homozygous dominant It is unknown because not enough information is provided. homozygous recessive heterozygous
Selected Answer: homozygous recessive
Without knowing the genetic basis, humans have selectively bred for: Answers: unattached earlobes. straight hairline. transgenic tomatoes. cleft chins. increased body size in cattle.
Selected Answer: increaed body size in cattle
The phenotype of an organism can best be determined by: Answers: inbreeding. outbreeding. sequencing its genes. observing the organism. a reciprocal cross.
Selected Answer: observing the organism.
Peas (Pisum sativum) were well suited for Mendel's breeding experiments for all of the following reasons except: Answers: peas exhibit variations in a number of observable characteristics, such as flower color and seed shape. Mendel and his staff could control the pollination between different pea plants. it is easy to obtain large numbers of offspring from any given cross. many of the characteristics that vary in pea plants are controlled by single genes. peas have a particularly long generation time.
Selected Answer: peas have a particularly long generation time.
Phenylketonuria (PKU) is a disease characterized by the buildup of phenylalanine. The enzyme phenylalanine hydroxylase, which catalyzes the conversion of _________ to __________, is mutated and non-functional. Answers: arginine; phenylalanine phenylalanine; arginine tyrosine; phenylalanine phenylalanine; tyrosine None of the above is correct.
Selected Answer: phenylalanine; tyrosine
In snapdragons, flower color is inherited as a trait with incomplete dominance. There is an allele, CW, that produces no pigment, and an allele, CR, that produces red pigment. A plant with the CWCR genotype will produce _________________ flowers. Answers: no pink white two kinds of red
Selected Answer: pink
Two fruit flies are crossed, resulting in offspring with a 3:1 phenotypic ratio for a particular trait. This suggests: Answers: that the parents were both heterozygous for the gene associated with that trait. that one parent had complete dominance for the gene associated with that trait while the other parent had incomplete dominance. that the one parent was heterozygous for the gene associated with that trait and the other parent was homozygous. incomplete dominance. that the parents were both homozygous for the gene associated with that trait.
Selected Answer: that the parents were both heterozygous for the gene associated with that trait.
If a baby has "his father's nose," it's because: Answers: the baby has been cobbled together from a bunch of used parts. the baby has not inherited the "suppress father's nose allele" from his mother. the baby has inherited many alleles from his father that work together to shape the baby's nose. the baby has inherited the "father's nose" allele from his father. the baby has inherited the "father's nose" allele from his mother.
Selected Answer: the baby has inherited many alleles from his father that work together to shape the baby's nose.
We say that genes are linked when: Answers: they contain multiple alleles. they assort independently. they are located near each other on a single chromosome. they are responsible for producing the same protein. they produce a balanced polymorphism.
Selected Answer: they are located near each other on a single chromosome.
A cross between homozygous red-eyed flies and homozygous white-eyed flies results in progeny that all have red eyes. This result demonstrates: Answers: the law of independent assortment. a dihybrid cross. the norm of reaction. the blending model of genetics. dominance.
dominance.
The same genetic condition that causes sickle-cell anemia can also protect against: Answers: HIV-AIDS. cholera. yellow fever. malaria. hemophilia.
malaria.
Sex-linked traits: Answers: often are expressed in different frequencies in males and females. are coded for by genes on the Y-chromosome only. occur in females but not males. occur in males but not females. are coded for by genes on the autosomes.
often are expressed in different frequencies in males and females.
Which of the following is NOT a continuously varying trait? Answers: eye color height weight sickle-cell disease skin color
sickle-cell disease
In snapdragons, there is an allele for flower color, CW, that produces no pigment. A plant with the genotype CWCW will produce _____________ flowers. Answers: pink no red white purple
white
