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Chapter 14: Mendel and the Gene Idea
 
Chapter Quiz
 

Chapter Quiz


1 .       Which choice below is a basic difference between Mendel's particulate hypothesis and the blending hypothesis? (Concept 14.1E-Book) [Hint]

 The blending hypothesis, but not the particulate hypothesis, maintained that mutation is the major source of new gene combinations.
 The blending hypothesis, but not the particulate hypothesis, maintained that the two alleles at any given locus are always different.
 The blending hypothesis, but not the particulate hypothesis, maintained that the traits governed by genes in the egg are different from the traits governed by genes in the sperm.
 The blending hypothesis, but not the particulate hypothesis, maintained that after a mating, the genetic material provided by each of the two parents is mixed in the offspring, losing its individual identity.
 All of the above.
2 .       If a plant variety is true-breeding for a dominant trait, then _____. (Concept 14.1E-Book) [Hint]

 if the plant were allowed to self-pollinate, the dominant and recessive traits would consistently appear in a 3:1 ratio among the progeny
 the plant is heterozygous for the trait
 if the plant were crossed with a heterozygote, one-half of the progeny would show the dominant trait, and one-half would show the recessive trait
 if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait
 the variety is immune to mutation
3 .       A = big apples; R = red apples; a = small apples; r = yellow apples. You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half of the new trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents? (Concept 14.1E-Book) [Hint]

 AArr and aaRr
 Aarr and aaRr
 AARr and Aarr
 AaRr and AaRr
 AaRr and aarr
4 .       Assume tall (T) is completely dominant to dwarf (t). If a homozygous dominant individual is crossed with a homozygous dwarf, the offspring will _____. (Concept 14.1E-Book) [Hint]

 all be intermediate in height
 all be tall
 be 1/2 tall and 1/2 dwarf
 be 3/4 tall and 1/4 dwarf
 all be short
5 .       The F1 generation differed from the F2 in Mendel's experiments in that _____. (Concept 14.1E-Book) [Hint]

 all of the F1 showed the dominant phenotype, whereas only half of the F2 did
 all of the F1 showed the dominant phenotype, but only three-fourths of the F2 did
 all of the F1 showed the dominant phenotype, and all of the F2 showed the recessive phenotype
 one-half of the F1 showed the dominant phenotype, and three-fourths of the F2 did
 none of the F1 showed the dominant phenotype, but one-half of the F2 did
6 .       In a certain plant, the alleles A, B, and C are completely dominant to the alleles a, b, and c. A plant with the genotype AABbcc will have the same phenotype as a plant with the genotype _____. (Concept 14.1E-Book) [Hint]

 Aabbcc
 aabbcc
 AaBBcc
 AABBCc
 none of the above
7 .       Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall plant was heterozygous? (Concept 14.1E-Book) [Hint]

 All of the offspring are short.
 All of the offspring are tall.
 The ratio of tall offspring to short offspring is 3:1.
 The ratio of tall offspring to short offspring is 1:1.
 None of the above.
8 .       What is indicated when a single-character testcross yields offspring that all have the dominant phenotype? (Concept 14.1E-Book) [Hint]

 The parent with the dominant phenotype was homozygous.
 The parent with the dominant phenotype was heterozygous.
 Epistasis has occurred.
 The alleles are codominant.
 Both parents are heterozygous.
9 .       If a homozygous dominant is crossed with a heterozygote for a given trait, the offspring will be _____. (Concept 14.1E-Book) [Hint]

 all of the dominant phenotype
 1/4 of the recessive phenotype
 all homozygous dominant
 all homozygous recessive
 present in a 9:3:3:1 ratio
10 .       In Mendel's monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation had the _____ phenotype because their genotype was _____ at the flower-color locus. (Concept 14.1E-Book) [Hint]

 white-flowered ... homozygous recessive
 white-flowered ... heterozygous
 purple-flowered ... homozygous recessive
 purple-flowered ... homozygous dominant
 purple-flowered ... heterozygous
11 .       If the two traits that Mendel looked at in his dihybrid cross of smooth yellow peas with wrinkled green peas had been controlled by genes that were located near each other on the same chromosome, then the F2 generation _____. (Concept 14.1E-Book) [Hint]

 would have contained four phenotypes in a 9:3:3:1 ratio
 would have contained only individuals that were heterozygous at both loci
 would have deviated from the 9:3:3:1 phenotypic ratio that is predicted by the law of independent assortment
 would have contained no individuals that were heterozygous at both loci
 none of the above
12 .       In carrying out his breeding studies, Mendel examined characters that had which of the following properties? (Concept 14.1E-Book) [Hint]

 They were controlled by loci that were (or behaved as if they were) on different chromosomes.
 It was possible to isolate true-breeding varieties for each trait.
 The traits varied in an either-or fashion.
 The characters each were controlled by a single gene.
 All of the above.
13 .       The law of independent assortment _____. (Concept 14.1E-Book) [Hint]

 states that the alleles at different loci segregate independently from one another during a dihybrid cross
 can account for a 9:3:3:1 ratio seen in the F2 generation
 applies only to genes that are present on different chromosomes (or behave as if they were)
 The first and second answers are correct.
 The first, second, and third answers are correct.
14 .       Homologous pairs of chromosomes often _____. (Concept 14.1E-Book) [Hint]

 carry different genes for different traits
 differ in length
 contain different alleles
 are not both present in diploid somatic cells
 are paired up in the G2 phase of the cell cycle
15 .       If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce? (Concept 14.2E-Book) [Hint]

 10,000
 200
 1,000
 100
 1,000,000
16 .       Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from the cross PpRr x PpRr will have white flowers and wrinkled seeds? (Concept 14.2E-Book) [Hint]

 0
 1/16
 1/4
 3/4
 1/2
17 .       An AABbccDdEeFF individual is crossed with an individual with the genotype AaBBCCDdEeff. What is the probability that their offspring will have the genotype AaBBCcddEEFf? (Concept 14.2E-Book) [Hint]

 1/2
 1/4
 1/16
 1/32
 1/64
18 .       If a heterozygous plant is allowed to self-pollinate, what proportion of the offspring will also be heterozygous? (Concept 14.2E-Book) [Hint]

 1/4
 1/3
 1/2
 2/3
 all of them
19 .       An individual with the genotype AABbCcDD can make how many different kinds of gametes? (Concept 14.2E-Book) [Hint]

 2
 4
 8
 16
 32
20 .       A red bull is crossed with a white cow and all of the offspring are roan, an intermediate color that is caused by the presence of both red and white hairs. This is an example of genes that are _____. (Concept 14.3E-Book) [Hint]

 nonhomologous
 epistatic
 codominant
 polygenic
 completely dominant
21 .       Flower color in snapdragons is an example of incomplete dominance. When a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with another pink-flowered plant, the progeny plants will be _____. (Concept 14.3E-Book) [Hint]

 100% pink
 100% red
 25% red, 50% pink, and 25% white
 50% pink and 50% red
 25% white and 75% red
22 .       Which choice below describes the Tay-Sachs allele at the molecular level? (Concept 14.3E-Book) [Hint]

 dominant
 incompletely dominant
 codominant
 recessive
 none of the above
23 .       A man who has type B blood and a woman who has type A blood could have children of which of the following phenotypes? (Concept 14.3E-Book) [Hint]

 A or B only
 AB only
 AB or O
 A, B, or O
 A, B, AB, or O
24 .       Which of the following matings cannot produce a child with blood type O? The letters refer to blood types (phenotypes). (Concept 14.3E-Book) [Hint]

 A x A
 A x B
 O x AB
 O x O
 none of the above
25 .       A woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood? (Concept 14.3E-Book) [Hint]

 100%
 75%
 50%
 25%
 0%
26 .       A single genetic locus that controls more than one trait is said to be _____. (Concept 14.3E-Book) [Hint]

 polygenic
 epistatic
 pleiotropic
 autotrophic
 somatic
27 .       Sometimes, one gene pair will interact to control the expression of a second gene pair (for example, albinism and coat color in mice). In this case, the genotype for the first gene can completely obscure the genotype at the second gene. This type of gene interaction is called _____. (Concept 14.3E-Book) [Hint]

 incomplete dominance
 epistasis
 gene regulation
 second pair control
 complete dominance
28 .       Tail length in a certain species of armadillo falls along a continuum, following a normal distribution. Assuming that environmental factors do not play an important role in determining tail length, this type of variation probably reflects _____. (Concept 14.3E-Book) [Hint]

 polygenic inheritance
 pleiotropy
 epistasis
 complete dominance
 incomplete dominance
29 .       Tay-Sachs disease runs in Rebecca's family. On a family pedigree, she saw a shaded circle. This represented a _____. (Concept 14.4E-Book) [Hint]

 male with Tay-Sachs
 female carrier
 male carrier
 female with Tay-Sachs
 male of unknown genotype
30 .       A man who can roll his tongue and a woman who cannot roll her tongue have a son who can roll his tongue (R = can roll tongue; r = can't roll tongue). The son is curious about whether his father is homozygous or heterozygous for the tongue-rolling trait. Which of the following facts would allow him to know? (Concept 14.4E-Book) [Hint]

 His father's mother cannot roll her tongue.
 His paternal grandfather and his paternal grandmother can both roll their tongues.
 The son's sister is a tongue roller.
 The son's own daughter cannot roll her tongue.
 The son submits his own blood sample to a local genotyping lab, and they establish that he is heterozygous for the trait.
31 .       Michelle and Keith are apparently normal, but their daughter was born with alkaptonuria, an inherited metabolic disorder. If alkaptonuria is like most other human hereditary disorders, the probability of their next child being born with alkaptonuria is _____. (Concept 14.4E-Book) [Hint]

 0
 1/4
 1/2
 2/3
 3/4
32 .       Tom's brother suffers from phenylketonuria (PKU), a recessive disorder. The brothers' parents do not have PKU. What are the chances that Tom, who is normal for this trait, is a carrier of PKU? (Concept 14.4E-Book) [Hint]

 1/4
 1/3
 1/2
 2/3
 4/3
33 .       A couple, both descended from eastern European (Ashkenazic) Jews, visit a genetic counselor before trying to have children. In view of their ethnic background, the counselor recommends that they be tested to see if they are carriers for _____. (Concept 14.4E-Book) [Hint]

 cystic fibrosis
 hemophilia
 sickle-cell disease
 hypercholesterolemia
 Tay-Sachs
34 .       Cystic fibrosis, which is usually lethal before the age of reproduction, is a homozygous recessive trait. Why do cases continue to arise, even though people with the disease rarely live to reproduce? (Concept 14.4E-Book) [Hint]

 Because new mutations continually introduce this harmful condition into the population.
 Because the harmful allele "hides" within heterozygous individuals, one-fourth of the offspring of two heterozygotes would be afflicted.
 Because mosquitoes can transfer the disease from person to person.
 Because people continue to make inappropriate lifestyle choices.
 None of the above.
35 .       The genetic disease cystic fibrosis is caused by a defective allele that _____. (Concept 14.4E-Book) [Hint]

 encodes a dysfunctional enzyme that fails to break down brain lipids
 causes hemoglobin molecules to malfunction
 encodes a defective chloride-channel membrane transport protein
 encodes a neurotoxin
 encodes an enzyme that breaks down muscle fibers
36 .       In people with sickle-cell disease, red blood cells break down, clump, and clog the blood vessels. The blood vessels and the broken cells accumulate in the spleen. Among other things this leads to physical weakness, heart failure, pain, and brain damage. Such a suite of symptoms can be explained by _____. (Concept 14.4E-Book) [Hint]

 the polygenic nature of sickle-cell disease
 the pleiotropic effects of the sickle-cell allele
 an epistatic interaction between the sickle-cell allele and a proteolytic enzyme gene
 a bacterial infection interacting with the sickle-cell allele
 side effects of the drugs used to cure sickle-cell disease
37 .       When two average-height parents give birth to a child exhibiting achondroplasia, it is most likely due to a new mutation. This is because _____. (Concept 14.4E-Book) [Hint]

 the frequency of achondroplasia is unknown
 achondroplasia is a relatively rare disorder
 achondroplasia is caused by an allele that is always expressed, therefore the parents must not have the allele
 such mutations are statistically predictable
 none of the above
38 .       It is far more common to find human genetic disease caused by _____ alleles than by _____ alleles because _____. (Concept 14.4E-Book) [Hint]

 dominant ... recessive ... dominant alleles have an evolutionary advantage over recessive alleles
 dominant ... recessive ... dominant alleles became dominant because they aid the survival of the organism carrying them
 recessive ... dominant ... harmful recessive alleles can survive in the heterozygote without any selection pressure against them
 recessive ... dominant ... even when homozygous, recessive alleles usually do not cause as much damage as dominant alleles
 none of the above
39 .       Huntington's disease is an example of a genetic disorder caused by _____. (Concept 14.4E-Book) [Hint]

 a lethal dominant allele that afflicts an individual later in life
 a nonlethal dominant allele
 a late-acting recessive allele
 homozygous recessive alleles
 multiple alleles
40 .       Heart disease, diabetes, cancer, alcoholism, and many mental illnesses can best be described as _____. (Concept 14.4E-Book) [Hint]

 simple Mendelian disorders
 infectious diseases caused by microorganisms
 multifactorial disorders with a possible polygenic component
 the symptoms of Huntington's disease
 the results of a bad lifestyle
41 .       Fetal cells may be removed along with fluid from the womb by a process known as _____. (Concept 14.4E-Book) [Hint]

 karyotyping
 testcrossing
 amniocentesis
 sonogramming
 chorionic villus sampling
42 .       In which genetic testing procedure would a physician remove a tiny tissue sample from the placenta? (Concept 14.4E-Book) [Hint]

 chorionic villus sampling
 amniocentesis
 fetoscopy
 ultrasound
 none of the above





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