Campbell’s Biology, 9e (Reece et al.)
Chapter 14 Mendel and the Gene Idea
The questions in Chapter 14 are mostly at the Application/Analysis skill level. The material in the
chapter invites students to apply Mendel’s laws, and by doing so encourages problem solving. Because
of the human-related Concept 14.4, a fair number of Synthesis/Evaluation questions are included as
well. Very little of the chapter lends itself to Knowledge/Comprehension questions only. In addition, to
help students make maximum use of information presented about one or more specific traits, a greater
number of questions than usual is grouped together to explore brief scenarios or figures.
Multiple-Choice Questions
1) What do we mean when we use the terms monohybrid cross and dihybrid cross?
A) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.
B) A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny.
C) A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid
cross involves only one.
D) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two
generations.
E) A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.
2) Why did the F1 offspring of Mendel’s classic pea cross always look like one of the two parental
varieties?
A) No genes interacted to produce the parental phenotype.
B) Each allele affected phenotypic expression.
C) The traits blended together during fertilization.
D) One phenotype was completely dominant over another.
E) Different genes interacted to produce the parental phenotype.
3) What was the most significant conclusion that Gregor Mendel drew from his experiments with pea
plants?
A) There is considerable genetic variation in garden peas.
B) Traits are inherited in discrete units, and are not the results of “blending.”
C) Recessive genes occur more frequently in the F1 generation than do dominant ones.
D) Genes are composed of DNA.
E) An organism that is homozygous for many recessive traits is at a disadvantage.
4) How many unique gametes could be produced through independent assortment by an individual with
the genotype AaBbCCDdEE?
A) 4
B) 8
C) 16
D) 32
E) 64
5) The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the
following is the major reason?
A) segregation of maternal and paternal alleles
B) recurrent mutations forming new alleles
C) crossing over during prophase I
D) different possible alignments of chromosomes
E) the tendency for dominant alleles to segregate together
6) Why did Mendel continue some of his experiments to the F2 or F3 generation?
A) to obtain a larger number of offspring on which to base statistics
B) to observe whether or not a recessive trait would reappear
C) to observe whether or not the dominant trait would reappear
D) to distinguish which alleles were segregating
E) to be able to describe the frequency of recombination
7) Which of the following differentiates between independent assortment and segregation?
A) The law of independent assortment requires describing two or more genes relative to one another.
B) The law of segregation requires describing two or more genes relative to one another.
C) The law of segregation requires having two or more generations to describe.
D) The law of independent assortment is accounted for by observations of prophase I.
E) The law of segregation is accounted for by anaphase of mitosis.
8) Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this
suggest?
A) that the parents were true-breeding for contrasting traits
B) that the trait shows incomplete dominance
C) that a blending of traits has occurred
D) that the parents were both heterozygous for a single trait
E) that each offspring has the same alleles for each of two traits
9) A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length
(T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
A) tt
B) Hh
C) HhTt
D) T
E) HT
10) When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what
is the chance of producing an offspring with the homozygous recessive phenotype?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%
11) Mendel accounted for the observation that traits which had disappeared in the F1 generation
reappeared in the F2 generation by proposing that
A) new mutations were frequently generated in the F2 progeny, “reinventing” traits that had been lost in
the F1.
B) the mechanism controlling the appearance of traits was different between the F1 and the F2 plants.
C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in
the F1.
D) the traits were lost in the F1 due to dominance of the parental traits.
E) members of the F1 generation had only one allele for each trait, but members of the F2 had two
alleles for each trait.
12) The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent
assortment most probably indicates which of the following?
A) None of the traits obeyed the law of segregation.
B) The diploid number of chromosomes in the pea plants was 7.
C) All of the genes controlling the traits were located on the same chromosome.
D) All of the genes controlling the traits behaved as if they were on different chromosomes.
E) The formation of gametes in plants occurs by mitosis only.
13) Mendel was able to draw his ideas of segregation and independent assortment because of the
influence of which of the following?
A) His reading and discussion of Darwin’s Origin of Species.
B) The understanding of particulate inheritance he learned from renowned scientists of his time.
C) His discussions of heredity with his colleagues at major universities.
D) His experiments with the breeding of plants such as peas and fuchsia.
E) His reading of the scientific literature current in the field.
14) Mendel’s observation of the segregation of alleles in gamete formation has its basis in which of the
following phases of cell division?
A) prophase I of meiosis
B) anaphase II of meiosis
C) metaphase I of meiosis
D) anaphase I of meiosis
E) anaphase of mitosis
15) Mendel’s second law of independent assortment has its basis in which of the following events of
meiosis I?
A) synapsis of homologous chromosomes
B) crossing over
C) alignment of tetrads at the equator
D) separation of homologs at anaphase
E) separation of cells at telophase
16) Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t).
What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?
A) 1/16
B) 3/16
C) 3/8
D) 1/2
E) 9/16
17) In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall
plant, what is the probability that the offspring will be short?
A) 1
B) 1/2
C) 1/4
D) 1/6
E) 0
18) In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC?
A) 1/4
B) 1/8
C) 1/16
D) 1/32
E) 1/64
19) Given the parents AABBCc × AabbCc, assume simple dominance for each trait and independent
assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent?
A) 1/4
B) 1/8
C) 3/4
D) 3/8
E) 1
20) Which of the following is the best statement of the use of the addition rule of probability?
A) the probability that two or more independent events will both occur
B) the probability that two or more independent events will both occur in the offspring of one set of
parents
C) the probability that either one of two independent events will occur
D) the probability of producing two or more heterozygous offspring
E) the likelihood that a trait is due to two or more meiotic events
21) Which of the following calculations require that you utilize the addition rule?
A) Calculate the probability of black offspring from the cross AaBb × AaBb, when B is the symbol for
black.
B) Calculate the probability of children with both cystic fibrosis and polydactyly when parents are each
heterozygous for both genes.
C) Calculate the probability of each of four children having cystic fibrosis if the parents are both
heterozygous.
D) Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are
each heterozygous for both.
E) Calculate the probability of purple flower color in a plot of 50 plants seeded from a self-fertilizing
heterozygous parent plant.
22) In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of
red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the
ratio of 1 red:2 roan:1 white?
A) red × white
B) roan × roan
C) white × roan
D) red × roan
E) The answer cannot be determined from the information provided.
23) Which of the following describes the ability of a single gene to have multiple phenotypic effects?
A) incomplete dominance
B) multiple alleles
C) pleiotropy
D) epistasis
24) Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in
symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best
describes this?
A) incomplete dominance
B) multiple alleles
C) pleiotropy
D) epistasis
E) codominance
25) Which of the following is an example of polygenic inheritance?
A) pink flowers in snapdragons
B) the ABO blood group in humans
C) Huntington’s disease in humans
D) white and purple flower color in peas
E) skin pigmentation in humans
26) Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants
produce blue flowers and others pink flowers. This can be best explained by which of the following?
A) the knowledge that multiple alleles are involved
B) the allele for blue hydrangea being completely dominant
C) the alleles being codominant
D) the fact that a mutation has occurred
E) environmental factors such as soil pH
27) Which of the following provides an example of epistasis?
A) Recessive genotypes for each of two genes (aabb) results in an albino corn snake.
B) The allele b17 produces a dominant phenotype, although b1 through b16 do not.
C) In rabbits and many other mammals, one genotype (cc) prevents any fur color from developing.
D) In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a combination of other
genes.
E) In cacti, there are several genes for the type of spines.
28) Most genes have many more than two alleles. However, which of the following is also true?
A) At least one allele for a gene always produces a dominant phenotype.
B) Most of the alleles will never be found in a live-born organism.
C) All of the alleles but one will produce harmful effects if homozygous.
D) There may still be only two phenotypes for the trait.
E) More than two alleles in a genotype is considered lethal.
29) How could you best predict the maximum number of alleles for a single gene whose polypeptide
product is known?
A) Search the population for all phenotypic variants of this polypeptide.
B) Count the number of amino acids in the polypeptide.
C) Mate all known genotypes and collect all possible offspring different from the parents.
D) Measure the rate of new mutations in the species and estimate the number since it first evolved.
E) Count the number of DNA nucleotides that are in the code for the polypeptides.
30) An ideal procedure for fetal testing in humans would have which of the following features?
A) the procedure that can be performed at the earliest time in the pregnancy
B) lowest risk procedure that would provide the most reliable information
C) the procedure that can test for the greatest number of traits at once
D) a procedure that provides a three-dimensional image of the fetus
E) a procedure that could test for the carrier status of the fetus
31) A scientist discovers a DNA-based test for one allele of a particular gene. This and only this allele, if
homozygous, produces an effect that results in death at or about the time of birth. Of the following,
which is the best use of this discovery?
A) Screen all newborns of an at-risk population.
B) Design a test for identifying heterozygous carriers of the allele.
C) Introduce a normal allele into deficient newborns.
D) Follow the segregation of the allele during meiosis.
E) Test school-age children for the disorder.
32) An obstetrician knows that one of her patients is a pregnant woman whose fetus is at risk for a
serious disorder that is detectable biochemically in fetal cells. The obstetrician would most reasonably
offer which of the following procedures to her patient?
A) CVS
B) ultrasound imaging
C) amniocentesis
D) blood transfusion
E) X-ray
33) The frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably
because this reduces the frequency of malaria. Such a relationship is related to which of the following?
A) Mendel’s law of independent assortment
B) Mendel’s law of segregation
C) Darwin’s explanation of natural selection
D) Darwin’s observations of competition
E) the malarial parasite changing the allele
34) Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately
metabolize a particular amino acid. The amino acid is not otherwise produced by humans. Therefore, the
most efficient and effective treatment is which of the following?
A) Feed them the substrate that can be metabolized into this amino acid.
B) Transfuse the patients with blood from unaffected donors.
C) Regulate the diet of the affected persons to severely limit the uptake of the amino acid.
D) Feed the patients the missing enzymes in a regular cycle, such as twice per week.
E) Feed the patients an excess of the missing product.
35) Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very
early senility and death, usually from coronary artery disease, at an average age of approximately 13.
Patients, who look very old even as children, do not live to reproduce. Which of the following represents
the most likely assumption?
A) All cases must occur in relatives; therefore, there must be only one mutant allele.
B) Successive generations of a family will continue to have more and more cases over time.
C) The disorder may be due to mutation in a single protein-coding gene.
D) Each patient will have had at least one affected family member in a previous generation.
E) The disease is autosomal dominant.
36) One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a
dominant gene, although it may range from mildly to very severely expressed. If a young child is the
first in her family to be diagnosed, which of the following is the best explanation?
A) The mother carries the gene but does not express it at all.
B) One of the parents has very mild expression of the gene.
C) The condition skipped a generation in the family.
D) The child has a different allele of the gene than the parents.
Art Questions
Use Figure 14.1 and the following description to answer the questions below.
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark
green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-
breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-
pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in Figure 14.1,
where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.
Figure 14.1
37) Which of the boxes marked 1-4 correspond to plants with dark leaves?
A) 1 only
B) 1 and 2
C) 2 and 3
D) 4 only
E) 1, 2, and 3
38) Which of the boxes correspond to plants with a heterozygous genotype?
A) 1
B) 1 and 2
C) 1, 2, and 3
D) 2 and 3
E) 2, 3, and 4
39) Which of the plants will be true-breeding?
A) 1 and 4 only
B) 2 and 3 only
C) 1, 2, 3, and 4
D) 1 only
E) 1 and 2 only
The following questions refer to the pedigree chart in Figure 14.2 for a family, some of whose members
exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle.
Figure 14.2
40) What is the genotype of individual II-5?
A) WW
B) Ww
C) ww
D) WW or ww
E) ww or Ww
41) What is the likelihood that the progeny of IV-3 and IV-4 will have the trait?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%