Chapter 14- Mendel and the Gene Flashcards
The work of Gregor Mendel provided an answer to two prevailing hypotheses popular
at the time. What were these two hypotheses?
A) Mitosis is only typical in vertebrates. Meiosis is only typical in invertebrates.
B) The two major hypotheses of the time were blending inheritance and inheritance of
acquired characteristics.
C) Animals use one set of rules for inheritance, and plants use a different set.
D) Peas and other domestic plants are unsuited for studies of inheritance, but wild
plants are perfectly suited.
E) Self-fertilization is the rule in plants, whereas cross-fertilization is the rule in animals.
The two major hypotheses of the time were blending inheritance and inheritance of
acquired characteristics.
Mendel studies seven different traits in the garden pea. What genetic term is used to
describe an observable trait, such as those studied by Mendel?
A) genotype
B) appearance
C) phenotype
D) haplotype
E) category
phenotype
Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. This
ratio suggests that ________.
A) the parents were true-breeding for contrasting traits
B) the particular trait shows incomplete dominance
C) a blending of traits has occurred
D) the parents were both heterozygous for the particular trait
E) each offspring has the same alleles for each of two different traits
the parents were both heterozygous for the particular trait
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
HT
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 percent
B) 25 percent
C) 50 percent
D) 75 percent
E) 100 percent
50 percent
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 generation
D) members of the F1 generation had only one allele for each trait, but members of the
F2 had two alleles for each trait
traits can be dominant or recessive, and the recessive traits were obscured by the
dominant ones in the F1 generation
Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both
of normal pigmentation, but both have one parent who is albino (without melanin
pigmentation). What is the probability that their first child will be an albino?
A) 0
B) 1/8
C) 1/2
D) 1/4
E) 1/3
1/4
Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both
of normal pigmentation, but both have one parent who is albino (without melanin
pigmentation). What is the probability that their first female child will have albinism?
A) 0
B) 1/8
C) 1/2
D) 1/4
E) 1/3
1/4
Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both
of normal pigmentation and have one child out of three who is albino (without melanin
pigmentation). What are the genotypes of the albino’s parents?
A) One parent must be homozygous for the recessive allele; the other parent can be
homozygous dominant, homozygous recessive, or heterozygous.
B) One parent must be heterozygous; the other parent can be homozygous dominant,
homozygous recessive, or heterozygous.
C) Both parents must be heterozygous.
D) One parent must be homozygous dominant; the other parent must be heterozygous.
E) Both parents must be homozygous dominant.
Both parents must be heterozygous.
A man has extra digits (six fingers on each hand and six toes on each foot). His wife
and their daughter have a normal number of digits. Having extra digits is a dominant
trait. The couple’s second child has extra digits. What is the probability that their next
(third) child will have extra digits?
A) 1/2
B) 1/16
C) 1/8
D) 3/4
E) 9/16
1/2
In tigers, a recessive allele causes a white tiger (absence of fur pigmentation). If one
phenotypically normal tiger that is heterozygous is mated to another that is
phenotypically white, what percentage of their offspring is expected to be white?
A) 50 percent
B) 75 percent
C) 0 percent
D) 100 percent
E) 25 percent
50 percent
Different ratios occur in crosses with single gene pairs or two gene pairs. What types of ratios are likely to occur in crosses dealing with a single gene pair?
A) 9:3:3:1, 1:2:1
B) 1:1:1:1, 1:4:6:4:1
C) 3:1, 1:1, 1:2:1
D) 4:1, 1:1, 1:4:1
3:1, 1:1, 1:2:1
A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation?
A) Albino is recessive; black is dominant.
B) Albino is dominant; black is incompletely dominant.
C) Albino and black are codominant.
D) Albino is recessive; black is codominant.
Albino is recessive; black is dominant.
Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves, and the following progeny were produced: 302 gray and 98 white. (a) What is the most probable genotype of each parent? (b) Based on your answer in (a) above, what genotypic and phenotypic ratios are expected in these progeny? (Assume the following symbols: G = gray and g = white.)
A) (a) GG × gg; (b) genotypic = 3:1, phenotypic = 1:2:1
B) (a) Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1
C) (a) GG × Gg; (b) genotypic = 1:2:1, phenotypic = 2:1
D) (a) gg × Gg; (b) genotypic = 1:2, phenotypic = 3:1
E) (a) Gg × Gg; (b) genotypic = 3:1, phenotypic = 9:3:3:1
(a) Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1
When Mendel crossed yellow-seeded and green-seeded pea plants, all the offspring
were yellow seeded. When he took these F1 yellow-seeded plants and crossed them to
green-seeded plants, what genotypic ratio was expected?
A) 1:2:1
B) 3:1
C) 9:3:3:1
D) 1:1
E) 1:1:1:1
1:1
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 the figure, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.
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
1, 2, and 3
Which of the boxes marked 1—4 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
2 and 3
Which of the boxes marked 1—4 correspond to plants that 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
1 and 4 only
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
0
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 allele was dominant.
One allele was dominant.
In humans, male-pattern baldness may be assumed to be controlled by an autosomal gene that occurs in two allelic forms. Allele B determines nonbaldness, and allele b determines pattern baldness. In males, because of the presence of testosterone, allele b is dominant over B. If a man and woman both with genotype Bb have a son, what is the chance that he will eventually be bald?
A) 0 percent
B) 25 percent
C) 33 percent
D) 50 percent
E) 75 percent
75 percent
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 that
are being studied, and a monohybrid cross involves organisms that are heterozygous
for only one character being studied.
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.
A dihybrid cross involves organisms that are heterozygous for two characters that
are being studied, and a monohybrid cross involves organisms that are heterozygous
for only one character being studied.
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
8
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 assortment of chromosomes into gametes
E) the tendency for dominant alleles to segregate together
different possible assortment of chromosomes into gametes
