Chapter 3 Flashcards
what term describes an individual possessing two of the same alleles at a gene locus?
heterozygous monohybrid wild type homozygous dihybrid
homozygous
mendel’s principle of segregation can be explained by what process?
mitosis none of these meiosis testcross fertilization
meiosis
which organism did Gregor Mendel use to discover the basic principles of genetics?
fruit fly pea plant bacterium nematode worm mouse
pea plant
when Mendel crossed a plant homozygous for round seeds to another plant homozygous for wrinkled seeds, he found that all the progeny had round seeds.
how is this explained?
the progeny were homozygous for the allele for round seeds
the allele for round seeds is recessive to the allele for wrinkled seeds
the allele for round seeds is dominant to the allele for wrinkled seeds
the parent that was homozygous for round seeds underwent self-pollination
segregation of alleles in the two parents produced gametes with both alleles
the allele for round seeds is dominant to the allele for wrinkled seeds
what is a cross that occurs between two individuals that differ in two characteristics?
trihybrid cross testcross dihybrid cross monohybrid cross backcross
dihybrid cross
if an Aa individual is crossed to an aa individual, what will be the phenotypic ratio in the offspring?
4: 0
1: 1:1:1
3: 1
2: 1
1: 1
1:1
a cross between a AABB individual and an aabb individual will produce what type of offspring?
half will be AABB and half will be aabb all will be AaBb half will be aaBB and half will be AAbb all will be AABB all will be aabb
all will be AaBb
an individual possesses two alleles at a locus and these two alleles separate when gametes are formed, one alleles going into each gamete.
the genetic concept is known as the
reciprocal cross chromosome theory of heredity concept of dominance principle of segregation principle of independent assortment
principle of segregation
what is the physical appearance or manifestation of a characteristic called in genetics?
independent assortment wild type phenotype genotype alleles
phenotype
what will the genotypic ratio in the offspring of two Aa parents that are crossed with each other?
1: 2:1
9: 3:3:1
2: 1
1: 1
3: 1
1:2:1
the principle of independent assortment involves at least how many different gene pairs?
2 4 5 1 3
2
How is a true breeding round‑seeded pea plant different from a hybrid round‑seeded pea plant?
They have the same genotype and phenotype.
They have the same genotype but different phenotypes.
They have a different genotype and phenotype.
They have the same phenotype but different genotypes.
They have the same phenotype but different genotypes.
Which of the statements can be concluded from Gregor Mendel’s experiments with pea plants?
A heterozygous phenotype is the same as a homozygous dominant phenotype.
Offspring inherit two alleles per gene from each parent.
For a given trait, two heterozygous parents produce offspring with three possible phenotypes.
Alleles of different genes are inherited independently of each other.
A heterozygous phenotype is the same as a homozygous dominant phenotype.
Alleles of different genes are inherited independently of each other.
Of the following ideas postulated by Gregor Mendel, which one requires at least two genes to be demonstrated?
One of two alleles from each parent is randomly transmitted to offspring.
Traits are not determined by blending.
Genes assort independently in diploids.
Traits are controlled by discrete units.
Some alleles are dominant and mask the effect of recessive alleles.
Genes assort independently in diploids.
In pea plants, plant height is controlled by a single autosomal dominant gene. Tall plants (H) are dominant to short plants (h).
A tall plant with the genotype capital H lowercase h crossed to a tall plant with the genotype capital H lowercase h.
In a cross of two tall heterozygous plants, which phenotype ratio is expected from the resulting offspring?
1: 1
1: 2:1
9: 3:3:1
3: 1
3:1
In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (𝐴) is dominant over albino characteristics (𝑎). For this question, assume the phenotype is determined by a single gene with two alleles.
If both parents have normal pigmentation, what are all of the possible genotypes that may be observed in their offspring?
Aa only
AA, Aa, or aa
AA or Aa only
aa only
AA, Aa, or aa
If both parents display the albino phenotype, what are all of the possible genotypes that may be observed in their offspring?
AA, Aa, and aa
AA and Aa
AA only
aa only
aa only
In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation (A) is dominant over albinism (a). For this question, assume it is a single gene with two alleles.
If both parents display the albino phenotype, what possible phenotypes may be observed in their offspring?
normal pigmentation or albinism
marbling of albino and normal pigmentation
normal pigmentation only
albinism only
albinism only
If two people have normal pigmentation, what possible phenotypes may be observed in their offspring?
albinism only
normal pigmentation or albinism
normal pigmentation only
marbling of albino and normal pigmentation
normal pigmentation or albinism
In pea plants, the allele for red flower color, F, is completely dominant to the allele for white flower color, f. Complete the Punnett square showing the genotypes possible among the offspring when two heterozygous individuals are crossed. Use the information from the Punnett square to answer the second question.
Ff x Ff
In this cross between two heterozygous pea plants, what are the chances that an offspring with red flowers will be produced?
3%
50%
75%
25%
75%
Phenylketonuria (PKU) is a disease that results from a recessive gene. Two normal parents produce a child with PKU.
What is the probability that a sperm from the father will contain the PKU allele?
2/3
1/4
3/4
1/2
1/3
What is the probability that an egg from the mother will contain the PKU allele?
1/3
2/3
1/2
1/4
3/4
What is the probability that their next child will have PKU?
1/3
1/2
3/4
2/3
1/4
What is the probability that their next child will be heterozygous for the PKU gene?
1/3
3/4
1/2
2/3
1/4
1/2
1//2
1/4
1/2
In fruit flies, gray bodies (G) are dominant over black bodies (g), and red eyes (R) are dominant over orange eyes (r). Each individual possesses two alleles for each trait.
If a fly that is homozygous dominant for both traits is crossed with a fly that is homozygous recessive for both traits, what is the predicted genotype of the offspring?
gray bodies and red eyes
GgRr, ggRr, Ggrr, and ggrr
black bodies and orange eyes
GgRr
GGRR
GgRr
In watermelons, bitter fruit (B) is dominant over sweet fruit (b), and yellow spots (S) are dominant over no spots (s). The genes for these two characteristics assort independently. A homozygous plant that has bitter fruit and yellow spots is crossed with a homozygous plant that has sweet fruit and no spots. The F1 are intercrossed to produce the F2.
What will be the phenotypic ratio in the F2?
1/4 bitter fruit, yellow spots; 1/4 bitter fruit, no spots; 1/4 sweet fruit, yellow spots; and 1/4 sweet fruit, no spots
9/16 bitter fruit, yellow spots; 3/16 bitter fruit, no spots; 3/16 sweet fruit, yellow spots; and 1/16 sweet fruit, no spots
All sweet fruit with no spots
All bitter fruit with yellow spots
1/2 bitter fruit, yellow spots and 1/2 sweet fruit, no spots
If an F1 plant is backcrossed with the bitter, yellow‑spotted parent, what phenotypes and proportions are expected in the offspring?
All sweet fruit with no spots
All bitter fruit with yellow spots
1/2 bitter fruit, yellow spots and 1/2 sweet fruit, no spots
1/4 bitter fruit, yellow spots; 1/4 bitter fruit, no spots; 1/4 sweet fruit, yellow spots; and 1/4 sweet fruit, no spots
9/16 bitter fruit, yellow spots; 3/16 bitter fruit, no spots; 3/16 sweet fruit, yellow spots; and 1/16 sweet fruit, no spots
If an F1 plant is backcrossed with the sweet, nonspotted parent, what phenotypes and proportions are expected in the offspring?
All bitter fruit with yellow spots
All sweet fruit with no spots
1/4 bitter fruit, yellow spots; 1/4 bitter fruit, no spots; 1/4 sweet fruit, yellow spots; and 1/4 sweet fruit, no spots
1/2 bitter fruit, yellow spots and 1/2 sweet fruit, no spots
9/16 bitter fruit, yellow spots; 3/16 bitter fruit, no spots; 3/16 sweet fruit, yellow spots; and 1/16 sweet fruit, no spots
9/16 bitter fruit, yellow spots; 3/16 bitter fruit, no spots; 3/16 sweet fruit, yellow spots; and 1/16 sweet fruit, no spots
All bitter fruit with yellow spots
1/4 bitter fruit, yellow spots; 1/4 bitter fruit, no spots; 1/4 sweet fruit, yellow spots; and 1/4 sweet fruit, no spots
In cats, curled ears result from an allele, Cu, that is dominant over an allele, cu, for normal ears. Black color results from an independently assorting allele, G, that is dominant over an allele for gray, g. A gray cat homozygous for curled ears is mated with a homozygous black cat with normal ears. All the F1 cats are black and have curled ears.
What phenotypes and proportions are expected from the two crosses?
Two of the F1 cats mate:
9/16 black cats, curled ears; 3/16 black cats, normal ears; 3/16 gray cats, curled ears; and 1/16 gray cats, normal ears
An F1 cat mates with a stary at that is gray and possesses normal ears:
1/4 black cats, curled; 1/4 black cats, normal ears; 1/4 gray cats, curled ears; and 1/4 gray cats, normal ears
Suppose two parents, a father with the genotype AaBbCcDdee and a mother with the genotype aabbCcDDEe, want to have children. Assume each locus follows Mendelian inheritance patterns for dominance.
What proportion of the offspring will have each of the specified characteristics? Round your answers to two decimal places.
same genotype as the father: 0.03 phenotypically resemble the father: 0.09 same genotype as the mother: 0.03 phenotypically resemble the mother: 0.09 phenotypically resemble neither parent: 0.81
