Genetics: Patterns of Inheritance Flashcards Preview

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Flashcards in Genetics: Patterns of Inheritance Deck (32):
1

The following results were observed from a mating between two black and white speckled cats: 5 black cats, 12 black and white speckled cats, and 4 white cats. Which of the following best describe the relationship between alleles of the coat color gene?

a) Linked
b) Mendelian
c) Polygenic
d) Codominance
e) Incomplete dominance

d) Codominance

2

Which of the following terms best describes a situation in which heterozygotes demonstrate a phenotype which is intermediate between the homozygotes?

a) Hybrid dominance
b) Incomplete dominance
c) Blended dominance
d) Limited dominance
e) Codominance

b) Incomplete dominance

3

The red blood cells from a person with AB blood type exhibit which of the following phenotypes?
a) None of these answers are correct.
b) Both the 'A' and 'B' phenotype in each red blood cell
c) The 'A' phenotype
d) Either the 'A' or 'B' phenotype in separate red blood cells
e) The 'B' phenotype

b) Both the 'A' and 'B' phenotype in each red blood cell

4

Incomplete dominance governs the pigment gene of a flower. A mating between heterozygotes yields the following phenotypic ratio: 15 red flowers, 32 pink flowers and 14 white flowers. Which of the following best describes the situation?

a) The heterozygotes were red.
b) The flower pigment gene is defined by multiple alleles.
c) The flower pigment gene is defined by a pink and red allele.
d) The results comply with Mendelian predictions.
e) The flower pigment gene is defined by a red and a white allele.

e) The flower pigment gene is defined by a red and a white allele.

5

Which of the following is not an example of phenotypic variability?

a) Two PJS patients have regular colonoscopies every year. Each year, patient A has about ten to twelve polyps removed from his gastrointestinal tract. Patient B, on the other hand, sometimes has one polyp removed, sometimes has two polyps removed, and many times the doctors don't find any polyps during the annual colonoscopy.
b) The penetrance of RP11 is about 60-70%.
c) A female patient who has the causative allele for RP11 experiences visual field loss and begins to lose her night vision as a teenager. She continues to lose her vision throughout her twenties. By the time she's 35, she is considered to be legally blind.
d) All of these are examples of phenotypic variability.
e) A boy with PJS has dark spots around his mouth and lips and on his fingers, but no polyps. His sister who also has PJS has a large number of gastrointestinal polyps, but no dark spots around her mouth or on her fingers.

c) A female patient who has the causative allele for RP11 experiences visual field loss and begins to lose her night vision as a teenager. She continues to lose her vision throughout her twenties. By the time she's 35, she is considered to be legally blind.

6

The extent to which a trait or condition is expressed is called what?

a) a syndrome
b) expressivity
c) phenotypic variability
d) severity
e) penetrance

b) expressivity

7

What is a syndrome?

a) a group of genetic factors that occur together
b) a range of different phenotypes
c) any trait or group of traits that is mainly determined by genetic factors
d) a grouping of recognizable characteristics that occur together and have a common cause
e) any genetic trait that results in a medical condition

d) a grouping of recognizable characteristics that occur together and have a common cause

8

A geneticist is studying a rare, autosomal dominant syndrome that is characterized by the following three hallmarks: a significantly increased risk for cancer, exceptional height, and early hearing loss. If the syndrome is 70% penetrant, what does this mean?

a) on average, people who have this syndrome will develop 70% of the hallmarks that characterize the syndrome
b) each child of an affected parent has a 70% chance of also developing the syndrome
c) the life expectancy of people with this syndrome is only 70% of the average human life span
d) a person who has the causative allele has a 70% chance of developing the syndrome
e) a person who has the causative allele has a 70% lifetime risk for cancer

d) a person who has the causative allele has a 70% chance of developing the syndrome

9

Which of the following statements is true?

a) Autosomal dominant conditions rarely show very much phenotypic variability.
b) Only certain genetic conditions have incomplete penetrance.
c) If a genetic condition shows variable expressivity, it cannot also have incomplete penetrance.
d) If a genetic condition shows variable expressivity, then it must also have incomplete penetrance.
e) All autosomal dominant genetic conditions sometimes skip a generation.

b) Only certain genetic conditions have incomplete penetrance.

10

Generally speaking, what are the odds that an autosomal dominant condition will be passed from an affected individual to their child?

a) 0%
b) 100%
c) It's impossible to know.
d) 25%
e) 50%

e) 50%

11

A criss-cross inheritance pattern is seen in what type of genetic inheritance?

a) autosomal recessive inheritance
b) A criss-cross inheritance pattern is not associated with any specific type of genetic inheritance.
c) complex inheritance
d) autosomal dominant inheritance
e) sex-linked inheritance

e) sex-linked inheritance

12

A scientist is studying an animal and determines that a gene is located on autosome two. It controls antler production in the male animals. This is an example of a

a) Sex-linked trait
b) Sex-limited trait
c) Carrier trait
d) Dominant trait
e) Recessive trait

b) Sex-limited trait

13

Which of the following statements are true?

I. A human with two X chromosomes and a Y chromosome is male.
II. A human with one X chromosome is female.
III. All children of a color blind woman and a man who is not color blind will carry a color blind allele.

a) I, II and III
b) II
c) I
d) I and II
e) II and III

a) I, II and III

14

Hemophilia is an X-linked recessive trait. Consider a cross between a woman who is a carrier and a man who suffers from hemophilia. Which of the following statements are true?

I. All sons of these parents will be a hemophiliac.
II. Sons who suffer from hemophilia received the hemophilia allele from their mother.
III. Half of the daughters of this cross are predicted to be hemophiliacs.

a) I
b) III
c) I and II
d) II
e) II and III

e) II and III

15

Alleles A and B are linked on chromosome 1. Alleles C and D are linked on chromosome 2. If a crossover event does not occur between either set of genes, which gamete genotype could NOT be produced by an individual heterozygous at each locus.

a) a-b; c-d
b) A-B; C-d
c) A-B; C-D
d) a-b; C-D
e) A-B; c-d

b) A-B; C-d

16

Alleles A, B, C and D are linked on one chromosome and alleles a, b, c and d are linked on the homolog. During meiosis, a crossover event occurs between genes A and B. Which of the following is an example of a chromatid that could be found in one of the resulting gametes?

a) A-B-C-D
b) A-b-c-d
c) A-B-C-d
d) a-b-c-d
e) A-B-c-d

b) A-b-c-d

17

Genes A and B are located on the same chromosome arm in the following orientation: centromere, gene A, gene B, telomere. Which of the following chromatids could be produced by a crossover event which occurs between gene B and the telomere in a heterozygote in which the dominant alleles are linked on one homolog and the recessive ones are linked on the other homolog?

I. A B
II. a B
III. A b
IV. a b

a) I, II, III and IV
b) I, II and III
c) II and III
d) I and IV
e) I, II and IV

c) II and III

18

The laboratory environment can be controlled.
II. True-breeding strains can be generated.
III. Specific combinations of alleles can be engineered.

a) I and II
b) I
c) I and III
d) II and III
e) I, II and III

e) I, II and III

19

Evaluate each of the following sets of data separately. Which of them provide evidence that the trait is polygenic?

I. The genotype at loci A, B and C can affect the length of an organism by an average of 0.6, 0.4 and 0.3 cm, respectively.
II. Three different alleles of gene D affect the length of an organism by an average of 0.6, 0.4 and 0.3 cm, respectively.
III. Loci E, F and G play a role in three independent pathways which each play a role in determining the length of an organism.

a) II and III
b) I, II and III
c) I and II
d) I and III
e) II

d) I and III

20

Which of the following statements could not be used to describe a multifactorial trait?

a) Two independent genetic pathways affect the trait.
b) The phenotypic consequences of genes affecting the trait are additive.
c) An environmental factor affects the trait.
d) Since only one gene affects the trait, it cannot be multifactorial.
e) A continuous range of traits is possible.

d) Since only one gene affects the trait, it cannot be multifactorial.

21

Which of the following statements is true?

I. The one thousandth base pair on chromosome one of an organism is an example of a locus.
II. Changing the DNA in a gene by one base pair could create a new allele.
III. A somatic cell in a diploid organism possesses two copies of each homolog.

a) II
b) I and II
c) I
d) III
e) I, II and III

e) I, II and III

22

Which of the following is NOT an example of a phenotype?

a) Binding affinity of hemoglobin for oxygen
b) Height of a giraffe
c) Color of a feather
d) Wheat resistance to fungal infection
e) DNA sequence of the alcohol dehydrogenase gene


e) DNA sequence of the alcohol dehydrogenase gene

23

Consider the following experiment: A scientist determines that the number of dorsal spines of her experimental fish is determined by a single locus. She mates a fish with 1 dorsal spine with a fish of the same species with 2 dorsal spines. The mating produces ten fish, which all have 1 dorsal spine. Which of the following statements could NOT be true?

a) The progeny fish may be capable of producing progeny with only 1 spine.
b) The progeny fish are homozygous for the '1-spine' allele.
c) The '1-spine' parent fish has a homozygous genotype at the dorsal spine locus.
d) The '2-spine' parent fish has a homozygous genotype at the dorsal spine locus.
e) '2 dorsal spines' is a recessive phenotype.

b) The progeny fish are homozygous for the '1-spine' allele.

24

Which of the following is NOT an example of a homozygous genotype?

a) GG
b) ww
c) tt
d) Rr
e) ZZZZ

d) Rr

25

Which of the following statements do NOT help explain Mendel's law of segregation?

a) Each allele is associated with a specific homolog.
b) At a given locus, a diploid parent can only contribute one allele to its offspring.
c) Homologous chromosomes segregate into separate gametes during meiosis.
d) Each gene is located on a specific chromosome.
e) Alleles of different genes sort independently.

e) Alleles of different genes sort independently.

26

Gregor Mendel proposed which of the following concepts?

I. The law of independent assortment
II. The law of segregation
III. The theory of evolution
IV. Natural selection

a) I, II, III and IV
b) I
c) I and II
d) II, III and IV
e) I, II and IV

c) I and II

27

A scientist is studying an animal which can be found with either black or white fur. Which of following COULD be true?

I. Mating an animal with black fur with an animal with white fur only produces animals with white fur.
II. The genotype of the animal with black fur is Bb.
III. Mating the animal with black fur to another animal with black fur produces both black and white animals.
IV. The genotype of the animal with black fur is bb.

a) II and III
b) II, III and IV
c) I and IV
d) I, II, III and IV
e) I, II and III

d) I, II, III and IV

28

If the homozygous recessive phenotype for gene B is lethality, what percentage of viable progeny from a monohybrid cross will exhibit the dominant phenotype.

a) 25%
b) 100%
c) 75%
d) 0%
e) 50%

b) 100%

29

Which of the following statements is true?

I. A dihybrid cross is a cross between individuals heterozygous at one gene.
II. The law of independent assortment describes the relationship between alleles of a single gene.
III. The law of segregation describes the manner in which genes on different chromosomes segregate.
IV. Homologous chromosomes segregate into different gametes.

a) I
b) IV
c) I, II, III, and IV
d) II, III and IV
e) II and III

b) IV

30

You could draw which of the following conclusions from a dihybrid cross which produces a 9:3:3:1 ratio of phenotypes?

I. The alleles of one gene sort independently of another gene.
II. The alleles of the two genes in question exhibit a simple dominant/recessive relationship.
III. The animals which were crossed were both homozygous with respect to at least one locus in question.

a) I, II and III
b) II
c) I and II
d) I
e) I and III

c) I and II

31

. Which of the following crosses most likely produced the following results: 56 blue, two-horned lizards, 18 blue, one-horned lizards, 20 green, two-horned lizards, and 6 green, one-horned lizards.

a) Bb x Bb
b) BBHH x bbhh
c) BBHh x BbHh
d) BbHh x BbHh

d) BbHh x BbHh

32

If gene A is located on chromosome 1 and gene B is located on chromosome 2, which of the following genotypic frequencies could be produced among the progeny of the following cross: AABb x aaBb

I. 25% AaBB, 50% AaBb and 25% Aabb
II. 75% AaBB
III. 25% bb

a) III
b) I and III
c) I
d) I and II
e) II

b) I and III