Exam 3

Question 1

Linkage occurs…
a. when the law of segregation is violated
b. when genes independently assort
c. when genes do not independently assort because they are on the same chromosome
d. when genes are on different chromosomes

Answer 1

c. when genes do not independently assort because they are on the same chromosome

Question 2

T/F: The environment has no influence upon the phenotype of an individual.

Answer 2

False

Question 3

Genetically identical individuals may have different phenotypes if…
a. mutations occur that alter the genes
b. the genes are on different chromosomes
c. the genes are on the same chromosome
d. the expression of the genes are different because the individuals were exposed to different environmental influences.

Answer 3

d. the expression of the genes are different because the individuals were exposed to different environmental influences.

Question 4

T/F: Mutations in two different genes may produce the same phenotypic effect

Answer 4

True

Question 5

If you cross two mutants with the same phenotype together… (Select all that apply)
a. they will always have the mutant phenotype
b. they may have the mutant phenotype if both mutant individuals have mutations in the same gene
c. they may produce the normal phenotype if the mutant individuals have mutations in two different gene
d. they may have the normal phenotype if the two mutant individuals have mutations in the same gene
e. They may have the mutant phenotype if the two mutant individuals have mutations in two different genes
f. They will always have the normal phenotype

Answer 5

b. They may have the mutant phenotype if both mutant individuals have mutations in the same gene,
c. they may produce the normal phenotype if the mutant individuals have mutations in two different genes

Question 6

T/F: Each trait is controlled by only one gene

Answer 6

False

Question 7

In recessive epistasis… (select all that apply)
a. Individuals homozygous recessive for the nonepistatic gene always have the same phenotype
b. individuals homozygous recessive for the epistatic gene always have the same phenotype
c. individuals homozygous dominant for the epistatic gene always have the same phenotype
d. individuals homozygous dominant for the nonepistatic gene can have different phenotypes

Answer 7

b. individuals homozygous recessive for the epistatic gene always have the same phenotype
d. individuals homozygous dominant for the nonepistatic gene can have different phenotypes

Question 8

If a black lab is mated with a yellow lab and they produce only chocolate and yellow puppies.. (select all)
a. the black lab must have been homozygous recessive for the epistatic gene
b. the black lab parent must have been homozygous dominant for the epistatic gene
c. the black lab parent must have been heterozygous for the epistatic gene.
d. the yellow lab parent must have been homozygous recessive for the epistatic gene
e. the yellow lab parent must have been homozygous dominant for the epistatic gene
f. it is impossible to tell the genotype of the yellow lab parent
g. the yellow lab parent must have been homozygous recessive for the nonepistatic gene

Answer 8

c. the yellow lab parent must have been homozygous recessive for the epistatic gene
d. the yellow lab parent must have been homozygous recessive for the epistatic gene
f. it is impossible to tell the geneotype of the yellow lab parent

Question 9

In the case of duplicate recessive epistasis, the mutant phenotype shows up when individuals are

Answer 9

homozygous recessive for one gene or the other interacting gene, or homozygous recessive for both interacting genes

Question 10

If a trait is controlled by dominant epistasis and two double heterozygotes are crossed together, you would expect that ____ of the offspring will have the intermediate phenotype
(hint: fraction)

Answer 10

3/16

Question 11

If a trait is controlled by dominant suppression, individuals that have the dominant (most common) trait can be…
(select all)
a. homozygous recessive for both interacting genes
b. homozygous recessive for one epistatic gene but carrying a dominant allele of the other interacting gene
c. carrying a dominant allele of one gene but having any genotype for the other interacting gene
d. homozygous recessive for one gene or the other but not both

Answer 11

a. homozygous recessive for both interacting genes
c. carrying a dominant allele of one gene but having any genotype for the other interacting gene

Question 12

Two genes interact in a manner that requires that at least one dominant allele of at least one gene, either A or B, must be present to have the dominant phenotype. If a AaBb individual is crossed with another AaBb individual, what proportion on the offspring would you expect to have the recessive phenotype?

Answer 12

1/16

Question 13

You are carrying out a cross involving a trait controlled by two genes that interact in a duplicate interaction manner. The presence of dominant alleles, A and B result in phenotype #1, the presence of a dominant allele for only one of the genes produces phenotype #2, and the presence of no dominant alleles for either gene produces phenotype #3. An individual with the genotype AaBb is crossed with an individual with the genotype aaBb. What ratio should you expect in the next generation (listing the phenotypic groups in the order 1:2:3)?

Answer 13

3:4:1

Question 14

In rats with red eyes, the intensity of the eye color can be brick red, scarlet, or blush. This is due to three different alleles of the same gene that have a hierarchical dom/rec relationship. If scarlet is crossed to blush, all of the offspring are scarlet. However, if brick is crossed to scarlet, 3/4 of the offspring are brick and 1/4 are blush. Based on these results, a reasonable hypothesis would be that…
Select all that apply
a. scarlet is dominant to brick
b. brick is dominant to blush
c. brick is dominant to blush
d. blush is dominant to brick
e. blush is dominant to scarlet
f. scarlet is dominant to blush

Answer 14

b. brick is dominant to scarlet
c. brick is dominant to blush
f. scarlet is dominant to blush

Question 15

A man with type A blood has children with type B and AB blood. Assuming that all children are the offspring of the same mother, what blood type could that mother have?

Answer 15

B or AB

Question 16

Codominance occurs when…
a. heterozygotes have an intermediate phenotype
b. heterozygotes express both alleles simultaneously
c. homozygotes have extreme phenotypes
d. 3 or more alleles are involved in determining the phenotype

Answer 16

b. heterozygotes express both alleles simultaneously

Question 17

A white cow is mated with a red bull. The F1 offspring are said to be roan, meaning they have a mixture of red and white spots. Since both phenotypes are exhibited it suggests the trait is showing…

Answer 17

codominance

Question 18

The earliest evidence to suggest that chromosomes were the home of the genetic material came from

Answer 18

placing all known mutations in a species into a number of linkage groups that always matched the number of homologous pairs of chromosomes

Question 19

In order to identify chromosomes in a karyotype, scientists
(Select all)
a. stop cells in the middle of division
b. stain the chromosomes with dyes to identify characteristic banding patterns
c. use DNA sequencing to identify sequences on the chromosomal body
d. measure the size of the chromosome
e. pay attention to the position of the centromere on the chromosome

Answer 19

a. stop cells in the middle of division
b. stain the chromosomes with dyes to identify characteristic banding patterns
d. measure the size of the chromosome
e. pay attention to the position of the centromere on the chromosome

Question 20

Duplications refer to situations where

Answer 20

a region of a chromosome carrying one or more than one genes is repeated multiple times on the same chromosome

Question 21

Chromosomal duplications often alter the development of an organism because

Answer 21

they cause some protein products to be too abundant relative to other protein products

Question 22

Duplications are important for evolution because

Answer 22

they create extra copies of genes allowing organisms to “experiment” without any selective disadvantage

Question 23

If an individual is heterozygous for a duplication, while the chromosomes synapse during prophase I…

Answer 23

the chromosome with the duplication will have a loop that bubbles off to the side

Question 24

When multiple copies of a gene exist on the same chromosome due to a duplication, copies can be gained or lost during meiosis because
(Select all)
a. recombination results the production of acentric and dicentric chromosomes
b. the way in which homozygous duplicated chromosomes pair during prophase I
c. incorrect segregation during anaphase I
d. recombination involving the first duplicated region of one chromosome and the second duplicated region of the other chromosome

Answer 24

b. the way in which homozygous duplicated chromosomes pair during prophase I
d. recombination involving the first duplicated region of one chromosome and the second duplicated region of the other chromosome

Question 25

A deletion occurs when a segment of a chromosome is...

Answer 25

broken off and lost

Question 26

Which of the following statements are true regarding deletions? (Select all) a. they result in cruciform structures during synapsis in prophase I b. if heterozygotes for the deletion, the chromosome with deletion loops outward during synapsis of prophase I c. individuals heterozygous for a deletion may have developmental issues if it disrupts the relative dosage of important proteins d. if homozygous for the deletion it may be lethal if the deletion is large enough e. the effects of the deletion can be reversed by a reverse mutation f. if heterozygous for the deletion, recombination can still occur in the deleted region

Answer 26

b. if heterozygous for the deletion, the chromosomes without the deletion loops outward during synapsis of prophase I c. individuals heterozygous for the deletion may have developmental issues if it disrupts the relative dosage of important proteins d. if homozygous for the deletion it may be lethal if the deletion is large enough

Question 27

When using individuals carrying deletions to map a gene to a general region of a chromosome, individuals homozygous recessive for the mutant gene is crossed to an individual heterozygous for the deletion. If all of the offspring have the dominant phenotype...

Answer 27

the gene being mapped must be outside the deleted region

Question 28

Inversions occur when

Answer 28

a segment of a chromosome breaks off and is reattached in the opposite orientation that it was originally in

Question 29

T/F: A paracentric inversion is when the segment of the chromosome inverted contains the centromere

Answer 29

false

Question 30

Which of the following statements are true about inversions? a. individuals homozygous for the inversion form inversions loops when synapsed during prophase I b. Individuals heterozygous for the inversion form inversion loops when synapsed during prophase I c. individuals homozygous for an inversion cannot undergo recombination in the inverted region d. individuals heterozygous for an inversion cannot go through recombination in the inverted region e. individuals heterozygous for an inversion produce some inviable gametes if recombination occurs inside the loop f. individuals heterozygous for an inversion produce some inviable gametes if recombination occurs outside of the inversion loop.

Answer 30

b. individuals heterozygous for the inversion form inversion loops when synapsed during prophase I e. individuals heterozygous for an inversion produce some inviable gametes if recombination occurs inside the loop

Question 31

Heterozygous for this inversion that is AB/ab is crossed to an individual ab/ab, what percentage of the offspring will be Ab/ab?

Answer 31

5%

Question 32

T/F: Individuals heterozygous for an inversion have fertility issues because when recombination occurs inside of the inverted region, 1/2 of the gametes have extensive duplication and deficiencies.

Answer 32

True

Question 33

Which of these does not alter the total amount of genetic material? a. reciprocal translocation b. deletion c. duplication d. nondisjunction

Answer 33

a. reciprocal translocation

Question 34

Two chromosomes have the following segments, where * represents the centromere: KLM*NOPQR STUV*WXYZ What type of chromosome mutation would result in the following chromosomes: KLM*NOPQR STXW*VUYZ

Answer 34

pericentric inversion

Question 35

Characteristics of deletions include: (Select all) a. no reversion b. the formation of cruciform structures c. asymmetric pairing d. the reduction of viable gametes e. the formation of unpaired loops in heterozygotes

Answer 35

a. no reversion e. the formation of unpaired loops in heterozygotes

Question 36

If a gene goes through a duplication and one of the copies undergoes a frameshift mutation, what will be the consequence in homozygous individuals?

Answer 36

Wild type phenotype

Question 37

An individual is heterozygous for a paracentric inversion. The inverted region of the chromosome spans 26 cM of genetic space. What percentage of gametes produced by this individual will be viable? (hint: percentage)

Answer 37

87%

Question 38

Which of the following is most likely to occur? a. The production of a viable gamete in a reciprocal translocation heterozygote. b. the production of gametes that have undergone two recombination events in genetic spaces of 30 and 40 centimorgans. c. the production of viable offspring in a cross between two triploids. d. the production of a viable gamete in an individual heterozygous for an inversion that spans 20 centimorgans of genetic space e. the production of children with Trisomy 21 by a female with Trisomy 21

Answer 38

d. The production of viable gamete in an individual heterozygous for an inversion that spans 20 centimorgans of genetic space.

Question 39

Inversions and translocations are similar in that they do not alter the amount of genetic material present. However, both can produce phenotypic effects because

Answer 39

the change in arrangement of the segment of the chromosome changes the regulatory elements influencing expression of the gene.

Question 40

Trisomic individuals can be produced when... (Select all) a. a triploid is mated with a diploid b. nondisjunction has occurred in one parent c. a tetraploid is mated with a diploid d. a trisomic is mated with an individual that is euploid

Answer 40

b. nondisjunction has occured in one parent d. a trisomic is mated with an individual that is euploid

Question 41

Which form of aneuploidy describes an organism that is missing a single chromosome?

Answer 41

monosomy

Question 42

Assuming that these individuals could survive and make gametes, which would be the most infertile? a. a tetraploid daylily b. monosomy 8 in corn c. a triploid tulip d. trisomy 7 in a toad

Answer 42

c. a triploid tulip

Question 43

T/F: Individuals with an even ploidy level are usually sterile because they produce offspring with extreme aneuploidy.

Answer 43

False

Question 44

T/F an advantage of molecular markers is that they are more numerous than morphological markers

Answer 44

true