Biology 156 Unit 12

Front 1

Genes located close together on the same chromosome are referred to as ___ genes and generally ___.

Back 1

linked, do not sort independently during meiosis

Front 2

When is Mendel's principle of independent assortment not followed?

Back 2

when genes are linked

Front 3

How can new combinations of alleles be created when genes are linked?

Back 3

crossing over during meiosis

Front 4

When crossing over recombines linked genes into assortments of alleles not found in parents, they are called:

Back 4

recombinant genes

Front 5

In a cross of a purple-flowered, short-stemmed plant with a yellow flowered, long-stemmed plant, the expected phenotypic ratio is 1 purple short : 1 purple-long : 1 yellow-short : 1 yellow-long. When you do the actual cross you observe a 5 purple-short : 1 purple-long : 1 yellow-short : 5 yellow long phenotypic ratio. Which of the following explains these results?

Back 5

both A and C are correct
A. the genes are linked
C. purple-long and yellow-short individuals are recombinants

Front 6

The percentage of offspring that show a recombination of alleles of linked genes is called the

Back 6

recombination frequency

Front 7

The smaller the number of map units between linked alleles, the:

Back 7

smaller the recombination frequency

Front 8

Which of the following kinds of data could be used to map the relative position of three genes on a chromosome?

Back 8

the frequencies with which the corresponding traits occur together in offspring

Front 9

What is the normal complement of sex chromosomes in a human male?

Back 9

one X chromosome and one Y chromosome

Front 10

What is the normal complement of sex chromosomes in a human female

Back 10

two X chromosomes

Front 11

How many sex chromosomes are in a human gamete?

Back 11

1

Front 12

The sex of human offspring is determined by:

Back 12

whether the egg is fertilized by a sperm carrying an X or Y chromosome

Front 13

In ants and bees, there are no sex chromosomes. Females are ___, and males are ___.

Back 13

diploid, haploid

Front 14

What is meant by the statement that “male bees are fatherless”?

Back 14

male bees develop from unfertilized eggs

Front 15

A plant species in which individual plants produce both sperm and eggs is called:

Back 15

monoecious

Front 16

An animal species in which an individual produces both sperm and eggs is called:

Back 16

hermaphroditic

Front 17

A gene located on a sex chromosome is called a:

Back 17

sex-linked gene

Front 18

On what human chromosome are sex-linked genes unrelated to sex determination usually found?

Back 18

X chromosome

Front 19

Recessive sex-linked human conditions include which of the following?

Back 19

all of the above
A. red-green color blindness
B. hemophilia
C. Duchenne muscular dystrophy

Front 20

Why are X-linked recessive disorders more common in males than in females?

Back 20

both B and C are correct
B. males need to inherit only one copy of the recessive allele for the condition to be fully expressed
C. females must inherit two copies of the recessive gene for the condition to be fully expressed

Front 21

Suppose that in ladybugs, the genes for color and spot size are very closely linked. A heterozygous beetle with the dominant orange color and dominant big spots is crossed with a homozygous beetle with the recessive yellow color and small spots. All four possible phenotypes are produced: orange big spots, yellow small spots, orange small spots, and yellow big spots. If these genes are closely linked, what ratio (in the order of the phenotypes listed) would you expect to see in the offspring?

Back 21

10:10:1:1

Front 22

In a dihybrid cross involving linked genes, a heterozygous individual and a homozygous recessive individual produce offspring of four different phenotypes. 90 out of 100 offspring have the same combination of traits as a parent, but 10 out of 100 offspring exhibit a recombination of traits. What is the recombination frequency?

Back 22

10%

Front 23

In a dihybrid cross involving linked genes, there is a recombination frequency of 20%. What is the map distance between the two genes?

Back 23

20 map units

Front 24

Hemophilia is an X-linked recessive disease. If a hemophiliac male and a normal (non-carrier) female have a son, what are the chances that the son will have hemophilia?

Back 24

0%

Front 25

Hemophilia is an X-linked recessive disease. If a hemophiliac male and a normal (non-carrier) female have a daughter, what are the chances that the daughter will have hemophilia?

Back 25

0%

Front 26

Hemophilia is an X-linked recessive disease. If a hemophiliac male and a normal (non-carrier) female have a daughter, what are the chances that the daughter will be a carrier?

Back 26

100%

Front 27

Hemophilia is an X-linked recessive disease. If a carrier female and a normal male have a son, what are the chances that the son will have hemophilia?

Back 27

50%

Front 28

Hemophilia is an X-linked recessive disease. If a carrier female and a normal male have a daughter, what are the chances that the daughter will have hemophilia?

Back 28

0%

Front 29

Hemophilia is an X-linked recessive disease. If a carrier female and a normal male have a daughter, what are the chances that the daughter will be a carrier?

Back 29

50%

Front 30

Red-green colorblindness is an X-linked recessive disease. If a color blind female and a normal male have a daughter, what are the chances that the daughter will be colorblind?

Back 30

0%

Front 31

Red-green colorblindness is an X-linked recessive disease. If a color blind female and a normal male have a daughter, what are the chances that the daughter will be a carrier?

Back 31

100%

Front 32

Red-green colorblindness is an X-linked recessive disease. If a color blind female and a normal male have a son, what are the chances that the son will be colorblind?

Back 32

100%

Front 33

In a cross between a white-eyed female fruit fly and red-eyed male, what percent of the female offspring will have white eyes? (White eyes are X-linked, recessive)

Back 33

0%

Front 34

A female Drosophila of unknown genotype was crossed with a white-eyed male fly, of genotype (w = white eye allele is recessive, w+= red-eye allele is dominant.) Half of the male and half of the female offspring were red-eyed, and half of the male and half of the female offspring were white-eyed. What was the genotype of the female fly?

Back 34

Xw+Xw

Front 35

In a cross between a pure bred, red-eyed female fruit fly and a white-eyed male, what percent of the male offspring will have white eyes? (white eyes are X-linked, recessive)

Back 35

0%

Front 36

What is the genotype of a red-eyed, yellow-bodied female fruit fly who is homozygous for the eye color allele?
Red eyes (w+) and tan bodies (y+) are the dominant alleles. (Both traits are X chromosome linked).

Back 36

Xw+yXw+y

Front 37

A white-eyed female fruit fly is crossed with a red-eyed male. Red eyes are dominant, and X-linked. What are the expected phenotypes of the offspring?

Back 37

All of the females will have red eyes; all of the males will have white eyes.

Front 38

Hemophilia in humans is due to an X-chromosome mutation. What will be the results of mating between a normal (non-carrier) female and a hemophilac male?

Back 38

all sons are normal and all daughters are carriers.

Front 39

A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color blindness (or alternatively, hemophilia), marries a normal male. What proportion of their male progeny will have red-green color blindness (or alternatively, will be hemophiliac)?

Back 39

50%

Front 40

Women have sex chromosomes of XX, and men have sex chromosomes of XY.

Which of a man's grandparents could not be the source of any of the genes on his Y-chromosome?

Back 40

Mother's Mother, Mother's Father, and Father's Mother.

Front 41

Women have sex chromosomes of XX, and men have sex chromosomes of XY.

Which of a women's grandparents could not be the source of any of the genes on either of her X-chromosomes

Back 41

Father's Father.

Front 42

A human female "carrier" who is heterozygous for the recessive, sex-linked trait red color blindness, marries a normal male.

What proportion of their female progeny will show the trait?

Back 42

0

Front 43

The alleles for eye color and for body color are on the X chromosome of Drosophila, but not on the Y. Red eye color (w+) is dominant to white eye color (w), and tan body color (y+) is dominant to yellow body color (y).

What is the genotype of a yellow-bodied, red-eyed female who is homozygous for eye color?

Back 43

Xw+yXw+y

Front 44

The alleles for eye color and for body color are on the X chromosome of Drosophila, but not on the Y. Red eye color (w+) is dominant to white eye color (w), and tan body color (y+ ) is dominant to yellow body color (y).
What is the genotype of a tan-bodied, white-eyed male?

Back 44

Xwy+y

Front 45

What offspring would you expect from a cross between the female Drosophila described in problem 1 (red eyes and a yellow body, homozygous recessive for the yellow body color allele and homozygous dominant for the eye color allele) and the male described in problem 2 (hemizygous for both the recessive (white) eye color allele and dominant (tan) body color allele?)
A reminder that the alleles for eye color and for body color are on the X chromosome of Drosophila, but not on the Y. Red eye color (w+) is dominant to white eye color (w), and tan body color (y+) is dominant to yellow body color (y)

Back 45

Daughters would be tan-bodied, red-eyed; the sons would be yellow-bodied, red-eyed

Front 46

If we mated the F1 female and male flies from the cross obtained in problem 3, what male phenotype in the F2 generation would be evidence that crossing over had occured during gamete formation?

Daughters were tan-bodied, red-eyed, heterozygous for both eye and body color. The sons were yellow-bodied, red-eyed hemizygous.

Back 46

white eyes and yellow bodies and red eyes and tan bodies

Front 47

Audrei is the family member who contacted us. She and her father Sydney are color blind, but her mother, Barbara, has normal vision. What is Audrei's genotype?

Back 47

homozygous recessive for the red-green color blind allele

Front 48

Now that we determined that Audrei is homozygous recessive for the red-green color blind allele. What is her father's genotype?

Back 48

hemizygous with a recessive allele

Front 49

We have determined that Audrei is homozygous recessive for the red-green color blind allele and that her father is hemizygous with a recessive allele. What is the mother's genotype? Remember that Audrei's mother does not have a color perception defect.

Back 49

heterozygous carrier of the red-green color blind allele

Front 50

What is the genotype of Audrei's sister Caroline, who has normal vision?

Back 50

heterozygous carrier of the red-green color blind allele

Front 51

In her message, Audrei also tells us that her sister Liz and brother Paul are also color blind, but that her brother David has normal vision. How will Liz be represented on the family pedigree?

Back 51

affected

Front 52

Paul, like Liz, is color blind. How will he be represented in the family pedigree?

Back 52

male affected

Front 53

Andrew and Jason have not been tested. What is the possibility that they will have the color perception defect?

Back 53

50%

Front 54

We don't know if any of Audrei's grandparents were red-green color blind, but we can make some educated guesses. Is it possible that all of Audrei's grandparents have normal vision?

Back 54

yes

Front 55

Would we predict that Stephen's father is color blind?

Back 55

no

Front 56

What is the probability that Audrei's sons will be color blind?

Back 56

100%

Front 57

What is the probability that Audrei's daughters will be color blind?

Back 57

O% if the father has normal vision, and
100% if the father is red-green color blind