Midterm 3

Question 1

Bar-eyed is a sex-linked dominant trait in Drosophila. If you cross a heterozygous female to a bar-eyed male, what is the probability that the offspring would be a bar-eyed female?

Answer 1

1/2

Question 2

A man has 6 fingers on each hand, and 6 toes on each foot. His wife and daughter have 5 fingers, and toes on their hands, and feet. Extra digits is a dominant trait. What is the chance that the man’s next child would have extra digits?

Answer 2

50%

Question 3

What is the probability of a dominant phenotype in the offspring of 2 heterozygotes?

Answer 3

75%

Question 4

John, and Carol are both married, and both of their parents are carriers of cystic fibrosis. What is the probability that John, AND Carol are carriers, AND the baby is homozygous recessive?

Answer 4

1/9

Question 5

Which of the following statements correctly describes a gene for a trait that is a sex linked?

Answer 5

Gene exists on X and Y chromosomes

Question 6

Which of the following would allow you to determine that you found a sex-linked mutant?

Answer 6

Ratios of female and male offspring conditions were different

Question 7

For a cross with individuals that are heterozygous at 3 loci, what is the probability of a recessive homozygote at 1 locus and a heterozygote at the 2 other loci?

Answer 7

3/16

Question 8

An organism homozygous for red color was crossed with an organism homozygous for white color. All 100 offspring of this first fertilization were pink. This example represents:

Answer 8

Incomplete Dominance

Question 9

The allele for tall (T) plants is incompletely dominant over the allele for short (t) plants. What is the F1 phenotypes ratios from a cross between two Tt plants?

Answer 9

1 tall:2 intermediate:1 short

Question 10

Patient X has Type A blood and needs a blood transfusion. Which of the following donor blood types would you administer?

Answer 10

Blood w/Type B antibodies

Question 11

What is the expected genotype ratio from the F2 progeny of a F1 test cross of a single autosomal recessive trait?

Answer 11

1:2:1

Question 12

What is the probability that an offspring of 2 heterozygotes would be homozygous for the recessive allele?

Answer 12

25%

Question 13

Which of the following statements correctly describes the terms monohybrid cross and dihybrid cross?

Answer 13

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.

Question 14

Which of the following correctly describes the DNA content of a human skin cell?

Answer 14

Has a total of 46 chromosomes

Question 15

A number of characteristics of the common garden pea made it a perfect model system to use for Mendel’s breeding experiments EXCEPT for:

Answer 15

Cannot control test crosses

Question 16

White eyes is a recessive sex-linked trait in Drosophila. If a white-eyed female fruit fly is mated to a red-eyed male, produces:

Answer 16

100% white-eyed males, and 100% red-eyed females

Question 17

John and Marry do NOT have cystic fibrosis, but their first child DOES have the condition. What do we know about the genotypes of John and Mary?

Answer 17

Both John and Mary are carriers

Question 18

A gray-bodied, vestigial-winged fly is crossed with a black-bodied, normal-winged fly. The F1 progeny is test crossed. Among the resulting offspring, _____ is a parental type, and _____ is a recombinant type.

Answer 18

gray-bodied, vestigial-winged … black-bodied, vestigial-winged

Question 19

Heterozygote individuals for sickle cell anemia have both round, and sickle shaped red blood cells. This indicates that the sickle cell anemia trait is:

Answer 19

Co-dominant

Question 20

How many alleles are there in an individual that has a genotype of AaBBCCDdEeFf?

Answer 20

12

Question 21

Which of the following correctly describes blood from a universal blood donor?

Answer 21

Red blood cell with no carbohydrates

Question 22

is/are “carriers” for an autosomal recessive trait.

Answer 22

Male and female heterozygotes

Question 23

What phenotype ratio do expect in the F2 generation from a dihybrid cross if you are examining Multiple Traits that undergo independent assortment?

Answer 23

9:3:3:1

Question 24

Which of the following individuals is a universal blood recipient?

Answer 24

Man with AB blood type

Question 25

If you toss a coin, what is the probability that after 2 coin tosses, both will come up tails?

Answer 25

25%

Question 26

A man heterozygous with type B blood, and a woman heterozygous with type A blood have the potential of producing children with the following phenotype combinations:

Answer 26

Type A, type B, type AB, or type O

Question 27

You cross a mutant ebony body female and with a wild type (WT) gray body male. F1 progeny was: 502 WT females, and 498 WT males. Then you cross a WT gray F1 female with a WT gray F1 male. Your F2 progeny was: 750 WT females, 748 WT males, 249 ebony females, and 247 ebony males. Based on this inheritance pattern, the ebony body trait is most likely:

Answer 27

Autosomal recessive

Question 28

is/are “carriers for an X-linked recessive trait.

Answer 28

Female heterozygotes

Question 29

A woman has heterozygous blood type A, and a man has heterozygous blood type B, what is the probability that they will have a son with blood type A?

Answer 29

12.5%

Question 30

What is the expected phenotype ratio from the F2 progeny of a F1 test cross of a single autosomal recessive trait?

Answer 30

3:1

Question 31

John, and Carol are both married, and both of their parents are carriers of cystic fibrosis. What is the probability that John, AND Carol will have a baby WITHOUT cystic fibrosis?

Answer 31

8/9

Question 32

To determine the genotype of an individual that has dominant phenotypes for genes A and B you perform a test cross. To perform this test cross, you would mate your dominant phenotype with which individual?

Answer 32

aabb

Question 33

The allele for tall plants is dominant over the allele for short plants. A true-breeding tall plant is crossed with a short plant, and one of their offspring is crossed with a short plant. Out of 20 offspring resulting from the cross, about _______ should be tall.

Answer 33

10

Question 34

After a dihybrid cross you find the following ratios of offspring with flower colors: 9/16 Dark Red flowers; 3/16 Red flowers; 4/16 white flowers. How are these ratios best explained?

Answer 34

Epistasis

Question 35

In tigers, the recessive allele from one gene causes both an absence of fur pigmentation (white tiger) phenotype and a cross-eyed phenotype. In this species, the heterozygotes for this gene are phenotypically normal tigers. This example demonstrates:

Answer 35

Pleiotropy

Question 36

For a cross with individuals AaBbCCDdEe X AaBbccDdEE, what is the probability that the offspring would have following genotype: aaBBCcDdEE?

Answer 36

1/64

Question 37

For a cross with 2 individuals that are heterozygous at 2 loci (A and B), what is the probability of a recessive homozygote at locus A, and heterozygote at locus B?

Answer 37

1/8

Question 38

If you toss a coin, what is the probability that after 2 coin tosses, both will come up tails?

Answer 38

25%

Question 39

How many alleles are there in an individual that has a genotype of AaBBCCDdEeFf?

Answer 39

12

Question 40

The following offspring were observed from many crossings of the same pea plants. What genotypes were the parents? 465 purple axial flowers, 152 purple terminal flowers, 140 white axial flowers, 53 white terminal flowers.

Answer 40

PpAa x PpAa (9:3:3:1)