Chapter 12

Match each of the following terms with its correct definition. a. When displayed traits are unchanged over multiple generations b. The first generation of offspring from a parental cross c. True-breeding plants used in an initial cross d. A result of a cross between two first generation organisms e. The allele that is expressed no matter what other allele is present f. The allele that is expressed only if two identical copies are present. g. Any organism with 2 identical alleles of a gene h. Any organism with 2 different alleles of a gene i. An F1 heterozygote (for a single trait) j. The genetic makeup of an organism k. The physical traits of an organism l. The likelihood of something occurring if the occurrence is a matter of chance m. An organism that is heterozygous for two different traits n. Where an allele is found on a chromosome o. When one allele cannot completely mask the effects of another allele p. When alleles at one locus mask the expression of alleles at a different locus q. When different genes contribute to a particular phenotype r. When a single allele has multiple phenotypic effects. 59. F2 generation 60. F1 generation 61. dominant 62. homozygous 63. recessive 64. phenotype 65. dihybrid 66. heterozygous 67. pleiotropy 68. P generation 69. probability 70. genotype 71. true breeding 72. locus 73. polygenic inheritance 74. epistasis 75. monohybrid 76. incomplete dominance

59. ANS: D 60. ANS: B 61. ANS: E 62. ANS: G 63. ANS: F 64. ANS: K 65. ANS: M 66. ANS: H 67. ANS: R 68. ANS: C 69. ANS: L 70. ANS: J 71. ANS: A 72. ANS: N 73. ANS: Q 74. ANS: P 75. ANS: I 76. ANS: O

Your father is heterozygous for a recessive disorder. You know your mom has two "good" alleles. What is the probability that you will have the disorder? a. 0% b. 25% c. 50% d. 75% e. 100%

A

Your father is heterozygous for the recessive disorder phenylketonuria (PKU). You know your mom has two "good" alleles. What is the probability that you will have the disorder? a. 0% but you will have a 50% chance of passing the "bad" allele on to your children b. 0% and you don't need to worry about passing the "bad" allele on to your children c. 25% for you and 25% for your children d. 50% for you and 50% for your children e. 50% for you and 25% that you'll pass the "bad" allele on to your children

A

Your mother has albinism, which is a recessive trait. Your father has cystic fibrosis, which is also a recessive trait. You just got married and discover that your new father-in-law has albinism and cystic fibrosis. What are the odds that your first child will have both albinism and cystic fibrosis? a. 1/16. b. 1/8. c. 1/4. d. 1/2. e. 0.

A

Your parents are both heterozygous for the recessive disorder phenylketonuria (PKU). What is the probability that you will have the disorder? a. 25% regardless of the health of your 3 siblings b. 50% no matter whether or not you have siblings c. 75% no matter whether or not you have siblings d. 100% even if you are an only child e. 25% but only if your three siblings are healthy.

A

Use the five types of allele interactions listed below for the following question(s). a. Dominance b. Incomplete dominance c. Codominance d. Epistasis e. Polygenic inheritance 77. Snapdragons have two alleles and three colors due to this. 78. Human blood type AB is an example of this allele interaction. 79. Mice have three colors of fur due to this allele interaction. 80. Human height is an example of this. 81. Peas being wrinkled or round is an example of this.

ANS: B 78. ANS: C 79. ANS: D 80. ANS: E 81. ANS: A

The key difference between incomplete dominance and codominance is a. with incomplete dominance, the recessive allele cannot be detected; in codominance, the expression of the recessive allele is apparent. b. with incomplete dominance it is possible to detect the expression of a recessive allele; in codominance, both alleles contribute equally to the phenotype. c. with codominance it is possible to detect the expression of a recessive allele; in incomplete dominance, both alleles contribute equally to the phenotype. d. with incomplete dominance, it is possible to detect the expression of the dominant allele; in codominance, both alleles contribute equally to the phenotype. e. the two terms mean the same thing.

B

We now know that some of the 7 alleles Mendel studied are on the same chromosome in pea plants. Despite this, the law of independent assortment still applies. How can you explain this? a. There is recombination via the synaptonemal complex during mitosis. b. There is recombination via the synaptonemal complex during meiosis. c. The law of independent assortment applies to all alleles regardless of their arrangement on chromosomes. d. Mendel was a good enough mathematician to design experiments that would result in the predicted ratios. e. Mendel was incredibly lucky.

B

45. Your father has type B blood. Your mother has type O blood. You get tested and learn that your blood is also type O. What does this tell you? a. You were adopted and your parents didn't tell you. b. Your mother had a secret affair. c. Your father's genotype is IBi and your mother's genotype is ii. d. Your father's genotype is IBIB and your mother's genotype is ii. e. Your father's genotype is IAIB and your mother's genotype is ii.

C

If your mother and father are both heterozygous for Huntington disease, which is caused by a dominant allele, the odds of your having the disorder are a. 1/4. b. 1/2. c. 3/4. d. 1. e. 0.

C

If your mother and father both have cystic fibrosis, which is caused by a recessive allele, the odds of your having only one allele for the disorder are a. 1/4. b. 1/2. c. 3/4. d. 1. e. 0.

C

Which of the following shows an F1 monohybrid cross? a. RrMM ´ Rrmm b. RRMM ´ rrmm c. Rr ´ Rr d. rr ´ RR e. Rr ´ rr

C

If your mother and father both have cystic fibrosis, which is caused by a recessive allele, the odds of your having cystic fibrosis are a. 1/4. b. 1/2. c. 3/4. d. 1. e. 0.

D

Two snapdragons heterozygous for alleles that encode red and white flower color are crossed. If the red and white alleles show incomplete dominance, what will be the phenotypes and ratios of the F2 generation? a. 100% pink b. 100% red c. 50% white, 50% red d. 25% red, 50% pink, 25% white e. 25% pink, 50% white, 25% red

D

Your mother has albinism, which is a recessive trait. Your father has cystic fibrosis, which is also a recessive trait. You just got married and discover that your new father-in-law has albinism and cystic fibrosis. What are the odds that your first child will have neither albinism nor cystic fibrosis? a. 1/16 b. 3/8 c. 1/8 d. 9/16 e. 0

D

46. You have type O blood (genotype ii). Who can you donate blood to in an emergency? a. type O only b. type B only c. type A only d. type AB only e. types A, B, AB, and O

E

A man and woman are each heterozygous for the autosomal recessive gene for albinism. They already have two non-albino children and want to have two more. What is the probability that their next two children will be phenotypically identical to each other with regard to skin color (i.e., either both albino or neither albino)? a. 1/16 b. 3/16 c. 4/16 d. 9/16 e. 10/16

E

R is the dominant allele for a round pea, r is the recessive allele for a wrinkled pea. If you cross plants having round peas with plants having wrinkled peas, a. both pea plants are homozygous. b. you are conducting a dihybrid cross. c. you are crossing two parental pea plants. d. the progeny plants will all have wrinkled peas. e. you will be able to determine if the round pea plant is homozygous or heterozygous.

E

A dihybrid test cross should always result in 50% of the progeny being recessive for both traits.

F

Mendel knew about and understood incomplete dominance.

F

Polygenic inheritance is proof of the blending theory of inheritance.

F

An F1 organism is always homozygous.

False

Cross-pollination occurs within a single plant while self-pollination occurs between two plants.

False

A test cross always uses a homozygous recessive organism as one parent.

T

Dwarf pea plants have deficient levels of the hormone gibberellin.

T

The environment can impact the phenotype controlled by polygenic inheritance.

T

There is no limit to the number of alleles that exist for a gene.

T

43. You cross a pink snapdragon (CRCW) with a white snapdragon (CWCW). What percentage of the progeny will be red? a. 0% b. 25% c. 50% d. 75% e. 100%

a

5. If purple flower color is dominant in pea plants, a cross between P generation purple and white plants will result in a. all purple flowers in the F1 generation. b. all white flowers in the F1 generation. c. all purple flowers in the F1 generation but a lighter purple than in the parents. d. mostly purple flowers in the P1 generation, with an occasional white flower. e. half of the plants having purple flowers, the other half having white flowers.

a

A testcross is used to a. determine if a parent with a dominant trait is heterozygous or homozygous. b. determine which allele is dominant. c. determine if the progeny of an experimental cross will get a random assortment of alleles . d. prove that an organism is true-breeding. e. cross an individual with a dominant phenotype with a homozygous dominant individual to prove the alleles are indeed dominant.

a

Identify the disorder caused by a dominant allele. a. achondroplasia b. cystic fibrosis c. albinism d. sickle cell disease e. PKU

a

If a woman has blood type O and a man has blood type AB, what is the probability that they will have a child with blood type O? a. 0 b. 1/16 c. 1/4 d. 1/2 e. 3/4

a

Mendel studied what he called characters and traits. What is the relationship between these terms? a. Characters were heritable characteristics; traits were variations of characters. b. Traits were heritable characteristics; characters were variations of traits. c. Characters were the unknown package of transfer to the next generation; traits resulted from this transfer. d. Characters were passed to the next generation; traits were never passed to the next generation. e. Characters and traits were synonymous in Mendel's writings.

a

Mouse pigmentation is subject to epistasis of the B alleles by the d alleles. B (black) is dominant over b (brown). D is dominant over d. Homozygous d is epistatic to the black and brown genes. Given this information, what will result from a F1 cross between two mice? a. 9/16 black, 3/16 brown, 4/16 white b. 9/16 white, 3/16 brown, 4/16 black c. 9/16 black, 6/16 brown, 1/16 white d. 9/16 white, 6/16 brown, 1/16 black e. All black mice

a

Use the sum rule to determine the probability of either event X or event Y occurring if they cannot occur simultaneously. (In the equations below, Px means probability of event X; Py means probability of event Y.) a. = Px + Py b. = PxPy c. = (Px)2 + (Py)2 d. = (Px + Py)2 e. = Px2Py2

a

When did Gregor Mendel perform his experiments with garden peas? a. in the 1860s, the same decade as the United States' Civil War b. in the 1760s, predating the formation of the United States of America c. in the 1620s, the decade in which William Shakespeare died d. in the 1720s, the decade in which Bach composed the Brandenburg Concertos e. in the 1820s, the decade in which Ecuador became independent from Spain

a

2. What is the main premise of the blending theory of inheritance that predominated before 1900? a. We inherit traits from both of our parents. b. Traits are inherited via a mixing of parental blood. c. You're a perfect blend of traits from both of your biological parents. d. It explains the inheritance patterns of traits that skip a generation. e. It explains why children of one tall parent and one short parent generally have an adult height midway between their parents' heights.

b

37. Your mother has albinism, which is a recessive trait. You learn that your spouse's mother also has albinism. Neither you nor your spouse have albinism. What are the odds that your first child will have albinism? a. 0 b. 1/4 c. 1/2 d. 3/4 e. 1

b

A cross is done between parents with genotypes aaBbCc and aaBbcc. What is the probability that offspring will have the same genotype as the first parent? a. 1/8 b. 1/4 c. 3/8 d. 3/16 e. 9/16

b

A parent has a genotype of RrYy. What is the probability of having a gamete with the RY genotype? a. 1/2 b. 1/4 c. 3/4 d. 1/8 e. 0

b

If a monohybrid cross results in a 1:2:1 ratio for both the genotype and the phenotype in the F2 generation, then which type of inheritance might be at work? a. dominance b. incomplete dominance c. epistasis d. pleiotropy e. polygenic inheritanc

b

If your mother is heterozygous for Huntington disease, which is caused by a dominant allele, the odds of your inheriting the disorder from her are a. 1/4. b. 1/2. c. 3/4. d. 1. e. 0.

b

Your mother has albinism, which is a recessive trait. Your father has cystic fibrosis, which is also a recessive trait. You just got married and discover that your new father-in-law has albinism and cystic fibrosis. What are the odds that your first child will have either albinism or cystic fibrosis, but not both? a. 1/16 b. 3/8 c. 1/8 d. 1/4 e. 0

b

7. Use the product rule to determine the probability (P) of events X and Y both occurring. a. P = X2 + Y2 b. P = X2Y2 c. P = XY d. P = X + Y e. P = (X + Y)2

c

A cross is done between parents with genotypes aaBbCc and aaBbcc. What is the probability that offspring will have the same phenotype as the first parent? Assume that capital letters indicate dominant alleles and lower case letters indicate recessive alleles. a. 1/8 b. 1/4 c. 3/8 d. 3/16 e. 9/16

c

A patient presents the following symptoms: anemia, dilation of heart, lung damage and pneumonia, rheumatism, abdominal pain, and kidney failure. After learning about their family history, you run a genetic test for which disorder? a. Cystic fibrosis b. Albinism c. Sickle cell disease d. Achondroplasia e. Pleiotropy

c

A plant of genotype CCdd is crossed to ccDD and the F1 testcrossed to ccdd. If the genes are on different chromosomes, the percentage of ccdd offspring will be a. 10 b. 20 c. 25 d. 30 e. 50

c

Mendel crossed true-breeding plants having yellow peas with plants having green peas. The resulting plants all had yellow peas. An F1 cross resulted in of the plants having yellow peas and of the plants having green peas. What does this tell you about the alleles for color? a. yellow is usually the dominant color, but sometimes green can be dominant b. green is the dominant color c. yellow is the dominant color d. yellow is the recessive color e. the F1 plants must have had some green peas that went unnoticed.

c

Mendel selected 7 traits in pea plants to study. What was lucky about this choice? a. Peas are easy to raise and have short life cycles. b. All 7 traits were easy to characterize. c. The 7 alleles segregated independently from each other. d. He knew enough mathematics to apply rules of probability to his results. e. The 7 traits were all located on the same plant chromosome.

c

The different alleles in human blood type are a demonstration of a. incomplete dominance. b. codominance. c. dominance and codominance. d. dominance and incomplete dominance. e. dominance, codominance, and incomplete dominance.

c

Which of the following is a dihybrid cross? a. RrMM ´ Rrmm b. RRMM ´ rrmm c. RrMm ´ RrMm d. rrMM ´ RRmm e. RrMm ´ rrmm

c

A couple are both heterozygous for the dominant allele for polydactyly. They want to have three children. What is the probability that all three children will have polydactyly? a. 3/4 b. 9/64 c. 1/64 d. 27/64 e. 1/2

d

A man and woman are each heterozygous for the autosomal recessive disorder cystic fibrosis. If they want to have three children, what is the probability that only one of the children will have cystic fibrosis? a. 1/4 b. 3/4 c. 9/16 d. 9/64 e. 27/64

d

If the probability of X occurring is 1 in 4, and the probability of Y occurring is 1 in 5, the probability of both occurring is a. (1/4)2 + (1/5)2 = (1/16) + (1/25) = (25/400) + (16/400) = 41/400. b. (1/4) + (1/5) = (5/20) + (4/20) = 9/20. c. (1/4)2(1/5)2 = (1/16)(1/25) = 1/400. d. (1/4)(1/5) = 1/20. e. (1/4 + 1/5)2 = (5/20 + 4/20)2 = (9/20)2 = 81/400.

d

Round is the dominant trait for a pea; the recessive allele produces a wrinkled pea. How can you obtain true-breeding pea plants having round peas with the least amount of work? a. Cross plants having round peas with plants having wrinkled peas. Select round pea plants from the progeny because they are now true-breeding. b. Cross plants having round peas with other plants having round peas. Do this for multiple generations. c. Cross plants having round peas with plants having wrinkled peas. Select round pea plants from the progeny and do a test cross to determine which parental plants were homozygous dominant. Use these homozygous pea plants as your true-breeding plants. d. Cross plants having round peas with plants having wrinkled peas. This will tell you which round pea plants are homozygous dominant and are thus true-breeding. e. It's not possible. You can only get true-breeding plants that have wrinkled peas.

d

The probability of rolling a die twice and getting a 2 and a 6 in no particular order is a. 1/3 b. 1/4 c. 1/8 d. 1/18 e. 1/36

d

12. Which of the following is a test cross? (a "dash" means the allele's identity is unknown) a. R-MM ´ R-mm b. RRMM ´ rrmm c. R-M- ´ R-M- d. rrMM ´ RRmm e. R-M- ´ rrmm

e

47. You have type A blood (genotype IAi). Who can you donate blood to in an emergency? a. type O only b. type AB only c. type A only d. types A and B, not O e. types A and AB

e

According to Nicholas Katsanis at Duke University, which of the following are likely to be complex traits? a. schizophrenia b. diabetes c. hypertension d. obesity e. all of these

e

If your mother has cystic fibrosis, which is caused by a recessive allele, the odds of your inheriting the disease are a. 1/4. b. 1/2. c. 3/4. d. 1. e. More information is needed to determine the odds.

e

In snapdragons the red allele CR is incompletely dominant over the white allele CW. Which two plants would you cross to produce a true-breeding pink snapdragon? a. pink with pink b. pink with red c. red with white d. pink with white e. it's impossible to accomplish

e

Mouse pigmentation is subject to epistasis of the B alleles by the d alleles. B (black) is dominant over b (brown). D is dominant over d. Homozygous d is epistatic to the black and brown genes. Given this information, what genotypes give you a white mouse? a. BBdd b. Bbdd c. bbDD d. bbDd e. BBdd and Bbdd

e

The ability of an individual heterozygous for two different genes to produce its four gamete types in equal numbers reflects Mendel's Law(s) of a. Segregation. b. Independent Assortment. c. Punnett Squares. d. Chromosome Theory. e. Segregation and Independent Assortment.

e

Which individual established the connection between genes, meiosis, and fertilization? a. Gregor Mendel b. Hugo de Vries c. Carl Correns d. Erich von Tschermak e. Walter Sutton

e