10.2-11.3 Test

This diagram shows how pea plants can be used to conduct monohybrid crosses. What is the genotype for the P1 Tall pea plant? Need a Hint? A) Tt B) TT C) F1 D) F2

B

What is the genotype ratio for the offspring in this Punnett Square? Need a Hint? A) 4TT: 2Tt: 1tt B) 1TT: 2Tt: 1tt C) 2TT: 1Tt: 1tt D) 2TT: 1Tt: 2tt

B

Which of the following statements is NOT true? Need a Hint? A) If an organism has two alleles for a trait that are the same, it is said to be homozygous for that trait. B) The way an organism looks and behaves is called its genotype. C) A hybrid is the offspring of two parents that have different forms of a trait. D) Dominant alleles are represented with upper-case letters.

B

11 What does this figure represent? Need a Hint? A) meiosis II B) allele combinations in a Punnett square C) phenotypes in a Punnett square D) Mendel's law of segregation

b

15 What is produced by the crossing over and independent assortment of genes? Need a Hint? A) X chromosomes B) genetic recombination C) Y chromosomes D) alleles

b

2 Traits such as skin color and height which result from multiple genes are called ____. Need a Hint? A) alleles B) polygenic traits C) pedigrees D) inactive chromosomes

b

The protective caps at the end of chromosomes are called ____. Need a Hint? A) karyotypes B) telomeres C) disjunctions D) polygenic caps

b

When an organism has two alleles for a trait that are the same, it is said to be __________ for that trait. Need a Hint? A) heterozygous B) homozygous C) segregated D)

b

Which of the following statements is NOT true? Need a Hint? A) A hybrid is the offspring of two parents that have different forms of a trait. B) The way an organism looks and behaves is called its genotype. C) If an organism has two alleles for a trait that are the same, it is said to be homozygous for that trait. D) Dominant alleles are represented with upper-case letters.

b

Which statement is not true of genes located close together on the same chromosome? Need a Hint? A) They travel together during gamete formation. B) They always segregate independently. C) They are linked together. D) They do not segregate independently.

b

Which statement pertains to Mendel's law of segregation? Need a Hint? A) Homozygous organisms are called hybrids. B) Two alleles for each trait separate during meiosis. C) Allele pairs are called a genotype. D) Dominant traits are visible.

b

2 Down syndrome results from a (an) ____ chromosome. Need a Hint? A) enlarged B) missing C) extra D) weak

c

3 This Punnett square shows incomplete dominance in snap dragons. What do the Rr alleles represent? Need a Hint? A) an example of codominance B) homozygous intermediate traits C) heterozygous intermediate traits D) homozygous recessive traits

c

5 What genetic condition does this table give examples of? Need a Hint? A) environmental influences on chromosomes B) normal chromosomal pairs C) sex chromosomes that have separated abnormally D) dosage compensation in chromosomes

c

The diagram in Figure 10-2 shows a diploid cell with two homologous pairs of chromosomes. Due to independent assortment, the possible allelic combinations that could be found in gametes produced by the meiotic division of this cell are _____. Need a Hint? A) Bb, Dd, BB, and DD B) Bd and bD only C) BD, bD, Bd, and bd D) BbDd and BDbd

c

What conclusion can be made from this figure? Need a Hint? A) alleles are not allowed to combine B) random assortment results in eight possible gametes C) random assortment results in four possible gametes D) gametes are not allowed to form

c

What is the genotype of generation 1 in Figure 10-5? Need a Hint? A) ii B) II C) Ii D) I

c

When Mendel conducted his experiments, he needed to transfer pollen grains from a male reproductive organ to a female reproductive organ in a plant. What is this process called? Need a Hint? A) monohybrid B) heredity C) cross pollination D) recessive

c

Which of these pertains to Mendel's law of independent assortment? Need a Hint? A) observable characteristics of a trait B) separation of alleles during meiosis C) random distribution of alleles D) protein production

c

4 Which statement is true regarding sex chromosomes? Need a Hint? A) Males have dosage compensation. B) Females have an X and Y chromosomes. C) Males have two X chromosomes. D) Females have dosage compensation.

d

According to Figure 10-5, the constricted pod shape is _____. Need a Hint? A) hybrid B) dominant C) segregated D) recessive

d

An organism with two different alleles for a particular trait is ____. Need a Hint? A) incapable of reproduction B) homozygous C) heterozygous and homozygous D) heterozygous

d

How should the top row of Figure 10-7 read? Need a Hint? A) mMxX, mMxx, mmxX, mmxx B) MMxX, MMxx, MmxX, Mmxx C) mMXX, mMXx, mmXX, mmXx D) MMXX, MMXx, MmXX, MmXx

d

What is the genotype in the bottom left-hand quadrant in Figure 10-6? Need a Hint? A) wW B) WW C) ww D) Ww

d

What is the phenotype of generation 1 in Figure 10-5? Need a Hint? A) Ii B) constricted C) II D) inflated

d

What technique did Mendel use to better understand inherited traits? Need a Hint? A) removed dominant alleles B) cross pollinated same-sex plants C) allowed plants to self-fertilize D) cross pollinated male and females

d

Which condition occurs when a human zygote has 47 chromosomes? Need a Hint? A) No special condition occurs. This is the normal number of human chromosomes. B) genetic recombination C) interphase D) Down's syndrome

d

73. A heterozygous organism is best described as which of these?

hybrid

14. T/F ​The separation of genes during crossing over occurs more frequently between genes that are far apart on a chromosome than for genes that are close together

T

​19. t/F Gregor Mendel's research supports the idea each organism carries a pair of alleles.

T

10 ____ are heterozygous for two different traits. Need a Hint? A) Dihybrids B) Monohybrids C) Alleles D) Recessive genes

a

14 This chromosome map of a fruit fly represents ____. Need a Hint? A) a single X chromosome B) y, w, and v chromosomes C) a series of X and Y chromosomes D) multiple Y chromosomes

a

3 What can be performed in order to investigate what genes a parent might be carrying? Need a Hint? A) fetal testing B) disease screening C) telomeres D) vaccination

a

4 Having only one of a particular type of chromosome is called ____. Need a Hint? A) monosomy B) trisomy C) trisomy 21 D) down syndrome

a

5 Which of these is not an example of the environment influencing phenotype? Need a Hint? A) chemicals causing gene mutation B) dry plant losing leaves C) dog's thicker fur in cold weather D) lack of sun causing flowers to die

a

An interaction in which one allele hides the effect of another allele is called ____. Need a Hint? A) epistasis B) nondisjunction C) dosage compensation D) sex determination

a

Using Figure 10-3, which process would result in the formation of chromosome C from chromosomes A and B? Need a Hint? A) crossing over B) independent assortment C) segregation D) asexual reproduction

a

What does the TT represent in this Punnett square? Need a Hint? A) a genotype consisting of two dominant alleles B) a heterozygous trait C) a single allele D) a genotype consisting of two recessive alleles

a

55. Using Figure 10-3, which process would result in the formation of chromosome C from chromosomes A and B? Figure 10-3 a. asexual reproduction c. crossing over b. independent assortment d. segregation

55. ANS: C Crossing over leads to new combinations of alleles on a given chromomosome.

57. Figure 10-7 What fraction of this cross will be recessive for both traits? a. 1/2 c. 1/8 b. 1/4 d. 1/16

57. ANS: D This is a classic F1 cross for two independent traits. The ratio is 9:3:3:1. Of the sixteen possible combinations, only one or 1/16 has a genotype with completely recessive alleles.

76. Two rabbits that were homozygous for both coat and eye color were crossed. The following are the phenotypes of their F2 generation. Which most strongly suggest that the genes for eye color and coat color are linked? a. 22 brown coat brown eye, 7 brown coat blue eye, 9 white coat blue eye, 4 white coat blue eye b. 62 brown coat brown eye, 21 brown coat blue eye, 18 white coat blue eye, 7 white coat blue eye c. 92 brown coat brown eye, 35 brown coat blue eye, 31 white coat blue eye, 11 white coat blue eye d. 95 brown coat brown eye, 12 brown coat blue eye, 16 white coat blue eye, 30 white coat

76. ANS: D With independent assortment, the ratio of phenotypes of the F2 generation from homozygous parents is expected to approximate 9:3:3:1. When linkage occurs, the traits do not assort independently and this ratio is not observed.

The large size of many fruits and flowers is the result of polyploidy, a condition in which the nuclei of an organism's cells contain extra sets of chromosomes. Polyploidy often occurs naturally, but it can also be artificially induced by plant breeders. How have breeders been able to mimic a naturally occurring phenomenon? Researchers have determined that the chemical colchicine suppresses cell division by preventing the formation of spindle fibers. Without these fibers, the sister chromatids cannot become properly oriented for separation into individual nuclei. In effect, mitosis is stopped after prophase. However, the cell may continue to make copies of its chromosomes. As a result, the nucleus of the cell contains multiple sets of chromosomes. Suppose a researcher wished to investigate how extra sets of chromosomes are produced. First, she treated two onion roots with a colchicine solution and left two roots untreated. After a period of several days, she placed thin slices from each root tip on separate slides, stained the specimens, and examined the slides under a microscope at high power. 89. How do you predict the slides of treated and untreated root tips will differ? 90. Describe what happens in each stage of interphase. 91. How does meiosis maintain a constant number of chromosomes in the body cells of organisms that reproduce sexually? 92. A researcher crossed a brown-eyed flightless fruit fly (bbff) with a heterozygous normal fruit fly (BbFf). Of the 235 offspring, 220 appeared either brown-eyed flightless or normal. What is the best explanation for this observation?

89. ANS: Answers may vary. The slides of untreated root tips will show cells in interphase and in various stages of mitosis. The slides of treated root tips will show cells only in interphase and in prophase, and they may show some cells with multiple sets of chromosomes. 90. ANS: During G1, a cell is growing, carrying out normal functions, and preparing to replicate its DNA. During synthesis, the cell copies its DNA in preparation for mitosis. Finally, G2 is the stage in which the cell prepares for division of the nucleus. 91. ANS: Meiosis reduces the number of chromosomes to n or half in the sperm and egg. When fertilization occurs, the 2n number of chromosomes is restored. 92. ANS: The traits are linked closely on the same chromosome. As a result, there is little crossing over between them, and they tend to stay together. (In fact, these traits are both found on chromosome number 2).

97. In humans, albinism is recessive to normal coloration. Assume that an albino woman and a man who is homozygous for normal coloration are planning to have children. What is the likelihood that their children will be albino? Defend your answer by including specific genotypes of the individuals involved.

97. ANS: Aside from the small chance of mutation, the likelihood is zero. The mother has a genotype of aa and the father's genotype is AA. Each child will have a heterozygous genotype, Aa. The child will carry the allele for albinism but will appear normal. (If the man were heterozygous Aa, then half the children would be expected to be albino.)

When Mendel conducted his experiments, he needed to transfer pollen grains from a male reproductive organ to a female reproductive organ in a plant. What is this process called? Need a Hint? A) cross pollination B) monohybrid C) recessive D) heredity

A

96. A squash plant that produces white fruit was crossed with a squash plant that produces yellow fruit to produce 25 offspring. Fourteen of the offspring produced white fruits, while 11 produced yellow fruit. Does this evidence support the idea that white fruit color is dominant to yellow? Defend your answer with specific information about the likely genotypes of the individual plants involved.

ANS: The evidence does not necessarily support the idea that white color is dominant to yellow. The results of this cross support the idea that one parent is a heterozygote (Aa) and the other is a homozygous recessive (aa). Similarly, each offspring has the same genotype of the parent that produces the same color fruit. It is not clear, however, which parent is the heterozygote. The ratio of offspring is nearly 1 to 1.

In guinea pigs, the allele for rough coat (R) is dominant to the allele for smooth coat (r), and the allele for black fur (B) is dominant to the allele for white fur (b). If two guinea pigs that are heterozygous for rough, black fur (RrBb) are mated, what are the possible phenotypes and what is the frequency of each? Show your work in a Punnett square, Figure 10-4.

ANS: The phenotypic ratio is 9 rough, black fur: 3 rough, white fur: 3 smooth, black fur: 1 smooth, white fur. See Solution 10-1.

Some biology students wanted to determine whether a pair of brown mice purchased at a pet store was homozygous dominant or heterozygous for fur color. They let the mice mate and examined the offspring. Six mice were born. All six had brown fur. Some of the students felt that this was enough evidence to prove that the mice were homozygous for brown fur color. Other students did not, so another experiment was planned. 94. Describe the next experiment the students could conduct to determine whether the parent mice are homozygous brown or heterozygous. Explain your answer. 95. In fruit flies, the allele for normal body (H) is dominant to the allele for hairy body (h), and the allele for red eye color (B) is dominant to the allele for brown (b). Use a Punnett square to determine the possible phenotypes and frequencies of the offspring from the cross Hhbb hhBb.

ANS: There are a number of ways students could respond correctly to this problem. a) The parent mice could be permitted to mate several more times and produce large numbers of offspring. The larger F1 population would increase the likelihood of the recessive phenotype being expressed. b) The students could allow several of the F1 mice to interbreed. If the parents are heterozygous, about 50% of their offspring should be heterozygous and with the larger numbers, there would be a greater chance of the recessive phenotype showing in the F3 population. c) The parent mice each could be mated with a homozygous recessive mouse. In that way, if a parent were heterozygous, there would be a 50% chance of the offspring showing the recessive trait. There are other possible correct responses. All of the responses should in some way indicate the need for more offspring because heredity operates according to the laws of probability. Both mice could be homozygous brown, and that is why the recessive allele does not segregate out and appear in the offspring. BUT, only one mating and six offspring are not enough to prove this mathematically. One of the pair of mice could be heterozygous and the other homozygous brown and again, the recessive trait would not be seen in the offspring. Another possibility is that both mice are heterozygous. There would be only a 25% chance that the recessive alleles would segregate out and combine during fertilization. Six offspring may not be a large enough sample mathematically to reasonably expect the 25% chance of white mice to be expressed. 95. ANS: The phenotypic ratio is 1 normal body hair red eye: 1 normal body brown eye: 1 hairy body red eye: 1 hairy body brown eye. See Solution 10-2.

71. Mendel took the pollen from a tall pea plant and pollinated the flower of a short pea plant. When he did this, he removed the male parts of the flower on the short plant. Why was it important that he remove the male parts from the flower of the short plant? a. because he wanted to prevent self pollination b. because the short plant was heterozygous c. because he wanted to prevent the development of seeds d. because the short plant was not a true-breeding plant

ANS: A He removed the male parts on the short plant because he wanted to avoid letting the plant self-pollinate. He wanted the pollen to come only from a tall plant.

53. In mink, brown fur color is dominant to silver-blue fur color. If a homozygous brown mink is mated with a silver-blue mink and 8 offspring are produced, how many would be expected to be silver-blue? a. 0 c. 6 b. 3 d. 8

ANS: A The brown mink will always donate a dominant allele to its offspring, which means all the offspring will have the dominant phenotype. None of the offspring would be silver-blue, which is the recessive color.

51. A white mouse whose parents are both white produces only brown offspring when mated with a brown mouse. The white mouse is most probably ____. a. homozygous recessive b. heterozygous c. homozygous dominant d. haploid

ANS: A The most likely scenario is that the white mouse displays the recessive trait. If this is the case, then the white mouse must be homozygous. If the white mouse were either homozygous dominant or heterozygous, then it would likely produce white offspring when mated with a brown mouse.

54. The diagram in Figure 10-2 shows a diploid cell with two homologous pairs of chromosomes. Due to independent assortment, the possible allelic combinations that could be found in gametes produced by the meiotic division of this cell are ____. Figure 10-2 a. Bb, Dd, BB, and DD c. BbDd and BDbd b. BD, bD, Bd, and bd d. Bd and bD only

ANS: B Chromosomes separate so that one of each gamete contains one member of each pair. Thus, B and b would not be found together, nor would D and d. However B can be combined with either D or d, and similarly b can be combined with either D or d.

75 two heterozygous individuals are crossed, what percent of their offspring are also expected to be Ifheterozygous? a. 0 c. 75 b. 50 d. 100

ANS: B Four combinations are equally likely: AA, Aa, aA, and aa. Of these, half are heterozygous.

72.Mendel crossed a true-breeding plant that produced green seeds with a true-breeding plant that produced yellow seeds to produce an F1 generation. The entire F1 generation produced yellow seeds. Then he crossed the F1 offspring with each other to produce the F2 generation. From the F2 generation, he counted 6022 yellow seeds.Which of these is the most likely estimate of the number of green seeds he collected from the F2 generation? a. 0 c. 6000 b. 2000 d. 18000

ANS: B In the F2 generation, we expect a 3 to 1 ratio of yellow to green seeds. Thus, if there are approximately 6000 yellow seeds, then we expect about 2000 green seeds.

69. A true-breeding tall pea plant is crossed with a true-breeding short pea plant, and all the offspring are tall. What is the most likely genotype of the offspring assuming a single-gene trait? a. tt c. TT b. Tt d. TTortt

ANS: B Since the parents are true breeding, they are most likely homozygous (TT and tt). This means the offspring are most likely heterozygous, Tt.

56. What is the genotype of generation 1 in Figure 10-5? a. II c. ii b. Ii d. I

ANS: B The first generation are all heterozygotes, or Ii.

65. Suppose an animal is heterozygous AaBb, and the traits are not linked. When meiosis occurs, what is the total number of possible combinations of gametes that can be made for these traits? a. 2 c. 6 b. 4 d. 8

ANS: B There are four combinations: AB, Ab, aB, and ab.

52. In chickens, rose comb (R) is dominant to single comb (r). A homozygous rose-combed rooster is mated with a single-combed hen. All of the chicks in the F1 generation were kept together as a group for several years. They were allowed to mate only within their own group. What is the expected phenotype of the F2 chicks? a. 100% rose comb b. 75% rose comb and 25% single comb c. 100% single comb d. 50% rose comb and 50% single comb

ANS: B This is the classic situation in which the F1 generation (all heterozygous) are crossed to produce offspring in a 3 to 1 ratio of dominant to recessive.

66. Suppose an animal is heterozygous AaBbCc, and the traits are not linked. When meiosis occurs, what is the total number of possible combinations of gametes that can be made for these traits? a. 3 c. 8 b. 6 d. 12

ANS: C Each of the following 8 combinations are possible: ABC, ABc, AbC, aBC, Abc, aBc, abC, and abc.

70. In mice, black is dominant to white color and color is determined by a single gene. Two black mice are crossed. They produce 2 black offspring and one white offspring. If the white offspring is crossed with one of its parents, what percent of the offspring are expected to be white? a. 0 c. 50 b. 25 d. 75

ANS: C The original parents must be heterozygous (Bb) since they produced both black and white offspring. The white offspring must be homozygous recessive (bb). If the white offspring is crossed with its parent then half the offspring will be white.

74. which situation are the phenotypes of F2 offspring expected to follow the ratio of 9:3:3:1. a monohybrid cross for 2 unlinked traits a monohybrid cross for 2 closely linked traits a dihybrid cross for 2 unlinked traits a dihybrid cross for 2 closely linked traits

ANS: C This ratio is expected in the F2 generation of a dihybrid cross when independent assortment takes place. This is the case when two traits are unlinked, or found on different chromosomes.

A geneticist crossed fruit flies to determine whether two traits are linked. The geneticist crossed a fly with blistery wings and spineless bristles (bbss) with a heterozygous fly that had normal wings and normal bristles (BbSs). Which results in the next generation would suggest these traits are linked? a. 35 normal wings, normal bristles, 28 normal wings, spineless bristles, 23 blistery wings, normal bristles, 30 blistery wings, spineless bristles b. 105 normal wings, normal bristles, 101 normal wings, spineless bristles, 111 blistery wings, normal bristles, 115 blistery wings, spineless bristles c. 198 normal wings, normal bristles, 200 normal wings, spineless bristles, 185 blistery wings, normal bristles, 189 blistery wings, spineless bristles d. 222 normal wings, normal bristles, 27 normal wings, spineless bristles, 22 blistery wings, normal bristles, 228 blistery wings, spineless bristles

ANS: D Linkage is evident if two of the phenotypic combinations occur at a much greater rate than the other two.

87. The possible combination of genes in any gamete due to independent assortment equals 2n, where n equals the number of ____________________.

ANS: chromosome pairs

85. An individual with the genotype Aa is ____________________ for the trait.

ANS: heterozygous

86. Genes on separate chromosomes follow Mendel's law of ____________________.

ANS: independent assortment

88. The term ____________________ refers to the occurrence of one or more sets of extra chromosomes in an organism.

ANS: polyploidy

What is the phenotype ratio for the offspring in this Punnett Square? Need a Hint? A) 3 round yellow; 3 round green: 3 wrinkled yellow: 3 wrinkled green B) 3 round yellow; 9 round green: 1 wrinkled yellow: 3 wrinkled green C) 9 round yellow; 3 round green: 3 wrinkled yellow: 1 wrinkled green D) 9 round yellow; 3 round green: 3 wrinkled yellow: 9 wrinkled green

C

Female and male sex cells are called __________. Need a Hint? A) hybrids B) alleles C) genotypes D) gametes

D

12. T/F Mendel's work on garden pea plants resulted in the discovery that genetic traits of parents always blend together in subsequent generations.

F

13. T/F In humans, the ability to roll one's tongue is a dominant trait. Therefore, a tongue roller can only have children who are also tongue rollers.

F

Which of these squares has the tt genotype?

square 4