Mastering bio Ch. 14

Assuming independent assortment for all gene pairs, what is the probability that the following parents, AABbCc × AaBbCc, will produce an AaBbCc offspring? a. 3/4 b. 1/2 c. 1/16 d. 1/8

d

Karen and Steve each have a sibling with sickle-cell disease. Neither Karen nor Steve nor any of their parents have the disease, and none of them have been tested to see if they have the sickle-cell trait. Based on this incomplete information, calculate the probability that if this couple has a child, the child will have sickle-cell disease. Express your answer as a fraction using the slash symbol and no spaces (for example, 1/16).

1/9

In maize (corn plants) a dominant allele I inhibits kernel color, while the recessive allele i permits color when homozygous. At a different locus, the dominant allele P causes purple kernel color, while the homozygous recessive genotype pp causes red kernels. If plants heterozygous at both loci are crossed, what will be the phenotypic ratio of the offspring? _____ colorless: _____ purple: _____ red Express your answer as three whole numbers separated by colons (for example, 5:2:1).

12:3:1 The dominant allele I is epistatic to the P/p locus, and thus the genotypic ratio for the F1 generation will be 9 I_P_ (colorless) : 3 I_pp (colorless) : 3 iiP_ (purple) : 1 iipp (red). Overall, the phenotypic ratio is 12 colorless : 3 purple : 1 red.

**The figure below shows the pedigree for a family. Dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. Males are represented by squares, females by circles. From this pedigree, this trait seems to be inherited _____. a. as an autosomal dominant b. as an autosomal recessive c. as a result of epistasis d. from mothers

a

A man with type A blood marries a woman with type B blood. Their child has type O blood. What is the genotype of the child? a. ii b. I A i c. I B i d. I A I B

a

Select the correct explanation for the fact that a carrier of a recessive genetic disorder does not have the disorder. a. In a recessive disorder, only a single functioning allele is necessary to determine a normal phenotype. b. Affected individuals have recessive mutations, but a carrier has a dominant mutation. c. The dominant allele for the gene determining the disorder represses protein production from the recessive allele.

a

A man with type A blood marries a woman with type B blood. Their child has type O blood. What genotypes would you expect in future offspring from this marriage? Select all that apply. a. ii b. I A i c. I B i d. I A I A e. I B I B f. I A I B

a b c f

Which of the following is true about a plant with the genotype AABbcc? a. It is homozygous at two loci. b. It is triploid. c. It is heterozygous at two loci. d. It will not express the recessive c allele. e. It has recessive alleles at three loci.

a An organism having a pair of identical alleles at a given locus is said to be homozygous for that locus. Here, the plant is homozygous at loci A and C.

Consider pea plants with the genotypes GgTt and ggtt . These plants can each produce how many type(s) of gametes? a. four ... one b. four ... two c. two... one d. one ... two e. one ... one

a GgTt individuals can produce the following gametes: GT, Gt, gT, and gt. A ggtt plant can produce only gt.

**Look at the Punnett square, which shows the predicted offspring of the F2 generation from a cross between a plant with yellow-round seeds (YYRR) and a plant with green-wrinkled seeds (yyrr). Select the correct statement about wrinkled yellow seeds in the F2 generation. a. In a set of 16 individuals from the F2 generation, 3 will produce wrinkled yellow seeds. b. The chance that an individual taken at random from the F2 generation produces wrinkled seeds is 25% and the chance that the same individual produces yellow seeds is 75%. c. Wrinkled and yellow traits are linked in peas.

b

Quantitative characters vary in a population along a continuum. How do such characters differ from the characters investigated by Mendel in his experiments on peas? a. The nature of inheritance of quantitative characters is poorly understood, and Mendel understood the nature of inheritance for the characters he studied in his peas. b. Quantitative characters are due to polygenic inheritance, the additive effects of two or more genes on a single phenotypic character. A single gene affected all but one of the pea characters studied by Mendel. c. Environment and genes affect quantitative characters, whereas only genes determined the pea characters studied by Mendel.

b

The pattern of inheritance (monohybrid, dihybrid, sex-linked, and genes linked on the same chromosomes) can be predicted from data if one is given the parent or offspring genotypes or phenotypes. Two organisms, with genotypes BbDD and BBDd, are mated. Assuming independent assortment of the B/b and D/d genes, determine the genotypic ratios in offspring that would occur. a. 1/2 BBDD 1/2 bbdd b. 1/4 BBDD 1/4 BbDD 1/4 BBDd 1/4 BbDd c. 1/4 BBDD 1/2 BbDd 1/4 bbdd d. 9/16 BBDD 3/16 BbDD 3/16 BBDd 1/16 bbdd

b

Which of the following calculations require that you utilize the addition rule? a. Calculate the probability of black offspring from the cross AaBb × AaBb, where B is the symbol for black. b. Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both. c. Calculate the probability of children with both cystic fibrosis and polydactyly when parents are each heterozygous for both genes. d. Calculate the probability of each of four children having cystic fibrosis if the parents are both heterozygous.

b

You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits? a. Red is completely dominant. b. Red shows incomplete dominance over white. c. Pink is dominant, and red and white are recessive. d. Both red and white are pleiotropic.

b

Which of the following do you expect if an individual is heterozygous for the sickle-cell trait? a. He or she will not develop sickle-cell disease. b. He or she will show some symptoms of the disease. c. He or she will be more apt to acquire a serious case of malaria. d. He or she will have full-blown sickle-cell disease because the allele is dominant. e. None of the above.

b A heterozygote will produce both normal and abnormal hemoglobin.

When a dominant allele coexists with a recessive allele in a heterozygote individual, how do they interact with each other? a. The dominant allele prevents transcription of the recessive allele. b. They do not interact at all. c. The dominant allele prevents expression of the recessive allele by an unknown mechanism.

b An allele is called dominant because it appears in the phenotype of a heterozygote, not because it subdues a recessive allele. Read about dominance.

In rabbits, the homozygous CC is normal, Cc results in deformed legs, and cc results in very short legs. The genotype BB produces black fur, Bb brown fur, and bb white fur. If a cross is made between brown rabbits with deformed legs and white rabbits with deformed legs, what percentage of the offspring would be expected to have deformed legs and white fur? a. 100% b. 33% c. 25% d. 50%

c

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I? Mendel's second law of independent assortment has its basis in which of the following events of meiosis I? a. crossing over b. synapsis of homologous chromosomes c. arrangement of chromosome pairs at the equator d. separation of cells at telophase

c

Two organisms with genotype AaBbCcDdEE mate. These loci are all independent. What fraction of the offspring will have the same genotype as the parents? a. 9/64 b. 3/4 c. 1/16 d. 1/4 e. 4/3

c The offspring of Aa ×Aa will be Aa 50% (one-half) of the time. The same is true for Bb, Cc, and Dd. Two EE individuals can only have EE offspring, so that probability is 1. The chance of an offspring being identical to the parent is therefore (1/2)4, or 1/16

**The following question refer to the pedigree chart in the figure below for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the genotype of individual II-5? a. ww or Ww b. Ww c. WW d. ww

d

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following? a. the alleles being codominant b. the allele for blue hydrangea being completely dominant c. the knowledge that multiple alleles are involved d. environmental factors such as soil pH

d

The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following? a. None of the traits obeyed the law of segregation. b. The diploid number of chromosomes in the pea plants was 7. c. All of the genes controlling the traits were located on the same chromosome. d. All of the genes controlling the traits behaved as if they were on different chromosomes.

d

What is an allele? a. the recessive form of a gene b. a type of chromosome c. a variety of pea plant used by Mendel d. an alternative version of a gene e. the dominant form of a gene

d

Which of the following statements about independent assortment and segregation is correct? a. The law of independent assortment is accounted for by observations of prophase I. b. The law of segregation requires describing two or more genes relative to one another. c. The law of segregation is accounted for by anaphase of mitosis. d. The law of independent assortment requires describing two or more genes relative to one another.

d

Which of the following statements is a correct explanation for the observation that all offspring exhibit a phenotype for a particular trait that appears to be a blend of the two parental varieties? a. The genes for the trait are recessive in both of the parents. b. The genes for the trait are dominant in both of the parents. c. The genes are linked and do not separate during meiosis. d. Neither of the parental genes is dominate over the other.

d

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative. Which of the following is a possible phenotype for the father? a. B positive b. O negative c. A negative d. AB negative

a

Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both of normal pigmentation, but both have one parent who is albino (without melanin pigmentation). What is the probability that their first child will be an albino? a. 1/4 b. 0 c. 1 d. 1/2

a

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? a. 8 b. 16 c. 4 d. 64

a

In some parts of Africa, the frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following? a. Darwin's explanation of natural selection b. Mendel's law of segregation c. Mendel's law of independent assortment d. the malarial parasite changing the allele

a

In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC? a. 1/64 b. 1/4 c. 1/16 d. 1/8

a

A man with type A blood marries a woman with type B blood. Their child has type O blood. What is the genotype of the man? a. ii b. I A i c. I B i d. I A I A

b

Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true? a. His daughters will die of Huntington's disease but not his sons. b. It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease. c. All of his children will develop Huntington's disease. d. His sons will develop Huntington's disease but not his daughters. e. There is not enough information to answer the question.

b

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce_____. a. 25% sharp-spined, 50% dull-spined, 25% spineless progeny b. all sharp-spined progeny c. 50% sharp-spined, 50% dull-spined progeny d. It is impossible to determine the phenotypes of the progeny.

b

Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves, and the following progeny were produced: 302 gray and 98 white. (a) What is the most probable genotype of each parent? (b) Based on your answer in (a) above, what genotypic and phenotypic ratios are expected in these progeny? (Assume the following symbols: G = gray and g = white.) a. (a) GG × gg; (b) genotypic = 3:1, phenotypic = 1:2:1 b. (a) Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1 c. (a) GG × Gg; (b) genotypic = 1:2:1, phenotypic = 2:1 d. (a) gg × Gg; (b) genotypic = 1:2, phenotypic = 3:1

b

In his breeding experiments, Mendel first crossed true-breeding plants to produce a second generation, which were then allowed to self-pollinate to generate the offspring. How do we name these three generations? a. P1 ... P2 ... P3 b. P ... F1 ... F2 c. F1 ... F2 ... F3 d. P1 ... P2 ... F e. F ... P1 ... P2

b

Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height? a. incomplete dominance b. a combination of polygenic inheritance and environmental factors c. a combination of multiple alleles and codominance d. a combination of complete dominance and environmental factors e. a combination of epistasis and environmental factors

b Several genes (polygenic inheritance) control height in humans, giving an overall normal distribution. Environmental factors such as nutrition smooth out the curve.

A man with type A blood marries a woman with type B blood. Their child has type O blood. What is the genotype of the woman? a. ii b. I A i c. I B i d. I B I B

c

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The flower color trait in radishes is an example of which of the following? a. sex linkage b. codominance c. incomplete dominance d. a multiple allelic system

c

Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system? a. 8 b. 16 c. 4 d. 2

c

**Each chromosome in this homologous pair possesses a different allele for flower color. Which statement about this homologous pair of chromosomes is correct? a. Each of these homologous chromosomes consists of a single chromatid. Therefore, they must come from a haploid cell. b. These homologous chromosomes are formed by DNA replication. c. These homologous chromosomes represent a maternal and a paternal chromosome.

c Homologous chromosomes initially come together during fertilization with the contribution of a set of chromosomes from the sperm and the egg.