This Document Contains Chapters 10 to 11 Chapter 10: Meiosis and Sexual Life Cycles 10.1 Multiple-Choice Questions 1) If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be her most probable and efficient route to establishing a line of such plants? A) Backtrack through her previous experiments to obtain another plant with the same traits. B) Breed this plant with another plant with much weaker traits. C) Clone the plant asexually to produce an identical one. D) Force the plant to self-pollinate to obtain an identical one. E) Add nitrogen to the soil of the offspring of this plant so the desired traits continue. Answer: C 2) Which of the following defines a genome? A) representation of a complete set of a cell's polypeptides B) the complete set of an organism's polypeptides C) the complete set of a species' polypeptides D) a karyotype E) the complete set of an organism's genes Answer: E 3) Which is the smallest unit containing the entire human genome? A) one human somatic cell B) one human chromosome C) all of the DNA of one human D) the entire human population E) one human gene Answer: A 4) If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following? A) at most, 2 alleles for that gene B) up to 18 chromosomes with that gene C) up to 18 genes for that trait D) a haploid number of 9 chromosomes E) up to, but not more than, 18 different traits Answer: A 5) Which of the following is a true statement about sexual vs. asexual reproduction? A) Asexual reproduction, but not sexual reproduction, is characteristic of plants and fungi. B) In sexual reproduction, individuals transmit 50% of their genes to each of their offspring. C) In asexual reproduction, offspring are produced by fertilization without meiosis. D) Sexual reproduction requires that parents be diploid. E) Asexual reproduction produces only haploid offspring. Answer: B 6) At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype? A) prophase B) metaphase C) anaphase D) telophase E) interphase Answer: B 7) Which of the following is true of a species that has a chromosome number of 2n = 16? A) The species is diploid with 32 chromosomes per cell. B) The species has 16 sets of chromosomes per cell. C) Each cell has eight homologous pairs. D) During the S phase of the cell cycle there will be 32 separate chromosomes. E) A gamete from this species has four chromosomes. Answer: C 8) Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? I. Alternation of generations II. Meiosis III. Fertilization IV. Gametes V. Spores A) I, IV, and V B) I, II, and IV C) II, III, and IV D) II, IV, and V E) I, II, III, IV, and V Answer: C 9) Which of these statements is false? A) In humans, each of the 22 maternal autosomes has a homologous paternal chromosome. B) In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY). C) Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote. D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis. E) Sexual life cycles differ with respect to the relative timing of meiosis and fertilization. Answer: D 10) Referring to a plant's sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes? A) sporophyte meiosis B) gametophyte mitosis C) gametophyte meiosis D) sporophyte mitosis E) alternation of generations Answer: B 11) Which of the following is an example of alternation of generations? A) A grandparent and grandchild each have dark hair, but the parent has blond hair. B) A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte). C) A diploid animal produces gametes by meiosis, and the gametes undergo fertilization to produce a diploid zygote. D) A haploid mushroom produces gametes by mitosis, and the gametes undergo fertilization, which is immediately followed by meiosis. E) A diploid cell divides by mitosis to produce two diploid daughter cells, which then fuse to produce a tetraploid cell. Answer: B 12) The human X and Y chromosomes A) are both present in every somatic cell of males and females alike. B) are about the same size and have approximately the same number of genes. C) are almost entirely homologous, despite their different names. D) include genes that determine an individual's sex. E) are called autosomes. Answer: D 13) Which of these is a karyotype? A) a natural cellular arrangement of chromosomes in the nucleus B) a display of all the cell types in an organism C) organized images of a cell’s chromosomes D) the appearance of an organism E) a display of a cell’s mitotic stages Answer: C 14) Mitosis is commonly found in all of the following except A) a haploid animal cell. B) a diploid animal cell. C) a haploid plant cell. D) a diploid plant cell. Answer: A 15) Which of these is a way that the sexual life cycle increases genetic variation in a species? A) by allowing crossing over B) by allowing an increase in cell number C) by increasing gene stability D) by conserving chromosomal gene order E) by decreasing mutation frequency Answer: A 16) A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following? A) It must be human. B) It must be a primate. C) It must be an animal. D) It must be sexually reproducing. E) Its gametes must have 23 chromosomes. Answer: E 17) A triploid cell contains three sets of chromosomes. If a cell of a usually diploid species with 42 chromosomes per cell is triploid, this cell would be expected to have which of the following? A) 63 chromosomes in 31 1/2 pairs B) 63 chromosomes in 21 sets of 3 C) 63 chromosomes, each with three chromatids D) 21 chromosome pairs and 21 unique chromosomes Answer: B 18) Which of the following best describes a karyotype? A) a pictorial representation of all the genes for a species B) a display of each of the chromosomes of a single cell C) the combination of all the maternal and paternal chromosomes of a species D) the collection of all the chromosomes in an individual organism E) a photograph of all the cells with missing or extra chromosomes Answer: B 19) Which of the following can utilize both mitosis and meiosis in the correct circumstances? A) a haploid animal cell B) a diploid cell from a plant stem C) any diploid animal cell D) a plantlike protist E) an archaebacterium Answer: D 20) The somatic cells of a privet shrub each contain 46 chromosomes. To be as different as they are from human cells, which have the same number of chromosomes, which of the following must be true? A) Privet cells cannot reproduce sexually. B) Privet sex cells have chromosomes that can synapse with human chromosomes in the laboratory. C) Genes of privet chromosomes are significantly different than those in humans. D) Privet shrubs must be metabolically more like animals than like other shrubs. E) Genes on a particular privet chromosome, such as the X, must be on a different human chromosome, such as number 18. Answer: C 21) In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common? A) length and position of the centromere only B) length, centromere position, and staining pattern only C) length, centromere position, staining pattern, and traits coded for by their genes D) length, centromere position, staining pattern, and DNA sequences E) They have nothing in common except they are X-shaped. Answer: C 22) To view and analyze human chromosomes in a dividing cell, which of the following is (are) required? A) a scanning electron microscope B) radioactive staining C) fluorescent staining and a transmission electron microscope D) DNA staining and a light microscope E) a stain particular to human cells Answer: D 23) The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following? A) mitosis in her ovary B) metaphase I of one meiotic event C) telophase II of one meiotic event D) telophase I of one meiotic event E) either anaphase I or II Answer: E 24) If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents? A) It has half the amount of DNA as the cell that began meiosis. B) It has the same number of chromosomes but each of them has different alleles than another cell from the same meiosis. C) It has half the chromosomes but twice the DNA of the originating cell. D) It has one-fourth the DNA and one-half the chromosomes as the originating cell. E) It is identical in content to another cell from the same meiosis. Answer: A 25) Which of the following might result in a human zygote with 45 chromosomes? A) an error in either egg or sperm meiotic anaphase B) failure of the egg nucleus to be fertilized by the sperm C) fertilization of a 23 chromosome human egg by a 22 chromosome sperm of a closely related species D) an error in the alignment of chromosomes on the metaphase plate E) lack of chiasmata in prophase I Answer: A 26) After telophase I of meiosis, the chromosomal makeup of each daughter cell is A) diploid, and the chromosomes are each composed of a single chromatid. B) diploid, and the chromosomes are each composed of two chromatids. C) haploid, and the chromosomes are each composed of a single chromatid. D) haploid, and the chromosomes are each composed of two chromatids. E) tetraploid, and the chromosomes are each composed of two chromatids. Answer: D 27) How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis? A) They have twice the amount of cytoplasm and half the amount of DNA. B) They have half the number of chromosomes and half the amount of DNA. C) They have the same number of chromosomes and half the amount of DNA. D) They have half the number of chromosomes and one-fourth the amount of DNA. E) They have half the amount of cytoplasm and twice the amount of DNA. Answer: D 28) When does the synaptonemal complex disappear? A) late prophase of meiosis I B) during fertilization or fusion of gametes C) early anaphase of meiosis I D) mid-prophase of meiosis II E) late metaphase of meiosis II Answer: A 29) Which of the following happens at the conclusion of meiosis I? A) Homologous chromosomes of a pair are separated from each other. B) The chromosome number per cell is conserved. C) Sister chromatids are separated. D) Four daughter cells are formed. E) Cohesins are cleaved at the centromeres. Answer: A 30) Chromatids are separated from each other. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II. Answer: E 31) Which of the following occurs in meiosis but not in mitosis? A) chromosome replication B) synapsis of chromosomes C) production of daughter cells D) alignment of chromosomes at the equator E) condensation of chromatin Answer: B 32) Whether during mitosis or meiosis, sister chromatids are held together by proteins referred to as cohesins. Such molecules must have which of the following properties? A) They must persist throughout the cell cycle. B) They must be removed before meiosis can begin. C) They must be removed before sister chromatids or homologous chromosomes can separate. D) They must reattach to chromosomes during G1. E) They must be intact for nuclear envelope re-formation. Answer: C 33) Experiments with cohesins have found that A) cohesins are protected from destruction throughout meiosis I and II. B) cohesins are cleaved from chromosomes at the centromere before anaphase I. C) cohesins are protected from cleavage at the centromere during meiosis I. D) a protein cleaves cohesins before metaphase I. E) a protein that cleaves cohesins would cause cellular death. Answer: C 34) A pair of homologous chromosomes includes which of the following sets of DNA strands? A) two single-stranded chromosomes that have synapsed B) two sister chromatids that have synapsed C) four sister chromatids D) four unique chromosomes E) eight sister chromatids Answer: B 35) When we see chiasmata under a microscope, that lets us know which of the following has occurred? A) asexual reproduction B) meiosis II C) anaphase II D) prophase I E) separation of homologs Answer: D 36) To visualize and identify meiotic cells at metaphase with a microscope, what would you look for? A) sister chromatids of a replicated chromosome grouped at the poles B) individual chromosomes all at the cell's center C) an uninterrupted spindle array D) the synaptonemal complex E) pairs of homologous chromosomes all aligned at the cell's center Answer: E For the following questions, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II 37) Homologous chromosomes are aligned at the equator of the spindle. A) I B) II C) IV D) VI E) VIII Answer: B 38) Synaptonemal complexes form or are still present. A) I only B) I and IV only C) I and VIII only D) II and VI only E) I, II, III, and IV only Answer: A 39) Centromeres of sister chromatids disjoin and chromatids separate. A) II B) III C) IV D) V E) VII Answer: E The following question refers to the essential steps in meiosis described below. 1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus 2. Alignment of homologous chromosomes at the metaphase plate 3. Separation of sister chromatids 4. Separation of the homologs; no uncoupling of the centromere 5. Synapsis; chromosomes moving to the middle of the cell in pairs 40) Which of the steps take(s) place in both mitosis and meiosis? A) 2 B) 3 C) 5 D) 2 and 3 only E) 2, 3, and 5 Answer: B 41) For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes? A) 23 B) 46 C) 460 D) 920 E) about 8 million Answer: E 42) Independent assortment of chromosomes is a result of A) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I. B) the random nature of the fertilization of ova by sperm. C) the random distribution of the sister chromatids to the two daughter cells during anaphase II. D) the relatively small degree of homology shared by the X and Y chromosomes. E) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I, the random nature of the fertilization of ova by sperm, the random distribution of the sister chromatids to the two daughter cells during anaphase II, and the relatively small degree of homology shared by the X and Y chromosomes. Answer: A 43) Independent assortment of chromosomes occurs. A) The statement is true for mitosis only. B) The statement is true for meiosis I only. C) The statement is true for meiosis II only. D) The statement is true for mitosis and meiosis I. E) The statement is true for mitosis and meiosis II. Answer: B 44) Which of the following best describes the frequency of crossing over in mammals? A) 50 per chromosome pair B) 2 per meiotic cell C) at least 1-2 per chromosome pair D) 1 per pair of sister chromatids E) a very rare event among hundreds of cells Answer: C 45) When homologous chromosomes cross over, what occurs? A) Two chromatids get tangled, resulting in one re-sequencing its DNA. B) Two sister chromatids exchange identical pieces of DNA. C) Specific proteins break the two strands of no sister chromatids and re-join them. D) Each of the four DNA strands of a homologous pair is broken, and the pieces are mixed. E) Maternal alleles are "corrected" to be like paternal alleles, and vice versa. Answer: C 10.2 Art Questions Refer to the life cycles illustrated in Figure 10.1 to answer the following questions. Figure 10.1 1) Which of the life cycles is (are) typical for animals? A) I only B) II only C) III only D) I and II E) I and III Answer: A 2) Which of the life cycles is (are) typical for plants and some algae? A) I only B) II only C) III only D) I and II E) I and III Answer: C 3) Which of the life cycles is (are) typical for most fungi and some protists? A) I only B) II only C) III only D) I and II E) I and III Answer: B 4) In part III of Figure 10.1, the progression of events corresponds to which of the following series? A) zygote, mitosis, gametophyte, mitosis, fertilization, zygote, mitosis B) sporophyte, meiosis, spore, mitosis, gametophyte, mitosis, gametes, fertilization C) fertilization, mitosis, multicellular haploid, mitosis, spores, sporophyte D) gametophyte, meiosis, zygote, spores, sporophyte, zygote E) meiosis, fertilization, zygote, mitosis, adult, meiosis Answer: B 5) In a life cycle such as that shown in part III of Figure 10.1, if the zygote's chromosome number is 10, which of the following will be true? A) The sporophyte's chromosome number per cell is 10 and the gametophyte's is 5. B) The sporophyte's chromosome number per cell is 5 and the gametophyte's is 10. C) The sporophyte and gametophyte each have 10 chromosomes per cell. D) The sporophyte and gametophyte each have 5 chromosomes per cell. E) The sporophyte and gametophyte each have 20 chromosomes per cell. Answer: A Refer to the drawings in Figure 10.2 of a single pair of homologous chromosomes as they might appear during various stages of either mitosis or meiosis, and answer the following questions. Figure 10.2 6) Which diagram represents anaphase I of meiosis? A) I B) II C) IV D) V E) VI Answer: A 7) Which diagram(s) represent(s) anaphase II of meiosis? A) II only B) III only C) IV only D) V only E) either II or V Answer: D You have isolated DNA from three different cell types of an organism, determined the relative DNA content for each type, and plotted the results on the graph shown in Figure 10.3. Refer to the graph to answer the following questions. Figure 10.3 8) Which sample(s) of DNA might be from a nerve cell arrested in G0 of the cell cycle? A) I B) II C) III D) either I or II E) either I or III Answer: A 9) Which sample(s) might represent an animal cell in the G2 phase of the cell cycle? A) I B) II C) III D) both I and II E) either II or III Answer: B 10) Which sample(s) might represent a zygote? A) I B) II C) III D) either I or II E) either II or III Answer: A Refer to the following information and Figure 10.4 to answer the following questions. A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence of one of its genes on chromosome 12, and has either long or short antennae as the result of a second gene on chromosome 19, as shown in Figure 10.4. Figure 10.4 11) A certain female's number 12 chromosomes both have the blue gene and number 19 chromosomes both have the long gene. As cells in her ovaries undergo meiosis, her resulting eggs (ova) may have which of the following? A) either two number 12 chromosomes with blue genes or two with orange genes B) either two number 19 chromosomes with long genes or two with short genes C) either one blue or one orange gene in addition to either one long or one short gene D) one chromosome 12 with one blue gene and one chromosome 19 with one long gene Answer: D 12) If a female of this species has one chromosome 12 with a blue gene and another chromosome 12 with an orange gene, and has both number 19 chromosomes with short genes, she will produce which of the following egg types? A) only blue short gene eggs B) only orange short gene eggs C) one-half blue short and one-half orange short gene eggs D) three-fourths blue long and one-fourth orange short gene eggs E) three-fourths blue short and one-fourth orange short gene eggs Answer: C 13) A female with a paternal set of one orange and one long gene chromosome and a maternal set comprised of one blue and one short gene chromosome is expected to produce which of the following types of eggs after meiosis? A) All eggs will have maternal types of gene combinations. B) All eggs will have paternal types of gene combinations. C) Half the eggs will have maternal and half will have paternal combinations. D) Each egg has a one-fourth chance of having either blue long, blue short, orange long, or orange short combinations. E) Each egg has a three-fourths chance of having blue long, one-fourth blue short, three-fourths orange long, or one-fourth orange short combinations. Answer: D 10.3 Scenario Questions Use the following information to answer the next questions. There is a group of invertebrate animals called rotifers, among which a particular group of species reproduces, as far as is known, only asexually. These rotifers, however, have survived a long evolutionary history without evidence of having been overcome by excessive mutations. 1) Because the rotifers develop from eggs, but asexually, what can you predict? A) The eggs and the zygotes are all haploid. B) The animals are all hermaphrodites. C) Although asexual, both males and females are found in nature. D) All males can produce eggs. E) No males can be found. Answer: E 2) How is natural selection related to sexual reproduction as opposed to asexual reproduction? A) Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction. B) Sexual reproduction results in the most appropriate and healthiest balance of two sexes in a population. C) Sexual reproduction results in the greatest number of new mutations. D) Sexual reproduction allows the greatest number of offspring to be produced. E) Sexual reproduction utilizes far less energy than asexual reproduction. Answer: A 10.4 End-of-Chapter Questions 1) A human cell containing 22 autosomes and a Y chromosome is A) a sperm. B) an egg. C) a zygote. D) a somatic cell of a male. E) a somatic cell of a female. Answer: A 2) Homologous chromosomes move toward opposite poles of a dividing cell during A) mitosis. B) meiosis I. C) meiosis II. D) fertilization. E) binary fission Answer: B 3) If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be A) 0.25x. B) 0.5x. C) x. D) 2x. E) 4x. Answer: D 4) If we continued to follow the cell lineage from question 3, then the DNA content of a single cell at metaphase of meiosis II would be A) 0.25x. B) 0.5x. C) x. D) 2x. E) 4x Answer: C 5) How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)? A) 2 B) 4 C) 8 D) 16 E) 32 Answer: D Chapter 11: Mendel and the Gene Idea 11.1 Multiple-Choice Questions 1) What do we mean when we use the terms monohybrid cross and dihybrid cross? A) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents. B) A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. C) A dihybrid cross involves organisms that are heterozygous for two characters, and a monohybrid cross involves only one. D) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations. E) A monohybrid cross results in a 9:3:3:1 ratio, whereas a dihybrid cross gives a 3:1 ratio. Answer: C 2) What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? A) There is considerable genetic variation in garden peas. B) Traits are inherited in discrete units, and are not the results of "blending." C) Recessive genes occur more frequently in the F1 generation than do dominant ones. D) Genes are composed of DNA. E) An organism that is homozygous for many recessive traits is at a disadvantage. Answer: B 3) How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? A) 4 B) 8 C) 16 D) 32 E) 64 Answer: B 4) The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason? A) segregation of maternal and paternal alleles B) recurrent mutations forming new alleles C) crossing over during prophase I D) different possible assortment of chromosomes into gametes E) the tendency for dominant alleles to segregate together Answer: D 5) Why did Mendel continue some of his experiments to the F2 or F3 generation? A) to obtain a larger number of offspring on which to base statistics B) to observe whether or not a recessive trait would reappear C) to observe whether or not the dominant trait would reappear D) to distinguish which alleles were segregating E) to be able to describe the frequency of recombination Answer: B 6) Which of the following differentiates between independent assortment and segregation? A) The law of independent assortment requires describing two or more genes relative to one another. B) The law of segregation requires describing two or more genes relative to one another. C) The law of segregation requires having two or more generations to describe. D) The law of independent assortment is accounted for by observations of prophase I. E) The law of segregation is accounted for by anaphase of mitosis. Answer: A 7) Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest? A) that the parents were true-breeding for contrasting traits B) that the trait shows incomplete dominance C) that a blending of traits has occurred D) that the parents were both heterozygous for a single trait E) that each offspring has the same alleles for each of two traits Answer: D 8) A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? A) tt B) Hh C) HhTt D) T E) HT Answer: E 9) When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? A) 0% B) 25% C) 50% D) 75% E) 100% Answer: C 10) Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that A) new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1. B) the mechanism controlling the appearance of traits was different between the F1 and the F2 plants. C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1. D) the traits were lost in the F1 due to dominance of the parental traits. E) members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait. Answer: C 11) 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. E) The formation of gametes in plants occurs by mitosis only. Answer: D 12) Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division? A) prophase I of meiosis B) anaphase II of meiosis C) metaphase I of meiosis D) anaphase I of meiosis E) anaphase of mitosis Answer: D 13) Mendel's second law of independent assortment has its basis in which of the following events of meiosis I? A) synapsis of homologous chromosomes B) crossing over C) alignment of tetrads at the equator D) separation of homologs at anaphase E) separation of cells at telophase Answer: C 14) Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? A) No genes interacted to produce the parental phenotype. B) Each allele affected phenotypic expression. C) The traits blended together during fertilization. D) One allele was dominant. E) Phenotype was not dependent on genotype. Answer: D 15) Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails? A) 1/16 B) 3/16 C) 3/8 D) 1/2 E) 9/16 Answer: D 16) In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? A) 1 B) 1/2 C) 1/4 D) 1/6 E) 0 Answer: E 17) In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC? A) 1/4 B) 1/8 C) 1/16 D) 1/32 E) 1/64 Answer: E 18) Given the parents AABBCc × AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent? A) 1/4 B) 1/8 C) 3/4 D) 3/8 E) 1 Answer: C 19) Which of the following is the best statement of the use of the addition rule of probability? A) the probability that two or more independent events will both occur B) the probability that two or more independent events will both occur in the offspring of one set of parents C) the probability that either one of two independent events will occur D) the probability of producing two or more heterozygous offspring E) the likelihood that a trait is due to two or more meiotic events Answer: C 20) Which of the following calculations require that you utilize the addition rule? A) Calculate the probability of black offspring from the cross AaBb × AaBb, when B is the symbol for black. B) Calculate the probability of children with both cystic fibrosis and polydactyly when parents are each heterozygous for both genes. C) Calculate the probability of each of four children having cystic fibrosis if the parents are both heterozygous. D) Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both. E) Calculate the probability of purple flower color in a plot of 50 plants seeded from a self-fertilizing heterozygous parent plant. Answer: D 21) Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information? A) It is recessive. B) It is dominant. C) It has a late age of onset (> 60). D) It is pleiotropic. E) It is epistatic. Answer: D 22) In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white? A) red × white B) roan × roan C) white × roan D) red × roan E) The answer cannot be determined from the information provided. Answer: B 23) Which of the following describes the ability of a single gene to have multiple phenotypic effects? A) incomplete dominance B) multiple alleles C) pleiotropy D) epistasis Answer: C 24) Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this? A) incomplete dominance B) multiple alleles C) pleiotropy D) epistasis E) codominance Answer: C 25) Which of the following is an example of polygenic inheritance? A) pink flowers in snapdragons B) the ABO blood group in humans C) Huntington's disease in humans D) white and purple flower color in peas E) skin pigmentation in humans Answer: E 26) 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 knowledge that multiple alleles are involved B) the allele for blue hydrangea being completely dominant C) the alleles being codominant D) the fact that a mutation has occurred E) environmental factors such as soil pH Answer: E 27) Which of the following provides an example of epistasis? A) Recessive genotypes for each of two genes (aabb) result in an albino corn snake. B) The allele b17 produces a dominant phenotype, although b1 through b16 do not. C) In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing. D) In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a combination of other genes. E) In cacti, there are several genes for the type of spines. Answer: C 28) A scientist discovers a DNA-based test for one allele of a particular gene. This and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. Of the following, which is the best use of this discovery? A) Screen all newborns of an at-risk population. B) Design a test for identifying heterozygous carriers of the allele. C) Introduce a normal allele into deficient newborns. D) Follow the segregation of the allele during meiosis. E) Test school-age children for the disorder. Answer: B 29) 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) Mendel's law of independent assortment B) Mendel's law of segregation C) Darwin's explanation of natural selection D) Darwin's observations of competition E) the malarial parasite changing the allele Answer: C 30) One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant gene, although it may range from mildly to very severely expressed. If a young child is the first in her family to be diagnosed, which of the following is the best explanation? A) The mother carries the gene but does not express it at all. B) One of the parents has very mild expression of the gene. C) The condition skipped a generation in the family. D) The child has a different allele of the gene than the parents. Answer: B 11.2 Art Questions Use Figure 11.1 and the following description to answer the questions below. In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in Figure 11.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Figure 11.1 1) Which of the boxes marked 1—4 correspond(s) to plants with dark leaves? A) 1 only B) 1 and 2 C) 2 and 3 D) 4 only E) 1, 2, and 3 Answer: E 2) Which of the boxes correspond(s) to plants with a heterozygous genotype? A) 1 only B) 1 and 2 C) 1, 2, and 3 D) 2 and 3 E) 2, 3, and 4 Answer: D 3) Which of the plants will be true-breeding? A) 1 and 4 only B) 2 and 3 only C) 1, 2, 3, and 4 D) 1 only E) 1 and 2 only Answer: A The following questions refer to the pedigree chart in Figure 11.2 for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. Figure 11.2 4) What is the genotype of individual II-5? A) WW B) Ww C) ww D) WW or ww E) ww or Ww Answer: C 5) What is the likelihood that the progeny of IV-3 and IV-4 will have the trait? A) 0% B) 25% C) 50% D) 75% E) 100% Answer: C 6) What is the probability that individual III-1 is Ww? A) 3/4 B) 1/4 C) 2/4 D) 2/3 E) 1 Answer: E Use the following pedigree (Figure 11.3) for a family in which 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. Figure 11.3 7) In each generation of this family after generation I, the age at diagnosis is significantly lower than would be found in nonfamilial (sporadic) cases of this cancer ( 63 years). What is the most likely reason? A) Members of this family know to be checked for colon cancer early in life. B) Hereditary (or familial) cases of this cancer typically occur at earlier ages than do nonfamilial forms. C) This is pure chance; it would not be expected if you were to look at a different family. D) This cancer requires mutations in more than this one gene. E) Affected members of this family are born with colon cancer, and it can be detected whenever they are first tested. Answer: B 8) From this pedigree, how does this trait seem to be inherited? A) from mothers B) as an autosomal recessive C) as a result of epistasis D) as an autosomal dominant E) as an incomplete dominant Answer: D 9) The affected woman in generation IV is thinking about her future and asks her oncologist (cancer specialist) whether she can know whether any or all of her children will have a high risk of the same cancer. The doctor would be expected to advise which of the following? I. genetic counseling II. prenatal diagnosis when/if she becomes pregnant III. testing to see whether she has the allele IV. testing to see whether her future spouse or partner has the allele A) I only B) II only C) I, II, and IV only D) I, II, and III only E) III and IV only Answer: C 11.3 Scenario Questions Use the following information to answer the questions below. Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. 1) If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? A) 65 B) 190 C) 250 D) 565 E) 750 Answer: B 2) Among the F2 offspring, what is the probability of plants with white axial flowers? A) 9/16 B) 1/16 C) 3/16 D) 1/8 E) 1/4 Answer: C Use the following information to answer the questions below. Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies. 3) These results indicate which of the following? A) Brown is dominant to black. B) Black is dominant to brown and to yellow. C) Yellow is dominant to black. D) There is incomplete dominance. E) Epistasis is involved. Answer: E 4) How many genes must be responsible for these coat colors in Labrador retrievers? A) 1 B) 2 C) 3 D) 4 E) 5 Answer: B 5) In one type cross of black × black, the results were as follows: 9/16 black 4/16 yellow 3/16 brown The genotype eebb must result in which of the following? A) black B) brown C) yellow D) a lethal result E) white Answer: C Use the following information to answer the questions below. 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 part of the radish we eat may be oval or long, with long being the dominant trait. 6) If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F1 will be expected to be which of the following? A) red and long B) red and oval C) white and long D) purple and long E) purple and oval Answer: D 7) In the F2 generation of the above cross, which of the following phenotypic ratios would be expected? A) 9:3:3:1 B) 9:4:3 C) 1:1:1:1 D) 1:1:1:1:1:1 E) 6:3:3:2:1:1 Answer: E 8) The flower color trait in radishes is an example of which of the following? A) a multiple allelic system B) sex linkage C) codominance D) incomplete dominance E) epistasis Answer: D Use the following information to answer the questions below. Drosophila (fruit flies) usually have long wings (+), but mutations in two different genes can result in bent wings (bt) or vestigial wings (vg). 9) If a homozygous bent wing fly is mated with a homozygous vestigial wing fly, which of the following offspring would you expect? A) all +bt +vg heterozygotes B) 1/2 bent and 1/2 vestigial flies C) all homozygous + flies D) 3/4 bent to 1/4 vestigial ratio E) 1/2 bent and vestigial to 1/2 normal Answer: A 10) If flies that are heterozygous for both the bent wing gene and the vestigial wing gene are mated, what is the probability of offspring with bent wings only? A) 1/8 B) 3/8 C) 1/4 D) 9/16 E) 3/16 Answer: E Use the following information to answer the questions below. Tallness (T) in snapdragons is dominant to dwarfness (t), and red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. 11) A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals? A) ttRr–dwarf and pink B) ttrr–dwarf and white C) TtRr–tall and red D) TtRr–tall and pink E) TTRR–tall and red Answer: D 12) If snapdragons are heterozygous for height as well as for flower color, a mating between them will result in what ratio? A) 9:3:3:1 B) 6:3:3:2:1:1 C) 1:2:1 D) 27:9:9:9:3:3:3:1 E) 9:4:3 Answer: B Use the following information to answer the questions below. Skin color in a certain species of fish is inherited via a single gene with four different alleles. 13) How many different types of gametes would be possible in this system? A) 1 B) 2 C) 4 D) 8 E) 16 Answer: C 14) One fish of this type has alleles 1 and 3 (S1S3) and its mate has alleles 2 and 4 (S2S4). If each allele confers a unit of color darkness such that S1 has one unit, S2 has two units, and so on, then what proportion of their offspring would be expected to have five units of color? A) 1/4 B) 1/5 C) 1/8 D) 1/2 E) 0 Answer: D Refer to the following information to answer the questions below. 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. 15) The relationship between genes S and N is an example of A) incomplete dominance. B) epistasis. C) complete dominance. D) pleiotropy. E) codominance. Answer: B 16) A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce A) all sharp-spined progeny. B) 50% sharp-spined, 50% dull-spined progeny. C) 25% sharp-spined, 50% dull-spined, 25% spineless progeny. D) all spineless progeny. E) It is impossible to determine the phenotypes of the progeny. Answer: A 17) If doubly heterozygous SsNn cactuses were allowed to self-pollinate, the F2 would segregate in which of the following ratios? A) 3 sharp-spined:1 spineless B) 1 sharp-spined:2 dull-spined:1 spineless C) 1 sharp-spined:1 dull-spined:1 spineless D) 1 sharp-spined:1 dull-spined E) 9 sharp-spined:3 dull-spined:4 spineless Answer: E Use the following information to answer the questions below. Feather color in budgies is determined by two different genes, Y and B, one for pigment on the outside and one for the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. 18) A blue budgie is crossed with a white budgie. Which of the following results is not possible? A) green offspring only B) yellow offspring only C) blue offspring only D) green and yellow offspring E) a 9:3:3:1 ratio Answer: D 19) Two blue budgies were crossed. Over the years, they produced 22 offspring, 5 of which were white. What are the most likely genotypes for the two blue budgies? A) yyBB and yyBB B) yyBB and yyBb C) yyBb and yyBb D) yyBB and yybb E) yyBb and yybb Answer: C Use the following information to answer the questions below. 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 and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. 20) Which of the following is a possible partial genotype for the son? A) IBIB B) IBIA C) ii D) IBi E) IAIA Answer: D 21) Which of the following is a possible genotype for the mother? A) IAIA B) IBIB C) ii D) IAi E) IAIB Answer: D 22) Which of the following is a possible phenotype for the father? A) A negative B) O negative C) B positive D) AB negative E) impossible to determine Answer: C 23) If both children are of blood type M, which of the following is possible? A) Each parent is either M or MN. B) Each parent must be type M. C) Both children are heterozygous for this gene. D) Neither parent can have the N allele. E) The MN blood group is recessive to the ABO blood group. Answer: A Refer to the following information to answer the questions below. Humanoids on the newly explored planet Brin (in a hypothetical galaxy in 50 years from the present) have a gene structure similar to our own, but many very different plants and animals. 24) One species of a small birdlike animal has an extremely variable tail length, an example of polygenic inheritance. Geneticists have come to realize that there are eight separate genes for tail length per haploid genome, with each gene having two alleles. One allele for each gene (a1, b1, and so on) increases the length by 1 cm, whereas the other allele (a2, b2, and so on) increases it by 0.5 cm. One bird was analyzed and found to have the following genotype: a1a1b2b2c1c2d1d2e2e2f1f2g1g1h1h2 What is the length of its tail? A) 6 cm B) 8 cm C) 12 cm D) 24 cm E) 36 cm Answer: C 25) One species of green plant, with frondlike leaves, a spine-coated stem, and purple cup-shaped flowers, is found to be self-pollinating. Which of the following is true of this species? A) The species must be haploid. B) Its reproduction is asexual. C) All members of the species have the same genotype. D) Some of the seeds would have true-breeding traits. E) All of its dominant traits are most frequent. Answer: D 26) If the environmental parameters, such as temperature, humidity, atmosphere, sunlight, and so on, are mostly Earthlike, which of the following do you expect of its types of leaves, stems, and flowers? A) The genes for them would have originated on Earth. B) Genes for these traits would have a common ancestor with those from Earth. C) Such plants could be safely eaten by humans. D) Genotypes for these traits would be identical to those of Earth plants with the same traits. E) Phenotypes would be selected for or against by these environmental factors. Answer: E Test Bank for Campbell Biology in Focus Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson, Jane B. Reece 9780321813664, 9780321962751, 9780134710679
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