front 1 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 dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied. C) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations. D) A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio. | back 1 B) A dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross involves organisms that are heterozygous for only one character being studied. |
front 2 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. | back 2 B) Traits are inherited in discrete units and are not the results of "blending." |
front 3 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) 64 | back 3 B) 8 |
front 4 4) The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason? A) recurrent mutations forming new alleles B) crossing over during prophase I C) different possible assortment of chromosomes into gametes D) the tendency for dominant alleles to segregate together | back 4 C) different possible assortment of chromosomes into gametes |
front 5 5) Mendel continued some of his experiments into the F2 or F3 generation to _____. A) obtain a larger number of offspring on which to base statistics B) observe whether or not a recessive trait would reappear C) observe whether or not the dominant trait would reappear D) distinguish which alleles were segregating | back 5 B) observe whether or not a recessive trait would reappear |
front 6 6) Which of the following statements about independent assortment and segregation is correct? 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 independent assortment is accounted for by observations of prophase I. D) The law of segregation is accounted for by anaphase of mitosis. | back 6 A) The law of independent assortment requires describing two or more genes relative to one another. |
front 7 7) 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) Hh B) HhTt C) T D) HT | back 7 D) HT |
front 8 8) 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) members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait | back 8 C) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1 |
front 9 9) 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. | back 9 D) All of the genes controlling the traits behaved as if they were on different chromosomes. |
front 10 10) 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 II of meiosis D) anaphase I of meiosis | back 10 D) anaphase I of meiosis |
front 11 11) 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 cells at telophase | back 11 C) alignment of tetrads at the equator |
front 12 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) 2 B) 4 C) 8 D) 16 | back 12 B) 4 |
front 13 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. | back 13 D) One allele was dominant. |
front 14 Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6022 yellow and 2001 green (8023 total). The allele for green seeds has what relationship to the allele for yellow seeds? A) dominant B) incomplete dominant C) recessive D) codominant | back 14 C) recessive |
front 15 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) 0 B) 1/2 C) 1/4 D) 1 | back 15 C) 1/4 |
front 16 Albinism is an autosomal (not sex-linked) recessive trait. A man and woman are both of normal pigmentation and have one child out of three who is albino (without melanin pigmentation). What are the genotypes of the albino's parents? A) One parent must be homozygous for the recessive allele; the other parent can be homozygous dominant, homozygous recessive, or heterozygous. B) One parent must be heterozygous; the other parent can be homozygous dominant, homozygous recessive, or heterozygous. C) Both parents must be heterozygous. D) One parent must be homozygous dominant; the other parent must be heterozygous. | back 16 C) Both parents must be heterozygous. |
front 17 A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation? A) Albino is recessive; black is dominant. B) Albino is dominant; black is incompletely dominant. C) Albino and black are codominant. D) Albino is recessive; black is codominant. | back 17 A) Albino is recessive; black is dominant. |
front 18 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 | back 18 B) (a) Gg . Gg; (b) genotypic = 1:2:1, phenotypic = 3:1 |
front 19 When Mendel crossed yellow-seeded and green-seeded pea plants, all the offspring were yellow seeded. When he took these F1 yellow-seeded plants and crossed them to green-seeded plants, what genotypic ratio was expected? A) 1:2:1 B) 3:1 C) 1:1 D) 1:1:1:1 | back 19 C) 1:1 |
front 20 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) 3/8 C) 1/2 D) 9/16 | back 20 C) 1/2 |
front 21 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) 0 | back 21 D) 0 |
front 22 In the cross AaBbCc . AaBbCc, what is the probability of producing the genotype AABBCC? A) 1/4 B) 1/8 C) 1/16 D) 1/64 | back 22 D) 1/64 |
front 23 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 with genotype AABBCc? A) 1/4 B) 3/4 C) 3/8 D) 1 | back 23 B) 3/4 |
front 24 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 either one of two independent events will occur C) the probability of producing two or more heterozygous offspring D) the likelihood that a trait is due to two or more meiotic events | back 24 B) the probability that either one of two independent events will occur |
front 25 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 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 | back 25 D) Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both. |
front 26 The centromere is a region in which | back 26 A) chromatids remain attached to one another until anaphase |
front 27 Starting with a fertilized egg (zygote), a series of five cell
divisions would produce an early embryo with how many cells? | back 27 D) 32 |
front 28 If there are 20 chromatids in a cell, how many centromeres are there?
| back 28 A)10 |
front 29 For a newly evolving protist, what would be the advantage of using
eukaryote-like cell division rather than binary fission? | back 29 B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes |
front 30 Suppose a biologist can separate one of a dozen pieces of chromatin
from a eukaryotic (animal) nucleus. It might consist of which of the
following? | back 30 D) two long strands of DNA plus proteins |
front 31 At which phase are centrioles beginning to move apart in animal
cells? | back 31 E) prophase |
front 32 If cells in the process of dividing are subjected to colchicine, a
drug that interferes with the formation of the spindle apparatus, at
which stage will mitosis be arrested? | back 32 D) metaphase |
front 33 If there are 20 centromeres in a cell at anaphase, how many
chromosomes are there in each daughter cell following cytokinesis?
| back 33 A) 10 |
front 34 Where do the microtubules of the spindle originate during mitosis in
both plant and animal cells? | back 34 B) centrosome |
front 35 Taxol is an anticancer drug extracted from the Pacific yew tree. In
animal cells, Taxol disrupts microtubule formation by binding to
microtubules and accelerating their assembly from the protein
precursor, tubulin. Surprisingly, this stops mitosis. Specifically,
Taxol must affect | back 35 A) the formation of the mitotic spindle |
front 36 Which of the following are primarily responsible for cytokinesis in
plant cells but not in animal cells? | back 36 B) Golgi-derived vesicles |
front 37 In which group of eukaryotic organisms does the nuclear envelope
remain intact during mitosis? | back 37 D) dinoflagellates and diatoms only |
front 38 Movement of the chromosomes during anaphase would be most affected by
a drug that | back 38 D) prevents shortening of microtubules. |
front 39 Measurements of the amount of DNA per nucleus were taken on a large
number of cells from a growing fungus. The measured DNA levels ranged
from 3 to 6 picograms per nucleus. In which stage of the cell cycle
did the nucleus contain 6 picograms of DNA? | back 39 D) G₂ |
front 40 A group of cells is assayed for DNA content immediately following
mitosis and is found to have an average of 8 picograms of DNA per
nucleus. How many picograms would be found at the end of S and the end
of G₂? | back 40 D) 16; 16 |
front 41 For anaphase to begin, which of the following must occur? | back 41 C) Cohesin must be cleaved enzymatically. |
front 42 Why do chromosomes coil during mitosis? | back 42 B) to allow the chromosomes to move without becoming entangled and breaking |
front 43 Which of the following best describes how chromosomes move toward the
poles of the spindle during mitosis? | back 43 D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules. |
front 44 Which of the following is a function of those spindle microtubules
that do not attach to kinetochores? | back 44 D) maintaining the region of overlap of microtubules in the cell's center |
front 45 During which phase of mitosis do the chromatids become chromosomes?
| back 45 A) telophase |
front 46 Which of the following was a discovery that had to be made before
human chromosomes could be correctly counted? | back 46 A) how to use a hypotonic solution to swell nuclei |
front 47 Which of the following is (are) required for motor proteins to
function in the movement of chromosomes toward the poles of the
mitotic spindle? | back 47 D) ATP as an energy source |
front 48 What is a cleavage furrow? | back 48 C) a groove in the plasma membrane between daughter nuclei |
front 49 Which of the following proteins are involved in binary fission as
well as eukaryotic mitotic division? | back 49 D) actin and tubulin |
front 50 Using which of the following techniques would enable your lab group
to distinguish between a cell in G₂ and a cell from the same organism
in G₁? | back 50 D) radioactive-labeled nucleotides |
front 51 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? | back 51 C) Clone the plant asexually to produce an identical one. |
front 52 The human genome is minimally contained in which of the following?
| back 52 A) every human cell |
front 53 In the human species, all somatic cells have 46 chromosomes. Which of
the following can also be true? | back 53 A) A plant species (privet shrubs) has 46 chromosomes per cell. |
front 54 Which of the following is a true statement about sexual vs. asexual
reproduction? | back 54 B) In sexual reproduction, individuals transmit 50% of their genes to each of their offspring. |
front 55 Which of the following defines a genome? | back 55 E) the complete set of an organism's genes |
front 56 At which stage of mitosis are chromosomes usually photographed in the
preparation of a karyotype? | back 56 B) metaphase |
front 57 The human X and Y chromosomes | back 57 D) include genes that determine an individual's sex. |
front 58 Which of the following is true of a species that has a chromosome
number of 2n = 16? | back 58 C) Each cell has eight homologous pairs. |
front 59 Eukaryotic sexual life cycles show tremendous variation. Of the
following elements, which do all sexual life cycles have in common?
| back 59 C) II, III, and IV |
front 60 Which of these statements is false? | back 60 D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis. |
front 61 Referring to a plant's sexual life cycle, which of the following
terms describes the process that leads directly to the formation of
gametes? | back 61 B) gametophyte mitosis |
front 62 Which of the following is an example of alternation of generations?
| back 62 B) A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte). |
front 63 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? | back 63 E) either anaphase I or II |
front 64 A given organism has 46 chromosomes in its karyotype. We can
therefore conclude which of the following? | back 64 E) Its gametes must have 23 chromosomes. |
front 65 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? | back 65 B) 63 chromosomes in 21 sets of 3 |
front 66 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? | back 66 C) Length, centromere position, staining pattern, and traits coded for by their genes. |
front 67 When does the synaptonemal complex disappear? | back 67 A) late prophase of meiosis I |
front 68 A cell divides to produce two daughter cells that are genetically
different. | back 68 B) The statement is true for meiosis I only. |
front 69 To visualize and identify meiotic cells at metaphase with a
microscope, what would you look for? | back 69 E) tetrads all aligned at the cell's center |
front 70 For the following question, match the key event of meiosis with the
stages listed below. | back 70 E) VII |
front 71 Independent assortment of chromosomes is a result of | back 71 A) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I. |
front 72 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. | back 72 E) crossing over of homologs |
front 73 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? | back 73 C) Genes of privet chromosomes are significantly different than those in humans. |
front 74 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)? | back 74 D) 16 |
front 75 If the DNA content of a diploid cell in the G₁ phase of the cell
cycle is x, then the DNA content of a single cell at metaphase of
meiosis II would be | back 75 C) x. |