1) In eukaryotic cells, chromosomes are composed of _____.

A) DNA and RNA
B) DNA only
C) DNA and proteins

D) DNA and phospholipids

C

2) What is the final result of mitosis in a human?

A) genetically identical 2n somatic cells
B) genetically different 2n somatic cells
C) genetically identical 1n somatic cells

D) genetically identical 2n gamete cells

A

3) Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
A) 8
B) 16

C) 32
D) 64

C

5) Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 1.5 times more DNA than G1 phase cells. The cells of this group are _____.

A) between the G1 and S phases in the cell cycle

B) in the G2 phase of the cell cycle
C) in the M phase of the cell cycle
D) in the S phase of the cell cycle

D

6) The first gap in the cell cycle (G1) corresponds to _____.

A) normal growth and cell function
B) the phase in which DNA is being replicated
C) the beginning of mitosis
D) the phase between DNA replication and the M phase

A

8) In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit _____.
A) cytokinesis
B) the attachment of microtubules to kinetochores

C) the splitting of the centrosomes
D) the disassembly of the nucleolus

B

11) Kinetochore microtubules assist in the process of splitting centromeres by _____.

A) using motor proteins to split the centromere at specific arginine residues
B) creating tension by pulling toward opposite poles
C) sliding past each other like actin filaments

D) phosphorylating the centromere, thereby changing its conformation

B

13) How is plant cell cytokinesis different from animal cell cytokinesis?
A) The contractile filaments found in plant cells are structures composed of carbohydrates; the cleavage furrow in animal cells is composed of contractile phospholipids.
B) Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow.
C) The structural proteins of plant cells separate the two cells; in animal cells, a cell membrane separates the two daughter cells.
D) Plant cells divide after metaphase but before anaphase; animal cells divide after anaphase.

B

14) FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in bacterial cytokinesis. Its function is analogous to _____.
A) the cleavage furrow of eukaryotic animal cells
B) the cell plate of eukaryotic plant cells

C) the mitotic spindle of eukaryotic cells
D) the microtubule-organizing center of eukaryotic cells

A

15) At which phase are centrioles beginning to move apart in animal cells?

A) anaphase
B) prometaphase
C) metaphase

D) prophase

D

16) If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?
A) 10
B) 20

C) 40
D) 80

A

17) Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____.
A) the structure of the mitotic spindle
B) anaphase
C) formation of the centrioles
D) chromatid assembly

A

18) Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
A) kinetochores
B) Golgi-derived vesicles

C) actin and myosin
D) centrioles and centromeres

B

19) Movement of the chromosomes during anaphase would be most affected by a drug that prevents _____.
A) nuclear envelope breakdown
B) elongation of microtubules

C) shortening of microtubules
D) formation of a cleavage furrow

C

22) The beginning of anaphase is indicated by which of the following?

A) Chromatids lose their kinetochores.
B) Cohesin attaches the sister chromatids to each other.
C) Cohesin is cleaved enzymatically.

D) Spindle microtubules begin to polymerize.

C

23) During which phase of mitosis do the chromatids become chromosomes?

A) telophase
B) anaphase
C) prophase

D) metaphase

B

24) A cleavage furrow is _____.
A) a ring of vesicles forming a cell plate
B) the separation of divided prokaryotes
C) a groove in the plasma membrane between daughter nuclei
D) the space that is created between two chromatids during anaphase

C

27) If the cell whose nuclear material is shown in the accompanying figure continues toward completion of mitosis, which of the following events would occur next?
A) spindle fiber formation
B) nuclear envelope breakdown

C) formation of telophase nuclei
D) synthesis of chromatids

C

Several organisms, primarily protists, have what are called intermediate mitotic organization.

32) These protists are intermediate in what sense?
A) They reproduce by binary fission in their early stages of development and by mitosis when they are mature.
B) They use mitotic division but only have circular chromosomes.
C) They maintain a nuclear envelope during division.
D) None of them form spindles.

C

Several organisms, primarily protists, have what are called intermediate mitotic organization.

33) What is the most probable hypothesis about these intermediate forms of cell division?
A) They represent a form of cell reproduction, which must have evolved completely separately from those of other organisms.
B) They rely on totally different proteins for the processes they undergo.
C) They may be more closely related to plant forms that also have unusual mitosis.
D) They show some but not all of the evolutionary steps toward complete mitosis.

D

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and, therefore, can be assayed to track their incorporation. In a set of experiments, a student—faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.

34) Which of the following questions might be answered by using the method described? A) How many cells are produced by the culture per hour?
B) What is the length of the S phase of the cell cycle?
C) How many picograms of DNA are made per cell cycle?

D) When do spindle fibers attach to chromosomes?

B

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and, therefore, can be assayed to track their incorporation. In a set of experiments, a student—faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.

35) The research team used their experiments to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that _____.
A) the presence of the pathogen made the experiments too contaminated to trust the results
B) infection causes lymphocytes to divide more rapidly
C) infection causes cell cultures in general to reproduce more rapidly
D) infection causes lymphocyte cultures to skip some parts of the cell cycle

B

36) Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely _____.
A) an animal cell in the process of cytokinesis
B) a plant cell in the process of cytokinesis

C) an animal cell in the S phase of the cell cycle

D) a plant cell in metaphase

B

38) The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?
A) spindle formation
B) spindle attachment to kinetochores

C) cell elongation during anaphase
D) cleavage furrow formation and cytokinesis

D

39) Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?
A) intact centromeres
B) a microtubule-organizing center

C) ATP as an energy source
D) synthesis of cohesin

C

42) MPF is a dimer consisting of _____.

A) a growth factor and mitotic factor
B) ATP synthetase and a protease
C) cyclin and tubulin

D) cyclin and a cyclin-dependent kinase

D

43) Cyclin-dependent kinase (Cdk) is _____.
A) inactive, or "turned off," in the presence of cyclin
B) present only during the S phase of the cell cycle
C) the enzyme that catalyzes the attachment of chromosomes to microtubules

D) an enzyme that attaches phosphate groups to other proteins

D

44) What happens if MPF (mitosis-promoting factor) is introduced into immature frog oocytes that are arrested in G2?

A) Nothing happens.
B) The cells undergo meiosis.
C) The cells enter mitosis.
D) Cell differentiation is triggered.

C

45) Once a cell completes mitosis, molecular division triggers must be turned off. What happens to MPF during mitosis?
A) It is completely degraded.
B) It is exported from the cell.

C) The cyclin component of MPF is degraded.
D) The Cdk component of MPF is degraded and exported from the cell.

C

46) The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in _____.
A) telophase
B) prophase

C) prometaphase
D) metaphase

D

47) Which of the following is released by platelets in the vicinity of an injury?

A) PDGF
B) MPF
C) cyclin

D) Cdk

A

48) Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?
A) PDGF
B) MPF

C) cyclin
D) Cdk

C

49) Which of the following is a protein maintained at steady levels throughout the cell cycle that requires cyclin to become catalytically active?
A) PDGF
B) MPF

C) cyclin
D) Cdk

D

50) Which of the following triggers the cell's passage past the G2 checkpoint into mitosis? A) PDGF

B) MPF
C) cyclin
D) Cdk

B

51) The cyclin component of MPF is destroyed toward the end of which phase?

A) G1

B) S

C) G2

D) M

D

53) Density-dependent inhibition is explained by which of the following?
A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors.
B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
C) As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor.
D) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.

B

55) Anchorage dependence of animal cells in vitro or in vivo depends on which of the following?

A) attachment of spindle fibers to centrioles
B) response of the cell cycle controls to signals from the plasma membrane
C) the binding of cell-surface phospholipids to those of adjoining cells

D) response of the cell cycle controls to the binding of cell-surface phospholipids

B

58) Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?
A) Cancer cells are no longer density-dependent.

B) Cancer cells are no longer anchorage-dependent.
C) Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.

D) Transformation introduces new chromosomes into cells.

C

59) Exposure of zebrafish nuclei to meiotic cytosol resulted in phosphorylation of NEP55 and L68 proteins by cyclin-dependent kinase 2. NEP55 is a protein of the inner nuclear membrane, and L68 is a protein of the nuclear lamina. What is the most likely role of phosphorylation of these proteins in the process of mitosis?

A) They enable the attachment of the spindle microtubules to kinetochore regions of the centromere.
B) They are involved in the disassembly and dispersal of the nucleolus.
C) They are involved in the disassembly of the nuclear envelope.

D) They assist in the movement of the centrosomes to opposite sides of the nucleus

C

60) Density-dependent inhibition is a phenomenon in which crowded cells stop dividing at some optimal density and location. This phenomenon involves binding of a cell-surface protein to its counterpart on an adjoining cell's surface. A growth inhibiting signal is sent to both cells, preventing them from dividing. Certain external physical factors can affect this inhibition mechanism.

Select the statement that makes a correct prediction about natural phenomena that could occur during the cell cycle to prevent cell growth.
A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to allow cell growth.

B) As cells become more numerous, the protein kinases they produce begin to compete with each other until only one cell has the proteins necessary for growth.
C) As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.

D) As cells become more numerous, more and more of them enter the synthesis part of the cell cycle and duplicate DNA to inhibit cell growth.

C

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.
D) Force the plant to self-pollinate to obtain an identical one.

C

2) Which of the following defines a genome?
A) the complete set of an organism's polypeptides
B) the complete set of a species' polypeptides
C) a karyotype
D) the complete set of an organism's genes and other DNA sequences

D

4) Quaking aspen can send out underground stems for asexual reproduction. Sexual reproduction is not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the cells of the underground stems?
A) 9

B) 10
C) 19
D) 38

D

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 half of their nuclear genes to each of their offspring.
C) In asexual reproduction, offspring are produced by fertilization without meiosis.
D) Asexual reproduction produces only haploid offspring

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 diploid cell has eight homologous pairs.

D) A gamete from this species has four chromosomes.

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, II, and IV
B) II, III, and IV
C) II, IV, and V
D) I, II, III, IV, and V

B

9) In a plant's sexual life cycle _____.
A) sporophytes produce gametes by meiosis
B) gametophytes produce gametes by mitosis
C) gametophytes produce gametes by meiosis
D) sporophytes produce gametes by mitosis

B

13) 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) failure of an egg to complete meiosis II

D) incomplete cytokinesis during spermatogenesis after meiosis I

A

14) 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) They have nothing in common except that they are X-shaped.

C

19) Homologous chromosomes _____.

A) are identical

B) carry information for the same traits

C) carry the same alleles

D) align on the metaphase plate in meiosis II

B

23) If a cell has completed meiosis I 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 half the chromosomes but twice the DNA of the originating cell.

C) It has one-fourth the DNA and one-half the chromosomes as the originating cell.

D) It is identical in content to another cell formed from the same meiosis I event.

A

25) 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

D

26) How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? They have _____.
A) half the number of chromosomes and half the amount of DNA.
B) the same number of chromosomes and half the amount of DNA.

C) half the number of chromosomes and one-fourth the amount of DNA.

D) half the amount of cytoplasm and twice the amount of DNA.

C

27) 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 remains the same.
C) Sister chromatids are separated.
D) Four daughter cells are formed.

A

28) Sister chromatids separate from each other during _____.

A) meiosis I only
B) meiosis II only
C) mitosis and meiosis I

D) mitosis and meiosis II

D

29) Which of the following occurs in meiosis but not in mitosis?

A) chromosome replication
B) synapsis of chromosomes
C) alignment of chromosomes at the equator

D) condensation of chromosomes

B

30) When we first see chiasmata under a microscope, we know that _____.

A) meiosis II has occurred
B) anaphase II has occurred
C) prophase I is occurring

D) separation of homologs has occurred

C

41) Somatic cells of roundworms have four individual chromosomes per cell. How many chromosomes would you expect to find in an ovum from a roundworm?
A) four
B) two

C) eight
D) a diploid number

B

42) Which of the following can occur by the process of meiosis but not mitosis?

A) Haploid cells fuse to form diploid cells.
B) Haploid cells multiply into more haploid cells.
C) Diploid cells form haploid cells.

D) A diploid cell combines with a haploid cell.

C

44) What is a major difference between meiosis II and mitosis in a diploid animal?

A) Homologues align on the metaphase plate in meiosis II.
B) Sister chromatids separate in mitosis, and homologues separate in meiosis II.

C) Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells.

D) Crossover takes place in meiosis II

C

45) What is a major difference between mitosis and meiosis I in a diploid organism?
A) Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I.
B) Sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis II.
C) DNA replication takes place prior to mitosis, but not before meiosis I.
D) Only meiosis I results in daughter cells that contain identical genetic information.

A

47) For the duration of meiosis I, each chromosome _____.

A) is paired with a homologous chromosome
B) consists of two sister chromatids joined by a centromere

C) consists of a single strand of DNA

D) is joined with its homologous pair to form a synaptonemal complex

B

51) Independent assortment of chromosomes occurs during _____

A) meiosis I only
B) meiosis II only
C) mitosis and meiosis I

D) mitosis and meiosis II

A

53) Independent assortment of chromosomes is a result of _____.
A) the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I
B) the random combinations of eggs and sperm during fertilization
C) the random distribution of the sister chromatids to the two daughter cells during anaphase II

D) the diverse combination of alleles that may be found within any given chromosome

A

54) 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) Corresponding segments of non-sister chromatids are exchanged.
D) Maternal alleles are "corrected" to be like paternal alleles and vice versa.

C

55) 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 greatest number of new mutations.

C) Sexual reproduction allows the greatest number of offspring to be produced.

D) Sexual reproduction utilizes far less energy than asexual reproduction.

A

56) The diploid number of a roundworm species is 4. Assuming there is no crossover, and random segregation of homologues during meiosis, how many different possible combinations of chromosomes might there be in the offspring (not including variety generated by crossing over)?

A) 4
B) 8
C) 16
D) 64

C

57) The bulldog ant has a diploid number of two chromosomes. Therefore, following meiosis, each daughter cell will have a single chromosome. Diversity in this species may be generated by mutations and _____.
A) crossing over

B) independent assortment
C) crossing over and independent assortment D) nothing else

C

58) The fastest way for organisms to adapt to a changing environment involves _____.

A) mutation
B) asexual reproduction
C) sexual reproduction

C

59) Imagine that there are twenty-five different species of protists living in a tide pool. Some of these species reproduce both sexually and asexually, and some of them can reproduce only asexually. The pool gradually becomes infested with disease-causing viruses and bacteria. Which species are more likely to thrive in the changing environment?

A) the sexually reproducing species
B) the asexually reproducing species
C) Sexually and asexually reproducing species are equally likely to thrive.

A

60) In eukaryotes, genetic information is passed to the next generation by processes that include mitosis or meiosis. Which of the explanations identifies the correct process and supports the claim that heritable information is passed from one generation to another?
A) During mitosis, DNA replication occurs twice within the cell cycle to insure a full set of chromosomes within each of the daughter cells produced.

B) Mitosis, followed by cytokinesis, produces daughter cells that are genetically different from the parent cell, thus insuring variation within the population.
C) In asexual reproduction, a single individual is the sole parent and passes copies of its genes to its offspring without the fusion of gametes.

D) Single-celled organisms can fuse their cells, reproducing asexually through mitosis to form new cells that are not identical to the parent cell.

C

61) Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms.

Which statement best represents the connection between reproduction and evolution?
A) Plants that use sexual reproduction are rare since this type of reproduction in plants does not contribute to genetic diversity.
B) In order to increase genetic diversity for evolution in sexually reproducing organisms, mutations must occur in the zygote after fertilization.
C) Since prokaryotic organisms reproduce asexually, there is no mechanism for them to add genetic diversity for evolution.
D) Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.

D

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.

B

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.

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) 64

B

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.

A

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.

D

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

D

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

C

15) 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

B

20) 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.

A

22) 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

C

23) 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

C

25) 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

D

26) 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

B

27) 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

B

28) 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.

D

29) 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. Among the F2 offspring, what is the probability of plants with white axial flowers?

A) 9/16
B) 1/16
C) 3/16
D) 1/4

C

31) Phenylketonuria is an inherited disease caused by a recessive autosomal allele. If a woman and her husband are both carriers, what is the probability that their first child will be a phenotypically normal girl?
A) 1/4

B) 1/16
C) 3/16
D) 3/8

D

32) Assuming independent assortment for all gene pairs, what is the probability that the following parents, AABbCc × AaBbCc, will produce an AaBbCc offspring?
A) 1/2
B) 1/16

C) 1/8
D) 3/4

C

33) Suppose two AaBbCc individuals are mated. Assuming that the genes are not linked, what fraction of the offspring are expected to be homozygous recessive for the three traits?
A) 1/4
B) 1/8

C) 1/16
D) 1/64

D

34) 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

B

35) Which of the following describes the ability of a single allele to have multiple phenotypic effects?
A) incomplete dominance
B) multiple alleles

C) pleiotropy
D) epistasis

C

36) Which of the following is an example of polygenic inheritance?

A) pink flowers in snapdragons
B) the ABO blood group in humans
C) white and purple flower color in peas

D) skin pigmentation in humans

D

38) Which of the following provides an example of epistasis?
A) Recessive genotypes for each of two genes (aabb) results in an albino corn snake.
B) In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing.
C) In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a combination of other genes.
D) In cacti, there are several genes for the type of spines.

B

39) 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. 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) white and long
C) purple and long
D) purple and oval

C

42) 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. The relationship between genes S and N is an example of _____.
A) incomplete dominance
B) epistasis
C) pleiotropy
D) codominance

B

43) 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) all sharp-spined progeny
B) 50% sharp-spined, 50% dull-spined progeny
C) 25% sharp-spined, 50% dull-spined, 25% spineless progeny
D) It is impossible to determine the phenotypes of the progeny.

A

44) 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. 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) 9 sharp-spined:3 dull-spined:4 spineless

D

45) 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. 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

D