chapter 12 - TeacherWeb

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____________________________ 1. most cells that will no longer divide are in this
____________________________ 2. sister chromatids separate and chromosomes
move apart
____________________________ 3. mitotic spindle begins to form
____________________________ 4. cell plate forming or cleavage furrow pinching
cells apart
____________________________ 5. chromosomes replicate
____________________________ 6. chromosomes line up at equatorial plate
____________________________ 7. phase after DNA replication
____________________________ 8. chromosomes become visible
____________________________ 9. kinetochore-microtubule interactions move
chromosomes to midline
____________________________ 10. restriction point occurs in this phase
11. One of the major differences in the cell division of prokaryotic cells compared to
eukaryotic cells is that
a. cytokinesis does not occur in prokaryotic cells
b. genes are not replicated on chromosomes in prokaryotic cells
c. the duplicated chromosomes are attached to the nuclear membrane in
prokaryotic cells and are separated from each other as the membrane
d. the chromosomes do not separate along a mitotic spindle in prokaryotic
e. the chromosome number is reduced by half in eukaryotic cells but not
prokaryotic cells
12. A plant cell has 12 chromosomes at the end of mitosis. How many chromosomes
would it have in the G2 phase of its next cell cycle?
a. 6
b. 9
c. 12
d. 24
e. It depends on whether it is undergoing mitosis or meiosis.
13. The longest part of the cell cycle is
a. Prophase
b. G1 phase
c. G2 phase
d. Mitosis
e. Interphase
14. In animal cells, cytokinesis involves
a. the separation of sister chromatids
b. the contraction of the contractile ring of microfilaments
c. depolymerization of kinetochore microtubules
d. a protein kinase that phosphorylates other enzymes
e. sliding of nonkinetochore microtubules past each other
15. Humans have 46 chromosomes. That number of chromosomes will be found in
a. cells in anaphase
b. the egg and sperm cells
c. the somatic cells
d. all the cells of the body
e. only cells in interphase
16. Sister chromatids
a. have one-half the amount of genetic material as does the original
b. start to move along kinetochore microtubules toward opposite poles
during telophase
c. each have their own kinetochore
d. are formed during prophase
17. Which of the following would not be exhibited by cancer cells?
a. changing levels of MPF concentration
b. passage through the restriction point
c. density-dependent inhibition
d. metastasis
e. response to growth factors
18. Which of the following is not true of a cell plate?
a. It forms at the site of the metaphase plate.
b. It results from the fusion of microtubules.
c. It fuses with the plasma membrane.
d. A cell wall is laid down between its membranes.
e. It forms during telophase in plant cells.
19. A cell that passes the restriction point will most likely
a. undergo chromosome duplication
b. have just completed cytokinesis
c. continue to divide only if it is a cancer cell
d. show a drop in MPF concentration
e. move into the G0 phase
20. The rhythmic changes in cyclin concentration in a cell cycle are due to
a. its increased production once the restriction point is passed
b. the cascade of increased production once its enzyme is phosphorylated by
c. its degradation by an enzyme phosphorylated by MPF
d. the changing ratio of cytoplasm to genome
e. the binding of the growth factor PDGF
1. The restoration of the diploid chromosome number after halving in meiosis is due
a. synapsis
b. fertilization
c. mitosis
d. DNA replication
e. Chiasmata
2. What is a karyotype?
a. a genotype of an individual
b. a unique combination of chromosomes found in a gamete
c. a blood type determination of an individual
d. a pictorial display of an individual’s chromosomes
e. a species-specific diploid number of chromosomes
3. What are autosomes?
a. sex chromosomes
b. chromosomes that occur singly
c. chromosomal abnormalities that result in genetic defects
d. chromosomes found in mitochondria and chloroplasts
e. none of the above
4. A synaptonemal complex would be found during
a. prophase I of meiosis
b. fertilization or syngamy of gametes
c. metaphase II of meiosis
d. prophase of mitosis
e. anaphase I of meiosis
5. During the first meiotic division (meiosis I)
a. Homologous chromosomes separate.
b. The chromosome number becomes haploid.
c. Crossing over between nonsister chromatids occurs.
d. Paternal and maternal chromosomes assort randomly.
e. All of the above occur.
6. A cell with a diploid number of 6 could produce gametes with how many different
combination of maternal and paternal chromosomes?
a. 6
b. 8
c. 12
d. 64
e. 128
7. The DNA content of a cell is measured in the G2 phase. After meiosis I, the
DNA content of one of the two cells produced would be
a. equal to that of the G2 cell
b. twice that of the G2 cell
c. one-half that of the G2 cell
d. one-fourth that of the G2 cell
e. impossible to estimate due to independent assortment of homologous
8. In many fungi and some protists,
a. The zygote is the only haploid stage.
b. Gametes are formed by meiosis.
c. The multicellular organism is haploid.
d. The gametophyte generation produces gametes by mitosis.
e. Reproduction is exclusively asexual.
9. In the alternation of generations found in plants,
a. the sporophyte generation produces spores by mitosis
b. the gametophyte generation produces gametes by mitosis
c. the zygote will develop into a sporophyte generation by meiosis
d. spores develop into the haploid sporophyte generation
e. the gametophyte generation produces spores by meiosis
10. Which of the following is not a source of genetic variation in sexually
reproducing organisms?
a. crossing over
b. replication of DNA during S phase before meiosis I
c. independent assortment of chromosomes
d. random fertilization of gametes
e. mutation
11. Meiosis II is similar to mitosis because
a. sister chromatids separate
b. homologous chromosomes separate
c. DNA replication precedes the division
d. they both take the same amount of time
e. haploid cells are produced
12. Homologous chromosomes
a. have identical genes
b. have genes for the same traits at the same loci
c. are found in gametes
d. separate in meiosis II
e. are all of the above
13. Asexual reproduction of a diploid organism would
a. be impossible
b. involve meiosis
c. produce identical offspring
d. show variation among sibling offspring
e. involve asexual spores produced by mitosis
14. In a sexually reproducing species with a diploid number of 8, how many different
combinations of paternal and maternal chromosomes would be possible in the
a. 8
b. 16
c. 64
d. 256
e. 512
15. The calculation of offspring in question 14 includes only variation resulting from
a. crossing over
b. random fertilization
c. independent assortment of chromosomes
d. a, b and c
e. only b and c
________ 1. codominance
a. true breeding variety
________ 2. homozygous
b. cross between two hybrids
________ 3. heterozygous
c. cross that involves two different gene
________ 4. phenotype
_________ 5. polygenic trait
_________ 6. pleiotropy
_________ 7. epistasis
__________ 8. testcross
__________ 9. dihybrid cross
__________ 10. incomplete dominance
d. an allele that is not expressed in the
e. the physical characteristics of an
f. genotype with two different alleles for
same locus
g. genotype with multiple allele for same
h. one gene influences the expression of
another gene
i. both alleles are fully expressed in
j. single gene with multiple phenotypic
k. heterozygote is intermediate between
homozygous phenotypes
l. two or more genes with additive effect
on phenotype
m. cross with homozygous recessive to
determine genotype of unknown
11. According to Mendel’s law of segregation,
a. There is a 50% probability that a gamete will get a dominant allele.
b. Gene pairs segregate independently of other genes in gamete formation.
c. Allele pairs separate in gamete formation.
d. The laws of probability determine gamete formation.
e. There is a 3:1 ratio in the F2 generation.
12. After obtaining two heads from two tosses of a coin, the probability of tossing the
coin and obtaining a head is
a. ½
b. ¼
c. 1/6
d. 1/8
e. 1/16
13. The probability of tossing three coins simultaneously and obtaining two heads
and one tail is
a. ½
b. ¾
c. 1/8
d. 1/16
e. 3/8
14. A multifactorial disease
a. can usually be traced to consanguineous matings
b. is caused by recessively inherited lethal genes
c. has both genetic and environmental causes
d. has a collection of symptoms traceable to an epistatic gene
e. is usually associated with quantitative traits
15. The F2 generation
a. has a phenotypic ratio of 3:1
b. is the result of the self-fertilization or crossing of F1 individuals
c. can be used to determine the genotype of individuals with the dominant
d. has a phenotypic ratio that equals its genotypic ratio
e. has 16 different genotypic possibilities
16. The base height of the dingdong plant is 10 cm. Four genes contribute to the
height of the plant, and each dominant allele contributes 3 cm to height. If you
cross a 10-cm plant (quadruply homozygous recessive) with a 34-cm plant, how
many phenotypic classes will there be in the F2?
a. 4
b. 5
c. 8
d. 9
e. 64
17. A 1:1 phenotypic ratio is a testcross indicates that
a. The alleles are dominant
b. One parent must have been homozygous recessive.
c. The dominant phenotype parent was a heterozygote.
d. The alleles segregated independently.
e. The alleles are codominant.
18. Carriers of genetic disorders
a. are indicated by solid symbols on a family pedigree.
b. are involved in consanguineous matings.
c. will produce children with the disease.
d. are heterozygotes for the gene that can cause the disorder
e. have a homozygous recessive genotype.
19. If both parents are carriers of a lethal recessive gene, the probability that their
child will inherit and express the disorder is
a. 1/8
b. ¼
c. ½
d. ½ x ½ x ¼ , or 1/16
e. 2/3 x 2/3 x ¼, or 1/9
20. Two true-breeding varieties of garden peas are crossed. One parent had red, axial
flowers, and the other had white, terminal flowers. All F1 individuals had red,
terminal flowers. If 100 F2 offspring were counted, how many of them would
you expect to have red, axial flowers?
a. 6
b. 19
c. 25
d. 56
e. 75
1. The chromosomal theory of inheritance states that
a. Genes are located on chromosomes.
b. Chromosomes and their associated genes undergo segregation during
c. Chromosomes and their associated genes undergo independent assortment
in gamete formation.
d. Mendel’s laws of inheritance relate to the behavior of chromosomes in
e. All of the above are correct.
2. A wild type is
a. the phenotype found most commonly in nature.
b. the dominant allele.
c. designated by a small letter if it is recessive or a capital letter if it is
d. your basic party animal.
e. a trait found on the X chromosome.
3. Sex-linked traits
a. are carried on an autosome but expressed only in males.
b. are coded for by genes located on a sex chromosome.
c. are found in only one or the other sex, depending on the sex-determination
system of the species.
d. are always inherited from the mother in mammals and fruit flies.
e. depend on whether the gene was inherited from the mother or the father.
4. Linkage and cytological maps for the same chromosome
a. are both based on mutant phenotypes and recombination data.
b. may have different sequences of genes.
c. have both the same sequence of genes and intergenic distances.
d. have the same sequence of genes but different intergenic distances.
e. are created using chromosomal abnormalities.
5. The genetic event that results in Turner Syndrome is probably
a. nondisjunction
b. deletion
c. parental imprinting
d. monoploidy
e. independent assortment
6. A 1:1:1:1 ratio of offspring from a dihybrid testcross indicates that
a. The genes are linked.
b. The dominant organism was homozygous.
c. Crossing over has occurred.
d. The genes are 25 map units apart.
e. The genes are not linked.
7. Genes A and B are linked 12 map units apart. A heterozygous individual, whose
parents were AAbb and aaBB, would be expected to produce gametes in the
following frequencies:
a. 44% AB
b. 6%AB
c. 12%AB
d. 6%AB
e. 38%AB
8. A female tortoise-shell cat is heterozygous for the gene that determines black or
orange coat color, which is located on the X chromosome. A male tortoise-shell
a. is hemizygous at this loci
b. must have had a tortoise-shell mother
c. must have resulted from a nondisjunction and has an extra Barr body in
his cells
d. must have three alleles for coat color, one from his father and two from his
e. would be hermaphroditic
9. A son inherits color blindness from his
a. mother
b. father
c. mother only if she is color-blind
d. father only if he is color-blind
e. mother only if she is not color-blind
10. Genomic imprinting
a. explains cases in which the gender of the parent from whom an allele is
inherited affects the expression of that allele.
b. is greatest in females because of the larger maternal contribution of
c. is more likely to occur in offspring of older mothers.
d. may explain the transmission of Duchenne muscular dystrophy
e. involves a and b
11. A cross of a wild-type red-eyed female Drosophila with violet-eyed male
produces all red-eyed offspring. If the gene is sex-linked, what should the
reciprocal cross (violet-eyed female x red-eyed male) produce? (Assume that
the red allele is dominant to the violet allele.)
a. all violet-eyed flies
b. 3 red-eyed flies to 1 violet-eyed
c. a 1:1 ratio of red and violet eyes in both males and females
d. red-eyed females and violet-eyed males
e. all red-eyed flies
12. Which of the following chromosomal alterations does not alter genic balance but
may alter phenotype because of differences in gene expression?
a. deletion
b. inversion
c. duplication
d. nondisjunction
e. genomic imprinting
1. One of the reasons most scientists believed proteins were the carriers of genetic
information was that
a. Proteins were more heat stable than nucleic acids.
b. The protein content of duplicating cells always doubled prior to division.
c. Proteins were much more complex molecules than nucleic acids.
d. Early experimental evidence pointed to proteins as the hereditary material.
e. Proteins were found in DNA.
2. Transformation involves
a. the transfer of genetic material, often from one bacterial strain to another
b. the creation of a strand of RNA from a DNA molecule
c. the infection of bacterial cells by phage
d. the type of semiconservative replication shown by DNA
e. the replication of DNA along the lagging strand
3. The DNA of an organism has thymine as 20% of its bases. What percentage of its
bases would be guanine?
a. 20%
b. 30%
c. 40%
d. 60%
e. 80%
4. In his work with pneumonia-causing bacteria and mice, Griffith found that
a. DNA was the transforming agent.
b. The R and S strains mated.
c. Heat-killed S cells could cause pneumonia when mixed with heat-killed R
d. Some heat-stable chemical was transferred to R cells to transform them
into S cells.
e. A T2 phage transformed R cells to S cells.
5. When T2 phages are grown with radioactive sulfur,
a. Their DNA is tagged.
b. Their proteins are tagged.
c. Their DNA is found to be of medium density in a centrifuge tube.
d. They transfer their radioactivity to E. coli chromosomes when they infect
the bacteria.
e. Their excision enzymes repair the damage caused by the radiation.
6. Meselson and Stahl
a. provided evidence for the semiconservative model of DNA replication
b. were able to separate phage protein coats from E. coli by using a blender.
c. found that DNA labeled with 15N was of intermediate density.
d. grew E. coli on labeled phosphorus and sulfur.
e. found that DNA composition was species specific.
7. Watson and Crick concluded that each base could not pair with itself because
a. There would not be room for the helix to make a full turn every 3.4 nm.
b. The width of 2 nm would not permit two purines to pair together.
c. The bases could not be stacked 0.34 nm apart.
d. Identical bases could not hydrogen-bond together.
e. They would be on antiparallel strands.
8. The joining of nucleotides in the polymerization of DNA requires energy from
a. DNA polymerase
b. the hydrolysis of the terminal phosphate group of ATP
c. RNA nucleotides
d. the hydrolysis of GTP
e. the hydrolysis of phosphates from nucleoside triphosphates
9. Continuous elongation of a new DNA molecule along one strand of DNA
a. requires the action of DNA ligase as well as polymerase.
b. occurs because DNA ligase can only elongate in the 5’ to 3’ direction.
c. makes a single Okazaki fragment.
d. occurs on the leading strand.
e. occurs on the lagging strand.
10. Which of the following statements about DNA polymerase is incorrect?
a. It joins complementary base pairs to each other.
b. It is able to proofread and correct for errors in its base-pairing in bacteria.
c. It is unable to join free nucleotides unless an RNA primer is present.
d. It only works in the 5’ to 3’ direction.
e. It is found in eukaryotes and prokaryotes.
11. Thymine dimmers, covalent links between adjacent thymine bases in DNA, may
be induced by UV light. When they occur, they are repaired by
a. excision enzymes.
b. DNA polymerase.
c. ligase.
d. primase.
e. a, b, and c are all needed.
12. Which letter indicates the 5’ end of this single DNA strand?
13. At which letter would the next nucleotide by added?
14. Which letter indicates a phosphodiester bond formed by DNA polymerase?
15. The base sequence of the DNA strand made from this template would be (from
top to bottom)
a. ATC
b. CGA
c. TAC
d. UAC
e. ATG
1. In Beadle and Tatum’s study of Neurospora, they were able to identify three
classes or arginine auxotrophs, mutants that needed arginine added to minimal
media in order to grow. The pathway in the production of arginine includes the
following steps: precursor ---- ornithine ----- citrulline ----- arginine. What
nutrient(s) had to be added to the minimal medium in order for the class of mutant
with a defective enzyme for the precursor ---- ornithine step to grow?
a. precursor only
b. ornithine only
c. citrulline only
d. ornithine or citrulline
e. precursor, ornithine, and citrulline
2. Transcription involves the transfer of information from
a. DNA to RNA.
b. RNA to DNA.
c. mRNA to an amino acid sequence.
d. DNA to an amino acid sequence.
e. the nucleus to the cytoplasm.
3. Which of the following is not true of an anti-codon?
a. It consists of three nucleotides.
b. It is the basic unit of the genetic code.
c. It extends from one end of a tRNA molecule.
d. It may pair with more than one codon, especially if it has the base inosine
in its third position.
e. Its base uracil base-pairs with adenine.
4. RNA polymerase
a. is the protein responsible for the production of ribonucleotides.
b. is the enzyme that creates hydrogen bonds between nucleotides on the
DNA template strand and their complementary RNA nucleotides.
c. is the enzyme that transcribes exons, but does not transcribe introns.
d. is a ribozyme composed of snRNPs.
e. begins transcription at a promoter sequence and moves along the template
strand of DNA in a 5’ to 3’ direction.
5. Transfer RNA
a. forms hydrogen bonds with the anticodon in the A site of a ribosome.
b. binds to its specific amino acid in the active site of an aminoacyl-tRNA
c. uses GTP as the energy source to bind its amino acid.
d. is translated from mRNA.
e. is formed in the nucleolus.
6. Translocation involves
a. the hydrolysis of a GTP molecule.
b. the movement of the tRNA in the A site to the P site.
c. the movement of the mRNA strand on triplet length in the A site.
d. the release of the tRNA in the P site.
e. all of the above.
7. Changes in a polypeptide following translation may involve
a. the addition of sugars or lipids to certain amino acids.
b. the action of enzymes to add amino acids at the beginning of the chain.
c. the removal of poly-A from the end of the chain.
d. the addition of a 5’ cap of a modified guanosine residue.
e. all of the above.
8. Several proteins may be produced at the same time from a single mRNA by
a. the action of several ribosomes in a cluster called a polyribosome.
b. several RNA polymerase molecules working sequentially.
c. signal sequences that associate ribosomes with rough ER.
d. containing several promoter regions.
e. the involvement of multiple spliceosomes.
9. Which enzyme is responsible for the synthesis of tRNA?
a. RNA replicase
b. RNA polymerase
c. aminoacyl-tRNA synthetase
d. ribosomal enzymes
e. ribozymes
10. In RNA processing,
a. Exons are excised before the mRNA is translated.
b. Assemblies of protein and snRNPs, called splicesomes, may catalyze
c. The RNA transcript that leaves the nucleus ay be much longer than the
original transcript.
d. Large quantities of rRNA are assembled into ribosomes.
e. Signal sequences are added to the 5’ end of the transcript.
11. Base-pair substitutions may have little effect on the resulting protein for all of the
following reasons except which one?
a. The redundancy of the code may result in a silent mutation.
b. As long as the substitution is three nucleotides, the reading frame is not
c. The missense mutation may not occur in a critical part of the protein.
d. The new amino acid may have similar properties to the replaced one.
e. The wobble phenomenon would result in no change in translation.
12. A ribozyme is
a. an exception to the one gene-one RNA molecule axiom.
b. an enzyme that adds the 5’ cap and poly-A tail to mRNA.
c. an example of rearrangement of protein domains caused by RNA splicing.
d. an RNA molecule that functions as an enzyme.
e. an enzyme that produces both small and large ribosomal subunits.
13. A signal sequence
a. is most likely to be found on proteins produced by bacterial cells.
b. directs an mRNA molecule into the cisternal space of ER.
c. is a sign to help bind the small ribosomal unit at the initiation codon.
d. would be the first 20 or so amino acids of a protein destined for secretion
from the cell.
e. is part of the 5’ cap.
14. A base deletion early in the coding sequence of a gene may result in
a. a nonsense mutation.
b. a frameshift mutation
c. multiple missense mutations.
d. a nonfunctional protein.
e. all of the above.
15. The bonds between the anticodon of a tRNA molecule and the complementary
codon of mRNA are
a. formed by the input of energy from GTP.
b. formed by the input of energy from ATP.
c. hydrogen bonds.
d. catalyzed by aminoacyl-tRNA synthetase.
e. formed in the P site of the ribosome.
16. A prokaryotic gene 600 nucleotides long can code for a polypeptide chain of
about how many amino acids?
a. 100
b. 200
c. 300
d. 600
e. 1800

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