WorksheetsBio 121 Exam
Total questions: 115
Worksheet time: 10hrs 35mins
How many genes are present in the human genome?
tens of thousands
23
A hundred thousand
46
what is a locus?
A type of spore made only by fungi
the precise DNA sequence of a gene
the precise location of a gene on a chromosome
a cell with two chromosome sets
Sexual and asexual reproduction are alike in that_______
they both involve two parents
in both cases, every parent transmits all of its genes to its progeny
they both require meiosis to complete the reproductive cycle
they can both occur in multicellular organisms
A karyotype is.............
A list of all the genes a person carries
the physical trait a person has
a method of identifying crossover events
a photograph of all the chromosomes in a single cell from an individual
Fertilization produces
a haploid zygote
a diploid zygote
a diploid zygote, except during the gametophyte stage of alternations of generation
a diploid and haploid zygote
Which of the following statements is most accurate
diploid cells can divide by meiosis
haploid cells cannot divide by meiosis
haploid cells can divide by mitosis
all the above
Which of the following is part of the life cycle called alternation of generations?
Zygote
Spores
Spores
All of the listed responses are correct.
The sexual cycle of the diploid, multicellular algal genus Fucus involves..........
both mitosis and meiosis but not fertilization
mitosis, meiosis, and fertilization
only meiosis and fertilization
mitosis only
A life cycle in which the only multicellular form is haploid is most typical of.
prokaryotes
plants
fungi
fish
In sexually reproducing species, the chromosome number remains stable over time because
______and_________
always alternate.
meiosis; mitosis
meiosis I; meiosis lI
mitosis; fertilization
meiosis; fertilization
The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the
somatic (body) cells of a rabbit?
132
22
44
11
Which of the following represents a mismatch or incorrect description?
Anaphase: there is movement of the chromosomes to the poles
Metaphase: the nuclear envelope disappears
Telophase: chromosomes become more extended
Prophase: chromosomes become more tightly coiled
At what point do sister chromatids separate?
Anaphase
G2 phase
prophase
Metaphase
In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle?
The G1 phase
Cytokinesis
Prophase
Metaphase
At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell?
telophase
interphase
prophase
metaphase
You would know that a dividing cell was a plant cell rather than an animal cell if you saw that
it had two pairs of centrioles during prophase
it had formed a cleavage furrow
it had microtubules
it had formed a cell plate
Which of the following processes does not occur in dividing bacteria?
Inward pinching of the plasma membrane
Separation of the origins of replication
Replication of DNA
Mitosis
During binary fission in a bacterium,
the two DNA molecules divide in half, forming four DNA fragments
the origins of replication move apart
the two DNA molecules attach to the centrioles
the two DNA molecules break up into plasmids
Which of the following is involved in the binary fission of most bacteria?
Formation of a spindle apparatus
Formation of a cell plate
Distribution of a copy of the single parental chromosome to each daughter cell
Disintegration of the nuclear membrane
When a cell in S phase is fused with a cell in G1
DNA synthesis begins immediately in the original G, nucleus
the replication of DNA occurring in the original S nucleus is terminated
the chromosomes of the original G nucleus condense in preparation for mitosis
the two nuclei fuse and additional division is arrested
Tissue culture experiments with PDF demonstrate that without this substance,
bacterial cells lose their resistance to antibiotics
animal cells are unable to attach to the substratum
the various kinases, such as MPF, are unable to bind to cyclin
fibroblasts fail to divide
You would be ‚unlikely to see which of the following human cells dividing?
Cancer cell
Skin cell
Nerve cell
Cell from an embryo
Which of the following hypotheses is best supported by observing cancer cells in a culture?
The cancer cells exhibit anchorage dependence.
The cancer cells spend the majority of their time in the Go phase.
The cancer cells spend the majority of their time in the Go phase.
The cancer cells produce molecules that inhibit the growth factors required for cell division.
What is the difference between a benign tumor and a malignant tumor?
Cells of benign tumors do not metastasize; those of malignant tumors do.
Benign tumors will not kill you; malignant tumors will.
Benign tumors arise by transformation; malignant tumors do not.
Cells of benign tumors metastasize; those of malignant tumors do not.
If a human somatic cell is just about to divide, it has
_________ chromatids.
46
0
92
23
Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present?
98
23
92
94
Which of the following does not occur during mitosis?
condensation of chromatin
separation of chromatids
alignment of chromosomes along the cell's equator
replication of chromosomes
During what phase in the cell cycle would you find the most DNA per cell?
G1
G2
S
S1
Generally speaking, how many genetic codes are there?
Four
20
one for each organism
one
The number of nucleotide bases "read" together on the mRNA to designate each amino acid is______; this unit is called a(n)_________.
two; anticodon
three; triose
two; dipeptide
three; codon
Which statement is true?
it takes three genes to code for one protein.
Each gene codes for three proteins.
Each amino acid in a protein is coded for by three bases in the DNA.
Each DNA base codes for three amino acids.
When RNA is being made, the RNA base___ always pairs with the base _____ in DNA
T and G
U and A
A and U
U and T
Who formulated the one gene one enzyme hypothesis
Watson and Crick
Hershey and Chase
Franklin
Beadle and Tatum
Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of_________
RNA
DNA
Carbohydrates
Proteins
Which of the following considerations was/were important in the choice of viruses and bacteria for early experiments on DNA?
They have short generation times.
They typically have relatively small genomes
Their chromosomes have a simpler structure.
All of the listed responses are correct.
In the "beads on a string" structure of unfolded chromatin, the "beads" are
heterochromatin
nucleoids
looped domains
nucleosomes
What is the major difference between bacterial chromosomes and eukaryotic chromosomes?
Bacterial chromosomes have much more protein associated with the DNA than eukaryotes.
Eukaryotes have a single circular chromosome, whereas bacteria have several linear chromosomes.
Bacteria usually have a single circular chromosome whereas eukaryotes have several linear chromosomes.
The DNA molecules of bacterial chromosomes have a slightly different structure than those of eukaryotic chromosomes.
In a comparison between asexually reproducing bacteria and sexually reproducing multicellular eukaryotes, uncorrected errors in replication are more likely to be transmitted to subsequent generations in bacteria than in multicellular eukaryotes. Which of the following provides the best evidence-based explanation for this difference?
Although the genome for each is represented as pairs of homologous chromosomes, errors in bacteria affect both homologs, but only one is affected in eukaryotes.
Unlike multicellular eukaryotes, bacteria lack DNA repair enzymes, so there are just more uncorrected errors at play.
Because they are asexual and single-celled, all uncorrected errors of replication in bacteria are transmitted to subsequent generations. Multicellular eukaryotes typically reproduce sexually, so uncorrected errors are transmitted only if they occur in germ cells that meiotically divide to produce gametes.
Only errors that lead to faster-growing strains are left uncorrected in bacteria, whereas all errors are detected and repaired in multicellular eukaryotes.
Telomeres
are shorter for younger individuals
remain the same regardless of the frequency of DNA replication
are found in both prokaryotic and eukaryotic cells
get longer with each round of DNA replication
telomerase
speed cell aging
is the enzyme that lengthens telomerase
slows the rate of cancer cell growth
prevents the loss of centromeric DNA
Which of the following statements is/are correct with regard to individuals with the disorder xeroderma pigmentosum?
Cells in these individuals have difficulty repairing thymine dimers.
These individuals usually have inherited defects in the nucleotide excision repair system.
These individuals are extremely sensitive to sunlight.
All of the listed responses are correct.
Unlike prokaryotic DNA replication, replication of eukaryotic chromosomes
involves two leading strands and no lagging strands
is error-free
cannot be completed by DNA polymerase
is semiconservative
The incorporation of an incorrect base into the DNA during replication
will trigger the cell to destroy the new strand, and replication will begin again
will almost certainly lead to the death of the cell
can be repaired by the mismatch repair system
cannot be repaired, and a new mutation will invariably result
Which set of enzymes is involved in nucleotide excision repair?
DNA polymerase, helicase, primase
Ligase, nuclease, and primase
Nuclease, DNA polymerase, primase
nuclease, DNA polymerase, and ligase
As a result of proofreading by DNA polymerases, the overall error rate in the completed DNA molecule is approximately
1 error per 100 nucleotides
1 error per 10,000,000,000 nucleotides
1 error per 1,000,000,000 nucleotides
1 error per 1,000 nucleotides
Once the DNA at the replication fork is unwound by helicases, what prevents the two strands from coming back together to re-form a double helix?
The helicase modifies the DNA in such a way as to eliminate the affinity between the two strands.
DNA polymerase follows the helicase so closely that there is no chance for the strands to come back together.
One of the strands is rapidly degraded, preventing the double helix from re-forming.
Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming.
Which one of the following statements regarding DNA replication is correct?
Ligase separates the two strands of the DNA double helix. Then DNA polymerase synthesizes the leading strand and primase synthesizes the lagging strand.
Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates.
all the above
none of the above
A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled
between the G2 phase and prophase
between the G1 and G2 phases
during the M phase of the cell cycle
between anaphase and telophase
A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture.
Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA at G of the cell cycle in one of the grasshopper daughter cells?
50 units
400 units
200 units
100 units
What appears to be the mechanism for genomic imprinting?
DNA methylation that silences particular genes
Crossing over
DNA methylation that activates particular genes
Both the first and third listed responses
Which of the following is false regarding sister chromatids?
Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
Sister chromatids are separated during mitosis.
Sister chromatids are attached to one another at the centromere.
Sister chromatids are created when DNA is replicated.
In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in
interphase
anaphase
prophase
S phase
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope?
anaphase
telophase
metaphase
S phase
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called
a chromatid
a centromere
chromatin
a chromoplast
The region of a chromosome in which the two double strands of replicated DNA are held together is called
a chromatid
chromatin
a centromere
a centriole
Why did Morgan choose Drosophila for his genetics experiments?
They have a long generation time.
A single mating can produce many offspring.
Both the second and fourth answers are correct.
Drosophila chromosomes can be easily distinguishable under a light microscope.
Wild type refers to
the most common phenotype thought to be found in the natural population
a kind of chromosomal deletion
any mutant genotype
extranuclear genes
Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in the early telophase of mitosis?
0
7
14
28
In a human skin cell that is going through the cell cycle, when do the centrosomes separate?
prophase
S phase
Metaphase
interphase
A person with two X chromosomes and one Y chromosome would appear to be
male
female
both male and female
neither male nor female
Which of the following is the only known viable human monosomy?
XXX
XO
XYY
XY
During interphase, the genetic material of a typical eukaryotic cell is
dispersed in the nucleus as long strands of chromatin
transported through the nuclear pores
condensed and the chromosomes are often visible under the light microscope
dispersed in the cytoplasm as long strands of chromatin
DNA replication occurs in
the G1 phase of interphase
prophase of mitosis
metaphase of mitosis
The S phase of interphase
It is proposed that a certain disorder affecting the inner ear is caused by mitochondrial DNA.
Which of the following observations would be the most decisive evidence against this idea?
Females and males have the disorder in equal numbers.
Mothers pass the disorder on to their offspring, but fathers do not.
Fathers with the disorder pass it on to all their children, but mothers with the disorder do not pass it along.
All of the listed responses are correct.
The centromere is a region in which
the new cell plate forms in telophase
the chromosomes are connected to the cell plate in metaphase
sister chromatids are attached to one another in prophase
chromosomes become aligned during metaphase
How many maternal chromosomes are present in a somatic human cell when it is not engaged in cell division?
23
48
92
184
A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with
16 chromosomes
64 chromosomes
32 pairs of chromosomes
none of the listed numbers of chromosomes
"Cytokinesis" refers to
the division of the entire cell
the division of the cytoplasm
the movement of a cell from one place to another
the reduction in the number of chromosomes
Following cytokinesis in an animal cell, how many centrioles does each new daughter cell possess?
two
one
six
eight
The phase of mitosis during which the chromosomes move toward separate poles of the cell is
prophase
prometaphase
anaphase
telophase
Hemophilia is an X-linked disorder. The daughter of a father with hemophilia and a carrier mother has a ____________ probability of having hemophilia.
33%
50%
0%
25%
Consider a woman who is a carrier of a recessive X-linked allele for hemophilia. Which of the following possibilities could explain the presence of the hemophilia allele in her genotype?
Both her mother and her father had hemophilia.
Either her mother was a carrier or her father had a dominant allele.
Either her mother was homozygous dominant or her father had hemophilia.
Either her mother was a carrier or her father had hemophilia.
The removal of the RNA primer and addition of DNA nucleotides to the 3' end of Okazaki fragments in its place is carried out by _______
DNA polymerase Ill
DNA polymerase I
nuclease
primase
The unwinding of DNA at the replication fork causes twisting and strain in the DNA ahead of the fork, which is relieved by an enzyme called
ligase
topoisomerase
A woman is a carrier for red-green color blindness, a sex-linked trait. Her husband is normal (not color-blind) for this trait. What are the chances that their newborn daughter will be red-green color-blind?
0%
50%
25%
75%
Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls?
Nondisjunction occurs in males but not in females.
To express an X-linked recessive allele, a female must have two copies of the allele, one of which is contributed by the father.
The allele is carried on the Y chromosome.
The gene for ear shape is on the X chromosome. (Sex determination in werewolves is the same as for "other" humans.) A certain female werewolf has pointy ears even though her father had round ears. What percentage of her sons will have round ears if she mates with a werewolf with round ears?
100%
75%
0%
50%
A woman is red-green color-blind. What can we conclude, if anything, about her father?
He has two Y chromosomes.
We have too little information to tell.
He is red-green color-blind.
For an X-linked trait, it is the contribution of ________ that determines whether a son will display the trait
the father
the mother
the grandparents
If a woman is heterozygous for a recessive sex-linked allele and her husband has the dominant allele, which one of the following is true about the probabilities for their children?
All of their sons will show the recessive trait.
None of their sons will show the recessive trait.
Half of their sons will show the recessive trait.
All of their daughters will be heterozygous.
Which of the following results of Thomas Hunt Morgan's experiments with white-eyed mutant flies was unexpected in light of Mendelian genetics?
The mutant allele (white eyes) was recessive.
Among the F2 progeny, only males had white eyes. All of the females had red eyes.
The Ft flies were crossed with each other, and the F2 progeny included red-eyed and white-eyed flies in a 3:1 ratio.
All of the listed responses are correct.
What is the probability that a human male will inherit an X-linked recessive allele from his father?
0%
50%
100%
25%
Which of the following properties were present in the characters that Mendel examined in his breeding experiments?
The traits varied in an either-or fashion.
It was possible to isolate true-breeding varieties for each trait.
All of the listed responses are correct.
They were controlled by loci that were (or behaved as if they were) on different chromosomes.
One event occurring during prophase is
the beginning of the formation of a spindle apparatus
the alignment of chromosomes in a single plane
the synthesis of a new nuclear envelope
cytokinesis
Which event or events occur during anaphase?
Cohesins joining sister chromatids at the centromeres are cleaved during anaphase.
A spindle made of microtubules is present during anaphase.
The centrioles are at opposite poles during anaphase.
All of the listed responses are correct.
27 The first amino acid inserted into a new polypeptide chain in eukaryotic cells is usually
alanine
methionine
serine
glycine
Which is a post-translational modification of a polypeptide?
Cleavage of a polypeptide into two or more chains
Removal of introns and splicing of exons
The growing polypeptide signals the ribosome to attach to the ER.
Formation of a polysome that allows simultaneous formation of many polypeptides from one mRNA transcript
Genomic imprinting in mammals appears to affect primarily genes involved in _
embryonic development
sex determination
function of the nervous system
digestion
Both chloroplasts and mitochondria
are found within the nucleus
display a Mendelian pattern of inheritance
carry extranuclear genes
have linear DNA
Which of the following would result in genetic variation by way of new combinations of alleles?
Independent alignment of homologous chromosomes during meiosis I
Random fertilization increasing the number of possible allele combinations in an individual
The exchange of alleles between homologous chromosomes during meiosis I
The first three responses are correct.
Individuals with an extra X chromosome
are generally sterile
have distinguishing physical features
are always female
may have abnormal intelligence or be at risk for learning disabilities
Which summary of protein synthesis is correct?
DNA exchanges its thymine units with uracil in polymerase. This activates polymerase, and it starts joining amino acids together.
Messenger RNA is made on a DNA template, and then amino-acid-bearing transfer RNAs bind to the mRNA through codon-anticodon pairing
Transfer RNAs line up on a ribosome, and amino acids bind to them with hydrogen bonds.
Replicated DNA leaves the nucleus, is transported to a ribosome, and catalyzes the polymerization of amino acids in a protein.
The bonds that hold tRNA molecules in the correct three-dimensional shape are
hydrogen bonds
hydrophobic interactions
peptide linkages
covalent bonds
Gene A is normallv found on chromosome number 15 in humans. If amniocentesis reveals fetal cells containing gene A on chromosome 17 but not on 15, the best explanation would be that
crossing over occurred during synapsis of meiosis I in one parent's gametes
at least one parent probably had a genetic abnormality
translocation occurred
an inversion of gene A occurred on chromosome 15
The chromosomal abnormality in which a fragment of a chromosome breaks off and then reattaches to the original chromosome in the same place but in the reverse direction is called
duplication
inversion
Because the frequency of crossing over is not uniform along the length of a chromosome,
the map unit is an unreliable unit of measurement and is rarely used today
pairs of homologous chromosomes contain small but significant differences in gene order
map units do not necessarily correlate to physical distances along the chromosome
recombination frequency cannot be used to determine the number of map units separating two genes
Which type of chromosomal alteration is responsible for the cri du chat syndrome?
inversion
deletion
translocation
duplication
Chromatids are
held together by the centrioles
found only in aberrant chromosomes
identical copies of each other if they are part of the same duplicated chromosome
composed of RNA
If a cell contains 60 chromatids at the start of mitosis, how many chromosomes will be found in each daughter cell at the completion of the cell cycle?
45
15
60
30
During translation in a eukaryotic cell,
polypeptides are synthesized at ribosomes, according to instructions carried by mRNA
tRNA carries amino acid molecules to the nucleus, where they are added to a growing polypeptide chain
mRNA is synthesized by the bonding of free nucleotides to the bases on the template strand of DNA
ribosomes move into the nucleus
The P site of a ribosome does which of the following?
It holds the tRNA carrying the growing polypeptide chain.
It holds the tRNA that is carrying the next amino acid to be added to the growing polypeptide chain.
It helps "unzip" DNA during transcription.
It catalyzes the addition of amino acids to the tRNAs.
Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16?
Extra copies of the other chromosomes are probably fatal to the developing embryo.
There are probably more genes on chromosome 21 than on the others.
Nondisjunction of chromosomes 3 and 16 probably occurs much less frequently.
There are probably more genes on chromosome 21 than on the others.
When a person has Down syndrome, he or she has an extra chromosome 21. Therefore, Down syndrome is a kind of______ and results from ________
aneuploidy; nondisjunction of chromosome 21
genomic imprint; excessive methylation of either the paternal or maternal chromosome 21
replication error; an extra cycle of DNA synthesis during the S phase
polyploidy; occurrence of meiosis without cytokinesis
A gray-bodied, vestigial-winged fly is crossed with a black-bodied, normal-winged fly. The F progeny is test crossed. Among the resulting offspring, _________ is a parental type, and______ is a recombinant type
gray-bodied, normal-winged; black-bodied, vestigial-winged
black-bodied, normal-winged; black-bodied, normal-winged
gray-bodied, normal-winged; black-bodied, normal-winged
black-bodied, normal-winged; black-bodied, vestigial-winged
During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as
meiotic failure
gametic infertility
nondisiunction
In Klinefelter syndrome, individuals are phenotypically male, but they have reduced sperm production and may have some breast development in adolescence. The cells of Klinefelter individuals have two X chromosomes and one Y (they are XXY instead of XY). This occurs because of what meiotic error?
Polyploidy
Nondisiunction
Translocation
The function of the mitotic cell cycle is to produce daughter cells that
have a random assortment of maternal and paternal chromosomes
have the same number of chromatids as the parent cell had chromosomes
are genetically identical to the parent cell (assuming no mutation has occurred)
have the same number of chromosomes as the parent cell but not the same genetic content
Cells that have an abnormal number of some particular chromosome are said to be
polyploid
trisomy
hexaploid
aneuploid
_______is usually less severe than___ and species have been observed in plants, fish, amphibians, and even mammals.
Trisomy; polyploidy; trisomic
Polyploidy; aneuploidy; polyploid
Monosomy; polyploidy; monosomic
Nondisjunction; disjunction; nondisjunctional
At one point, as a cell carried out its day-to-day activities, the nucleotides GAT were paired with the nucleotides CUA. This pairing occurred
during translation
in a double-stranded DNA molecule
during transcription
when an mRNA codon paired with a tRNA anticodon
The function of tRNA during protein synthesis is to
attach mRNA to the small subunit of the ribosome
process mRNA
guide ribosomal subunits out of the nucleus through nuclear pores
deliver amino acids to their proper site during protein synthesis
Which accurately describes the usual process of eukaryotic transcription?
Both introns and exons are transcribed, but neither type of transcribed region leaves the nucleus.
Both introns and exons are transcribed, but the RNA transcribed from introns does not leave the nucleus.
Exons are not transcribed.
Introns are not transcribed.
Which statement correctly describes mRNA processing?
Exons are cut out of the primary transcript, and the introns are spliced together.
Introns are cut out of the primary transcript, and the resulting exons are spliced together.
Introns are cut out of the primary transcript and spliced together at the end of the transcript.
Exons are cut out of the primary transcript and transported to the endoplasmic reticulum.
One strand of a DNA molecule has the following sequence: 3'-AGACAAACTATCCACCTC-5'. In order for that strand to be transcribed, there would have to be a specific recognition sequence, called a(n)_______to the left of the DNA sequence indicated.
AUG codon
intron
promoter
centromere
In transcription,____
the promoter region acts as an initial binding site for RNA polymerase
only one of the DNA strands is used as the template
the RNA nucleotides used are produced by the cell
All of the answer choices are correct.
