LAUNCHPAD QUESTIONS
Replication of DNA in a eukaryote occurs during which phase of the cell cycle? A. M phase B. G1 phase C. G2 phase D. S phase
S phase
The division of the cell's cytoplasm in a eukaryotic cell is known as: A. mitosis. B. C. cell fission. D. both cytokinesis and mitosis.
cytokinesis
As a piece of linear DNA is replicated, the leading strand will have _____ RNA primer(s) and the lagging strand will have _____ RNA primer(s). A. one; two B. one; one C. many; one D. one; many E. many; many
one; many
In meiosis, recombination occurs: A. during prophase I and II and involves exchange of chromosome fragments between all four chromatids. B. only during prophase I and involves exchange between chromatids of homologous chromosomes. C. only during prophase I and involves exchange of chromosome fragments between sister chromatids. D. during prophase I and II and involves exchange of chromosome fragments between sister chromatids.
only during prophase I and involves exchange between chromatids of homologous chromosomes
Synapsis is best described as the: A. pairing of homologous chromosomes in prophase I. B. exchange of genetic information between sister chromatids. C. exchange of genetic information between non-sister chromatids. D. alignment of non-sister chromatids at the metaphase plate.
pairing of homologous chromosomes in prophase I
Many of the specific functions that are triggered when a cell passes one of the cell cycle checkpoints result from activation of enzymes and other proteins. A common mechanism for this activation is: A. ATP synthesis. B. signal transduction. C. polymerization of tubulin. D. phosphorylation of specific proteins.
phosphorylation of specific proteins.
The main function of DNA polymerase is to add new nucleotides to the 3′-end of a growing chain. What is the second role of this enzyme in DNA replication? A. synthesis of RNA primer B. unwinding of the DNA duplex C. joining Okazaki fragments D. stabilizing strands of DNA at replication fork E. proofreading
proofreading
In which phase of mitosis do chromosomes condense? A. telophase B. metaphase C. prophase D. anaphase
prophase
The epithelial cells in the skin of an animal have 24 chromosomes. How many chromosomes are present in the gametes of this animal? A. 48 B. 12 C. 6 D. 24
12
How many chromosome pairs are there in a normal human genome? A. 64 B. 22 C. 23 D. 26
23
A new nucleotide can only be added to the _____ end of a growing DNA strand. DNA therefore always grows in the _____ direction. A. 5′; 5′ to 3′ B. 3′; 3′ to 5′ C. 5′; 3′ to 5′ D. 3′; 5′ to 3′
3′; 5′ to 3′
The leading strand is the daughter strand that has its _____ end pointed toward the replication fork and is therefore synthesized _____. A. None of the other answer options is correct. B. 3′; in a series of segments C. 3′; continuously D. 5′; continuously E. 5′; in a series of segments
3′; continuously
The lagging strand is the daughter strand that has its _____ end pointed toward the replication fork and is therefore synthesized _____. A. 5′; in a series of segments B. None of the other answer options is correct. C. 3′; in a series of segments D. 3′; continuously E. 5′; continuously
5′; in a series of segments
At the start of mitosis, how many sister chromatids are present in a human cell? A. 46 B. 23 C. 92 D. 12
92
TRUE/FALSE: During meiosis, two rounds of DNA synthesis are required to form four gametes from one parent cell.
False
Cell cycle checkpoints: A. act as a brake on cell division if something is not right. B. provide opportunities to check if the cell has carried out steps necessary for cell division. C. All of these choices are correct. D. can involve the protein p53.
All of these choices are correct
Cell division is regulated by: A. signals about the nutritional status of the cell. B. signals that indicate that the cell has reached a sufficient size. C. signals that indicate that DNA has been replicated. D. All of these choices are correct. E. growth factor signals.
All of these choices are correct
How would the loss of p53 activity affect a cell? A. The G1/S checkpoint would not be functional. B. CDK activity would not be appropriately regulated. C. All of these choices are correct. D. DNA damage could accumulate.
All of these choices are correct
In replication of a linear double-stranded DNA molecule, one end of each strand becomes shorter in each round of replication. This happens because: A. the RNA primer cannot be replaced at the very end of a DNA strand. B. All of these choices are correct. C. DNA polymerase elongates a growing DNA strand at only the 3′ end. D. each replicated DNA strand requires an RNA primer.
All of these choices are correct
Sexual reproduction results in an increase in genetic diversity because: A. during metaphase I, the bivalents line up in a random orientation so that gametes inherit a random set of maternally and paternally derived chromosomes. B. All of these choices are correct. C. during prophase I, genes that are paternally and maternally derived recombine so that the gametes have chromosomes that are different from the parents' chromosomes. D.during fertilization, the gametes that fuse are random so that a large number of chromosomal combinations are possible in the new organism.
All of these choices are correct
Sexual reproduction results: A. in a new generation with the same number of chromosomes as each parent. B. from combining genetic material from two gametes. C. in offspring that are not genetically identical. D. in a new generation that is not genetically identical to its parents. E. All of these choices are correct.
All of these choices are correct
Which of the following statements regarding the cell cycle is TRUE? A.Different levels of cyclins are observed at different cell cycle stages. B. All of these choices are correct. C. It can be "paused" by the action of p53. D. It has many major cell cycle checkpoints. E. It is regulated by cyclins and CDKs.
All of these choices are correct
Reproduction by mitotic cell division: A. persists in mature plant cells for continued growth. B. results in two daughter cells that are genetically identical. C. continues in mature adult humans to replace damaged and worn-out cells. D. is asexual reproduction. E. All of these choices are correct.
All of these choices are correct.
Which of these events does NOT include a checkpoint in the cell cycle? A. the transition from G2 to M phase B. the beginning of M phase C. the transition from G1 to S phase D. All of these events include a checkpoint in the cell cycle.
All of these events include a checkpoint in the cell cycle.
Mitochondria contain their own double-stranded, circular DNA and replicate on their own. Why don't they suffer the same consequences as our cells in terms of limited division? A. Because they have high telomerase activity and their DNA is circular and so doesn't shorten in replication. B. Because they have high telomerase activity. C. Because mitochondrial DNA is circular, it doesn't shorten when it replicates. D. Since mitochondrial DNA only contains a few genes, it can last a lot longer. E. Shortening of the DNA is only a problem with nuclear DNA; shortening of mitochondrial DNA isn't catastrophic.
Because mitochondrial DNA is circular, it doesn't shorten when it replicates
A cell that is not actively dividing is in what phase of the cell cycle? A. G2 B. G1' C.G0 D. G1
G0
The enzyme responsible for proofreading a growing DNA strand and for replacing mismatched nucleotides is: A. DNA replicase. B. DNA polymerase. C. topoisomerase II. D. DNA ligase. E. helicase.
DNA polymerase
The enzyme responsible for replacing RNA primers with DNA is a type of: A. DNA polymerase. B. topoisomerase II. C. DNA ligase. D. DNA replicase. E. helicase.
DNA polymerase
The enzyme that catalyzes the addition of new nucleotides to a growing DNA strand is: A.DNA ligase. B. topoisomerase II. C. DNA polymerase. D. helicase. E. DNA replicase.
DNA polymerase
Why are primers needed for DNA replication? A. They help with the joining of Okazaki fragments. B. They help direct the placement of the telomeres. C. DNA polymerase can only add nucleotides to an existing chain. D. The primers help with the proofreading function of DNA polymerase. E. A tiny amount of RNA is needed to tell the cell where genes are located.
DNA polymerase can only add nucleotides to an existing chain
Which of the following is NOT a characteristic of meiotic cell division? A. Cell division requires two rounds of nuclear division. B. Cell division results in the formation of four daughter cells. C. Daughter cells are genetically identical. D. Cell division results in the production of gametes.
Daughter cells are genetically identical
Which major checkpoint delays the cell cycle when DNA replication is incomplete? A. None of the checkpoints delays the cell cycle when DNA replication is incomplete. B. G2 checkpoint C. M checkpoint D. G1 checkpoint E. G1, G2, and the M checkpoints
G2 checkpoint
Which of the following is NOT true of mitotic cell division? A. It does not require DNA replication B. It occurs in eukaryotes, but not in prokaryotes C. It is a highly regulated process D. It is a form of asexual reproduction E. It is a process that is very important in the life cycle of sexually reproducing organisms
It does not require DNA replication
What would happen if crossing over occurred between sister chromatids? A. Genetic diversity would decrease due to the loss of gene combinations. B. Gene rearrangement would lead to changes in gene expression. C. Genetic diversity would increase due to the addition of gene combinations. D. Nothing would happen because sister chromatids are genetically identical or nearly identical.
Nothing would happen because sister chromatids are genetically identical or nearly identical.
What would happen to the variation between organisms in a population if their DNA polymerase did NOT have a proofreading function? A. The amount of variation would increase. B. The amount of variation would stay the same. C. The amount of variation would decrease.
The amount of variation would increase
Paramecium is a single-cell eukaryotic organism that can reproduce by mitotic cell division. Prior to the M phase of the cell cycle, which of the following must occur? A. The nuclear envelope must disintegrate B. The cell must first be fertilized C. The cell must replicate its chromosomes D. Sister chromatids must be serparated E. The nucleus must divide
The cell must replicate its chromosomes
A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells? A. These cells are normal. B. Within these cells, the cell cycle has been halted at the G2/M transition. C. All of these cells have entered meiosis. D.All of these cells have entered mitosis. E. These cells likely contain damaged DNA.
These cells likely contain damaged DNA.
Which of the following is NOT true about gametes? A. They fuse to form a new organism during fertilization. B. They are formed by meiotic cell division. C. They are called eggs and sperm in animals. D. They have half as many chromosomes as a somatic cell of the same individual. E. They are genetically identical to other gametes formed during meiosis
They are genetically identical to other gametes formed during meiosis
How do new cyclin proteins appear in the cytoplasm? A. They are imported from outside the cell. B. They are made through protein synthesis. C. They are recycled. D. All of these choices are correct.
They are made through protein synthesis
_____ relieves the tension on the double helix during DNA replication. A. A single-stranded binding protein B. DNA polymerase C. Helicase D. An RNA primer E. Topoisomerase
Topoisomerase
TRUE/FALSE: A mutation acquired by a bacterium will likely be inherited by all daughter cells
True
TRUE/FALSE: Synthesis of nucleic acids always occurs in the 5' → 3' direction.
True
Most of the significant changes in activities and functions that accompany passage through a cell cycle checkpoint are regulated by the: A. inhibition of cyclin proteins. B. changes in membrane polarization. C. activation of DNA polymerase. D. activation of microtubules. E. activation of kinase enzymes.
activation of kinase enzymes.
In which phase of mitosis do sister chromatids separate? A. metaphase B. telophase C. prophase D.anaphase
anaphase
In which phase of mitosis do spindle microtubules shorten? A. prophase B. telophase C. anaphase D. metaphase
anaphase
When do sister chromatids separate in meiosis? A. anaphase II B. telophase I C. anaphase I D. metaphase II
anaphase II
Which of the following reasons explains why bacteria can continually divide? A. because they are so simple B. because DNA replication is much quicker in bacteria than in eukaryotes C. because they only have one chromosome D. because they have plasmids E. because their DNA is circular so the DNA never shortens after replication
because their DNA is circular so the DNA never shortens after replication
Mitosis MOST likely evolved from what process? A. meiosis B. binary fission C. cytokinesis D. the cell cycle
binary fission
The region of a replicated chromosome where sister chromatids remain attached is called the: A. chiasmata B. centrosome C. kinetochore D. centromere
centromere
Telomerase is fully active in _____ and _____ cells, but almost completely inactive in _____ cells. A. stem; blood; germ B. somatic; germ; stem C. somatic; blood; germ D. germ; stem; somatic E. germ; somatic; stem
germ; stem; somatic
In contrast to linear DNA replication, circular DNA replication typically: A. has a single origin of replication. B. All of these choices are correct. C. does not produce Okazaki fragments. D. occurs only at a single replication fork. E. does not produce a replication bubble
has a single origin of replication
What is the name of the enzyme that separates the two strands of DNA during replication? A. primase B. topoisomerase C. DNA polymerase D. helicase E. DNA ligase
helicase
Which of the following enzymes is responsible for unwinding the double helix at the replication fork? A. DNA polymerase B. ligase C. topoisomerase D. primase E. helicase
helicase
The following enzymes play important roles in DNA replication: DNA polymerase, primase, ligase, helicase. In what order do they work during replication? A. DNA polymerase, primase, ligase, helicase B. primase, helicase, ligase, DNA polymerase C. helicase, primase, DNA polymerase, ligase D. ligase, helicase, DNA polymerase, primase E. DNA polymerase, helicase, primase, ligase
helicase, primase, DNA polymerase, ligase
Another name for non-sister chromatids is: A. bivalents. B. homologous chromosomes. C. chiasmata. D. diploids.
homologous chromosomes
Paired chromosomes in a cell that share the same set of genes are called: A. sister chromatids B. homologous chromosomes C. non-sister chromatids D. bivalent chromosomes
homologous chromosomes
A eukaryotic chromosome has _____ origin(s) of replication, and a bacterial chromosome has _____ origin(s) of replication. A. many; one B. one; one C. many; three D. many; two E. one; many
many; one
In which phase of mitosis do chromosomes line up at the middle of the cell? A. telophase B. anaphase C. prophase D. metaphase
metaphase
In a long DNA molecule, each origin of replication produces a _____ with a _____ on each side. A. replication fork; replication bubble B. replication fork; DNA ligase C. None of the other answer options is correct. D. replication bubble; DNA ligase E. replication bubble; replication fork
replication bubble; replication fork
Which of the following is NOT needed for DNA replication? A. nucleotides B. None of the other answer options is correct. C. enzymes D. ribosomes E. DNA
ribosomes
During meiosis II: A. non-sister chromatids exchange maternal and paternal DNA. B. All of these choices are correct. C. bivalents are formed during prophase II and are taken apart during anaphase II. D. sister chromatids are separated. E. chromosomes undergo reductional division.
sister chromatids are separated
If you were able to find a drug that could inhibit the reactivation of telomerase activity in cancer cells, the cancer cells would: A. slowly erode their chromosome ends. B. stop dividing immediately. C. become less invasive. D. eventually die from lack of energy. E. gradually revert to normal cells.
slowly erode their chromosome ends
The enzyme _____ compensates for chromosomes shortening at the tips after each round of DNA replication. A. DNA polymerase B. DNA replicase C. DNA ligase D. telomerase E. topoisomerase II
telomerase
In which phase of mitosis does the nuclear envelope reform? A. telophase B. anaphase C. metaphase D. prophase
telophase
In DNA replication, each individual parent strand acts as a _____ strand for the synthesis of a _____ strand. A. template; daughter B. daughter; template C. duplicate; daughter D. template; duplicate E. daughter; duplicate
template; daughter
What feature of double-stranded DNA makes it necessary to have a leading strand and a lagging strand during replication? A. the hydrogen bonding between bases B. the negative charge on the sugar-phosphate backbone C. the base stacking of the bases D. the antiparallel orientation of the strands
the antiparallel orientation of the strands
Mitotic cell division is considered asexual because: A. this form of cell division is most similar to binary fission. B. the daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical. C. the daughter cells are genetically identical. D. the daughter cells receive DNA from one parent cell.
the daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical
What is the function of histone proteins? A. to organize the microtubules that make up the spindle B. to connect chromosomes to the mitotic spindle C. to package DNA in eukaryotic chromosomes D.to attach sister chromatids together
to package DNA in eukaryotic chromosomes
Energy is required in order to add a nucleotide to the growing strand of DNA during replication. From where does that energy come? A. primase B. helicase C. DNA polymerase D. the incoming nucleotide E. DNA ligase
the incoming nucleotide
Okazaki fragments are found on _____ strand of DNA. A. the leading B. the lagging C. the parental D. both the leading and lagging
the lagging
The centrosome is: A. a region of the chromosome where kinetochores attach. B. All of these choices are correct. C. a region of the chromosome where sister chromatids are attached to each other. D. the microtubule organizing center for the mitotic spindle. E. a region of the chromosome where microtubules attach to chromosomes during mitosis.
the microtubule organizing center for the mitotic spindle
A lack of telomerase activity limits what? A. the number of times a cell can divide B. the number of replication bubbles that form during replication C. the rate of DNA replication D. the number of Okazaki fragments that can be linked together E. the rate of meiosis
the number of times a cell can divide
Why are the X and Y chromosomes NOT considered homologous? A. they come from different parents B. mammalian males carry two very different chromosomes C. they do not carry the same set of genes D. they do not carry the same set of genes, and mammalian males carry two very different sex chromosomes
they do not carry the same set of genes, and mammalian males carry two very different sex chromosomes
What is the function of the enzyme DNA polymerase? A. to synthesize a strand of mRNA using DNA as a template B. to synthesize a strand of mRNA using mRNA as a template C. to synthesize a strand of DNA using DNA as a template D. to synthesize a polypeptide using DNA as a template E. to synthesize a strand of DNA using a polypeptide as a template
to synthesize a strand of DNA using DNA as a template
A cell in prophase I of meiosis has _____ as many chromosomes as each of the daughter cells following cytokinesis of meiosis II. A. twice B. four times C. one quarter D. half
twice
Sister chromatids are BEST described as two DNA molecules that have: A. different genes in the same order and possibly having different alleles of some genes. B. virtually identical sequences of nucleotides. C. different alleles of the same genes arranged in a different order. D. the same genes in the same order but having different alleles. E. the same alleles of the same genes in a different order.
virtually identical sequences of nucleotides
When we say that DNA replication is semiconservative, we mean that: A. parental DNA stays in the parent cell and daughter DNA ends up in the daughter cell. B. when DNA is replicated, one double helix contains both parental strands and one contains two newly synthesized daughter strands. C. None of the other answer options is correct. D. when DNA is replicated, each new double helix contains one parental strand and one newly synthesized daughter strand. E. only half of an organism's DNA is replicated during each cell division.
when DNA is replicated, each new double helix contains one parental strand and one newly synthesized daughter strand
