AP Biology: Mitosis and Meiosis

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes? A) 12 B) 16 C) 23 D) 46 E) 92

D

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. E) tetraploid, and the chromosomes are each composed of two chromatids.

D

All of the following occur during prophase of mitosis in animal cells *except* A) the centrioles move toward opposite poles B) the nucleolus can no longer be seen C) the nuclear envelope disappears D) chromosomes are duplicated E) the spindle is organized

D

Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with A) a single large nucleus. B) high concentrations of actin and myosin. C) two abnormally small nuclei. D) two nuclei. E) two nuclei but with half the amount of DNA.

D

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis? A) They have twice the amount of cytoplasm and half the amount of DNA. B) They have half the number of chromosomes and half the amount of DNA. C) They have the same number of chromosomes and half the amount of DNA. D) They have half the number of chromosomes and one-fourth the amount of DNA. E) They have half the amount of cytoplasm and twice the amount of DNA.

D

How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle? A) The daughter cells have half the amount of cytoplasm and half the amount of DNA. B) The daughter cells have half the number of chromosomes and half the amount of DNA. C) The daughter cells have the same number of chromosomes and half the amount of DNA. D) The daughter cells have the same number of chromosomes and the same amount of DNA. E) The daughter cells have the same number of chromosomes and twice the amount of DNA

D

If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested? A) anaphase B) prophase C) telophase D) metaphase E) interphase

D

proto-oncogenes

stimulate cell division, the mutated versions are called oncogenes and are always "on" which accelerates cell divison

internal controls

protein molecules present in varying concentrations during cell cycle ex: Cdk, cyclin

external controls

proteins and other signals generated by other cells that stimulate cell division ex: growth factors

kinetochore

proteins associated with centromere where the mitotic spindles attach

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in A) G1 B) G2 C) prophase D) metaphase E) anaphase

A

Cells that are in a nondividing state are in which phase? A) G0 B) G2 C) G1 D) S E) M

A

G₁ is represented by which numbered part(s) of the cycle? *graph is in definition* A) I or V B) II or IV C) III only D) IV only E) V only

A

If a cell has completed the first meiotic division 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 the same number of chromosomes but each of them has different alleles than another cell from the same meiosis. C) It has half the chromosomes but twice the DNA of the originating cell. D) It has one-fourth the DNA and one-half the chromosomes as the originating cell. E) It is identical in content to another cell from the same meiosis.

A

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) 30 D) 40 E) 80

A

If there are 20 chromatids in a cell, how many centromeres are there? A) 10 B) 20 C) 30 D) 40 E) 80

A

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in A) cells with more than one nucleus B) cells that are unusually small C) cells lacking nuclei D) destruction of chromosomes E) cell cycles lacking an S phase

A

Independent assortment of chromosomes is a result of A) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I. B) the random nature of the fertilization of ova by sperm. C) the random distribution of the sister chromatids to the two daughter cells during anaphase II. D) the relatively small degree of homology shared by the X and Y chromosomes. E) the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I, the random nature of the fertilization of ova by sperm, the random distribution of the sister chromatids to the two daughter cells during anaphase II, and the relatively small degree of homology shared by the X and Y chromosomes.

A

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, taxol must affect A) the fibers of the mitotic spindle B) anaphase C) formation of the centrioles D) chromatid assembly E) the S phase of the cell cycle

A

The MPF protein complex turns itself off by A) activating a process that destroys cyclin component. B) activating an enzyme that stimulates cyclin. C) binding to chromatin. D) exiting the cell. E) activating the anaphase-promoting complex.

A

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to A) disruption of mitotic spindle formation B) inhibition of regulatory protein phosphorylation C) suppression of cyclin production D) myosin denaturation and inhibition of cleavage furrow formation E) inhibition of DNA synthesis

A

Which of the following happens at the conclusion of meiosis I? A) Homologous chromosomes are separated. B) The chromosome number per cell is conserved. C) Sister chromatids are separated. D) Four daughter cells are formed. E) The sperm cells elongate to form a head and a tail end.

A

Which of the following is released by platelets in the vicinity of an injury? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

A

Which sample might represent a zygote? *graph is in definition* A) I B) II C) III D) either I or II E) either II or III

A

Which sample of DNA might be from a nerve cell arrested in G0 of the cell cycle? *graph is in definition* A) I B) II C) III D) either I or II E) either I or III

A

1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus 2. Alignment of tetrads at the metaphase plate 3. Separation of sister chromatids 4. Separation of the homologs; no uncoupling of the centromere 5. Synapsis; chromosomes moving to the middle of the cell in pairs Which of the steps takes place in both mitosis and meiosis? A) 2 B) 3 C) 5 D) 2 and 3 only E) 2, 3, and 5

B

During which phase of mitosis do the chromatids become chromosomes? A) telophase B) anaphase C) prophase D) metaphase E) cytokinesis

B

For a newly evolving protist, what would be the advantage of using eukaryote -like cell division rather than binary fission? A) Binary fission would not allow for the formation of new organisms. B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes. C) Cell division would be faster than binary fission. D) Cell division allows for lower rates of error per chromosome replication. E) Binary fission would not allow the organism to have complex cells.

B

Homologous chromosomes move to opposite poles of a dividing cell during A) mitosis B) meiosis I C) meiosis II D) fertilization E) binary fission

B

How is the S phase of the cell cycle measured? A) counting the number of cells produced per hour B) determining the length of time during which DNA synthesis occurred in the cells C) comparing the synthesis versus the breakdown of S protein D) determining when the S chromosome is synthesized E) stopping G1 and measuring the number of picograms of DNA per cell

B

If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will A) move directly into telophase B) complete the cycle and divide C) exit the cycle and switch to a nondividing state D) show a drop in MPF concentration E) complete cytokinesis and form new cell walls

B

The somatic cells derived from a single-celled zygote divide by which process? A) meiosis B) mitosis C) replication D) cytokinesis alone E) binary fission

B

What is the name for the special region on a duplicated chromosome that holds the sister chromatids together? A) centrosome B) centromere C) kinetochore D) desmosome E) microtubule organizer region

B

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? A) centromere B) centrosome C) centriole D) chromatid E) kinetochore

B

Which number represents DNA synthesis? *graph is in definition* A) I B) II C) III D) IV E) V

B

Which number represents the point in the cell cycle during which the chromosomes are replicated? *graph is in definition* A) I B) II C) III D) IV E) V

B

Which of the following are primarily responsible for cytokinesis in plant cells? A) kinetochores B) Golgi-derived vesicles C) actin and myosin D) centrioles and basal bodies E) cyclin-dependent kinases

B

Which of the following triggers the cellʹs passage past the G2 checkpoint into mitosis? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

B

Which sample might represent an animal cell in the G2 phase of the cell cycle? *graph is in definition* A) I B) II C) III D) both I and II E) either II or III

B

Why do chromosomes coil during mitosis? A) to increase their potential energy B) to allow the chromosomes to move without becoming entangled and breaking C) to allow the chromosomes to fit within the nuclear envelope D) to allow the sister chromatids to remain attached E) to provide for the structure of the centromere

B

A sample of human cells is suspended in a nutrient solution overnight. The next day, the scientist observes that the cells have undergone high rates of division. Why does this lead her to suspect that the cells are cancerous? A) Cancer cells do not exhibit density dependent inhibition. B) Cancer cells do not require growth factors. C) Cancer cells do not exhibit anchorage dependence. D) Cancer cells ignore typical cell cycle checkpoints.

C

At which of the numbered regions would you expect to find cells at metaphase? *graph is in definition* A) I and IV B) II only C) III only D) IV only E) V only

C

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor? A) metastasis B) changes in the order of cell cycle stages C) lack of appropriate cell death D) inability to form spindles E) inability of chromosomes to meet at the metaphase plate

C

Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur? A) Cancer cells are no longer density dependent. B) Cancer cells are no longer anchorage dependent. C) Chromosomally abnormal cells can still go through cell cycle checkpoints. D) Chromosomally abnormal cells still have normal metabolism. E) Transformation introduces new chromosomes into cells.

C

Chromosomes first become visible during which phase of mitosis? A) prometaphase B) telophase C) prophase D) metaphase E) anaphase

C

If a chemical signals in the cytoplasm control the progression of a cell to the M phase of the cell cycle, then fusion of a cell in G1 with a cell in early M phase would most likely result in A) replication of chromosomes only in the G1 cell B) exiting of both cells from the cell cycle and into the G0 phase C) condensation in chromatin in preparation of nuclear division in both cells D) transfer of organelles from the G1 cell to the cell in the M phase

C

In order for anaphase to begin, which of the following must occur? A) Chromatids must lose their kinetochores. B) Cohesin must attach the sister chromatids to each other. C) Cohesin must be cleaved enzymatically. D) Kinetochores must attach to the metaphase plate. E) Spindle microtubules must begin to depolymerize.

C

MPF reaches its threshold concentration at the end of this stage. *graph is in definition* A) I B) II C) III D) IV E) V

C

One difference between cancer cells and normal cells is that cancer cells A) are unable to synthesize DNA B) are arrested at the S phase of the cell cycle C) continue to divide even when they are tightly packed together D) cannot function properly because they are affected by density-dependent inhibition E) are always in the M phase of the cell cycle

C

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants A) the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils B) sister chromatids are identical, but they differ from one another in animals C) a cell plate begins to form at telophase, whereas in animals, a cleavage furrow is initiated at that stage D) chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase E) spindle poles contain centrioles, whereas spindle poles in animals do not

C

The sexual life cycle creates genetic variation in a population. Which of the following is not a source of genetic variation? A) Independent assortment of chromosomes B) Random fertilization C) Separation of homologs D) Crossing over

C

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 cell has eight homologous pairs. D) During the S phase of the cell cycle there will be 32 separate chromosomes. E) A gamete from this species has four chromosomes.

C

Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis? A) telophase B) prophase C) anaphase D) metaphase E) prometaphase

D

In the figure above, mitosis is represented by which numbered part(s) of the cycle? *graph is in definition* A) I B) II C) III D) IV E) V

D

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle was the nucleus with 6 picograms of DNA? A) G0 B) G1 C) S D) G2 E) M

D

Meiosis II is similar to mitosis in that A) homologous chromosomes synapse B) DNA replicates before the division C) the daughter cells are diploid D) sister chromatids separate during anaphase E) the chromosome number is reduced

D

Movement of the chromosomes during anaphase would be most affected by a drug that A) reduces cyclin concentrations B) increases cyclin concentrations C) prevents elongation of microtubules D) prevents shortening of microtubules E) prevents attachment of the microtubules to the kinetochore

D

Movement of the chromosomes during anaphase would be most affected by a drug that A) reduces cyclin concentrations B) increases cyclin concentrations C) prevents elongation of microtubules D) prevents shortening of microtubules E) prevents attachment of the microtubules to the kinetochore

D

Several organisms, primarily protists, have what are called intermediate mitotic organization. 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 never coil up their chromosomes when they are dividing. C) They use mitotic division but only have circular chromosomes. D) They maintain a nuclear envelope during division. E) None of them form spindles.

D

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A)4 B) 8 C)16 D) 32 E) 64

D

Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following? A) one-twelfth of the genes of the organism B) two chromosomes, each with six chromatids C) a single circular piece of DNA D) two long strands of DNA plus proteins E) two chromatids attached together at a centromere

D

The human X and Y chromosomes A) are both present in every somatic cell of males and females alike B) are of approximately equal size and number of genes C) are almost entirely homologous, despite their different names D) include genes that determine an individual's sex E) include only genes that govern sex determination

D

What causes the decrease in the amount of cyclin at a specific point in the cell cycle? A) an increase in production once the restriction point is passed B) the cascade of increased production once its protein is phosphorylated by Cdk C) the changing ratio of cytoplasm to genome D) its destruction by a process initiated by the activity of its complex with a cyclin E) the binding of PDGF to receptors on the cell surface

D

When we see chiasmata under a microscope, that lets us know which of the following has occurred? A) asexual reproduction B) meiosis II C) anaphase II D) prophase I E) separation of homologs

D

Which of the following is a function of those spindle microtubules that do not attach to kinetochores? A) maintaining an appropriate spacing among the moving chromosomes B) producing a cleavage furrow when telophase is complete C) providing the ATP needed by the fibers attached to kinetochores D) maintaining the region of overlap of microtubules in the cell's center E) pulling the poles of the spindles closer to one another

D

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) protein kinase D) cyclin E) Cdk

D

Which of the following proteins are involved in binary fission as well as eukaryotic mitotic division? A) cyclins B) Cdks C) MPF D) actin and tubulin E) cohesins

D

Which of these statements is *false*? A) In humans, each of the 22 maternal autosomes has a homologous paternal chromosome. B) In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY). C) Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote. D) At sexual maturity, ovaries and testes produce diploid gametes by meiosis. E) Sexual life cycles differ with respect to the relative timing of meiosis and fertilization.

D

A given organism has 46 chromosomes in its karyotype. We can therefore conclude which of the following? A) It must be human. B) It must be a primate. C) It must be an animal. D) It must be sexually reproducing. E) Its gametes must have 23 chromosomes.

E

A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation? A) The cell would prematurely enter anaphase. B) The cell would never leave metaphase. C) The cell would never enter metaphase. D) The cell would never enter prophase. E) The cell would undergo normal mitosis, but fail to enter the next G1 phase.

E

At which phase are centrioles beginning to move apart in animal cells? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase

E

During which phases of mitosis are chromosomes composed of two chromatids? A) from interphase through anaphase B) from G1 of interphase through metaphase C) from metaphase through telophase D) from anaphase through telophase E) from G2 of interphase through metaphase

E

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes? A) 23 B) 46 C) 460 D) 920 E) about 8 million

E

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) DNA synthesis D) cell elongation during anaphase E) cleavage furrow formation

E

The formation of a cell plate is beginning across the middle of a cell and nuclei are re -forming at opposite ends of the cell. What kind of cell is this? A) an animal cell in metaphase B) an animal cell in telophase C) an animal cell undergoing cytokinesis D) a plant cell in metaphase E) a plant cell undergoing cytokinesis

E

Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk

E

Which of the following statements is *not* true? A) Mitosis produces new nuclei with exactly the same chromosomal endowment as the parent nucleus. B) Mitosis may occur without cytokinesis. C) Mitosis and cytokinesis are required for asexual reproduction. D) All cells come from a preexisting cell. E) The mitotic spindles in prokaryotic cells are composed of microtubules.

E

gamete

a mature male/female haploid cell that unites with another cell of the opposite sex during sexual reproduction to produce a zygote

sister chromatids

a pair of identical chromosomes that are attached at the centromere

homologous chromosomes

a pair of non-identical chromosomes that carry the same genes

chromatid

a replicated chromsome

G2 checkpoint

checks for DNA damage and the DNA replication completeness, if a cell receives the go-ahead signal, it moves to M phase

G1 checkpoint

checks for cell size, nutrients, growth factors and DNA damage, if a cell receives the go-ahead signal, it moves to S phase

M checkpoint

checks for chromosome attachment to spindle at metaphase, if a cell receives the go-ahead signal, it finishes mitosis

chromosome

coiled up DNA around histone proteins

cytokinesis

cytoplasm divides in two, happens at the end of telophase

metasis

development of malignant growth, first stage of cancer

zygote

diploid cell that has 1/2 DNA from the mother and 1/2 the DNA from the father, eventually becomes a baby

haploid

human cell with 23 chromosomes (n) ex: germ (sex) cells

diploid

human cell with 46 chromosomes (2n) ex: liver, muscle cells

tumor supressor genes

inhibit cell division, the mutated versions are always "off" letting the cell cycle go uninterrupted

chromatin

loose, uncoiled DNA

G0

phase where cell is not dividing anymore and has left the cell cycle, it can be reversible in some cells and has led to interesting research on the possibility of a cure for paralysis

apoptopis

programmed cell death, if a cell has too many flaws in its DNA, it undergoes this

centromere

the region of the chromosome where the mitotic spindles attach via the kinetochore

induction

when one group of cells influences the development of another group of cells