exam 3

A human bone marrow cell in the prophase stage of mitosis contains 46 chromosomes. Therefore, there are a total of __________ sister chromatids in this cell. 92 23 46 23 or 46, depending on whether you look at the beginning or end of prophase

92

Mature human neuron (nerve) cells and muscle cells become cancerous more easily than other cell types. are permanently in a state of nondivision. cease dividing after a predetermined number of cell generations. continue to divide throughout their lifetime.

are permanently in a state of nondivision.

A cell replicates its entire chromosomal DNA only __________. when the cell needs RNA before it is about to divide when it makes protein to repair damage caused by mutation

before it is about to divide

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called cytokinesis. binary fission. mitosis. telophase.

cytokinesis

Which of the following is a feature of plant cell division that distinguishes it from animal cell division? formation of a cleavage furrow production of four (rather than two) new cells per mitotic division lack of cytokinesis formation of a cell plate

formation of a cell plate

Both mitosis and meiosis are preceded by telophase. interphase. prometaphase. prophase.

interphase

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes. 64 16 8 32 30

16 because it is half of 32

Normal human gametes carry _____ chromosomes. 23 pairs of 46 pairs of 23 5 46

23

What is the typical result when a diploid cell undergoes meiosis? four haploid cells two diploid cells two haploid cells four diploid cells

four haploid cells

During anaphase I, __________ sister chromatids separate and migrate toward opposite poles homologous chromosomes separate and migrate toward opposite poles chromosomes line up in one plane nuclear membranes re-form

homologous chromosomes separate and migrate toward opposite poles

Nucleoli are present during _____. prometaphase anaphase metaphase prophase interphase

interphase

When we say that an organism is haploid, we mean that _____. its cells each have one set of chromosomes its cells each have two sets of chromosomes Its cells have one half of a chromosome its cells each have one chromosome

its cells each have one set of chromosomes

Asexual reproduction _____. produces offspring that always look exactly like the parent produces offspring genetically identical to the parent is limited to plants leads to a loss of genetic material

produces offspring genetically identical to the parent

Many cancer drugs known as "antimitotics" target microtubules. What is the first stage of mitosis at which these drugs are likely to have an effect? telophase metaphase anaphase prophase

prophase

The correct order of events during meiosis is prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II. prophase I, anaphase I, telophase I, metaphase I, meiosis II. metaphase I, prophase I, telophase I, anaphase I, cytokinesis, meiosis II. prophase I, anaphase I, metaphase I, telophase I, meiosis II, cytokinesis. metaphase I, prophase I, anaphase I, telophase I, cytokinesis, meiosis II.

prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.

The exchange of parts between nonhomologous chromosomes is called _____. inversion transformation crossing over reciprocal translocation

reciprocal translocation

During anaphase II, __________. nuclear membranes re-form sister chromatids separate and migrate toward opposite poles homologous chromosomes separate and migrate toward opposite poles the cell is diploid

sister chromatids separate and migrate toward opposite poles

Which of these cells is (are) haploid?

After Meiosis I and Meiosis II (C &D)

Which of the following statements is false? Two haploid cells fuse during fertilization. An X chromosome is an autosome. A zygote is a fertilized egg. Gametes are haploid cells.

An X chromosome is an autosome.

The first step of bacterial replication is _____. pinching of the plasma membrane separation of daughter cells attachment of the DNA to the plasma membrane DNA replication

DNA replication

The chromosomes line up in the center of the cell during which phase of mitosis? Prophase Metaphase Interphase Anaphase Telophase

Metaphase

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis? Telophase Metaphase Anaphase Interphase Prophase

Prophase

Which of the following is a key difference between meiosis and mitosis? Chromosomes condense. Chromosomes migrate to opposite poles. Chromosomes align at the metaphase plate. Synapsis occurs.

Synapsis occurs.

Cancer is not usually inherited because the cancerous cells usually interfere with the ability to produce gametes. the causes of cancer are not usually genetic. people with cancer usually die before reproducing. the chromosomal changes in cancer are usually confined to somatic cells.

The chromosomal changes in cancer are usually confined to somatic cells

What must happen before a cell can begin mitosis? The nuclear envelope must break up. The sister chromatids must be separated. The chromosomes must be duplicated. The nucleus must divide in two. A mitotic spindle must form.

The chromosomes must be duplicated.

What would be the immediate consequence of destroying a cell's centrosomes? The nuclear envelope could never re-form. The mitotic spindle would not form. The nuclear envelope would never break down. Sister chromatids would lose their centromeres.

The mitotic spindle would not form.

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other? The sequences are identical. The sequences are similar, but not identical. The sequence in one chromatid is complementary to the sequence in the other. The sequences are unrelated.

The sequences are identical.

What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells? the amount of DNA present whether the DNA is housed in a nucleus or not whether the DNA is linear or circular all of the above are differences between prokaryotic and eukaryotic DNA

all of the above are differences between prokaryotic and eukaryotic DNA

Eukaryotic chromosomes differ from prokaryotic chromosomes in that they are housed in a membrane-enclosed nucleus. include fewer proteins. are simpler. are circular in structure.

are housed in a membrane-enclosed nucleus.

Bacteria divide by: mitosis binary fission sexual reproduction meiosis

binary fission

As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of density-dependent inhibition. growth factor inhibition. density-independent inhibition. anchorage independence.

density-dependent inhibition.

A benign tumor differs from a malignant tumor in that a benign tumor spreads from the original site. is cancerous. does not metastasize. never causes health problems.

does not metastasize.

Gametes are produced by _____. meiosis asexual reproduction the cell cycle mitosis fertilization

meiosis

After fertilization, the resulting zygote begins to divide by __________. meiosis mitosis schizogony binary fission

mitosis

The kinetochores are __________. sites at which microtubules attach to chromosomes used to organize tubulin into elongated bundles called spindle fibers found as each spindle interlocks at the cell's equator and then moves apart, causing the cell to elongate the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis

sites at which microtubules attach to chromosomes

An example of a cell that is 2n is a __________. sperm or ovum gametophyte somatic cell haploid cell

somatic cell

Cytokinesis often, but not always, accompanies _____. interphase telophase prometaphase metaphase anaphase

telophase

During which phase of mitosis does the nuclear envelope re-form? telophase metaphase anaphase prophase

telophase

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis? Anaphase Metaphase Prophase Telophase Interphase

Anaphase

Which of the following statements correctly describes the timing of DNA synthesis? DNA is synthesized in G2 of interphase immediately preceding mitosis. DNA is synthesized in the S phase of interphase. DNA is synthesized continuously throughout the cell cycle DNA is synthesized only during mitosis.

DNA is synthesized in the S phase of interphase.

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis? Anaphase Metaphase Interphase Prophase Telophase

Telophase

What event will immediately follow the event shown in this image?

The cell will divide into two plant cells.

Centromeres divide and sister chromatids become full-fledged chromosomes during _____. prometaphase telophase metaphase anaphase interphase

anaphase

Which processes lead to most genetic variation in sexually reproducing organisms? independent orientation of chromosomes in meiosis crossing over cytokinesis random fertilization

independent orientation of chromosomes in meiosis crossing over random fertilization

during _____ the cell grows and replicates both its organelles and its chromosomes. cytokinesis mitosis G1 interphase S

interphase

Spindle fibers attach to kinetochores during _____. anaphase telophase prometaphase interphase metaphase

prometaphase

Chromosomes become visible during _____. prophase interphase prometaphase anaphase metaphase

prophase

DNA replication occurs in _____. prophase of both mitosis and meiosis the S phase of interphase the G1 phase of interphase in reproductive cells only metaphase of meiosis only

the S phase of interphase

The genetic material is duplicated during G1. G2. the mitotic phase. the S phase.

the S phase.

Crossing over is _____. the movement of genetic material from one chromosome to a nonhomologous chromosome an independent assortment of chromosomes the formation of tetrads the exchange of homologous portions of nonsister chromatids

the exchange of homologous portions of nonsister chromatids

During _____ both the contents of the nucleus and the cytoplasm are divided. G1 G2 the mitotic phase mitosis S

the mitotic phase

During mitosis, the chromosomes move because _____. they slide along microfilament bundles of the duplication of the centrosome they diffuse within the nucleus to areas where they are less concentrated they attach to a dynamic, precisely regulated mitotic spindle

they attach to a dynamic, precisely regulated mitotic spindle

During prophase a homologous pair of chromosomes consists of _____. one chromosome and four chromatids one chromosome and two chromatids four chromosomes and two chromatids two chromosomes and two chromatids two chromosomes and four chromatids

two chromosomes and four chromatids