Bio Chapter 9

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

If there are 20 centromeres in a cell during anaphase of mitosis, how many chromosomes are there in each daughter cell following cytokinesis?

10

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 each contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in a daughter cell of one of these cells?

100 units

When not engaged in the processes leading to cell division, how many chromosomes from your mother are present in the nucleus of each of your somatic cells?

23

Beginning with a fertilized egg (zygote), how many cells would be present in an embryo following a series of five cell divisions?

32

A cell entering mitosis with 32 chromosomes will produce daughter cells with __________.

32 chromosomes; the same number of chromosomes as the parent cell from which they are produced.

If a human somatic cell is in metaphase, it has __________ chromatids.

92

Down syndrome is characterized by cells having three copies of chromosome 21. As a somatic cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present in the cell's nucleus?

94

If you saw a cell with chromosomes condensing, you would know that the cell was in A. prophase. B. prometaphase. C. metaphase. D. anaphase. E. telophase

A. prophase

Density-dependent inhibition is explained by which of the following statements? As cells become more numerous, the cell surface proteins of adjacent cells bind to each other and send signals that inhibit cell division. As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce growth factors. As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor. As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.

As cells become more numerous, the cell surface proteins of adjacent cells bind to each other and send signals that inhibit cell division.

If you were counting chromosomes in the gametes and the somatic cells of a giraffe, what should be the ratio of the number in the former to the number in the latter? A. 1:1 B. 1:2 C. 1:3 D. 1:4 E. 1:8

B. 1:2

How does nuclear DNA enter daughter cells? A. during replication with microtubule proteins B. as identical copies of the same chromosomes C. during G1 when ribosomes disappear D. as four copies of each chromosome per daughter cell E. attached to all other chromosomes in that cell

B. as identical copies of the same chromosomes

Told to label this model of the cell cycle during which the cell divides, you would look in the part representing

B. cytokinesis

If asked what part of the cell cycle an adult's eukaryotic was in, you would be most likely correct if you guessed A. prophase. B. interphase. C. G1 phase. D. anaphase. E. S phase.

B. interphase

If the nuclear envelope has disappeared but the condensed chromosomes are not yet lined up, the cell is in A. prophase. B. prometaphase. C. metaphase. D. anaphase. E. telophase.

B. prometaphase

If you saw a cell with condensed chromosomes lined up in the center of the cell, you would know that the cell was in A. prophase. B. prometaphase. C. metaphase. D. anaphase. E. telophase.

C. metaphase

What is the difference between a benign tumor and a malignant tumor?

Cells of benign tumors do not metastasize; those of malignant tumors do.

The cleavage furrow forms during which stage of mitosis and cell division of an animal cell?

Cytokinesis

For what is cell division used? A. infection B. growth C. repair D. B and C

D. B and C

If you saw a cell with chromosomes separating but not yet at the poles, you would know that the cell was in A. prophase. B. prometaphase. C. metaphase. D. anaphase. E. telophase.

D. anaphase

If you were asked to label a model of a chromosome, the central portion of a replicated chromosome would be labeled A. kinetochore. B. sister. C. arm. D. centromere. E. Not enough information is provided to decide.

D. centromere

Which of the following does not occur during mitosis?

Duplication of chromosomes

If you saw a cell reversing the changes to chromosomes seen in prophase, you would know that the cell was in A. prophase. B. prometaphase. C. metaphase. D. anaphase. E. telophase.

E. telophase

Which of the following molecules or structures are primarily responsible for cytokinesis in plant cells but not in animal cells?

Golgi-derived vesicles

Researchers established a number of cultured cell lines derived from different tumors. How might they determine which ones are malignant?

Identify the ones with aberrant chromosome number or structure.

Which of the following molecules is released by human platelets in the vicinity of a cut to stimulate proliferation of skin cells?

PDGF

The person credited with the axiom, "Every cell from a cell" is __________.

Rudolf Virchow

Humans produce skin cells by mitosis and gametes by meiosis. Which of the following statements about the nuclei of skin cells is correct?

They contain twice as much DNA as the nuclei of gametes produced by meiosis.

Which of the following characteristics is associated with cancer cells?

They evade the normal controls that trigger programmed cell death.

When a cell is in late anaphase of mitosis, which of the following may be observed?

a clear area in the center of the dividing cell

Which best describes the kinetochore? A. a structure composed of several proteins that associate with the centromere region of a chromosome and that can bind to spindle microtubules B. the centromere region of a metaphase chromosome at which the D N A can bind with spindle proteins C. the array of vesicles that will form between two dividing nuclei and give rise to the metaphase plate D. the ring of actin microfilaments that will cause the appearance of the cleavage furrow E. the core of proteins that forms the cell plate in a dividing plant cell

a structure composed of several proteins that associate with the centromere region of a chromosome and that can bind to spindle microtubules

At what time will the chromosome shown be split into two chromosomes, each the same as the other?

anaphase

At which phase of mitosis do the sister chromatids become daughter chromosomes?

anaphase

The function of mitosis and cytokinesis is to produce daughter cells that ___________.

are genetically identical to the parent cell

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 G1 and G2 phases

Most animal cells exhibit anchorage dependence, which means that in order to divide,

cells must be attached to a substrate or extracellular matrix of a tissue.

The complex of DNA and protein that makes up a eukaryotic chromosome is properly called __________.

chromatin

The cell cycle is regulated at the molecular level by a set of proteins known as

cyclins

During interphase, the genetic material of a typical eukaryotic cell is __________.

dispersed in the nucleus as long strands of chromatin

Cytokinesis refers to __________.

division of the cytoplasm

Observations of cancer cells in culture support the hypothesis that cancer cells __________.

do not exhibit density-dependent inhibition (a phenomenon in which crowded cells stop dividing.)

Tissue culture experiments with PDGF demonstrate that without this substance __________.

fibroblasts fail to divide

Sister chromatids are __________.

identical copies of a chromosome

You would know a dividing cell was a plant cell rather than an animal cell if you saw that __________.

it had formed a cell plate

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following characteristics is most desirable?

it targets only rapidly dividing cells

Besides the ability of some cancer cells to divide uncontrollably, what else might logically result in formation of a tumor?

lack of appropriate cell death

Stained microtubules are marked with a laser during mitosis. How would you explain the results shown? A. Chromosomes are separated by microfilaments. B. Chromosomes are not separated. C. Microtubules shorten at the centrosome end. D. Microtubules shorten at the chromosome end. E. None of the answers is correct

microtubules shorten at the centrosome end

Which of the following processes does not occur in dividing bacteria?

mitosis

You would be unlikely to see which of the following human cells dividing?

nerve cell

What will be the result if a eukaryotic cell completes mitosis but does not undergo cytokinesis?

one cell with two nuclei, each identical to the nucleus of the parent cell

During binary fission of a bacterium, __________.

origins of replication move apart

During which phase of mitosis in animal cells do centrioles begin to move apart?

prophase

In a human skin cell that is going through the cell cycle, when do the centrosomes separate?

prophase

One event occurring during prophase is __________.

the beginning of the formation of a mitotic spindle

Diatoms and some yeasts are unicellular eukaryotes that have mechanisms of nuclear division that may resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?

the nuclear envelope remains intact during division