Biology Ch.12

A cell contains 40 chromatids at the beginning of mitosis. How many chromosomes will it contain at the completion of cytokinesis? A. 20 B. 10 C. 40 D. 5 E. 160 F. 80

A

Chromatids are __________. A. identical copies of each other if they are part of the same chromosome B. found only in aberrant chromosomes C. held together by the centrioles D. composed of RNA E. the bacterial equivalent of eukaryotic chromosomes

A

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division? A. cleavage B. DNA replication C. formation of the cell plate D. binary fission E. formation of the mitotic spindle

A

Cytokinesis often, but not always, accompanies _____. A. telophase B. prometaphase C. metaphase D. anaphase E. interphase

A

Cytokinesis refers to __________. A. division of the cytoplasm B. division of the nucleus C. division of the entire cell D. movement of a cell from one place to another E. reduction in the number of chromosomes

A

DNA replication occurs in __________. A. the S phase of interphase in both somatic and reproductive cells B. prophase of both mitosis and meiosis C. the cytokinesis portion of the cell's life cycle D. the G1 phase of interphase in reproductive cells only E. metaphase of meiosis only

A

During binary fission in a bacterium __________. A. the origins of replication move apart B. the two DNA molecules float free in the cell and are guided to daughter cells by a spindle-like apparatus C. the two DNA molecules divide in half, forming four DNA fragments D. the two DNA molecules attach to the centrioles E. the two DNA molecules break up into plasmids

A

How many chromatids does a human somatic cell contain after interphase and just prior to mitosis? A. 92 B. 23 C. 184 D. 69 E. 46 F. 22

A

Observations of cancer cells in culture support the hypothesis that cancer cells __________. A. do not exhibit density-dependent inhibition B. produce molecules that inhibit the growth factors required for cell division C. spend the majority of their time in the G0 phase D. exhibit anchorage dependence E. all of the listed responses are correct

A

Spindle fibers attach to kinetochores during _____. A. prometaphase B. anaphase C. telophase D. metaphase E. interphase

A

The complex of DNA and protein that makes up a eukaryotic chromosome is properly called __________. A. chromatin B. a centromere C. a chromoplast D. a centrosome E. a chromatid

A

What is the difference between a benign tumor and a malignant tumor? A. Cells of benign tumors do not metastasize; those of malignant tumors do. B. Cells of benign tumors metastasize; those of malignant tumors do not. C. Benign tumors will not kill you; malignant tumors will. D. Benign tumors arise by transformation; malignant tumors do not. E. Benign tumors do not arise by transformation; malignant tumors do.

A

Which of the following events occurs during prometaphase of mitosis? A. The nuclear envelope fragments. B. The centrosomes move away from each other. C. The sister chromatids are pulled toward opposite sides of the cell. D. The nuclear envelope forms again. E. The chromosomes align along the metaphase plate of the cell. F. The mitotic spindle forms.

A

Which of the following is true of kinetochores? A. They are sites at which microtubules attach to chromosomes. B. They interdigitate at the cell's equator and then move apart, causing the cell to elongate. C. They are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers. D. They are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis. E. They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow.

A

Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope? A. Telophase B. Metaphase C. Interphase D. Anaphase E. S phase

A

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis? A. They need both if they are producing animal gametes. B. They need only meiosis if they produce egg cells. C. A single-celled organism only needs mitosis. D. They need only mitosis to make large numbers of cells such as sperm. E. They need meiosis if the cells are producing organs such as ovaries.

A

_____ is a carcinogen that promotes colon cancer. A. fat B. UV light C. estrogen D. a virus E. testosterone

A

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? A. 46 B. 92 C. 46 or 92, depending on the portion of prophase examined D. 23 or 46, depending on the portion of prophase examined E. 23

B

During interphase, the genetic material of a typical eukaryotic cell is __________. A. dispersed in the cytoplasm as long strands of chromatin B. dispersed in the nucleus as long strands of chromatin C. transported through the nuclear pores D. condensed and the chromosomes are often visible under the light microscope E. attached to microtubule spindle fibers

B

In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle? A. Prophase B. Cytokinesis C. The G1 phase D. Metaphase E. Anaphase

B

The spread of cancer cells to other locations in the body is known as __________. A. None of the listed responses is correct. B. metastasis C. density-dependent inhibition D. transformation E. a benign tumor F. chemotherapy

B

Which of the following events does not occur during prophase of mitosis? A. The chromosomes condense. B. The mitotic spindle breaks down. C. Nucleoli disappear. D. The mitotic spindle forms. E. Each duplicated chromosome appears as two identical sister chromatids. F. The centrosomes move away from each other.

B

Which of the following events occurs during telophase of mitosis? A. The nuclear envelope fragments. B. Two distinct daughter nuclei form in the cell. C. DNA replicates. D. The sister chromatids separate. E. The chromosomes align on the metaphase plate. F. The chromosomes condense.

B

Why is it difficult to observe individual chromosomes with a light microscope during interphase? A. The spindle must move them to the metaphase plate before they become visible. B. They have uncoiled to form long, thin strands. C. Sister chromatids do not pair up until division starts. D. The DNA has not been replicated yet. E. They leave the nucleus and are dispersed to other parts of the cell.

B

You would know a dividing cell was a plant cell rather than an animal cell if you saw that __________. A. it had formed a cleavage furrow B. it had formed a cell plate C. it had two pairs of centrioles during prophase D. it had microtubules E. the nucleolus was visible during metaphase

B

During prophase a homologous pair of chromosomes consists of _____. A. one chromosome and four chromatids B. one chromosome and two chromatids C. two chromosomes and four chromatids D. four chromosomes and two chromatids E. two chromosomes and two chromatids

C

Which event or events occur during anaphase? A. The centrioles are at opposite poles B. A spindle made of microtubules is present C. All of the listed responses are correct. D. The centromeres divide E. Identical chromatids move to opposite poles

C

Which of the following correctly matches a phase of the cell cycle with its description? A. M: duplication of DNA B. G2: cell division C. G1: follows cell division D. S: immediately precedes cell division E. All of the above are correctly matched.

C

Which of the following events does not occur during interphase of the cell cycle? A. Protein production B. Production of the endoplasmic reticulum C. Separation of the sister chromatids D. Duplication of the chromosomes E. Production of new mitochondria F. Growth of the cell

C

Which of the following is found in binary fission but not in mitosis? A. The result produces 2 nuclei. B. Replication of DNA begins at an origin. C. Duplicated chromosomes attach to the plasma membrane. D. Replicated strands of DNA separate. E. Following the process, a membrane separates the 2 copies.

C

Which of the following structures is/are part of the mitotic spindle? A. The aster B. Centrosome C. All of the listed responses are part of the mitotic spindle. D. Kinetochore microtubules E. Nonkinetochore microtubules

C

A cell biologist examined the DNA content of a cell from a fruit fly larva during the G1 phase and determined that it had 150 units of DNA. After measuring the DNA content of the same type of cell after the G2 phase, it was discovered that the cell had 300 units of DNA. How is this possible? A. The DNA was replicated after the G2 phase of interphase. B. The DNA was replicated prior to interphase. C. The DNA was not replicated. This was the result of a mutation. D. The DNA was replicated during the S phase of interphase, which occurs between the two G phases. E. The DNA was replicated during the G2 phase of interphase. F. The DNA was replicated during the G1 phase of interphase.

D

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? A. S B. M C. G2 D. G1 E. cytokinesis

D

How does the process of mitosis differ between most eukaryotes and other eukaryotes such as diatoms and dinoflagellates? A. Sister chromatids are not separated during mitosis in diatoms and dinoflagellates. B. Microtubules do not facilitate the movement of chromosomes in diatoms and dinoflagellates. C. The chromosomes are not duplicated prior to mitosis in diatoms and dinoflagellates. D. The nuclear envelope fragments in most eukaryotes but remains intact in diatoms and dinoflagellates. E. The nuclear envelope remains intact in most eukaryotes but fragments in diatoms and dinoflagellates. F. None of the listed responses is correct.

D

Nucleoli are present during _____. A. anaphase B. prometaphase C. prophase D. interphase E. metaphase

D

Which of the following events occurs during metaphase of mitosis? A. The mitotic spindle forms. B. The chromosomes condense. C. The nuclear envelope disappears. D. The chromosomes align along the metaphase plate of the cell. E. The sister chromatids are pulled apart toward opposite sides of the cell. F. The nuclear envelope forms again.

D

Which of the following events occurs during telophase of mitosis A. The chromosomes align on the metaphase plate. B. DNA replicates. C. The chromosomes condense. D. Two distinct daughter nuclei form in the cell. E. The nuclear envelope fragments. F. The sister chromatids separate.

D

Which of the following is true of benign tumors, but not malignant tumors? A. They are the result of the transformation of normal cells. B. They have an unusual number of chromosomes. C. They can divide indefinitely if an adequate supply of nutrients is available. D. They remain confined to their original site E. They migrate from the initial site of transformation to other organs or tissues.

D

Centromeres divide and sister chromatids become full-fledged chromosomes during _____. A. interphase B. metaphase C. telophase D. prometaphase E. anaphase

E

Checkpoints in the cell cycle control system __________. A. only stop cells from dividing B. ensure that a cell keeps dividing C. have no effect on the cell cycle D. stop cancer cells from dividing E. regulate the cell cycle through a variety of stop and go signals F. only signal cells to undergo mitosis

E

Chromosomes become visible during _____. A. prometaphase B. anaphase C. metaphase D. interphase E. prophase

E

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this? A. division of the organism into many cells, most lacking nuclei B. inability to duplicate DNA C. a decrease in chromosome number D. a rapid rate of gamete production E. large cells containing many nuclei

E

One event occurring during prophase is __________. A. the synthesis of a new nuclear envelope B. the alignment of chromosomes in a single plane C. cytokinesis D. division of the centromere E. the beginning of the formation of a spindle apparatus

E

The function of the mitotic cell cycle is to produce daughter cells that __________. A. have a random assortment of maternal and paternal chromosomes B. have the same number of chromosomes as the parent cell but not the same genetic content C. have the same number of chromatids as the parent cell had chromosomes D. None of the listed responses is correct. E. are genetically identical to the parent cell (assuming no mutation has occurred)

E

The region of a chromosome holding the two double strands of replicated DNA together is called __________. A. a centriole B. a chromatid C. an aster D. chromatin E. a centromere

E

Which of the following events does not occur during interphase of the cell cycle? A. Protein production B. Duplication of the chromosomes C. Production of the endoplasmic reticulum D. Production of new mitochondria E. Separation of the sister chromatids F. Growth of the cell

E

Which of the following events occurs during anaphase of mitosis? A. The nuclear envelope fragments. B. Spindle fibers attach to the centromeres of the chromosomes. C. The chromosomes align along the metaphase plate of the cell. D. The mitotic spindle forms. E. The sister chromatids are pulled apart toward opposite sides of the cell. F. The nuclear envelope forms again.

E

Which of the following events occurs during telophase of mitosis? A. The nuclear envelope fragments. B. The chromosomes condense. C. DNA replicates. D. The sister chromatids separate. E. Two distinct daughter nuclei form in the cell. F. The chromosomes align on the metaphase plate.

E

Which of the following statements describes a cell that undergoes mitosis but not cytokinesis? A. The cell has undergone transformation and become a cancer cell. B. The cell does not contain a nucleus. C. The cell has not proceeded through interphase. D. The cell dies. E. The cell contains more than one nucleus. F. The cell has one nucleus.

E

Which of the following structures is/are part of the mitotic spindle? A. Centrosome B. Nonkinetochore microtubules C. Kinetochore microtubules D. The aster E. All of the listed responses are part of the mitotic spindle.

E

Which of these is NOT a carcinogen? A. testosterone B. UV light C. cigarette smoke D. fat E. all of the above are carcinogens

E

Which of the following statements correctly describes the difference(s) between mitosis and binary fission? A. There are no differences between binary fission and mitosis. B. Binary fission involves the replication and division of multiple chromosomes, whereas mitosis involves the replication and division of a single chromosome. C. None of the listed responses is correct. D. Binary fission in bacteria is completed by microtubules, but mitosis does not involve these structures. E. A cell plate forms across the middle of two cells dividing by binary fission, but this does not occur in mitosis. F. Binary fission involves the replication and division of a single chromosome, whereas mitosis involves the division of multiple, replicated chromosomes.

F

During _____ the cell grows and replicates both its organelles and its chromosomes.

Interphase

During _____ both the contents of the nucleus and the cytoplasm are divided.

the mitotic phase