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9th Edition of the famed Campbell Biology Series! Chapter 12

Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?

They need both if they are producing animal gametes.

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?


Why is it difficult to observe individual chromosomes with a light microscope during interphase?

They have uncoiled to form long, thin strands.

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?


Nucleoli are present during _____.


Cytokinesis often, but not always, accompanies _____.


Chromosomes become visible during _____.


Centromeres divide and sister chromatids become full-fledged chromosomes during _____.


Spindle fibers attach to kinetochores during _____.


When the separate chromosomes are being pulled from one place to another? This animation illustrates the events of _____.


When the two "circular" cells attached become sister cells? This animation illustrates the events of _____.

Cytokinesis as it occurs in Animal Cells

When the chromosomes become visible? This animation illustrates the events of _____.


When chromosomes align laterally (along the metaphase plate: imaginary line located midway between the poles of the duplicated chromosomes and the original chromosomes), before they separate. This animation illustrates the events of _____.


When the chromosomes break the nuclear envelope, and attach to microtubules


When the two "square" cells attached become sister cells? This animation illustrates the events of _____.

Cytokinesis as it occurs in Plant Cells

When the sister cells are completely divided through Cytokinesis. This animation illustrates the events of _____.


During prophase a homologous pair of chromosomes consists of _____.

Two (2) chromosomes and Four (4) Chromatids

Cell division occurs during this short phase, which generally involves two discrete processes: the contents of the nucleus (mainly the duplicated chromosomes) are evenly distributed to two daughter nuclei, and the cytoplasm divides in two.

Mitotic Phase

DNA synthesis (or replication) occurs during this phase. At the beginning of the phase, each chromosome is single. At the end, after DNA replication, each chromosome consists of two sister chromatids.

S Phase

Typically, this phase accounts for 90% of the cell cycle. It is a time of high metabolic activity. The cell grows by producing proteins and organelles, and chromosomes are replicated.


This is when division of the nucleus occurs. The chromosomes that have been replicated are distributed to two daughter nuclei.


This third subphase of interphase is a period of metabolic activity and growth. During this phase the cell makes final preparations for division.

G2 Phase

This is the portion of the cell cycle just after division, but before DNA synthesis. During this time the cell grows by producing proteins and organelles.

G1 Phase

This is the step in the cell cycle when the cytoplasm divides in two.


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

The Mitotic Phase: The Mitotic Phase encompasses both Mitosis and Cytokinesis!

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


Which of the following is true of kinetochores?

They are sites at which microtubules attach to chromosomes.

Which of the following correctly matches a phase of the cell cycle with its description?

G1: follows cell division

In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?

Large cells containing many nuclei.

Which of the following is found in binary fission but not in mitosis?

Duplicated chromosomes attach to the plasma membrane.

Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division?


Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?


Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?

They remain confined to their original site

Which of the following is a function of the S phase in the cell cycle?

The synthesis of sister chromatids

The copying of chromosomes occurs during which of the following phases of the cell cycle?

S Phase

For the first several divisions of early frog embryos, cells proceed directly from the M phase to the S phase and back to M without gaps. Which of the following is likely to be true about dividing cells in early frog embryos?

The cells get smaller with each generation

True or false? The M phase is characterized by the replication and division of a cell's chromosomes.

False: Cells replicate their chromosomes during the S phase and divide partition their chromosomes during the M phase.

If an organism normally has 34 chromosomes, how many molecules of DNA should there be in the G1 phase of the cell cycle?


Which of the following events would cause the cell cycle to arrest?

Poor nutrition conditions

DNA replication produces two identical DNA molecules called ______, which separates during mitosis.

Sister Chromatids

After chromosomes condense, the ______ is the region where the identical DNA molecules are most tightly attached to each other


During Mitosis, microtubules attach to chromosomes at the _______.


In dividing cells, most of the cell's growth occurs during ______.


The ____________ is a cell structure consising of microtubules, which forms during early mitosis and plays a role in cell division

Mitotic Spindle

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called _______.


In most eukaryotes, division of the nucleus is followed by ________, when the rest of the cell divides.


The ________ are the organzing centers for mcrotubules involed in seperatng chromasomes during mitosis


Which of the following statements are true of cytokinesis in plant cells? Two that apply.

1. Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.

2. The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells.

Which species does this apply to? The cells divide by constriction of a ring protein. (2 apply)

Bacteria & Animal

Which species does this apply to? The presence of a cell wall prevents the cell from dividing by constriction. (1 apply)


Which species does this apply to? Tubulin subunits or tubulin-like molecules function in the division of the cell. (2 apply)

Bacteria & Plants

A mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumor's origin.

Benign Tumor

A method of asexual reproduction by "division in half." In prokaryotes, binary fission does not involve mitosis, but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process.

Binary Fission

(1) The conversion of a normal animal cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer.


A cancerous tumor containing cells that have significant genetic and cellular changes and are capable of invading and surviving in new sites. Malignant tumors can impair the functions of one or more organs.

Malignant Tumor

An imaginary structure located at a plane midway between the two poles of a cell in metaphase on which the centromeres of all the duplicated chromosomes are located.

Metaphase Plate

The spread of cancer cells to locations distant from their original site.


Any cell in a multicellular organism except a sperm or egg or their precursors.

Somatic Cell

One difference between cancer cells and normal cells is that cancer cells....

continue to divide even when they are tightly packed together.

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