Chapter 8 Mastering Biology

benign tumor

A _________ is a lump of abnormal cells that, although growing out of control, remains at its original site.

malignant tumor

A _________ is an abnormally growing mass of cells that is actively spreading through the body.

cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues

A benign and a malignant tumor differ in that _____.

100 units

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 contained 200 units of DNA. What would be the amount of DNA in one of the grasshopper daughter cells?

cytokinesis in a plant cell

A cell is treated with a drug that prevents the formation of intracellular (within the cell) vesicles. Which of the following processes would be blocked?

interphase.

A cell preparing to undergo meiosis duplicates its chromosomes during

before it is about to divide

A cell replicates its entire chromosomal DNA only __________.

24

A certain species of animal has six pairs of chromosomes. How many DNA molecules are present in the nuclei of these animals during G2 phase?

cytokinesis

A cleavage furrow forms in an animal cell during _____.

16

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

diploid organisms

A diploid zygote develops into ______ by mitosis

inversion

A fragment of chromosome 21 reattaches to chromosome 21, but in the reverse direction. What is the name given to this change?

92

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.

46

A human somatic cell contains _____ chromosomes.

haploid and the sister chromatids are joined

At the conclusion of meiosis I, the daughter cells are _____.

two haploid cells

At the end of telophase I of meiosis, as cytokinesis occurs, there are _____.

cytokinesis

At the end of the mitotic (M) phase, the cytoplasm divides in a process called _________________.

metaphase

At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell?

binary fission

Bacteria divide by:

16

Baker's yeast is an organism with 32 chromosomes that can perform asexual or sexual reproduction and exist as both a diploid and haploid cell. After meiosis, how many chromosomes will be present in each cell?

I: random fertilization; II: independent orientation; III: crossing over

Below are three statements. Classify them as examples of independent orientation, crossing over, or random fertilization. I: The formation of a zygote from an egg and a sperm is an unpredictable event. II: Random combinations of paternal and maternal chromosomes end up in gametes. III: An allele on the paternal chromosome 18 ends up on the maternal chromosome 18.

remain confined to their original site

Benign tumors differ from malignant tumors in that the cells of a benign tumor _____.

interphase

Both mitosis and meiosis are preceded by

anaphase

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

identical copies of each other if they are part of the same chromosome

Chromatids are _____.

prophase

Chromosomes become visible during _____.

G1

Consider the cell cycle shown below. Cells will usually divide if they receive the proper signal at a checkpoint in the _____ phase of the cell cycle.

mitosis

Consider the process by which bacterial populations grow. What process performs a similar function in humans?

It ensures that each daughter cell receives one copy of the chromosome.

During binary fission, one copy of the duplicating chromosome moves to the opposite end of the cell. What does this achieve?

It ensures the separation of the replicated chromosomes as new membrane is made.

During binary fission, the replicated bacterial chromosome attaches to the plasma membrane by specialized anchor proteins. What is the purpose of this attachment between chromosome and membrane?

They organize the microtubules.

During cell division, what role do centrosomes play?

prophase I.

During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

they attach to a dynamic, precisely regulated mitotic spindle

During mitosis, the chromosomes move because _____.

homologous chromosomes stick together in pairs.

During prophase I of meiosis,

two chromosomes and four chromatids

During prophase a homologous pair of chromosomes consists of _____.

47

Each cell in an individual with Down syndrome contains _____ chromosomes.

interphase

Eukaryotic cells spend most of their cell cycle in which phase?

meiosis

Gametes are produced by _____.

fertilization

Gametes go through ____ to become a zygote.

fertilization

Haploid gametes join in

centromere

Here i am representing a duplicated chromosome. What structure is represented by my waist where I am joined to my twin?

maternal chromosomes and paternal chromosomes

Homologous pairs of chromosomes include

22

How many pairs of autosomes do humans have?

They align and assort independently to form any of eight different combinations.

If the diploid number of chromosomes in a certain animal is 6 (2n = 6), there are three sets of two homologous chromosomes each, or three pairs. How do these three pairs align and separate in meiosis?

64

If we assume that crossing over does not occur, how many different combinations of chromosomes are possible in a zygote derived from diploid parents who each have three pairs of chromosomes?

meiosis I only

If you look through a microscope and see a cell with chromosomes lined up two by two, what stage of cellular reproduction must you be looking art?

the start of meiosis I

Imagine I've taken a snapshot of the chromosomes in a hypothetical cell. Two chromosomes lined up. You and your twin and your friends and her twin. Part of that snapshot looks like this (duplicated chromosomes lined up by homologous pair). What stage of the lifecycle must that cell be in?

10

Imagine you found a hypothetical organism. You examine one of its gametes and you see that it contains 5 chromosomes. How many chromosomes will one of its body cells contain just before mitosis begins?

G1, S, G2, M

Immune system cells enter a resting phase after undergoing mitosis. When activated - for example, by an infection - they can reenter the sequence of events in the cell cycle that leads to cell division. What would be the correct sequence of events?

two

In a cell with eight chromosomes, one chiasma develops during meiosis I in only one particular pair of homologs. How many recombinant chromosomes will there be at the completion of meiosis II?

distribution of a copy of the single parental chromosome to each daughter cell

In bacterial cells, binary fission involves _____.

male ... the male can contribute either an X or a Y chromosome

In humans, the _____ determines the sex of the offspring because _____.

are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes

In many organisms, including humans, chromosomes are found in homologous pairs. Homologous chromosomes _____.

sister chromatids are separated

In meiosis II, _____.

tissue repair/replacement of damaged cells and growth and development

In sexually reproducing multicellular organisms, the main functions of mitosis are _____.

Cancer cells continuously secrete growth factors into the cell culture medium.

In the laboratory, cancer cells fail to show density-dependent inhibition of growth in cell culture. What is one explanation that could account for this?

chiasma

In the picture below, the chromosomal region where the nonsister chromatids are crossing over is called a(n) _____.

Two of the embryos will be trisomic for chromosome 18, and two will contain a single copy of chromosome 18.

In theory, when a nondisjunction for chromosome 18 occurs during meiosis I, four gametes can be produced. If these gametes are fertilized with unaffected gametes from the second parent, what observations would you make concerning the resulting embryos?

1

Inbreeding has a number of interesting effects. For one, highly in-bred strains (varieties) may carry identical forms of every gene. Mice have 40 chromosomes in their diploid (2n) set. How many genetically distinct kinds of gametes (gametes with different genetic characteristics) could be produced through meiosis in an in-bred strain where there are identical forms of every gene?

genetic variation

Independent assortment and crossing over results in

shuffling cards and dealing out hands of poker.

Independent orientation of chromosomes at metaphase I and random fertilization are most like

they have uncoiled to form long, thin strands

Individual chromosomes are usually observed with a light microscope during mitosis, even though cells spend more time in interphase. This is because _____.

a- Pair of homologous chromosomes b- centromere c- sister chromatids

Label the diagram. both objects- a middle- b each strand- c

a- autosomes b- sex chromosomes c- karyotype

Label the diagram. the objects- a the x and y- b the entire thing- c

meiosis I

Looking through a light microscope at a cell undergoing meiosis, you see that the chromosomes have joined into XX-shaped tetrads. These tetrads are lined up along a plane that runs through the center of the cell. This cell is in _____.

telophase

Looking through a light microscope at a dividing cell, you see two separate groups of chromosomes on opposite ends of the cell. New nuclear envelopes are taking shape around each group. The chromosomes then begin to disappear as they unwind. You are witnessing _____.

are permanently in a state of nondivision.

Mature human nerve cells and muscle cells

haploid gametes

Meiosis forms

meiosis I and meiosis II

Meiosis includes

three steps. All of the chromosomes are duplicated in a diploid cell, and then there are two cell divisions to produce a total of four haploid gametes.

Meiosis is typically accomplished in _____.

diploid ... haploid

Meiosis starts with _____ cells and produces _____ gametes.

four haploid cells.

Meiosis starts with a single diploid cell and produces

two diploid cells ... four haploid cells

Mitosis and cytokinesis result in the formation of _____; meiosis and cytokinesis result in the formation of _____.

23

Normal human gametes carry _____ chromosomes.

interphase

Nucleoli are present during _____.

do not exhibit density-dependent inhibition

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

mitosis

Of the two processes we learned about, which is going on in my hand right now?

carcinoma

The most common type of cancer is a _________; this type always originates in tissues that line organs.

prophase

The phase of mitosis during which the mitotic spindle begins to form is

At metaphase, the mitotic spindle is fully formed and chromosomes are lined up in the center of the cell.

What occurs during this stage of mitosis?

In anaphase, sister chromatids separate and become full-fledged chromosomes that move to opposite poles.

What occurs during this stage of mitosis?

In prophase, microtubules form the mitotic spindle, and the nuclear envelope breaks up.

What occurs during this stage of mitosis?

In telophase, chromosomes become less condensed and new nuclear envelopes form.

What occurs during this stage of mitosis?

Most of the cell's lift is spent in interphase, when growth occurs. Cells that are about to divide replicate their DNA.

What occurs during this stage?

prophase- mitotic spindle forming metaphase- sister chromosomes separating telophase and cytokinesis- nuclear envelopes forming

What occurs in each stage?

4 haploid cells are produced and sister chromatids sparate

What occurs in meiosis II?

The mitotic spindle would not form.

What would be the immediate consequence of destroying a cell's centrosomes?

density-dependent inhibition.

When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of

G1

When examining cells in the laboratory, you notice that a particular cell has half as much DNA as the surrounding cells. It appears that this cell's cell cycle halted at checkpoint _____.

divide by mitosis

When forming buds, hydras _____.

Synapsis of homologous pairs occurs.

Which event occurs only during prophase I of the first meiotic division?

Chromosomes condense and are attached to spindle fibers and the nuclear envelope breaks down

Which events occur during prophase? Chromosomes are replicated. Chromosomes condense and are attached to spindle fibers. The nuclear envelope breaks down. The sister chromatids break apart and begin to separate.

A check that chromosome replication has been successfully completed

Which of the following checkpoints does not occur late in G1? A check that chromosome replication has been successfully completed A check that the cell is large enough for division A check that nutrients are sufficient A check that growth factors are present

XO

Which of the following indicates Turner syndrome? XXX XO XYY XXY

d- metaphase - chromosomes line up on the equatorial plane.

Which of the following is a correct representation of an event that occurs in mitosis? a- anaphase - the nuclear envelope disappears. b- prometaphase - there is movement of the chromosomes to the poles. c- prophase - chromosomes uncoil. d- metaphase - chromosomes line up on the equatorial plane.

XX

Which of the following is a normal human female? XXY XX X XXX

The organism must be able to control the timing and rate of cell division in different parts of its body.

Which of the following must occur for a plant or animal to grow and develop normally? The organism must be able to control the timing and rate of cell division in different parts of its body. The organism must receive a supply of the appropriate hormones from its parents. Sufficient light must be available to stimulate cell division. Sufficient oxygen must be available to stimulate cell division. Submit

cell growth and duplication of the chromosomes

Which of the following occurs during interphase? separation of newly formed DNA to opposite ends of the cell cell growth and duplication of the chromosomes cytokinesis a reduction in the size of the nuclear membrane

Two daughter nuclei, one at each pole of the cell, are generated.

Which of the following occurs during mitosis? Two genetically different daughter cells result. Chromosomes replicate. Organelles replicate. Two daughter nuclei, one at each pole of the cell, are generated.

d- prophase, prometaphase, metaphase, anaphase, telophase Submit

Which of the following shows mitosis in the correct chronological order? a- telophase, prophase, anaphase, prometaphase, metaphase b- anaphase, prometaphase, metaphase, prophase, telophase c- prometaphase, metaphase, prophase, telophase, anaphase d- prophase, prometaphase, metaphase, anaphase, telophase

DNA is synthesized in the S phase of interphase.

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

Genetic diversity is enhanced by mitosis.

Which of the following statements regarding genetic diversity is false? Genetic diversity is enhanced by independent orientation of chromosomes at metaphase I. Genetic diversity is enhanced by random fertilization. Genetic diversity is enhanced by crossing over during meiosis. Genetic diversity is enhanced by mitosis.

diploid zygote

fertilization forms a

genetically identical offspring

During asexual reproduction, yeast cells can produce _____.

the S phase

The genetic material is duplicated

sites at which microtubules attach to chromosomes

The kinetochores are _____.

First view: G1; second view: G2; third view: telophase

A skin cell of a red fox has 34 chromosomes. You look at the cell under a microscope and see that it has 34 chromosomes and one nucleus. Several hours later, you look at the same cell again and see that it has double the amount of DNA and one nucleus. A little while later, you see that it has 68 chromosomes and two nuclei. What stage of the cell cycle was this cell in when you viewed it at each time point?

A only

A technique called flow cytometry is used by scientists and researchers to count or sort cells based on specific properties. By labeling cellular DNA with a fluorescent dye, flow cytometry can sort cells based on the amount of DNA present, thereby making it possible to distinguish between cells that are in different stages of the cell cycle. Flow cytometry is especially useful to the medical community because it can help with the diagnosis of certain types of cancers. Below is a typical set of data that you might obtain when running a flow cytometry experiment using a sample of healthy skin cells. Use this figure to help you answer the following question. If you used flow cytometry to sort a sample of cancerous cells that have been treated with a drug to prevent them from replicating their DNA, what peaks would you expect to see on the resulting flow cytometry data set?

C

A technique called flow cytometry is used by scientists and researchers to count or sort cells based on specific properties. By labeling cellular DNA with a fluorescent dye, flow cytometry can sort cells based on the amount of DNA present, thereby making it possible to distinguish between cells that are in different stages of the cell cycle. Flow cytometry is especially useful to the medical community because it can help with the diagnosis of certain types of cancers. Below is a typical set of data that you might obtain when running a flow cytometry experiment using a sample of healthy skin cells. Use this figure to help you answer the following question. Which peak represents cells that contain the most DNA?

Trisomy for the other autosomal chromosomes is often lethal, and the affected embryos are miscarried.

Although in humans there are 22 pairs of autosomal chromosomes, only three different chromosomal trisomies are commonly seen in newborns. Of the remaining 19 autosomes, many trisomies have not been seen in newborns. Why not?

somatic cell

An example of a cell that is 2n is a __________.

cancer

An individual with a malignant tumor is said to have _________.

haploids

Are gametes haploids or diploids?

haploids

Are haploids or diploids used during meiosis?

diploids

Are haploids or diploids used during mitosis?

diploids

Are zygotes haploids or diploids?

can produce great variation among the offspring

Asexual and sexual reproduction differ in that sexual reproduction _____.

1; 2

Asexual reproduction requires ________ individual(s), whereas sexual reproduction requires _______ individual(s).

telophase I and prophase II

At a critical point in meiosis, the chromosomes do not replicate. This occurs between _____.

the exchange of homologous portions of nonsister chromatids

Crossing over is _____.

prophase I

Crossing over occurs during _____.

formation of a cleavage furrow

Cytochalasin B is a chemical that disrupts microfilament formation. This chemical would interfere with _____.

finishes mitosis by dividing the cytoplasm and organelles of the original parent cell into two separate daughter cells

Cytokinesis _____.

telophase

Cytokinesis often, but not always, accompanies _____.

division of the cell outside the nuclear material

Cytokinesis refers to _____.

the S phase of interphase

DNA replication occurs in _____.

homologous pairs of chromosomes

Diploid organisms have

nondisjunction of chromosome 21 during meiosis

Down syndrome can be the result of _____.

the mitotic phase

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

interphase

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

interphase

During _____, the cell carries out its normal functions and the chromosomes are thinly spread out throughout the nucleus.

sister chromatids separate and migrate toward opposite poles

During anaphase II, _____.

During mitosis, chromosomes are more condensed than during interphase.

Scientists commonly choose white blood cells that are going through mitosis to prepare karyotypes. Why?

meiosis

Sexual life cycle of diploid organisms involves

anaphase and telophase

Single sister chromatids are found in cells at mitotic _____.

prometaphase

Spindle fibers attach to kinetochores during _____.

prophase I

Synapsis occurs during _____.

The pairing up of homologous chromosomes and crossing over only occur during meiosis.

The M phase of mitosis and M phase of meiosis both occur after interphase. However, the two processes differ in the arrangement and behavior of their chromosomes. How?

homologous chromosomes ... sister chromatids

The _____ separate in meiosis I; the _____ separate in meiosis II.

Prophase

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?

Telophase

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?

Metaphase

The chromosomes line up in the center of the cell during which phase of mitosis?

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

The correct order of events during meiosis is

reciprocal translocation

The exchange of parts between nonhomologous chromosomes is called _____.

DNA replication

The first step of bacterial replication is _____.

are genetically identical to the parent cell (assuming no mutation has occurred)

The function of mitosis is to produce daughter cells that _____.

reproduction (production of gametes)

The function(s) of meiosis is/are _____.

Anaphase

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?

11

There are species of coffee plant with 22, 44, 66, and 88 chromosomes. All but one of these species is considered to be an example of polyploidy. Plant geneticists believe that the original haploid number of chromosomes in coffee was _____.

Only one copy of the X chromosome is active, regardless of the total number of X chromosomes.

Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X chromosome is not. What is the explanation for this difference?

False

True or false. Mitosis takes place during M phase of the cell cycle, which is longer than interphase.

meiosis

Variation occurs when chromosomes are shuffled in _____.

Interphase- G1 phase, S phase, G2 phase Mitotic (M) phase- Mitosis, Cytokinesis

What are the cell cycle stages?

Propase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis

What are the stages of meiosis I?

Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis

What are the stages of meiosis II?

Interphase, Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis, Meiosis II

What are the stages of meiosis?

Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis

What are the stages of mitosis?

gametes (egg and sperm cells)

What are these?

The cell will divide into two plant cells.

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

the amount of DNA present, whether the DNA is housed in a nucleus or not, and whether the DNA is linear or circular

What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?

four haploid cells

What is the typical result when a diploid cell undergoes meiosis?

zygote (2n)

What is this?

The chromosomes must be duplicated.

What must happen before a cell can begin mitosis?

asexual reproduction

What name is given to this process?

independent assortment and crossing over

What occurs during meiosis I?

In cytokinesis, the cytoplasm divides

What occurs during this stage after mitosis?

Prokaryotic chromosomes are more complex than those of eukaryotes.

Which of the following statements regarding prokaryotes is false? In prokaryotes, daughter chromosomes are separated by an active movement away from each other and the growth of a new plasma membrane between them. Most prokaryotes reproduce by binary fission. Prokaryotic cells are generally smaller and simpler than eukaryotic cells. Prokaryotic chromosomes are more complex than those of eukaryotes.

Mitosis allows organisms to generate genetic diversity.

Which of the following statements regarding the function of mitosis is false? Mitosis allows organisms to grow. Mitosis allows organisms to reproduce asexually. Mitosis allows organisms to generate genetic diversity. Mitosis allows organisms to repair tissues.

C and D

Which of these cells is (are) haploid? Parent cell- A DNA replicates- B 2 daughter cells- C 4 daughter cells- D

B and C

Which of these gametes contains one or more recombinant chromosomes?

E

Which of these phases encompasses all of the stages of mitosis?

independent orientation of chromosomes in meiosis, crossing over, random fertilization

Which processes lead to most genetic variation in sexually reproducing organisms?

Extra copies of the other somatic chromosomes are probably fatal.

Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16?

The sequences are identical.

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?

The chromosomes are housed in a membrane-enclosed nucleus.

You and your lab partner are observing a cell under a microscope, but you do not know whether it is a eukaryote or a prokaryote. Which of the following observations regarding the chromosomes would you use to immediately conclude that the cell is a eukaryote? The chromosomes contain very few proteins. The chromosomes are very simple in structure. The chromosomes are housed in a membrane-enclosed nucleus. The chromosomes are circular in structure.

The cells in flask B will have grown significantly, but the cells in flask A will have not grown at all.

You have two flasks (labeled A and B) that each contain an equal population of normal animal cells. You place flask A in a machine called a shaking incubator, which shakes the flask at 37°C and keeps the cells moving so as to not allow them to adhere to the bottom of the flask. Flask B is allowed to sit in an incubator (without shaking) at 37°C. If you let the cells in each flask grow for a week, which of the following results are you most likely to observe?

mitosis

Zygotes divide by _____ to become an embryo.

Metastasis

_________ is the spread of cancer cells from their site of origin to other sites in the body.