Chapter 7

what occurs during metaphase 2?

-the chromosomes are aligned on the metaphase plate -the kinetochores of the sister chromatids of each chromosome pointing toward opposite poles

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

1;2

how many cell divisions is meiosis involved with?

2

How many pairs of autosomes do humans have?

22

When observing a bird skin cell in G2 under a microscope, you count 160 total chromatids. How many chromosomes does a male chicken have in its sperm cells?

40

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

47

In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.

5

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

Polyploidy is involved in which of the following examples? A. Some plants alternate between haploid and diploid phases. B. A normal watermelon has 22 chromosomes but seedless watermelons have 33 chromosomes. C. XO females D. XYY males

A normal watermelon has 22 chromosomes but seedless watermelons have 33 chromosomes

Oncologists (medical doctors who treat cancer patients) routinely take biopsies (samples) of tissue from patients to determine whether the tissue is cancerous or not. What would be the best technique to use to determine whether cells from the tissue sample are cancerous?

Add cells from the tissue sample to a cell culture dish and compare their growth against a sample of noncancerous cells from the patient

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

An X chromosome is an autosome

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

Cell growth and duplication of the chromosomes

During meiosis I, homologous chromosomes form a tetrad and crossing over occurs. What is the outcome of crossing over?

Crossing over creates new combinations of genes present on a single chromosome

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

DNA is synthesized in the S phase of interphase

Both mitosis and meiosis are preceded by

Interphase

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

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

Which of the following statements regarding mitosis and meiosis is false? A. In animals, meiosis only occurs in the ovaries and testes. B. All sexual life cycles involve an alternation of diploid and haploid stages. C. A normal human zygote has 46 chromosomes. D. Mitosis produces daughter cells with half the number of chromosomes as the parent cell.

Mitosis produces daughter cells with half the number of chromosomes as the parent cell

Jacobsen syndrome, which can cause heart defects, intellectual deficiencies, and bleeding disorders, is caused by a deletion of the terminal end of chromosome 11. What method could you use to determine whether an individual has Jacobsen syndrome?

Perform a karyotype using a person's white blood cells

Which of the following features likely accounts for the difference between plant and animal cell cytokinesis? A. Animal cells lack chloroplasts. B. Plant cells have two sets of chromosomes; animal cells have one set of chromosomes. C. Plant cells have cell walls. D. Animal cells lack the microfilaments required for forming a cleavage furrow.

Plant cells have cell walls

DNA replication occurs in _____.

S phase

Which of the following statements regarding sexual and asexual reproduction is true? A. Sexual reproduction typically includes the development of unfertilized eggs. B. Sexual reproduction is more likely to increase genetic variation than is asexual reproduction. C. Only offspring from asexual reproduction inherit traits from two parents. D. Cell division only occurs after sexual reproduction.

Sexual reproduction is more likely to increase genetic variation than is asexual reproduction

During anaphase II, __________.

Sister chromatids separate and migrate toward opposite poles

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 are housed in a membrane-enclosed nucleus

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

The mitotic spindle would not form

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

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

You are observing a single cell under a microscope. You go home for the night, and the next day you see four cells. The four cells look similar, and when you stain them with a dye that binds to DNA they all appear to contain the same amount of DNA as the original cell. What likely happened overnight?

The single cell divided to form two new cells, and the two new cells each divided to form four total cells, all by asexual reproduction

A chromosomally normal human female

XX

what occurs during prophase 2?

a spindle forms and moves the chromsomes towards the middle

What is the definition of meiosis?

a type of cell division that results in formation of haploid gametes

Crossing over is important because it __________.

allows the exchange of different versions of genes between homologous chromosomes

which category of the life cycles in multi-cellular organisms does this definition describe: -two stages are apparent in plants and some algae

alternation of generation

these characteristics represent what stage in meiosis: -migration of chromosomes toward the two poles of the cell -Only the tetrads split up but the sister chromatids making up each double chromosome remain attached -six daughter chromosomes moves toward each pole

anaphase 1

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

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

Mature human neuron (nerve) cells and muscle cells

are permanently in a state of nondivision

The creation of genetically identical offspring by a single parent, without the participation of sperm and egg, is called

asexual reproduction

which reproduction represent these characteristics: -only one parent required -a result of mitotic cell division -resulting in formation of genetically identical individuals - most common in prokaryotes, Protists, some plants, and a few simple animals

asexual reproduction

what term best suits the definition: -error in chromosome number example: trisomy 21 - Down's Syndrome; higher risk due to maternal age increases

aueuploid

Karyotyping

can reveal alterations in chromosome number

what is the definition of euploid and example?

correct number of chromosome for a species humans have 22 pairs of autosomes and 1 pair of sex chromosomes

Meiosis differs from mitosis in that _____ only occurs in meiosis.

crossing over

the term that suits this definition: -the exchange of genetic material between homologous chromosomes resulting in chromosomes that incorporate genes from both parents (recombination).

crossing over

A cleavage furrow forms in an animal cell during _____.

cytokinesis

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

cytokinesis

these characteristics represent what stage in meiosis 1: -occurs during another stage of meiosis 1 two haploid daughter cells are formed

cytokinesis

Definition of inversion

detachment rotation reinsertion

which category of the life cycles in multi-cellular organisms does this definition describe: -most obvious in most animals

diploid

what are the three categories of life cycles in multi-cellular organisms?

diploid-dominant haploid-dominant alternation of generation

A benign tumor differs from a malignant tumor in that a benign tumor

does not metastasize

what is the female gamete called?

egg

You see a cell with several nuclei and you know that something is different about cell division. What is the most likely explanation?

failure of cytokinesis following mitosis

What is the term for the fusion of two gametes of opposite sex individuals resulting in a diploid zygote?

fertilization

Which of the following types of organisms commonly demonstrates polyploidy? A. fish B. flowering plants C. mammals D. reptiles

flowering plants

The function of meiosis is to make _____.

four cells with a haploid number of chromosomes

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

four haploid cells

what is the result of meiosis 2?

four new haploid gametes

what are the results of nondisjunction?

gametes with too many or too few chromosomes

which category of the life cycles in multi-cellular organisms does this definition describe: -most obvious in fungi and most algae

haploid

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

haploid and the sister chromatids are joined

At a chiasma, two ________ are attached to each other.

homologous or non-sister chromatids

Chromatids are _____.

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

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

interphase

these characteristics represent what stage in meiosis 1: -chromosomes duplicate -each chromosome consist of two genetically identical sister chromatids joined together -cell's centrosome has duplicated

interphase

what are common characteristics with mitosis and meiosis?

interphase - G1, S, and G2 prophase - chromosome visible

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

inversion

If a chromosome fragment breaks off and then reattaches to the original chromosome but in the reverse direction, the resulting chromosomal abnormality is called a(n)

inversion

If a fragment of a chromosome breaks off and then reattaches to the original chromosome at the same place but in the reverse direction, the resulting chromosomal abnormality is called _____.

inversion

When we say that an organism is haploid, we mean that _____.

its cells each have one set of chromosomes

what is the difference between mitosis and meiosis 2?

meiosis 2 starts with a haploid cell

What is the stage of cell division in a diploid organism if you see seven chromosomes, each consisting of a pair of sister chromatids?

meiosis II prophase

Nondisjunction occurs when

members of a chromosome pair fail to separate

During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles?

metaphase

these characteristics represent what stage in meiosis 1: - chromosomes tetrads are aligned in the m... plate -spindle micro-tubules are attached to kinetochores at the centromeres -within each tetrad, the homologous chromosomes are held together at sites of crossing over (line up in pairs) -the new arrangement forces the homologous chromosomes to move to opposite poles of the cell

metaphase 1

After fertilization, the resulting zygote begins to divide by __________.

mitosis

If scientists studying cancer could understand how to promote cell division in cells that do not ordinarily divide, this might help people who had injuries involving

muscle or nerve cells

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____.

nondisjunction

If the four cells shown resulted from cell division of a single cell with diploid chromosome number 2n = 4, what best describes what just occurred?

nondisjunction

what term best suits this definition: -occurs when pairs of chromosomes or sister chromatids fail to separate during meiosis

nondisjunction

Down syndrome can be the result of _____.

nondisjunction of chromosome 21 during meiosis

what occurs during telophase 2?

nuclei form at the cell poles cytokinesis occurs at the same time as well which result in four daughter cells (each with the haploid number of chromosomes)

definition of monosomy?

one less chromosome

A karyotype is most like A. photographs of every couple at a high school prom. B. the answer key to a multiple-choice exam. C. a movie showing the stages of the reproductive cycle of a beetle. D. a map showing the hidden location of buried treasure.

photographs of every couple at a high school prom

what is the definition of karyogram?

pictures of chromosomes from one somatic cell arranged by size, bonding patterns, and centromere position

what term best suits the definition: -individuals with one or more extra sets of chromosomes

polyploid

Independent orientation of chromosomes at metaphase I results in an increase in the number of

possible combinations of characteristics

Asexual reproduction _____.

produces offspring that are identical to the parent

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

prophase

these characteristics represent what stage in meiosis 1: -synapsis -tetrad -crossing over -chromosomes coil tightly and spindles form -nuclear envelope breaks into fragments -chromosome tetrads captured by spindle micro-tubules are moved toward the center of the cell

prophase 1

Synapsis occurs during _____

prophase I of meiosis

Crossing over occurs during

prophase I of meiosis I

Crossing over occurs during _____.

prophase I of meiosis I

The exchange of parts between nonhomologous chromosomes is called _____.

reciprocal translocation

which cycle includes: -meiosis -fertilization

sexual life cycle

Prior to mitosis and after S phase, each chromosome of a eukaryotic cell consists of a pair of identical structures called

sister chromatids

In meiosis II, _____.

sister chromatids separate

what is the name of the cell that match these characteristics: -non-sex cells -diploid number of chromosomes -nucleus contains two copies of each chromosome (homologous pairs) -one copy of each chromosome from each parent -one set of chromosome (from each parent)

somatic

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

somatic cell

what is the definition of recombinant?

something composed of genetic material from two sources

Definition of germ cells

special cells --- that are diploid--- that only produce haploid gamete by meiotic cell division

What is the male gamete called?

sperm

these characteristics represent what stage in meiosis 1: -chromosomes arrive at the poles of the cell -each pole of the cell has a haploid chromosome set even though each chromosome is still in duplicate form

telophase 1

the term that suits this definition: -two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase 1.

tetrad

what is the result of meiosis 1 in telophase and cytokinesis?

the cell has the haploid number of double stranded chromosomes

what occurs during anaphase 2?

the centromeres of the sister chromatids separate the sister chromatids of each pair (now individual chromosomes) move toward opposite poles

Cancer is not usually inherited because

the chromosomal changes in cancer are usually confined to somatic cells

Crossing over is _____.

the exchange of homologous portions of nonsister chromatids

what is the definition for synapsis?

the formation of a close association between homologous chromosome during prophase 1

what is the definition of chiasmata?

the structure that forms at the crossover points after genetic material is exchanged

You are studying chromosomal movement in a frog species whose haploid number is 3. What will you see in meiosis I prophase of this cell?

three chromosomes, each single-stranded (unduplicated)

what term best suits this definition: -occurs when a segment of genetic material breaks from one chromosome and reattaches to another chromosome or to a different part of the same chromosome

translocation

what term best suits the definition: -one extra chromosome

trisomy

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

two diploid cells : four haploid cells

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

two haploid cells

normal sex chromosomes

xx - female xy - male

sex chromosome errors in humans

xxx - female (no y) xo - no sex chromosome xxy - male (if a y is present)