Chapter 7
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 statements regarding sexual and asexual reproduction is true?
Sexual reproduction is more likely to increase genetic variation than is asexual reproduction.
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?
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.
At a chiasma, two ________ are attached to each other.
homologous or nonsister chromatids
Chromatids are _____.
identical copies of each other if they are part of the same chromosome
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 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
During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles?
metaphase
Asexual reproduction requires ________ individual(s), whereas sexual reproduction requires _______ individual(s)
1;2
At the end of telophase I of meiosis, as cytokinesis occurs, there are __________.
2 haploid cells
How many pairs of autosomes do humans have?
22
What is the typical result when a diploid cell undergoes meiosis?
4 haploid cells
Polyploidy is involved in which of the following examples?
A normal watermelon has 22 chromosomes but seedless watermelons have 33 chromosomes.
Which of the following statements is false?
An X chromosome is an autosome
Both mitosis and meiosis are preceded by
Interphase
Crossing over occurs during _____.
Prophase I
Synapsis occurs during _____.
Prophase I
DNA replication occurs in _____.
S phase of interphase
During anaphase II, __________.
Sister chromatids separate and migrate toward opposite poles.
Which of the following types of organisms commonly demonstrates polyploidy?
flowering plants
The function of meiosis is to make __________.
four cells with a haploid number of chromosomes
Eukaryotic cells spend most of their cell cycle in which phase?
interphase
A karyotype is most like
photographs of every couple at a high school prom.
Which of the following features likely accounts for the difference between plant and animal cell cytokinesis?
plants have cell wall
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
Mitosis and cytokinesis result in the formation of __________; meiosis and cytokinesis result in the formation of __________.
two diploid cells : four haploid cells
Which of the following represents a chromosomally normal human female?
xx
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
Crossing over is important because it __________.
allows the exchange of genes between homologous chromosomes
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.
Karyotyping
can reveal alterations in chromosome number
Which of the following occurs during interphase?
cell growth and duplication of the chromosomes
The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called
cytokinesis.
A benign tumor differs from a malignant tumor in that a benign tumor
does not metastasize.
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?
Mitosis produces daughter cells with half the number of chromosomes as the parent cell.
Meiosis differs from mitosis in that _____ only occurs in meiosis.
crossing over
A cleavage furrow forms in an animal cell during _____.
cytokinesis
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
When we say that an organism is haploid, we mean that _____.
its cells each have one set of chromosomes
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
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
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
At the conclusion of meiosis I, the daughter cells are _____.
haploid and the sister chromatids are joined
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 _____. View Available Hint(s)
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
Down syndrome can be the result of _____.
nondisjunction of chromosome 21 during meiosis
Independent orientation of chromosomes at metaphase I results in an increase in the number of
possible combinations of characteristics.
In meiosis II, _____.
sister chromatids separate
An example of a cell that is 2n is a __________.
somatic cell
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)
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.
The creation of genetically identical offspring by a single parent, without the participation of sperm and egg, is called
Asexual reproduction
Which of the following statements correctly describes the timing of DNA synthesis?
DNA is synthesized in the S phase of interphase.
Asexual reproduction _____.
produces offspring genetically identical to the parent
The phase of mitosis during which the mitotic spindle begins to form is
prophase
The exchange of parts between nonhomologous chromosomes is called _____.
reciprocal translocation
Prior to mitosis and after S phase, each chromosome of a eukaryotic cell consists of a pair of identical structures called
sister chromatids.
