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)
