chater 9
Rank the steps of meiosis I in the order in which they occur, beginning with the first phase at the top.
1. prophase I 2. metaphase I 3. anaphase I 4. telophase I
Other than trisomy 21, trisomies in what chromosomes are the next most common in infants?
18 13
How many rounds of cytokinesis occur during meiosis?
2
Mitotic divisions yield ______ daughter cells, and meiotic divisions yield ______ daughter cells.
2 4
Down syndrome can be caused by an extra copy of chromosome
21
theres a total of _ paries of chromosomes in a human diploid pair
23
If a cell has 16 pairs of chromosomes, how many unique configurations of chromatids can be produced in gametes as a result of random orientation during meiosis?
2^16
If an animal has 6 chromosome pairs in its cells, then 64 combinations of chromatids are possible for a gamete. If both male and female gametes have 64 possible chromosome combinations, how many genetically unique zygotes could be produced due to random fertilization? (Assume crossing over does not occur.)
4000
Diploid human cells contain a total of ______ chromosomes.
46
If a cell has 3 pairs of homologous chromosomes, how many unique configurations of chromatids can occur in gametes as a result of random orientation of chromosomes in metaphase I?
8
______ splits the cell into two cells after telophase I.
Cytokinesis
An extra copy of chromosome 21 causes
Down syndrome.
______ is the merging of a sperm and an egg to create a diploid zygote.
Fertilization
What occurs during telophase II and the process of cytokinesis that follows it?
Four haploid cells are formed.
What correctly describes metaphase I of meiosis I?
Homologous chromosomes line up as pairs along the center of the cell.
Select all of the following that are true about the cell shown in the image.
Metaphase of mitosis is shown. Homologous chromosomes are aligned singly.
______ results in genetically identical daughter cells, whereas ______ results in genetically different daughter cells.
Mitosis; meiosis
Select all of the following that occur in prophase I of meiosis.
Nuclear envelope breaks up. Crossing over occurs. Chromosomes condense. Spindle forms from microtubules.
What results in a random mixture of paternal and maternal genetic material in each daughter cell during meiosis?
Random orientation of chromosome pairs during metaphase I
Humans reproduce via
SEX
`Chlamydomonas is a unicellular green algae that exhibits a simple form of ______ reproduction in which two genetically different cells fuse to form a new individual.
SEXUAL
Select all of the following that are true about the X and Y chromosomes in humans.
X is much bigger than Y carry different genes
What occurs when chromosomes do not separate during meiotic divisions?
`nondisjunction
What is a karyotype?
a size-ordered chart of all the chromosomes in a cell
Consider one chromosome that contains alleles A, B, and C, and the homologous chromosome that contains the alleles a, b, and c. If crossing over occurred once during meiosis at a site on the chromosome between the B gene and the C gene, then what alleles could a resulting chromatid contain? Select all that apply.
a, b, C A, B, c
Different versions of a gene are called
alleles
Homologous chromosomes are separated, but sister chromatids remain attached at the centromere, during what phase of meiosis?
anaphase I
Sister chromatids of each chromosome in a cell are separated to opposite poles during
anaphase II
A cell that has one or a few extra or missing chromosomes is called a(n) _____ cell.
aneuploid
A cell that results from nondisjunction is called a(n) ______ cell.
aneuploid
The X and Y chromosomes in humans
are not homologous.
Bacteria and archaea reproduce by ______ reproduction when they produce genetically identical offspring.
asexual
When ______ reproduction occurs in a one-celled organism, the organism replicates its DNA and splits into two genetically identical cells.
asexual
While ______ reproduction is less costly, ______ reproduction is commonly utilized because it generates genetic diversity.
asexual; sexual
The 22 pairs of human chromosomes that are the same in both males and females are called .
autosomes
What chromosomes occur in pairs of the same size and contain the same genes in both genders?
autosomes
Select all of the following that are able to reproduce by asexual reproduction.
bacteria archaea many multicellular eukaryotes many unicellular eukaryotes
Select all the organisms that can produce gametes for sexual reproduction.
bread molds ferns humans
Select all of the following that are true about nondisjunction.
caused by malformed spindle fibers can occur at either anaphase I or anaphase II produces abnormal gametes
Sister chromatids of each chromosome in a cell are separated to opposite poles during
chiasma
The sites on homologous chromosomes where crossing over occurs are called
chiasmata.
A single molecule of DNA and its associated proteins form a
chromosomes
Diploid cells contain two full sets of
chromosomes
In eukaryotes, a molecule of genetic material and its associated proteins form a(n) , of which humans have 46 in each cell.
chromosomes
Select all of the following that apply to human autosomes.
chromosomes 1 through 22 homologous pairs
This image shows two ways that ______ during meiosis I to generate different combinations of chromatids in resulting gametes.
chromosomes can arrange
After a cell undergoes DNA replication,
chromosomes consist of identical sister chromatids.
Although bacteria are asexual, they can obtain new genetic material by forming a sex pilus with another individual in the process called .
conjugation
What is an ancient process in which genetic material is exchanged between bacterial cells?
conjugation
Short segments of DNA are exchanged between homologous chromosomes during prophase I in a process called _ over.
cross
In prophase I, allele shuffling between homologous chromosomes occurs in a process called
crossing over.
Select all of the following that are true about cells undergoing meiosis.
cytokinesis occurs after the distribution of genetic material interphase precedes meiosis I
A(n) ______ cell contains two sets of chromosomes, one set of chromosomes inherited from each parent.
diploid
Located in the ovaries and testes of animals, specialized cells called germ cells are ______ and undergo meiosis to produce ______.
diploid; gametes
What type of twins is produced if two sperm cells fertilize two separate egg cells, as shown in the image?
dizygotic twins
In what process does a chromosome consisting of a single chromatid become a chromosome consisting of two sister chromatids joined at the centromere?
dna replication
Symptoms of ______ syndrome include distinct facial features, possible mental impairment, and increased risk of congenital heart defects and leukemia.
down
Trisomy 13, 18 and 21 are all the result of a(n) ______, although infants with trisomy 13 and 18 don't often survive.
extra autosome
True or false: Sexual reproduction is only exhibited by multicellular organisms.
false
True or false: The younger the mother, the higher the chance of producing a child with Down syndrome.
false
What process occurs when gametes from two parents fuse?
fertilization
The special haploid cells required for sexual reproduction are called
gamete
are haploid sex cells, such as sperm cells and egg cells, that combine to form new offspring.
gamete
The abbreviation n or 1n represents a cell.
gametes
Alleles are alternate versions of
genes
Crossing over, random orientation of chromosomes, and random fertilization are mechanisms involved in meiosis and sexual reproduction that generate _ diversity.
genetic
The chromosomes of offspring are not identical to those of their parents or siblings because ______ is shuffled during meiosis.
genetic info
Sexual reproduction produces ______, while asexual reproduction produces ______.
genetically different offspring from two parents; genetically identical offspring from one parent
In animals, specialized diploid cells that undergo meiosis are called
germ cells
Two matching chromosomes having the same basic structure and same sequence of genes are called a ______ pair.
homologous
During meiosis I, what do spindle fibers pull apart?
homologous chromosomes
Crossing over is the process in which
homologous chromosomes exchange genes
Select all of the following that describe gametes.
include sperm and egg cells haploid
The risk of giving birth to a child with trisomy 21 ______ age of the mother.
increases with increasing
During what phase does the cell copy it's DNA and produce proteins necessary for cell division?
interphase
What phase of the cell cycle immediately precedes meiosis?
interphase
A chart showing the images of chromosomes in a cell arranged according to size is called a(n)
karyotype.
In humans, what gender typically has sex chromosomes that are XY?
male
What occurs during the interphase that precedes meiosis II?
manufacture of proteins
Select all of the following organisms that commonly survive as polyploids, which are organisms that have one or more complete sets of extra chromosomes.
many crop plants some flowering plants durum wheat
Homologous chromosomes are slightly different from each other because they
may carry different alleles for the same genes.
In sexually reproducing, eukaryotic organisms, what type of cell division results in the formation of genetically variable, haploid nuclei?
meiosis
Select all the processes that separate eukaryotic chromosomes.
meiosis mitosis
A cell in which homologous chromosomes are arranged in pairs along the equator of the cell is in what phase?
meiosis I
In meiosis shown in the image, homologous chromosomes separate in step A, which is called ______, and four haploid nuclei are formed in step B, which is called ______.
meiosis I; meiosis II
Dividing cells that contain only one chromosome from each homologous pair lined up singly at the equator of the cell must be undergoing
meiosis II.
Crossing over and random orientation of chromosomes lead to genetic variability in the process of ______, but the process of ______ does not generate genetic variability because it lacks these mechanisms.
meiosis; mitosis
During what phase of meiosis I does the spindle arrange the homologous pairs of chromosomes along the equator of the cell?
metaphase I
In the sexual life cycle, what type of cell division produces a multicellular organism from the zygote?
mitosis
What process produces daughter cells for growth and repair, but not for sexual reproduction?
mitosis
What type of cell division do somatic cells undergo?
mitosis
A process called ______ occurs throughout the life cycle of an organism, whereas ______ occurs only during gamete production.
mitosis; meiosis
In cell division called ______, the chromosome number in the daughter cells is the same as that in the parent cell, but in cell division called ______, the chromosome number in the daughter cells is half the number present in the parent cell.
mitosis; meiosis
A recombinant chromatid contains
new allele combinations different from either parental chromatid.
A process called is an error in meiosis in which chromosomes fail to separate and a gamete with too many or too few copies of a particular chromosome can be produced.
non disconjunction
What produces gametes with a missing or extra chromosome and results in embryonic, fetal, or infant death or a trisomic individual?
nondisjunction
Select all of the following that apply to asexual reproduction.
offspring genetically identical to parent DNA is replicated
For a particular gene, a chromosome typically carries ______ of each gene, and a homologous pair of chromosomes carries ______.
one allele; two alleles, one allele from each parent.
Cells that are haploid contain
one full set of genetic information.
Monozygotic twins, or identical twins, are produced from
one zygote.
What occurs during meiosis but not mitosis?
pairing of homologous chromosomes
A(n) ______ cell has at least one extra set of chromosomes.
polyploid
What is a cell with a complete extra set of chromosomes called?
polyploid
Select all of the following that take place during interphase preceding meiosis.
production of two identical sister chromatids attached at the centromere replication of DNA synthesis of proteins and enzymes needed for cell division
Crossing over only occurs in
prophase I of meiosis.
In sexual reproduction, exactly what egg cell matures and what sperm cell fertilizes the egg is
random and results in genetic variability.
Select all of the mechanisms that generate genetic variability in sexual organisms.
random fertilization random orientation of chromosomes crossing over
A chromatid that has undergone crossing over and has a different combination of alleles than either chromatid of the parents is called a
recombinant chromatid.
Select the two main functions of meisois.
reduce chromosome number to half in daughter cells shuffle genetic information
Select all of the following that describe mitosis.
results in 2 daughter cells starts with a diploid cell and results in diploid cells
Select all of the following that describe a homologous pair of chromosomes.
same size can have different alleles same light and dark banding patterns
In a human karyotype, there are 22 pairs of autosomes and 1 pair of _chromosomes.
sex
The X and Y chromosomes in humans are called
sex chromosomes
A species that reproduces by ______ has the greatest genetic variability and the greatest chance of surviving in a changing environment.
sexual
What type of reproduction produces offspring that are genetically different from each other and from the parents?
sexual
durin_ reproduction, genetic information from two parents combines to form an offspring.
sexual
Neurons and muscle cells of animals and leaf cells and root cells of plants are examples of
som atic cells
Mitosis occurs in ______ cells, whereas meiosis occurs in ______ cells.
somatic; germ
Select all of the following that are features of both mitosis and meiosis.
spindle fibers move and separate chromosomes preceded by interphase prophase, metaphase, anaphase, and telophase steps
After DNA replication, a diploid cell is
still diploid.
During prophase I of meiosis, a process called ______ is the precise aligning of homologous chromosomes that precedes crossing over.
synapsis
What is the process in which homologues align gene by gene in preparation for crossing over?
synapsis
During meiosis I, homologous chromosomes have completed their movement to opposite poles in
telophase 1
Select all of the following that are examples of polyploidy.
tetraploid plant species triploidy human embryo with three copies of each chromosome hexaploid cell
Select all of the following that can result from nondisjunction in humans.
trisomy failed development due to missing genetic material an extra copy of a chromosome
True or false: In some species, the chromosomes uncoil into thin threads between meiosis I and meiosis II.
true
How many rounds of cell division occur in meiosis?
two
After this homologous pair undergoes crossing over and meiosis, what resulting chromatids will be segregated into different haploid cells?
two parental chromatids, two recombinant chromatids
What process results in dizygotic (fraternal) twins?
two sperm cells fertilize two separate egg cells
Select the features of Down syndrome from the list below.
varying degrees of mental impairment distinctive facial features increased chance of congenital heart defects
Nondisjunction of the ______ chromosome during meiosis can produce offspring that are XXX or XXY.
x
In humans, the sex chromosomes of a female are typically_ and _ ; the sex chromosomes of a male are typically X and _
x x y
The diploid cell created from the fusion of gametes is called a(n)
zygote
The first diploid cell of a new organism, called a(n) _ , has a set of chromosomes from each parent. Listen to the complete question
zygote