bio chapter 9
Down syndrome can be caused by an extra copy of chromosome
21.
A diploid cell is indicated by what abbreviation?
2n
Diploid human cells contain a total of ______ chromosomes.
46
There are a total of__ pairs of chromosomes in a human diploid cell.
46
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
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.)
About 4,000
Select all of the following that apply to asexual reproduction..
DNA is replicated offspring genetically identical to parent
Symptoms of ______ syndrome include distinct facial features, possible mental impairment, and increased risk of congenital heart defects and leukemia.
Down
of entire genes can play a role in evolution because mutations in extra copies of the gene can sometimes lead to a gain of function.
Duplication
True or false: The younger the mother, the higher the chance of producing a child with Down syndrome. True false question.
False
is the merging of a sperm and an egg to create a diploid zygote.
Fertilization
are haploid sex cells, such as sperm cells and egg cells, that combine to form new offspring.
Gametes
What correctly describes metaphase I of meiosis I?
Homologous chromosomes line up as pairs along the center of the cell.
__results in genetically identical daughter cells, whereas ______ results in genetically different daughter cells.
Mitosis; meiosis
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
Select the true statement about human gametes.
Sperm and egg cells are very different in size.
Select all of the following that occur in prophase I of meiosis.
Spindle forms from microtubules. Chromosomes condense. Nuclear envelope breaks up. Crossing over occurs.
Nondisjunction of the ______ chromosome during meiosis can produce offspring that are XXX or XXY.
X
When an oogonium undergoes mitosis, it produces
a primary oocyte and another oogonium
A spermatogonium that undergoes mitosis produces
a primary spermatocyte and another spermatogonium.
What is a karyotype?
a size-ordered chart of all the chromosomes in a cell
Different versions of a gene are called
alleles
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
What type of reproduction produces offspring virtually identical to the parent?
asexual
When ______ reproduction occurs in a one-celled organism, the organism replicates its DNA and splits into two genetically identical cells.
asexual
In ______ reproduction, genetically identical offspring are produced, while in ______ reproduction, offspring are genetically different from each other.
asexual; sexual
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 the organisms that can produce gametes for sexual reproduction.
bread molds ferns humans
Select all of the following that are true about nondisjunction.
can occur at either anaphase I or anaphase II caused by malformed spindle fibers produces abnormal gametes
In eukaryotes, a molecule of genetic material and its associated proteins form a(n)____of which humans have 46 in each cell.
chromosome
A single molecule of DNA and its associated proteins form a
chromosome.
Select all of the following that apply to human autosomes.
chromosomes 1 through 22 homologous pairs
Diploid cells contain two full sets of
chromosomes.
Although bacteria are asexual, they can obtain new genetic material by forming a sex pilus with another individual in the process called
conjugation
Short segments of DNA are exchanged between homologous chromosomes during prophase I in a process called____ over
crossing
Chromosome abnormalities can occur due to misalignment of homologs during
crossing over.
In prophase I, allele shuffling between homologous chromosomes occurs in a process called
crossing over.
Chromosomal____ is an abnormality that results in the loss of one or more genes from a chromosome.
deletion
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
Chromosomal ______ is a chromosomal abnormality in which multiple copies of part of a chromosome are produced.
duplication
What type of chromosomal abnormality can lead to multiple copies of a gene, some of which can incur mutations that can lead to the evolution of a new function?
duplication
Select all of the following that can result from nondisjunction in humans.
failed development due to missing genetic material an extra copy of a chromosome trisomy
What process occurs when gametes from two parents fuse?
fertilization
In what type of plants are the gametophytes microscopic and dependent on the sporophyte for nutrition?
flowering plants
Select all the possible results of nondisjunction in sex chromosomes.
gamete contains an extra X gamete contains an extra Y XXX zygote gamete is missing a sex chromosome
The haploid gametophyte of a plant gives rise to haploid ______ by mitosis.
gametes
The special haploid cells required for sexual reproduction are called
gametes.
The multicellular haploid stage of the plant life cycle is called the
gametophyte.
In mosses and ferns, the multicellular haploid ______ are visible with the unaided eye; however, in flowering plants, only the multicellular diploid ______ are visible without a microscope.
gametophytes; sporophytes
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 information
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.
A(n) ______ cell contains only one copy of each chromosome.
haploid
The abbreviation n or 1n represents a___ cell
haploid
Select all of the following that are true about spermatids.
haploid equal-sized specialize into mature sperm
Select all of the following that are true about secondary spermatocytes.
haploid will enter meiosis II
Two chromosomes with the same size, centromere location, and gene sequence are called a(n)____ pair
homologous
Select all of the following that describe gametes.
include sperm and egg cells haploid
Select all of the following that are true about meiosis.
includes two cell divisions produces gametes with half the number of chromosomes as compared to somatic cells creates four haploid cells from one diploid cell
Select the features of Down syndrome from the list below.
increased chance of congenital heart defects varying degrees of mental impairment distinctive facial features
The risk of giving birth to a child with trisomy 21 ______ age of the mother.
increases with increasing
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
Homologous chromosomes are slightly different from each other because they
may carry different alleles for the same genes.
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
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
What process produces daughter cells for growth and repair, but not for sexual reproduction?
mitosis
A process called ______ occurs throughout the life cycle of an organism, whereas ______ occurs only during gamete production.
mitosis; meiosis
In the alternation of generations plant life cycle,
multicellular haploid and diploid structures are present.
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.
nondisjunction
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.
The production of egg cells is called
oogenesis
A diploid germ cell in the ovaries of a human female is called a(n)
oogonium.
The mature, haploid egg cell of a human female is also called a(n)
ovum.
What occurs during meiosis but not mitosis?
pairing of homologous chromosomes
Small, haploid cells that are produced in meiosis I and meiosis II during oogenesis and that do not participate in fertilization are called
polar bodies.
A secondary oocyte divides unequally during meiosis II to produce a large ovum and a smaller ______ that plays no further role in reproduction.
polar body
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
In human females, specialized cells that are diploid and will enter meiosis I are called
primary oocytes
In human males, specialized cells that are diploid and will enter meiosis I are called
primary spermatocytes.
Select all of the following that are true of an ovum (mature egg cell).
produced by meiosis II haploid
Homologous chromosomes pair up and crossing over occurs in what phase of meiosis?
prophase I
Crossing over only occurs in
prophase I of meiosis.
Select all of the following that are features of both mitosis and meiosis.
prophase, metaphase, anaphase, and telophase steps preceded by interphase spindle fibers move and separate chromosomes
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 crossing over random orientation of chromosomes
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 light and dark banding patterns can have different alleles same size
Meiosis I in human males produces two ______, which are haploid and will enter meiosis II.
secondary spermatocytes
Two ______ undergo meiosis II to produce four spermatids.
secondary spermatocytes
The X and Y chromosomes in humans are called
sex chromosomes
In a human karyotype, there are 22 pairs of autosomes and 1 pair of_____ chromosomes.
sexual
during ____ reproduction , genetic information from two parents combines to form an offspring.
sexual
A species that reproduces by ______ has the greatest genetic variability and the greatest chance of surviving in a changing environment.
sexual reproduction
What type of reproduction creates new combinations of traits that can help a species survive in a changing environment?
sexual reproduction
What type of reproduction produces offspring that are genetically different from each other and from the parents?
sexual reproduction
Humans reproduce via
sexual reproduction.
Mitosis occurs in ______ cells, whereas meiosis occurs in ______ cells.
somatic; germ
Select all of the following organisms that commonly survive as polyploids, which are organisms that have one or more complete sets of extra chromosomes.
some flowering plants many crop plants durum wheat
Human gametes are haploid cells and include two types:_____which are lightweight and can swim; and_____ which are large and packed with organelles.
sperm; eggs
Meiosis II in human males results in four haploid ______, which mature into four haploid ______.
spermatids; sperm
The production of sperm cells is called
spermatogenesis
A diploid germ cell in the testes of a human male is called a(n)
spermatogonium.
What plant structure gives rise to haploid spores by meiosis?
sporophyte
The multicellular diploid stage of the plant life cycle is called the
sporophyte.
An entire extra set of chromosomes in a human embryo, a condition called triploidy, will usually
stop development of the embryo.
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
Select all of the following that are examples of polyploidy.
tetraploid plant species triploidy hexaploid cell human embryo with three copies of each chromosome
In a process called conjugation, a bacterial cell
transfers genetic material to another bacterium.
The most common cause of Down syndrome is
trisomy 21.
How many rounds of cell division occur in meiosis?
two
Select all of the following that are true about primary spermatocytes.
will enter meiosis I diploid produced by mitosis of spermatogonium
Select all of the following that are true about primary oocytes.
will enter meiosis I produced by mitosis diploid
In humans, the sex chromosomes of a female are typically____ and ____ the sex chromosomes of a male are typically X and____
x;x;y