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