Biology 171 Chapter 9

Front 1

When a DNA molecule doubles, a chromosome is then comprised of two joined

________.

Back 1

chromatids

Front 2

Prokaryotic DNA molecules are packaged by ________ proteins, which associate with

DNA.

Back 2

basic

Front 3

In general, the division of the cell, called ________, follows immediately upon mitosis.

Back 3

cytokinesis

Front 4

The bacteria have a short sequence called ________ where DNA synthesis begins.

Back 4

ori

Front 5

The bacteria have a short sequence called ________ where DNA synthesis ends.

Back 5

ter

Front 6

During prophase I of meiosis a unique event occurs that results in the formation of

recombinant chromosomes. This event is termed ________.

Back 6

crossing over

Front 7

The structure present during mitosis that is composed of two identical DNA molecules complexed with proteins and joined at the centromere is called a ________.

Back 7

chromosome

Front 8

The stage of the cell cycle during which DNA replicates is called the ________.

Back 8

S phase

Front 9

________ is the fusion of two gametes.

Back 9

Fertilization

Front 10

During prometaphase, microtubules associate with specialized structures in the

centromere regions called ________.

Back 10

kinetochore

Front 11

Occasionally, a homologous chromosome pair will fail to separate during anaphase I of meiosis. The resulting cells, one of which lacks a copy of this chromosome while the other contains both members of the homologous pair, are called ________ cells.

Back 11

aneuploid

Front 12

During a process known as ________, a piece of one chromosome can break off and

become joined to a different chromosome.

Back 12

translocation

Front 13

The orderly distribution of genetic information occurs in prokaryotic cells by a process

known as ________.

Back 13

binary fission

Front 14

A cell with three homologous sets of chromosomes is called a ________ cell.

Back 14

triploid

Front 15

The heritable information of the cell is ________.

Back 15

DNA

Front 16

The process that ensures the genetic information is passed on to a cell's daughter cells is

________.

Back 16

mitosis

Front 17

The process that ensures that only one of each pair of chromosomes is included in a

gamete is ________.

Back 17

meiosis

Front 18

The main role of nucleosomes in eukaryotic cells is to ________ the DNA.

Back 18

package

Front 19

The G2 phase always follows ________.

Back 19

S phase

Front 20

The G in G1 and G2 is short for ________.

Back 20

Gap

Front 21

The chromatin ________ during prophase.

Back 21

condenses

Front 22

The milestone event that defines entry into prometaphase is ________.

Back 22

loss of the nuclear envelope

Front 23

In plants a ________ forms at the equatorial region of the cell

Back 23

cell plate

Front 24

The cell plate is derived from the ________ of the cell.

Back 24

Golgi apparatus

Front 25

The "invisible thread" that pinches cells into two during cell division is made of

________and ________.

Back 25

actin; myosin

Front 26

A zygote usually has ________ copies of each chromosome.

Back 26

2

Front 27

A ________ is the number, form, and type of chromosomes found in a cell, usually

similar within species and different between species.

Back 27

karyotype

Front 28

A ________ is one of a pair of chromosomes having the same overall genetic

composition and sequence.

Back 28

homolog

Front 29

Nondisjunction causes the production of ________ cells.

Back 29

aneuploid

Front 30

Down syndrome can be caused by an extra chromosome ________.

Back 30

21

Front 31

During meiosis in a tetraploid or a triploid plant, more problems are expected in

________ plants.

Back 31

triploid

Front 32

During prokaryotic cell division, two chromosomes separate from each other and

distribute into the daughter cells by A) attachments to microtubules. B) a mitotic spindle. C) repellent forces. D) attachment to separating membrane regions. E) All of the above

Back 32

D) Attachment to separating membrane regions

Front 33

Prokaryotic cells take at least __________ minute(s) to divide. A) 1 B) 2 C) 20 D) 200 E) 1000

Back 33

C) 20

Front 34

Bacteria typically have __________ while eukaryotes have __________.

A) one chromosome that is circular, many that are linear B) several chromosomes that are circular, many that are linear C) one chromosome that is linear, many that are circular D) two chromosome that are circular, eight that are linear E) None of the above

Back 34

A) one chromosome that is circular, many that are linear.

Front 35

Chromosomes contain large amounts of five different interacting proteins, all of which

are known as A) pentanes. B) hexosamines. C) histones. D) protein hormones. E) histamines.

Back 35

c) histones

Front 36

The appropriate decisions to enter the S phase and the M phase of the cell cycle depend

on a pair of biochemicals called

A) actin and myosin. B) Cdk's and cyclin. C) ligand and receptor. D) MSH and MSH-receptor. E) ATP and ATPase.

Back 36

B) Cdk's and cyclin

Front 37

Sex and reproduction A) are not the same thing. B) are identical. C) both involve combining genetic material from two cells. D) both involve the formation of new individuals. E) None of the above

Back 37

A) are not the same thing

Front 38

The molecules that make up a chromosome are A) DNA and RNA. B) DNA and proteins. C) proteins and lipids. D) nucleotides and nucleosides. E) proteins and phospholipids.

Back 38

B) DNA and proteins

Front 39

39. During mitosis and meiosis the chromatin compacts. Which of the following processes is

made easier by this compaction?

A) The orderly distribution of genetic material to two new nuclei B) The replication of the DNA C) Exposing the genetic information on the DNA D) The unwinding of DNA from around the histones E) The disappearance of the nuclear membrane

Back 39

A) The orderly distribution of genetic material to two new nuclei

Front 40

The basic structure of chromatin has sometimes been referred to as beads on a string of

DNA. These beads are called

A) chromosomes. B) chromatids. C) supercoils. D) interphases. E) nucleosomes.

Back 40

E) nucleosomes

Front 41

DNA replication occurs A) during both mitosis and meiosis. B) only during mitosis. C) only during meiosis. D) during the S phase. E) during G2.

Back 41

D) during the S phase

Front 42

Around __________ base pairs wrap around each core particle in a __________ . A) 1000, solenoid B) 20000, chromosome C) 146, nucleosome D) 1000, chromosome E) 20,000, solenoid

Back 42

C) 146, nucleosome

Front 43

When cyclin binds Cdk, A) the cell transitions from G2 to S. B) kinase activation occurs. C) chromosomes condense. D) the cell quickly enters M phase. E) the cell begins apoptosis.

Back 43

B) kinase activation occurs

Front 44

Mature nerve cells are incapable of cell division. These cells are probably in A) G1. B) the S phase. C) G2. D) mitosis. E) meiosis.

Back 44

A) G1

Front 45

A cell cycle consists of A) mitosis and meiosis. B) G1, the S phase, and G2. C) prophase, metaphase, anaphase, and telophase. D) interphase and mitosis. E) meiosis and fertilization.

Back 45

D) Interphase and mitosis

Front 46

Evidence in yeast suggest that the maturation promoting factor of sea urchins was A) a cyclin. B) MFP. C) an S nuclease. D) a Cdk. E) a Cdk/cyclin phosphatase.

Back 46

D) a Cdk

Front 47

The cells of the intestinal epithelium are continually dividing, replacing dead cells lost from the surface of the intestinal lining. If you examined a population of intestinal

epithelial cells under the microscope, most of the cells would

A) be in meiosis. B) be in mitosis. C) be in interphase. D) have condensed chromatin. E) b and d

Back 47

C) be in interphase

Front 48

DNA damage by UV radiation causes the synthesis of A) p53. B) DNA. C) Cdk. D) cyclin. E) p21.

Back 48

E) p21

Front 49

The uncondensed length of human DNA found in chromosomes is __________, whereas

a typical cell's is 10 µm in length.

A) 5 µm B) 2 µm C) 2 meters D) 20 meters E) 2.54 inches

Back 49

C) 2 meters

Front 50

The products of mitosis are A) one nucleus containing twice as much DNA as the parent nucleus. B) two genetically identical cells. C) four nuclei containing half as much DNA as the parent nucleus. D) four genetically identical nuclei. E) two genetically identical nuclei.

Back 50

E) two genetically identical nuclei

Front 51

The mitotic spindle is composed of A) chromosomes. B) chromatids. C) microtubules. D) chromatin. E) centrosomes.

Back 51

C) microtubules

Front 52

Centrosomes are A) constricted regions of phase chromosomes. B) regions where microtubules polymerize. C) the central region of the same cell. D) the region where the membrane constricts during cytokinesis. E) part of cilia.

Back 52

B) regions where microtubules polymerize

Front 53

When dividing cells are examined under a light microscope, chromosomes first become

visible during A) interphase. B) the S phase. C) prophase. D) G1. E) G2.

Back 53

C) prophase

Front 54

The structures that line up the chromosomes on the equatorial plate during metaphase are

called A) asters. B) polar and kinetochore microtubules. C) centrosomes. D) centrioles. E) histones.

Back 54

B) polar and kinetochore microtubules

Front 55

The microtubules of the mitotic spindle attach to a specialized structure in the centromere

region of each chromosome, called the

A) kinetochore. B) nucleosome. C) equatorial plate. D) aster. E) centrosome.

Back 55

A) kinetochore

Front 56

After the centromeres separate during mitosis, the chromatids, now called __________,

move toward opposite poles of the spindle.

A) centrosomes B) kinetochores C) half spindles D) asters E) daughter chromosomes

Back 56

E) daughter chromosomes

Front 57

In plant cells, cytokinesis is accomplished by the formation of a(n) A) aster. B) membrane furrow. C) equatorial plate. D) cell plate. E) spindle.

Back 57

D) cell plate

Front 58

The distribution of mitochondria between the daughter cells during cytokinesis A) is random. B) is directed by the mitotic spindle. C) is directed by the centrioles. D) results in all of the mitochondria remaining in the parent cell. E) occurs only during meiosis.

Back 58

A) is random

Front 59

Genetically diverse offspring result from A) mitosis. B) cloning. C) sexual reproduction. D) cytokinesis. E) anaphase.

Back 59

C) sexual reproduction

Front 60

During asexual reproduction, the genetic material of the parent is passed on to the

offspring by A) homologous pairing. B) meiosis and fertilization. C) mitosis and cytokinesis. D) karyotyping. E) chiasmata.

Back 60

C) mitosis and cytokinesis

Front 61

Meiosis can occur A) in all organisms. B) only when an organism is diploid. C) only in multicellular organisms. D) only in haploid organisms. E) only in single-celled organisms.

Back 61

B) only when an organism is diploid

Front 62

All zygotes are A) multicellular. B) diploid. C) animals. D) clones. E) gametes.

Back 62

B) diploid

Front 63

In all sexually reproducing organisms, the diploid phase of the life cycle begins at A) spore formation. B) gamete formation. C) meiosis. D) mitosis. E) fertilization.

Back 63

E) fertilization

Front 64

The members of a homologous pair of chromosomes A) are identical in size and appearance. B) contain identical genetic information. C) separate to opposite poles of the cell during mitosis. D) are found only in haploid cells. E) are present only after the S phase.

Back 64

A) are identical in size and appearance

Front 65

The diagnosis of Down syndrome is made by examining the individual's A) spores. B) karyotype. C) chromatin. D) nucleosomes. E) kinetochores.

Back 65

B) karyotype

Front 66

During meiosis, the sister chromatids separate during A) anaphase II. B) anaphase I. C) the S phase. D) synapsis. E) telophase II.

Back 66

A) anaphase II

Front 67

The exchange of genetic material between chromatids on homologous chromosomes

occurs during A) interphase. B) mitosis and meiosis. C) prophase I. D) anaphase I. E) anaphase II

Back 67

C) prophase I

Front 68

At the end of the first meiotic division, each chromosome consists of A) chiasmata. B) a homologous chromosome pair. C) four copies of each DNA molecule. D) two chromatids. E) a pair of polar microtubules.

Back 68

D) two chromatids

Front 69

The four haploid nuclei found at the end of meiosis differ from one another in their exact

genetic composition. Some of this difference is the result of

A) cytokinesis. B) replication of DNA during the S phase. C) separation of sister chromatids at anaphase II. D) spindle formation. E) crossing over during prophase I.

Back 69

E) crossing over during prophase I

Front 70

Diploid cells of the fruit fly Drosophila have 10 chromosomes. How many chromosomes

does a Drosophila gamete have?

A) 1 B) 2 C) 5 D) 10 E) 20

Back 70

C) 5

Front 71

During meiosis I in humans, one of the daughter cells receives A) only maternal chromosomes. B) a mixture of maternal and paternal chromosomes. C) the same number of chromosomes as a diploid cell. D) a sister chromatid from each chromosome. E) one-fourth the amount of DNA in the parent nucleus.

Back 71

B) a mixture of maternal and paternal chromosomes

Front 72

The fact that most monosomies and trisomies are lethal to human embryos illustrates A) the importance of the orderly distribution of genetic material during meiosis. B) the exchange of genetic information during crossing over. C) the advantage of sexual reproduction to the survival of a population. D) that each chromosome contains a single molecule of DNA. E) that meiosis results in the formation of haploid gametes.

Back 72

A) the importance of the orderly distribution of genetic material during meiosis

Front 73

A triploid nucleus cannot undergo meiosis because A) the DNA cannot replicate. B) not all of the chromosomes can form homologous pairs. C) the sister chromatids cannot separate. D) cytokinesis cannot occur. E) a cell plate cannot form.

Back 73

B) not all of the chromosomes can form homologous pairs.

Front 74

A bacterial cell gives rise to two genetically identical daughter cells by a process known

as

A) nondisjunction. B) mitosis. C) meiosis. D) fission. E) fertilization.

Back 74

D) fission

Front 75

Which of the following is not part of sexual reproduction? A) The segregation of homologous chromosomes during gamete formation B) The fusion of sister chromatids during fertilization C) The fusion of haploid cells from a diploid zygote D) The reduction in chromosome number during meiosis E) The production of genetically distinct gametes during meiosis

Back 75

B) The fusion of sister chromatids during fertilization

Front 76

Chromatin condenses to form discrete, visible chromosomes A) early in G1. B) during S. C) during telophase. D) during prophase. E) at the end of cytokinesis.

Back 76

D) during prophase

Front 77

Chromosomes "decondense" into diffuse chromatin A) at the end of telophase. B) at the beginning of prophase. C) at the end of interphase. D) at the end of metaphase. E) only in dying cells.

Back 77

A) at the end of telophase

Front 78

Microtubules that form the mitotic spindle tend to originate from or terminate in A) centromeres and telomeres. B) euchromatin. C) centrioles and telomeres. D) the nuclear envelope. E) centrioles and centromeres (kinetochores).

Back 78

E) centrioles and centromeres (kinetochores)

Front 79

Asexual reproduction produces genetically identical individuals because A) chromosomes do not have to replicate. B) it involves chromosome replication without cytokinesis. C) no meiosis or fertilization takes place. D) the only cell division that occurs is meiosis. E) the mitotic spindle prevents nondisjunction.

Back 79

C) no meiosis or fertilization takes place

Front 80

One difference between mitosis and meiosis I is that A) homologous chromosome pairs synapse during mitosis. B) chromosomes do not replicate in the interphase preceding meiosis. C) homologous chromosome pairs synapse during meiosis but not mitosis. D) spindles composed of microtubules are not required during meiosis. E) sister chromatids separate during meiosis but not mitosis.

Back 80

C) homologous chromosome pairs synapse during meiosis but not mitosis.

Front 81

Genetic recombination occurs during A) prophase of meiosis I. B) interphase preceding meiosis II. C) mitotic telophase. D) fertilization. E) formation of somatic cells.

Back 81

A) prophase of meiosis I

Front 82

The number of chromosomes is reduced to half during A) anaphase of mitosis and meiosis. B) meiosis II. C) meiosis I. D) fertilization. E) interphase.

Back 82

C) meiosis I

Front 83

The total DNA content of each daughter cell is reduced during meiosis because A) chromosomes do not replicate during the interphase preceding meiosis I. B) chromosomes do not replicate between meiosis I and II. C) half of the chromosomes from each gamete are lost during fertilization. D) sister chromatids separate during anaphase of meiosis I. E) chromosome arms are lost during crossing over.

Back 83

B) chromosomes do not replicate between meiosis I and II

Front 84

Many chromosome abnormalities (trisomies and monosomies) are not observed in the

human population because

A) they are lethal and cause spontaneous abortion of the embryo early in development. B) all trisomies and monosomies are lethal early in childhood. C) meiosis distributes chromosomes to daughter cells with great precision. D) they are so difficult to count. E) the human meiotic spindle is self-correcting.

Back 84

A) they are lethal and cause spontaneous abortion of the embryo early in development.

Front 85

In a haploid organism, most mitosis occurs A) after fertilization and before meiosis. B) after meiosis and before fertilization. C) between meiosis I and II. D) during G1. E) in diploid cells.

Back 85

B) after meiosis and before fertilization

Front 86

The event in the cell division process that clearly involves microfilaments rather than

microtubules is

A) chromosome separation during anaphase. B) movement of chromosomes to the metaphase plate. C) chromosome condensation during prophase. D) disappearance of the nuclear envelope during prophase. E) cytokinesis in animal cells.

Back 86

E) cytokinesis in animal cells

Front 87

Trisomies and monosomies can result from accidents that occur during meiosis called A) nondisjunctions. B) inversions. C) reciprocal translocations. D) recombinations. E) acrocentricities.

Back 87

A) nondisjunction

Front 88

Chromosome number is reduced during meiosis because the process consists of A) two cell divisions without any chromosome replication. B) a single cell division without any chromosome replication. C) two cell divisions in which half of the chromosomes are destroyed. D) two cell divisions and only a single round of chromosome replication. E) four cell divisions with no chromosome replication.

Back 88

A) two cell divisions without any chromosome replication

Front 89

Which of the following phases of the cell cycle is not part of interphase? A) M B) S C) G1 D) G2 E) G0

Back 89

A) M

Front 90

During mitotic anaphase, chromatids migrate A) from the poles of the cell toward the metaphase plate. B) from the metaphase plate toward the poles. C) toward the nuclear envelope. D) along with their sister chromatids toward one pole. E) along with the other member of the homologous pair toward the metaphase plate.

Back 90

B) from the metaphase plate toward the poles

Front 91

Which of the following does not occur during mitotic prophase? A) Disappearance of the nuclear envelope B) Chromosome condensation C) Migration of centrioles toward the cell poles D) Synapsis of homologous chromosomes E) Formation of the mitotic spindle

Back 91

D) Synapsis of homologous chromosomes

Front 92

Human males have __________ different types of chromosomes. A) 23 B) 24 C) 46 D) 48 E) 92

Back 92

B) 24

Front 93

Which of the following is not true of homologous chromosome pairs? A) They come from only one of the individual's parents. B) They usually contain slightly different versions of the same genetic information. C) They segregate from each other during meiosis I. D) They synapse during meiosis I. E) Each contains two sister chromatids at the beginning of meiosis I.

Back 93

A) They come from only one of the individual's parents.

Front 94

Which of the following is not true of sister chromatids? A) They arise by replication during S phase. B) They segregate from each other during each mitotic anaphase. C) They usually contain identical versions of the same genetic information. D) They segregate from each other during meiosis I. E) They are joined during prophase and metaphase at their common centromere.

Back 94

D) They segregate from each other during meiosis I.

Front 95

Chromatin consists of A) DNA and histones. B) DNA, histones, and many other nonhistone proteins. C) mostly RNA and DNA. D) RNA, DNA, and nonhistone proteins. E) DNA alone.

Back 95

B) DNA, histones, and many other nonhistone proteins.

Front 96

The DNA of an eukaryotic cell is A) double stranded. B) single stranded. C) circular. D) complex inverted. E) conservative.

Back 96

A) double stranded

Front 97

Nucleosomes are made of A) RNA. B) lipid. C) histones. D) chromatin. E) All of the above

Back 97

C) histones

Front 98

A cell that is postreproductive will remain in A) S. B) G1. C) G2. D) M. E) prophase.

Back 98

B) G1

Front 99

The kinetochore is made of A) protein. B) microtubules. C) DNA. D) a and b. E) All of the above

Back 99

E) All of the above

Front 100

The milestone that defines metaphase is when the chromosomes A) separate. B) come together. C) are at opposite poles. D) line up. E) cross over.

Back 100

D) line up

Front 101

The milestone that defines anaphase is when the chromosomes A) separate. B) come together. C) are at opposite poles. D) line up. E) cross over.

Back 101

A) separate

Front 102

The milestone that defines telophase is when the chromosomes A) separate. B) come together. C) are at opposite poles. D) line up. E) cross over.

Back 102

C) are at opposite poles

Front 103

The major drawback of asexual reproduction is A) that it takes too little time. B) the variation generated. C) it prevents change. D) it requires cytokinesis. E) the lack of variation among the progeny.

Back 103

E) the lack of variation among the progeny

Front 104

Haploid means: A) the genes are arranged haphazardly. B) containing only one copy of each chromosome. C) the process of meiosis. D) half again the number of chromosomes. E) All of the above

Back 104

B) containing only one copy of each chromosome

Front 105

A reduction step during meiosis is important because A) it returns the chromosome number to normal before fertilization. B) there is a mechanism for this. C) only one copy of each chromosome is necessary. D) otherwise chromosome copies would double each fertilization. E) fertilization requires this.

Back 105

D) otherwise chromosome copies would double each fertilization

Front 106

Interleukins and erythropoietin are A) growth factors. B) Cdk's. C) cyclins. D) antitumor agents. E) intracellular signaling molecules.

Back 106

A) growth factors

Front 107

Half of all human cancers have defective __________ associated with their cells. A) p53 B) p21 C) Cdk D) cyclin E) DNA polymerase

Back 107

A) p53

Front 108

Each diploid cell of a human female contains A) one of each type of chromosome. B) two of each type of chromosome. C) four of each type of chromosome. D) a total of 23 of each type of chromosome. E) a total of 46 of each type of chromosome.

Back 108

B) two of each type of chromosome

Front 109

The importance of synapsis and the formation of chiasmata is that A) reciprocal exchange of chromosomal sections occurs. B) the DNA on homologous chromosomes mix. C) as a result, an increase in the variation of progeny occurs. D) overt evidence is provided for maternal and paternal chromosomes mixing. E) All of the above

Back 109

E) All of the above

Front 110

A triploid plant has A) one extra chromosome. B) one extra set of chromosomes. C) three chromosomes. D) three times the chance of a monoploid. E) three attempts at ploidy.

Back 110

B) one extra set of chromosomes

Front 111

Nucleosomes are found A) only in interphase cells. B) only during mitosis. C) only during meiosis. D) in all chromatin. E) in the cytoplasm.

Back 111

D) in all chromatin

Front 112

The energy to move chromosomes during mitosis is provided by A) centrioles. B) DNA polymerization. C) migration of the centrosomes. D) formation of the cell plate. E) ATP.

Back 112

E) ATP

Front 113

During bacterial cell division, the two DNA molecules are separated by A) centrosomes. B) spindle fibers. C) nucleosomes. D) cell elongation. E) aneuploidy.

Back 113

D) cell elongation

Front 114

The process of programmed cell death is called A) necrosis. B) lysis. C) apoptosis. D) cell displacement. E) cellular suicide.

Back 114

C) apoptosis

Front 115

An indicator of programmed cell death is A) fragmented chromatin. B) swelling of the membrane. C) cell lysis. D) loss of transcription control. E) All of the above

Back 115

A) fragmented chromatin