Ch. 8 + 9 Mastering Biology

Question 1

Asexual and sexual reproduction differ in what way?

Answer 1

Sexual reproduction can produce great variation among offspring.

Question 2

In bacterial cells, what does binary fission involve?

Answer 2

Distribution of a copy of the single parental chromosome to each daughter cell.

Question 3

During binary fission, each copy of the duplicating chromosome moves to opposite ends of the cell. Why?

Answer 3

It ensures that each daughter cell receives one copy of the chromosome.

Question 4

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?

Answer 4

Sequences are identical.

Question 5

When does a cell replicate its entire chromosomal DNA?

Answer 5

Before it divides.

Question 6

What is the correct sequence of mitosis?

Answer 6

Interphase, prophase, metaphase, anaphase, and telophase and cytokinesis.

Question 7

What occurs during prophase of mitosis?

Answer 7

The mitotic spindle forms.

Question 8

What occurs during metaphase of mitosis?

Answer 8

Sister chromatids are centered.

Question 9

What occurs during anaphase of mitosis?

Answer 9

Chromosomes separate.

Question 10

What occurs during telophase and cytokinesis?

Answer 10

Nuclear envelopes form.

Question 11

What must happen before a cell can begin mitosis?

Answer 11

The chromosomes must be duplicated.

Question 12

During which phase of mitosis do the centrosomes move away from each other and the nuclear envelope breaks up?

Answer 12

Prophase.

Question 13

During which phase of mitosis do the chromosomes line up in the center of the cell?

Answer 13

Metaphase.

Question 14

During which phase of mitosis do the sister chromatids separate and begin moving toward opposite poles of the cell?

Answer 14

Anaphase.

Question 15

During which phase of mitosis do the chromosomes arrive at the poles and nuclear envelopes form?

Answer 15

Telophase.

Question 16

At the end of the mitotic (M) phase, the cytoplasm divides in a process called what?

Answer 16

Cytokinesis.

Question 17

When is DNA synthesized?

Answer 17

In the S phase of interphase.

Question 18

What is the correct sequence of mitosis in chronological order?

Answer 18

Prophase, prometaphase, metaphase, anaphase, telophase.

Question 19

What are kinetochores?

Answer 19

Sites at which microtubules attach to chromosomes.

Question 20

What is a feature of plant cell division that distinguishes it from animal cell division?

Answer 20

Formation of a cell plate.

Question 21

What must occur in order for a plant or animal to grow and develop normally?

Answer 21

The organism must be able to control the timing and rate of cell division in different parts of its body.

Question 22

What are the two types of cell division?

Answer 22

Mitosis and meiosis.

Question 23

What are the results of mitosis?

Answer 23

Asexual reproduction as well as cell growth and development.

Question 24

What is asexual reproduction in bacteria called?

Answer 24

Binary fission.

Question 25

What does mitosis produce?

Answer 25

Somatic cells.

Question 26

What does meiosis produce?

Answer 26

Gametes.

Question 27

What are gametes used in?

Answer 27

Sexual reproduction.

Question 28

Where does meiosis occur?

Answer 28

In gonads.

Question 29

What is a lump of abnormal cells that, although grows out of control, remains at its original site?

Answer 29

Benign tumor.

Question 30

What is an abnormally growing mass of cells that is actively spreading throughout the body?

Answer 30

Malignant tumor.

Question 31

What is the spread of cancer cells from their site of origin to other sites in the body?

Answer 31

Metastasis.

Question 32

An individual with a malignant tumor is said to have what?

Answer 32

Cancer.

Question 33

What is the most common type of cancer that originates in tissues that line organs?

Answer 33

Carcinoma.

Question 34

What are homologous chromosomes?

Answer 34

Chromosomes that are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes.

Question 35

At the conclusion of meiosis I, the daughter cells are what?

Answer 35

Haploid and the sister chromatids are joined.

Question 36

What happens in meiosis II?

Answer 36

Sister chromatids are separated.

Question 37

What is the function of meiosis?

Answer 37

To make four cells with a haploid number of chromosomes.

Question 38

What happens in anaphase I?

Answer 38

Homologous chromosomes move toward opposite poles.

Question 39

What happens during anaphase II?

Answer 39

Sister chromatids separate and migrate toward opposite poles.

Question 40

When does crossing over occur?

Answer 40

Prophase I.

Question 41

Meiosis differs from mitosis in that ___ only occurs in meiosis.

Answer 41

Crossing over.

Question 42

What is a key difference between meiosis and mitosis?

Answer 42

Synapsis occurs in meiosis.

Question 43

What is the outcome of crossing over?

Answer 43

Crossing over creates new combinations of genes present on a single chromosome.

Question 44

What is the chromosomal region where the nonsister chromatids cross over?

Answer 44

Chiasma (plural: chiasmata).

Question 45

What is the phenomenon called in which homologous chromosomes "stick together" and do not separate properly?

Answer 45

Nondisjunction.

Question 46

What does karyotyping reveal?

Answer 46

Alterations in chromosome number.

Question 47

If a chromosome fragment breaks off and then reattaches to the original chromosome but in the reverse direction, what is the chromosomal abnormality called?

Answer 47

Inversion.

Question 48

What is the exchange of parts between nonhomologous chromosomes?

Answer 48

Reciprocal translocation.

Question 49

What is genetics the study of?

Answer 49

The inheritance of genes.

Question 50

What are genes located on?

Answer 50

Chromosomes.

Question 51

Genes come in alternate forms called what?

Answer 51

Alleles.

Question 52

When copies of alleles are the same (example: ff) what are they called?

Answer 52

Homozygous.

Question 53

When copies of alleles are different (example: Ff) what are they called?

Answer 53

Heterozygous.

Question 54

A heterozygous expressed allele is called what?

Answer 54

Dominant.

Question 55

A heterozygous unexpressed allele is called what?

Answer 55

Recessive.

Question 56

Non-sex-related chromosomes are called what?

Answer 56

Autosomes.

Question 57

Sex-related chromosomes are called what?

Answer 57

Sex chromosomes.

Question 58

Sex chromosomes have genes that determine what?

Answer 58

Sex-linked traits.

Question 59

Amniocentesis and chorionic villus sampling allow for ___ and ___ of the fetus so that it can be tested for abnormalities.

Answer 59

Karyotyping ... biochemical testing.

Question 60

Mendel's view of the mechanism of heredity was radically different from the prevailing view of the time because he saw heredity working through what?

Answer 60

Unchanging (immutable), heritable factors that were contributed by each parent and never mixed.

Question 61

What does the blending hypothesis maintain?

Answer 61

After a mating, genes of the two parents are mixed in the offspring and lose their individual identities.

Question 62

What is an inherited feature that varies from individual to individual?

Answer 62

A character.

Question 63

What is one particular variation of a character?

Answer 63

A trait.

Question 64

What is a genetic cross involving parents that differ in a single character?

Answer 64

A monohybrid cross.

Question 65

Most human genes come in alternate versions called what?

Answer 65

Alleles.

Question 66

If an organism has two non-identical versions of a gene, the one that is expressed in the organism is called the ___ allele.

Answer 66

Dominant.

Question 67

If an organism has two non-identical versions of a gene, the one that is not expressed in the organism is called the ___ allele.

Answer 67

Recessive.

Question 68

The physical traits of an organism are called its ___.

Answer 68

Phenotype.

Question 69

The ___ is the genetic makeup of an organism.

Answer 69

Genotype.

Question 70

Research since Mendel's time has established that the law of segregation of genes during gamete formation applies to what?

Answer 70

All sexually reproducing organisms.

Question 71

Why can a child with cystic fibrosis be born to two parents who do not have the disease?

Answer 71

The disease is caused by a recessive allele.

Question 72

When you cross two heterozygotes (Aa), the offspring will most likely be what?

Answer 72

In the ratio 1:1 homozygotes to heterozygotes.

Question 73

In an individual of genotype Aa, where are the A and a alleles physically located?

Answer 73

One allele is on one chromosome, and the other is in the same position (locus) on the homologous chromosome.

Question 74

Mendel's principle of independent assortment applies to what?

Answer 74

The independent assortment of alleles of one gene relative to the alleles of any other gene.

Question 75

What is a testcross?

Answer 75

A mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest.

Question 76

Assuming that the probability of having a female child is 50% and the probability of having a male child is also 50%, what is the probability that a couple's first-born child will be female and that their second-born child will be male?

Answer 76

25%.

Question 77

Human genetic disorders are most often what?

Answer 77

Recessive.

Question 78

A carrier of a genetic disorder who does not show symptoms is most likely to be ___ for the trait and ___ to transmit it to offspring.

Answer 78

Heterozygous ... able.

Question 79

Many genetic disorders can be detected before birth. Procedures include ___, which is noninvasive, or ___, which allows the chromosomes of the fetus to be examined. Alternatively, maternal blood samples can be taken and tested for ___.

Answer 79

Ultrasound imaging ... chorionic villus sampling ... AFP.

Question 80

Snapdragons show incomplete dominance in their flowers. A pink snapdragon is crossed with a red snapdragon. What colors are the offspring?

Answer 80

50% red, 50% pink.

Question 81

You mate a finch homozygous for orange beak with a finch homozygous for ivory beak and get numerous offspring, all of which have a pale, ivory-orange beak. This pattern of color expression is most likely to be an example of what?

Answer 81

Incomplete dominance.

Question 82

In lentils, CSCS homozygotes have spotted seeds, CDCD homozygotes have dotted seeds, and CSCD heterozygotes have seeds with both spots and dots. What does this indicate?

Answer 82

CS and CD are codominant.

Question 83

Two individuals decide to have children. The expected blood group genotypes are 50% of blood type A, and 25% each of blood types AB and B. What genotypes are the parents?

Answer 83

IAi and IAIB.

Question 84

What is the expression of both alleles for a trait in a heterozygous individual?

Answer 84

Codominance.

Question 85

A woman with type O blood is expecting a child. Her husband is type A. What is the probability that the child will have type O blood?

Answer 85

50%.

Question 86

A single allele that controls more than one character is said to be what?

Answer 86

Pleiotropic.

Question 87

Two parents of mixed ethnicity have twins, one of which is born white and one of which is born black. This is because of what?

Answer 87

The polygenic nature of skin color genes.

Question 88

The individual features of all organisms are the result of what?

Answer 88

Genetics and the environment.

Question 89

Two identical twins are raised in different environments. They possess ___ genotypes and ___ phenotypes.

Answer 89

Identical ... variable.

Question 90

The chromosome theory of inheritance is based on what set of observations?

Answer 90

Genes segregate; chromosomes come in pairs.

Question 91

Genes located close together on the same chromosomes are referred to as ___ genes and generally ___.

Answer 91

Linked ... do not sort independently during meiosis.

Question 92

Linked genes generally do not follow what?

Answer 92

The laws of independent assortment.

Question 93

Crossing over recombines ___ into assortments of ___ not found in the parents.

Answer 93

Linked genes ... alleles.

Question 94

What is the mechanism that "breaks" the linkage between linked genes?

Answer 94

Crossing over.

Question 95

Any gene located on a sex chromosome is called what?

Answer 95

A sex-linked gene.

Question 96

A woman and her male partner have normal color vision. However, her father and her first son are colorblind. What is her genotype?

Answer 96

XCXc.

Question 97

Why does hemophilia appear rarely in females?

Answer 97

The female must possess the hemophilia gene on both X chromosomes.