Ch.8 Full Test Bank Sexual Reproduction and Heredity

Chapter 8: Sexual Reproduction and Heredity

Multiple-Choice Questions

By crossing different varieties of peas ______ discovered the principles of heredity.

a. William Bateson

b. Walter Sutton

c. Gregor Mendel

d. Hugo de Vries

e. Barbara McClintock

Which of the following statements about sexual reproduction is FALSE?

a. It is the principal mode of reproduction in prokaryotes.

b. Some eukaryotes do not reproduce sexually.

c. It involves the reduction of chromosome number.

d. It involves syngamy.

e. It involves a regular alternation between meiosis and fertilization.

Which of the following statements about homologous chromosomes is FALSE?

a. Both homologs are present in a zygote.

b. One homolog comes from one parent and the other homolog from the other parent.

c. Homologs resemble each other in the kinds of hereditary information they contain.

d. Homologs resemble each other in size but not in shape.

e. Homologs constitute a member of a pair.

Chromatin consists of:

a. DNA only.

b. histones only.

c. DNA and histones only.

d. histones and other proteins only.

e. DNA, histones, and other proteins.

Which of the following statements concerning histones is FALSE?

a. They are responsible for the folding of DNA.

b. They are present in four distinct types.

c. They are always present in chromatin.

d. They are synthesized during the S phase of the cell cycle.

e. They are positively charged.

A nucleosome consists of:

a. nonhistone chromosomal proteins.

b. eight histone molecules arranged in a spherical mass.

c. a strand of DNA that is not associated with histones.

d. a looped domain in the chromosome.

e. a core of histones wrapped with DNA.

A cell that unites with another cell is called a:

a. meiospore.

b. mitospore.

c. gamete.

d. diploid cell.

e. zygote.

The pairing of homologous chromosomes is called:

a. synapsis.

b. chiasma.

c. crossing-over.

d. recombination.

e. bivalence.

Which of the following statements about the synaptonemal complex is FALSE?

a. It forms just before prophase.

b. It is associated with the formation of bivalents.

c. It connects the axial cores of homologs.

d. It disappears during prophase I.

e. It is associated with crossing-over.

Crossing-over occurs during:

a. prophase II.

b. metaphase I.

c. telophase I.

d. metaphase II.

e. prophase I.

Homologous pairs of chromosomes separate during:

a. prophase II.

b. metaphase I.

c. anaphase I.

d. metaphase II.

e. anaphase III.

Nuclear envelopes form around single-stranded chromosomes during:

a. telophase II.

b. metaphase I.

c. prophase I.

d. telophase I.

e. metaphase II.

Unpaired double-stranded chromosomes line up on the equatorial plane during:

a. prophase II.

b. metaphase I.

c. anaphase I.

d. metaphase II.

e. anaphase II.

Sister chromatids become daughter chromosomes during:

a. prophase II.

b. metaphase I.

c. anaphase I.

d. metaphase II.

e. anaphase II.

If a cell has three pairs of homologous chromosomes, in how many ways could they be distributed among the haploid cells produced by meiosis?

a. two

b. three

c. four

d. eight

e. nine

Which of the following statements about alleles is FALSE?

a. They are different forms of the same gene.

b. Interactions between alleles determine the characteristics of diploid organisms.

c. They occupy different sites on homologous chromosomes.

d. The site of an allele is called its locus.

e. Dominant alleles are represented by uppercase letters, recessive alleles by lowercase letters.

The seeds of all the progeny of a cross between yellow-seeded plants and green-seeded plants are as yellow as those of the yellow-seeded parent. From this information, it is clear that:

a. this is an example of a dihybrid cross.

b. the F₁ generation consists entirely of yellow-seeded plants.

c. the F₂ generation consists entirely of yellow-seeded plants.

d. green is a dominant characteristic.

e. yellow is a recessive characteristic.

When a particular trait appears in the F₂ generation but not in the F₁ generation, it is an indication that:

a. a monohybrid cross is involved.

b. a dihybrid cross is involved.

c. true-breeding plants are involved.

d. the trait is recessive.

e. the trait is dominant.

If we say that the phenotype of an individual is purple, we are saying that:

a. the appearance of the individual is purple.

b. the genetic constitution of the individual is purple.

c. the individual is homozygous.

d. the individual is heterozygous.

e. purple is the dominant allele.

If the allele for red flower color is dominant over the allele for white flower color, which of the following represents a cross between a white-flowered plant and a plant heterozygous for flower color?

a. RR × RR

b. RR × Rr

c. RR × rr

d. Rr × Rr

e. Rr × rr

In peas, green pod color is dominant over yellow pod color. If a plant heterozygous for pod color is crossed with a plant homozygous recessive for pod color, what phenotypes would you expect in the offspring?

a. all with green pods

b. all with yellow pods

c. half with green pods and half with yellow pods

d. three-quarters with green pods and 1/4 with yellow pods

e. one-quarter with green pods and 3/4 with yellow pods

In peas, tall stem length is dominant over short length. What genotypic ratio would you expect in the offspring of a cross between a heterozygous tall plant and a homozygous short plant?

a. three homozygous tall: one homozygous short

b. one homozygous tall: one homozygous short

c. one heterozygous tall: one homozygous short

d. three heterozygous tall: one homozygous short

e. one homozygous tall: two heterozygous tall: one homozygous short

If W represents the allele for purple flower color, and w represents the allele for white flower color, what phenotypic ratio would you expect for the offspring of a testcross?

a. One WW: one ww

b. One WW: two Ww: one ww

c. Three WW: one ww

d. One WW: three ww

e. Three WW: two Ww: one ww

Consider the two traits, seed shape and seed color. R represents the allele for round seeds, r the allele for wrinkled seeds, Y the allele for yellow seeds, and y the allele for green seeds. Which of the following indicates a cross between a plant heterozygous for both traits and a plant homozygous recessive for both traits?

a. Ry × ry

b. Rryy × rryy

c. Rryy × Rryy

d. RrYy × Rryy

e. RrYy × rryy

Consider the two traits, seed shape and seed color. R represents the allele for round seeds, r the allele for wrinkled seeds, Y the allele for yellow seeds, and y the allele for green seeds. What phenotypic ratio would you expect in the offspring of a cross between a plant with wrinkled green seeds and a plant heterozygous for both traits?

a. nine round yellow: three round green: three wrinkled yellow: one wrinkled green

b. all round yellow

c. all wrinkled green

d. one round yellow: one round green: one wrinkled yellow: one wrinkled green

e. three round yellow: three round green: one wrinkled yellow: one wrinkled green

Which of the following is true of Mendel’s second law but not his first law?

a. The two alleles of a gene assort independently of the alleles of the other genes.

b. The two alleles of a gene separate from each other during the formation of gametes.

c. A plant heterozygous for a trait forms more gametes than a plant homozygous for that trait.

d. A plant homozygous for a trait forms more gametes than a plant heterozygous for that trait.

e. Alleles occupy the same locus on homologous chromosomes.

If two genes are linked, then by definition they:

a. are alleles of the same gene.

b. occur on the same chromosome.

c. occur on different chromatids of the same chromosome.

d. will segregate independently.

e. will undergo independent assortment.

Suppose that a plant has two genes that are linked, with Ab on one homolog of a homologous pair of chromosomes and aB on the other homolog. What gametes could the plant produce if crossing-over occurred between these genes during meiosis?

a. Ab and aB only

b. AB and ab only

c. Aa and Bb only

d. Ab, aB, AB, and ab only

e. Ab, aB, AB, ab, Aa, and Bb only

29. Mutations; p. 164; moderate: c

Consider a chromosome represented as ABC·DEFG, where · indicates the centromere. Suppose ultraviolet light causes the chromosome to change to AC·DEFG. What type of mutation has occurred?

a. duplication

b. inversion

c. deletion

d. translocation

e. transposon

30. Mutations; p. 164; moderate: b

Consider a chromosome represented as ABCD·EFG, where · indicates the centromere. Suppose ultraviolet light causes the chromosome to change to ACBD·EFG. What type of mutation has occurred?

a. duplication

b. inversion

c. deletion

d. translocation

e. transposon

Which of the following statements about transposons is FALSE?

a. They are also called “jumping genes.”

b. They are movable genetic elements.

c. They may lead to mutation.

d. Plasmids can function as transposons.

e. They occur only in bacteria.

The exchange of segments between nonhomologous chromosomes is called a(n):

a. deletion.

b. inversion.

c. duplication.

d. translocation.

e. point mutation.

Polyploidy refers to the:

a. loss of part of a chromosome.

b. gain of part of a chromosome.

c. gain or loss of some chromosomes.

d. gain of a complete set of chromosomes.

e. loss of a complete set of chromosomes.

Which of the following statements concerning mutations is FALSE?

a. Mutations may have favorable, unfavorable, or neutral effects.

b. In haploid organisms, the phenotype associated with a mutation is immediately exposed to the environment.

c. In diploid organisms, a mutation in one homolog may have less effect than if it occurred in both homologs.

d. Mutations provide the raw materials for evolutionary change.

e. The mutation rate in eukaryotes is about one mutant gene at a given locus per 2000 cell divisions.

When the phenotype of a heterozygote is intermediate between the phenotypes of its homozygous parents, the condition is known as:

a. pleiotropy.

b. aneuploidy.

c. epistasis.

d. polygenic inheritance.

e. incomplete dominance.

In snapdragons, a cross between a red-flowered plant and a white-flowered plant produces a plant with pink flowers. What offspring would you expect from a cross between two pink-flowered plants?

a. All pink

b. 1/2 pink and 1/2 white

c. 1/2 pink and 1/2 red

d. 1/4 red, 1/2 pink, 1/4 white

e. 1/4 pink, 1/2 red, 1/4 white

A population of organisms that has four alleles for a given gene is said to have:

a. self-sterility genes.

b. multiple alleles.

c. continuous variation.

d. polygenic inheritance.

e. incomplete dominance.

In peas, the dominant alleles A and B must be present for purple flower pigment to be produced; otherwise the flowers are white. What offspring would you expect from a cross between plants of genotypes Aabb and aaBb?

a. one purple: three white

b. three purple: one white

c. one purple: one white

d. nine purple: two white

e. two purple: three white

When a trait exhibits continuous variation in a population of organisms, it most likely is due to:

a. one gene having multiple effects.

b. one allele not completely masking another allele.

c. several alleles of the same gene interacting.

d. one gene masking the effect of another gene.

e. several different genes interacting.

In ______, a single gene has many different effects on the phenotype.

a. pleiotropy

b. continuous variation

c. epistasis

d. polygenic inheritance

e. incomplete dominance

Cytoplasmic inheritance in plants involves genes present in the:

a. cytosol only.

b. plastids only.

c. mitochondria only.

d. cytosol and plastids.

e. mitochondria and plastids.

Which of the following is NOT a possible cause of maternal inheritance?

a. The generative cell receives neither plastids nor mitochondria from the microspore.

b. The generative cell receives plastids and mitochondria but they degenerate.

c. Plastids and mitochondria are excluded from generative and sperm cells.

d. Plastids and mitochondria are present in sperm cells but are not transmitted into the egg.

e. Plastids and mitochondria are present in sperm cells but only plastids are transmitted into the egg.

An aquatic plant produces one type of leaf above water and another type of leaf under water. This is most likely an example of:

a. one gene having multiple effects.

b. interaction of the genotype with the environment.

c. one allele not completely masking another allele.

d. one gene masking the effect of another gene.

e. several different genes interacting.

Which of the following statements about asexual reproduction is FALSE?

a. It is also known as vegetative reproduction.

b. It results in offspring that are genetically identical to the parent.

c. It is common in higher plants.

d. Many plants reproduce asexually and sexually.

e. It increases the ability of a population to adapt to differing conditions.

Which of the following statements about sexual reproduction is FALSE?

a. It occurs only in eukaryotic organisms.

b. It is necessary for the survival of the population.

c. It involves a regular alternation between meiosis and fertilization.

d. It produces and maintains an infinite array of genetic diversity in populations.

e. It provides the basic mechanism of evolution.

True-False Questions

Mendel became famous during his lifetime for his work that marked the beginning of modern genetics.

A nucleosome is composed of histone proteins wrapped around a DNA filament.

Enzymes associated with the synthesis of DNA and RNA are part of the chromatin.

Crossing-over is the exchange of genetic material between the sister chromatids of a chromosome.

Sister chromatids separate during anaphase I.

It is likely that one of the four daughter cells resulting from meiosis will be genetically identical to one of the gametes that fused to produce the diploid line of cells undergoing meiosis.

Alleles occupy different loci on homologous chromosomes.

When you say that a plant is Gg for a particular trait you are referring to the genotype.

The notation pp indicates that a plant is homozygous dominant for that trait.

The term “phenotype” refers to the appearance of an individual.

A testcross involves crossing an individual dominant for a particular trait with an individual heterozygous for that trait.

If two genes are linked, then they are on the same chromosome.

The greater the distance between two genes on a chromosome, the smaller is the chance that they will undergo crossing-over during meiosis.

A linkage map provides the approximate positions of the genes on a chromosome.

A plasmid is part of the main bacterial chromosome.

A translocation occurs when parts of two nonhomologous chromosomes are exchanged.

Aneuploidy results from the duplication of whole sets of chromosomes.

A mutation in a haploid cell is more likely to have an effect on phenotype than a mutation in a diploid cell.

If a red-flowered plant is crossed with a white-flowered plant and the offspring all have pink flowers, then most likely this is due to incomplete dominance.

In a population of diploid organisms there can be only two alleles for each gene.

Cytoplasmic inheritance refers to genes located in mitochondria or plastids.

Plants that reproduce only asexually have evolved from ancestors that were capable of sexual reproduction.

In theory, sexual reproduction is unnecessary for the survival of a population of organisms in an unchanging environment.

Essay Questions

1. Sexual Reproduction; p. 154; easy

List the defining characteristics of homologous chromsomes.

2. The Eukaryotic Chromosome; p. 155; easy

Describe the structure of a nucleosome. What role do nucleosomes play in the cell?

3. The Process of Meiosis; pp. 155−158; moderate

Describe the major steps in meiosis.

4. The Phases of Meiosis; p. 156; moderate

What is a synaptonemal complex? What role does it play in meiosis?

5. The Process of Meiosis; p. 158; moderate

Discuss the ways in which meiosis produces genetic variability.

6. How Characteristics Are Inherited; pp. 160-162; moderate

Explain the difference between each of the following pairs of terms: dominant vs. recessive, homozygous vs. heterozygous, genotype vs. phenotype.

7. How Characteristics Are Inherited; pp. 162-163; moderate

Explain what is meant by the principle of segregation and the principle of independent assortment.

8. Mutations; p. 165; moderate

What is the difference between a deletion and a duplication in a chromosome? Between a translocation and an inversion?

9. Mutations; p. 166; moderate

Discuss the relationship between mutations and evolutionary change.

10. Broadening the Concept of the Gene; p. 166; moderate

What is meant by incomplete dominance? Use an example to explain the molecular basis for this phenomenon.

11. Broadening the Concept of the Gene; pp. 168-169; moderate

Why are cytoplasmically inherited traits maternally, rather than paternally, inherited? Give an example of cytoplasmic inheritance involving (a) chloroplasts and (b) mitochondria.

12. Advantages and Disadvantages of Asexual and Sexual Reproduction; p. 170; difficult

Compare the advantages and disadvantages of asexual and sexual reproduction.