Biology Chapter 13 Practice Test

How many genes are present in the human genome? ( Concept 13.1) 23 46 hundreds tens of thousands a virtually infinite number

tens of thousands Each chromosome has hundreds or thousands of genes; the entire human genome has on the order of 20,000 to 25,000 genes.

A life cycle in which the only multicellular form is haploid is most typical of _____. ( Concept 13.2) primates plants fungi protists fish

fungi Correct. In most fungi, the multicellular form is haploid, and fertilization (and creation of a zygote) is immediately followed by meiosis.

In sexually reproducing species, the chromosome number remains stable over time because _____ and _____ always alternate. ( Concept 13.2) meiosis ... fertilization meiosis ... mitosis mitosis ... fertilization meiosis ... interphase meiosis I ... meiosis II

meiosis ... fertilization Meiosis reduces the number of chromosomes by half, and fertilization restores the number to the diploid state.

Homologous chromosomes move toward opposite poles of a dividing cell during binary fission. fertilization. meiosis I. mitosis. meiosis II.

meiosis I.

The sexual cycle of the multicellular algal genus Fucus involves _____. ( Concept 13.2) mitosis only both mitosis and meiosis but not fertilization both mitosis and fertilization but not meiosis only meiosis and fertilization mitosis, meiosis, and fertilization

mitosis, meiosis, and fertilization All multicellular organisms undergo mitosis, and all diploid, sexually reproducing organisms undergo meiosis and fertilization, which are complementary processes.

Which life cycle stage is found in plants but not animals? multicellular haploid multicellular diploid gamete zygote unicellular diploid

multicellular haploid

If we continued to follow the cell lineage from question 5, then the DNA content of a single cell at metaphase of meiosis II would be 0.25x. 0.5x. x. 2x. 4x.

x.

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be 0.25x. 0.5x. x. 2x. 4x.

2x.

Which event occurs only during prophase I of the first meiotic division? ( Concept 13.3) Homologous chromosomes line up at the center of the cell. Synapsis of homologous pairs occurs. The nuclear membrane breaks down. Replication of DNA takes place. A spindle of microtubules forms.

Synapsis of homologous pairs occurs. Correct. Synapsis of homologous chromosomes occurs at prophase of meiosis I.

Regarding the role of cohesin protein in maintaining cohesion between sister chromatids, which of the following statements is false?( Concept 13.3) During meiosis I, cohesion holds sister chromatids together along their lengths as chiasmata form between homologs. During meiosis II, cohesion holds sister chromatids along their lengths as the second meiotic spindle forms. Cleavage of cohesins between sister chromatid arms at anaphase I allows homologs to separate. The first and second listed responses are false. The second and third listed responses are false. None of the listed responses is false.

During meiosis II, cohesion holds sister chromatids along their lengths as the second meiotic spindle forms. This statement is false. During meiosis II, cohesion holds the sister chromatids together at the centromeres prior to their separation at metaphase II.

In a diploid set of chromosomes, one member of each pair of homologous chromosomes is derived from the father (paternal), and the other comes from the mother (maternal). If 2n = 6, what is the probability of obtaining a gamete in which all the chromosomes are paternal ones? ( Concept 13.4) 1/4 1/8 1/16 1/32 The answer cannot be determined from these data.

1/8 The chance of any one paternal chromosome ending up in a particular gamete is 1/2, so the chance that all three would be of paternal origin would be (1/2)n, where n = 3.

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n 5 8)? 2 4 8 16 32

16

Which of the following occurs in meiosis, but not mitosis? ( Concept 13.3) The cells formed have the same combination of genes as found in the initial cell. Homologous chromosomes separate. The nuclear envelope disappears. Sister chromatids undergo disjunction. A spindle apparatus forms.

Homologous chromosomes separate. Correct. Homologous chromosomes separate during anaphase I. This event follows synapsis, an event unique to prophase I.

A clone is the product of _____. ( Concept 13.1) asexual reproduction sexual reproduction mitosis meiosis The first and third listed responses are correct. The second and fourth listed responses are correct.

The first and third listed responses are correct. asexual reproduction mitosis In asexual reproduction, an organism produces genetically identical progeny, or clones, by mitosis.

Spores and gametes are different in that _____. ( Concept 13.2) gametes never resemble spores morphologically gametes are always haploid whereas spores are diploid gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote only the formation of gametes contributes to genetic variation gametes are derived directly from sporophytes to form gametophytes

gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote Unlike a gamete, a spore gives rise to a multicellular organism without fusing with another cell.

Which of the following occurs during anaphase I? ( Concept 13.3) Homologs separate and migrate toward opposite poles. Sister chromatids separate and migrate toward opposite poles. Nuclei re-form. Chromosomes line up in one plane. The cell is haploid.

Homologs separate and migrate toward opposite poles. This occurs during anaphase I.

Meiosis II is similar to mitosis in that the daughter cells are diploid. the chromosome number is reduced. DNA replicates before the division. sister chromatids separate during anaphase. homologous chromosomes synapse.

sister chromatids separate during anaphase.

What is a locus? ( Concept 13.1) the precise location of a gene on a chromosome a structure that appears during prophase I and consists of two paired genes the precise DNA sequence of a gene a type of spore made only by fungi a cell with two chromosome sets

the precise location of a gene on a chromosome The location of a gene within the genome, including the identity of the particular chromosome that it maps to and its specific position on that chromosome, is called its locus.

Which of the following answers is not involved nor an outcome of crossing over? ( Concept 13.4) The DNA in two nonsister chromatids is broken by specific proteins at exact points. Chiasmata indicate where crossing over is occurring between homologs. the random alignment of homologous pairs of chromosome at metaphase I formation of chromosomes containing paternal and maternal alleles All of the listed responses pertain to the process of crossing over.

the random alignment of homologous pairs of chromosome at metaphase I Correct. This process is not related to crossing over but is an outcome of independent assortment.

Sexual and asexual reproduction are alike in that _____. ( Concept 13.1) they both give rise to genetically distinct offspring they both involve two parents they both require meiosis to complete the reproductive cycle they can both occur in multicellular organisms in both cases, every parent transmits all of its genes to its progeny

they can both occur in multicellular organisms Examples of both sexual and asexual reproduction have been observed in multicellular organisms.

What is the function of meiosis? ( Concept 13.3) to make exact copies of the parent cell to make one cell with twice the number of chromosomes as the parent pairs to make four cells with the same chromosome number as the parent to make cells with a haploid (half that of the parents) number of chromosomes to make diploid spores

to make cells with a haploid (half that of the parents) number of chromosomes The two cell divisions of meiosis, I and II, produce four haploid daughter cells, which are not genetically identical to the diploid parent cell.

Somatic cells in humans contain _____ set(s) of chromosomes and are therefore termed _____. (Concept 13.2) one ... diploid two ... haploid one ... haploid two ... diploid three ... triploid

two ... diploid

At the end of telophase I of meiosis and the first cytokinesis, there are _____. ( Concept 13.3) four haploid cells two diploid cells four diploid cells one haploid ovum and three polar bodies two haploid cells

two haploid cells Each of these cells carries a haploid set of chromosomes, each consisting of two chromatids.

Ignoring crossover, how many kinds of gametes can be produced by an organism with a diploid number of 8? ( Concept 13.4) 2 4 8 16 32

16 The number of combinations possible when chromosomes assort independently into gametes during meiosis is 2n, where n is the haploid number of chromosomes.

How many pairs of autosomes do humans have? ( Concept 13.2) 23 22 2 1 It depends on the sex of the individual.

22 Humans have 22 pairs of autosomes and one pair of sex chromosomes.

In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing _____ different types of gametes. ( Concept 13.4) 2^32 1 million 2^23 24 100,000

2^23 For each gamete there are two possibilities for each chromosome (the paternal or the maternal chromosome), and there are 23 different chromosomes per gamete.

The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit? ( Concept 13.2) 11 22 44 88 132

44 Haploid sex cells contain half as many chromosomes as diploid somatic cells.

In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes. ( Concept 13.2) 5 10 20 40 0

5 Haploid sex cells contain half as many chromosomes as diploid somatic cells.

Which, if any, of the following statements is true? ( Concept 13.2) Diploid cells can divide by mitosis. Diploid cells can divide by meiosis. Haploid cells can divide by mitosis. Haploid cells cannot divide by meiosis. All of the above responses are correct.

All of the above responses are correct. Correct. Diploid cells can divide by either mitosis or meiosis, but haploid cells can only divide by mitosis.

Which of the following statements reflects an advantage that sexual reproduction likely provides over asexual reproduction? ( Concept 13.4) In terms of energetic costs, sexual reproduction is a cheaper strategy than asexual reproduction for generating genetic variation in a population. Although sexual and asexual reproduction both offer opportunities for increasing genetic variation, sexual reproduction is comparatively lower in its energetic costs to the organism. Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment. Sexual reproduction maintains the same combination of alleles and does not run the risk of losing successful combination of alleles as is observed to occur in asexually reproducing organisms. Although both reproductive strategies perpetuate the same combination of alleles within individuals in a population, sexual reproduction is energetically less costly than asexual reproduction.

Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment. Correct. Asexual reproduction is cheaper than sexual reproduction but perpetuates the same combination of alleles in individuals over generations; thus, it does not provide the capacity for adaptation as do sexually reproducing organisms.

Which of the following occurs during anaphase II? ( Concept 13.3) Homologs separate and migrate toward opposite poles. Sister chromatids separate and migrate toward opposite poles. Nuclei re-form. Chromosomes line up in one plane. The synaptonemal complex disappears.

Sister chromatids separate and migrate toward opposite poles. This occurs during anaphase II.

The diploid number of chromosomes in a certain animal is 8 (2n = 8). How do the four pairs of homologous chromosomes align and separate during meiosis? ( Concept 13.4) All of the maternal chromosomes always move to one pole, and all the paternal chromosomes always move to the other pole. All 16 chromatids move together. Exactly two maternal and two paternal chromosomes always move to each of the two poles. The first to move influences all the others. They align and assort independently to form any of 16 different combinations.

They align and assort independently to form any of 16 different combinations. Correct. Because each pair of homologous chromosomes is positioned independently in metaphase I, the first meiotic division results in the independent assortment of paternal and maternal chromosomes into daughter cells. In a case in which 2n = 8, 16 combinations of chromosomes are possible for gametes.

Which of the following statements about homologous chromosomes is correct? ( Concept 13.2) They are found in animal cells but not in plant cells. They have genes for the same traits at the same loci. They pair up in prophase II. They are found in haploid cells. They are found in the cells of human females but not in human males.

They have genes for the same traits at the same loci. The chromosomes that make up a pair are called homologous chromosomes, and they carry genes controlling the same inherited characters.

Fertilization produces _____. ( Concept 13.2) a haploid zygote in some life cycles and a diploid zygote in others a haploid zygote a diploid zygote a diploid zygote, except during the gametophyte stage of alternation of generations a multicellular haploid organism in a life cycle with an alternation of generations

a diploid zygote Fertilization always involves the fusion of gametes and produces a diploid zygote.

A karyotype is _____. ( Concept 13.2) the physical traits a person has a method of identifying crossover events all the possible gametes a person could produce a photograph of all of an individual's chromosomes a list of all the genes a person carries

a photograph of all of an individual's chromosomes Karyotypes, ordered displays of an individual's chromosomes, are useful in identifying chromosomal abnormalities.

A human cell containing 22 autosomes and a Y chromosome is a sperm. a zygote. a somatic cell of a male. a somatic cell of a female. an egg.

a sperm.

Which of the following is part of the life cycle called alternation of generations? ( Concept 13.2) multicellular haploid stage (gametophyte) multicellular diploid stage (sporophyte) zygote spores all of the above

all of the above Correct. In alternation of generations, zygotes give rise to multicellular, diploid sporophytes, and spores give rise to multicellular, haploid gametophytes.

Which function makes meiosis lengthier and more complex than mitosis? ( Concept 13.3) decreasing the chromosome number to haploid introducing genetic variation among the daughter cells ensuring that each daughter cell gets a single, complete set of chromosomes undergoing two rounds of cytokinesis all of the above

all of the above Correct. Meiosis involves two divisions that typically result in four daughter cells (instead of two). Each cell has half the number of chromosomes of the original parent cell, and is, of course, not genetically identical to the parent cell.

Sister chromatids _____. ( Concept 13.2) are only involved in mitosis are pairs of chromosomes, one of which comes from the father and one of which comes from the mother are identical copies of each other formed during DNA synthesis have the same gene loci but may have different alleles of some genes are only involved in meiosis

are identical copies of each other formed during DNA synthesis Sister chromatids are identical and participate in both mitosis and meiosis.

Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place _____. ( Concept 13.2) during crossing over in meiosis when DNA is replicated during the S phase of the cell cycle when mitotic cytokinesis occurs at fertilization, when gametes fuse during gastrulation

at fertilization, when gametes fuse The union of haploid gametes at fertilization produces the zygote, or fertilized egg, which marks the beginning of the diploid phase of the life cycle.

Regions of chromosomes where nonsister chromatids cross over are called _____. ( Concept 13.3) inversions homologs kinetochores chiasmata tetrads

chiasmata Chiasmata are regions where crossing over has occurred.

Cytokinesis is the _____. ( Concept 13.3) exchange of homologous regions of nonsister chromatids formation of tetrads independent assortment of chromosomes lining up of tetrads at the metaphase plate division of one cell into two

division of one cell into two Correct. Cytokinesis normally accompanies both telophase I and telophase II, as well as the telophase of mitosis.

In a male mammal, every cell that undergoes meiosis gives rise to _____ sperm. ( Concept 13.3) one two four no set number zero

four One diploid parent cell gives rise to four haploid sex cells at the completion of the two meiotic divisions.

An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis? (Concept 13.3) two three four eight 16

four Because of the synapsis of homologous chromosomes, the number of tetrads in meiosis I will be the same as the haploid number of chromosomes.

What is the result when a diploid cell undergoes meiosis? ( Concept 13.3) two diploid cells two haploid cells four diploid cells four haploid cells two haploid cells and two diploid cells

four haploid cells

The major contribution of sex to evolution is that _____. ( Concept 13.4) it is the only mechanism for species to reproduce it provides a method to increase genetic variation it provides a way in which somatic mutations can be inherited The first and second listed responses are correct. The second and third listed responses are correct.

it provides a method to increase genetic variation Sexual life cycles produce enormous genetic variation among offspring.

When we say that an organism is haploid, we mean that _____. ( Concept 13.2) its cells each have one chromosome it has one half of a chromosome its cells have a single set of chromosomes its cells have two sets of chromosomes its cells have half of one set of chromosomes

its cells have a single set of chromosomes Many fungi and some protists exist as haploid organisms, and plants and some algae also have a haploid stage (called a gametophyte) as part of the life cycle called alternation of generations.

Humans have 46 chromosomes. This number of chromosomes will be found in _____. ( Concept 13.2) all cells in anaphase of mitosis all the egg and sperm cells all gamete-producing cells after meiosis I liver cells all the cells of the body

liver cells Liver cells are somatic cells, and they contain the characteristic diploid chromosome number.

Which of the following results in cells that contain half the parental chromosome number? ( Concept 13.3) cytokinesis mitosis meiosis interphase metaphase

meiosis Correct. The two cell divisions of meiosis, I and II, produce four haploid daughter cells.

Which of the following is a function of mitosis in humans? ( Concept 13.2) production of eggs production of sperm decreasing the number of chromosomes multiplication of body cells increasing genetic variability

multiplication of body cells This is a function of mitosis in humans. It is mitosis that enables a multicellular adult to form from a fertilized egg and produces cells for growth and tissue repair.

Unless the chromosomes were stained to show band patterns, a karyotype would be least likely to show which of the following? ( Concept 13.2) an extra chromosome a large part of a chromosome duplicated a missing chromosome part of a chromosome turned around the attachment of a large part of a chromosome to another chromosome

part of a chromosome turned around An inversion, which affects neither the number of chromosomes nor the length of a chromosome, is generally difficult to detect without staining to show chromosomal bands.

The synaptonemal complex _____. ( Concept 13.3) physically connects homologous chromosomes during prophase I physically connects homologous chromosomes during mitosis is broken down by enzymes during anaphase II is another name for chiasmata is formed by a protein called cohesin

physically connects homologous chromosomes during prophase I Correct. The synaptonemal complex helps to line up homologous chromosomes gene by gene.

Crossing over occurs during _____. ( Concept 13.3) cytokinesis metaphase I prophase II metaphase II prophase I

prophase I Crossing over resulting in genetic recombination occurs during this phase.

Synapsis occurs during _____. ( Concept 13.3) anaphase I prophase I cytokinesis prophase II metaphase I

prophase I Synapsis is the pairing of homologous chromosomes during prophase I.

Which of the following contributes to genetic variation in sexually reproducing species? ( Concept 13.4) crossing over, internal fertilization, independent assortment independent assortment, spindle formation, random fertilization random fertilization, DNA synthesis, independent assortment random fertilization, independent assortment, crossing over internal fertilization, spindle formation, crossing over

random fertilization, independent assortment, crossing over These three aspects of sexual reproduction increase genetic variation.

Although _____ is nearly universal among animals, bdelloid rotifers _____. ( Concept 13.4) asexual production ... have achieved great diversity by using sexual reproduction sexual reproduction ... reproduce asexually and achieve genetic diversity by mutations alone sexual production ... reproduce asexually because they inhabit very stable environments and the production of gametes would be an inefficient use of energy sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers

sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers Correct. Although bdelloid rotifers are incapable of sexual reproduction, they can carry out a form of "horizontal gene transfer" in which they take up DNA from the environment and incorporate it into their genome. This adaptation demonstrates that asexually reproducing animals are not limited to mutation alone in generating genetic diversity in a population.