Chapter 13 Practice Test

How many genes are present in the human genome?

tens of thousands

What is a locus?

the precise location of a gene on a chromosome

Sexual and asexual reproduction are alike in that __________.

they can both occur in multicellular organisms

A karyotype is __________.

a photograph of all the chromosomes in a single cell from an individual

Fertilization produces __________.

a diploid zygote

Which, if any, of the following statements is true?

Diploid cells can divide by either mitosis or meiosis, but haploid cells can divide only by mitosis.

Which of the following is part of the life cycle called alternation of generations?

All of the listed responses are correct.

The sexual cycle of the diploid, multicellular algal genus Fucus involves __________.

mitosis, meiosis, and fertilization

A life cycle in which the only multicellular form is haploid is most typical of __________.

fungi

In sexually reproducing species, the chromosome number remains stable over time because __________ and __________ always alternate.

meiosis ... fertilization

The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?

44

In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.

5

How many pairs of autosomes do humans have?

22

Sister chromatids __________.

are identical copies of each other formed through DNA synthesis

Which of the following statements about homologous chromosomes is correct?

They have genes for the same traits at the same loci.

When we say that an organism is haploid, we mean that __________.

its cells have a single set of chromosomes

Which of the following is a function of mitosis in humans?

multiplication of body cells

Somatic cells in humans contain __________ set(s) of chromosomes and are therefore termed __________.

two ... diploid

Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place __________.

at fertilization, when gametes fuse

Spores and gametes are different in that __________.

gametes can fuse to form a zygote, but spores can develop into independent organisms without first forming a zygote

Humans have 46 chromosomes. This number of chromosomes will be found in __________.

liver cells

Which of the following results in cells that contain half the parental chromosome number?

meiosis

At the end of telophase I of meiosis and the first cytokinesis, there are __________.

two haploid cells

What is the typical result when a diploid cell has completed meiosis?

four haploid cells

Synapsis occurs during __________.

prophase I

Which of the following occurs during anaphase II?

Sister chromatids separate and migrate toward opposite poles.

Which of the following occurs during anaphase I?

Homologs separate and migrate toward opposite poles.

Cytokinesis is the __________.

division of the cytoplasm to create two cells

What is the function of meiosis?

to make cells with a haploid (half that of the parents) number of chromosomes

Crossing over occurs during __________.

prophase I

Regions of chromosomes where nonsister chromatids cross over are called __________.

chiasmata

The synaptonemal complex __________.

physically connects homologous chromosomes during prophase I

An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis?

4

Which event occurs only during prophase I of the first meiotic division?

Synapsis of homologous pairs occurs.

Which of the following occurs in meiosis, but NOT mitosis?

Homologous chromosomes separate.

Which function makes meiosis lengthier and more complex than mitosis?

All of the listed responses are correct.

Which of the following contributes to genetic variation in sexually reproducing species?

random fertilization, independent assortment, crossing over

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?

They align and assort independently to form any of 16 different combinations.

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 that a particular gamete will contain only paternal chromosomes?

1/8

The major contribution of sex to evolution is that __________.

it provides a method to increase genetic variation

Which of the following answers is NEITHER involved with crossing over NOR an outcome of crossing over?

the random alignment of homologous pairs of chromosomes at metaphase I

Which of the following statements reflects an advantage that sexual reproduction likely provides over 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.

Although __________ is nearly universal among animals, bdelloid rotifers __________.

sexual reproduction ... reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers