A pair of homologous chromosomes includes which of the following sets of DNA strands?
A) two single-stranded chromosomes that have synapsed
B) two sister chromatids that have synapsed
C) four sister chromatids
D) four unique chromosomes
E) eight sister chromatids

two sister chromatids that have synapsed

When we see chiasmata under a microscope, that lets us know which of the following has
occurred?
A) asexual reproduction
B) meiosis II
C) anaphase II
D) prophase I
E) separation of homologs

prophase I

To visualize and identify meiotic cells at metaphase with a microscope, what would you look
for?
A) sister chromatids of a replicated chromosome grouped at the poles
B) individual chromosomes all at the cell's center
C) an uninterrupted spindle array
D) the synaptonemal complex
E) pairs of homologous chromosomes all aligned at the cell's center

pairs of homologous chromosomes all aligned at the cell's center

For the following questions, match the key event of meiosis with the stages listed below.
I. Prophase I V. Prophase II
II. Metaphase I VI. Metaphase II
III. Anaphase I VII. Anaphase II
IV. Telophase I VIII. Telophase II
37) Homologous chromosomes are aligned at the equator of the spindle.
A) I
B) II
C) IV
D) VI
E) VIII

II

Synaptonemal complexes form or are still present.
A) I only
B) I and IV only
C) I and VIII only
D) II and VI only
E) I, II, III, and IV only

I only

Centromeres of sister chromatids disjoin and chromatids separate.
A) II
B) III
C) IV
D) V
E) VII

VII

1. Formation of four new nuclei, each with half the chromosomes present in the parental nucleus
2. Alignment of homologous chromosomes at the metaphase plate
3. Separation of sister chromatids
4. Separation of the homologs; no uncoupling of the centromere
5. Synapsis; chromosomes moving to the middle of the cell in pairs
40) Which of the steps take(s) place in both mitosis and meiosis?
A) 2
B) 3
C) 5
D) 2 and 3 only
E) 2, 3, and 5

3

For a species with a haploid number of 23 chromosomes, how many different combinations
of maternal and paternal chromosomes are possible for the gametes?
A) 23
B) 46
C) 460
D) 920
E) about 8 million

about 8 million

Independent assortment of chromosomes is a result of
A) the random and independent way in which each pair of homologous chromosomes lines up at
the metaphase plate during meiosis I.
B) the random nature of the fertilization of ova by sperm.
C) the random distribution of the sister chromatids to the two daughter cells during anaphase II.
D) the relatively small degree of homology shared by the X and Y chromosomes.
E) the random and independent way in which each pair of homologous chromosomes lines up at
the metaphase plate during meiosis I, the random nature of the fertilization of ova by sperm, the
random distribution of the sister chromatids to the two daughter cells during anaphase II, and the
relatively small degree of homology shared by the X and Y chromosomes.

the random and independent way in which each pair of homologous chromosomes lines up at
the metaphase plate during meiosis I.

Independent assortment of chromosomes occurs.
A) The statement is true for mitosis only.
B) The statement is true for meiosis I only.
C) The statement is true for meiosis II only.
D) The statement is true for mitosis and meiosis I.
E) The statement is true for mitosis and meiosis II.

The statement is true for meiosis I only.

44) Which of the following best describes the frequency of crossing over in mammals?
A) ~50 per chromosome pair
B) ~2 per meiotic cell
C) at least 1-2 per chromosome pair
D) ~1 per pair of sister chromatids
E) a very rare event among hundreds of cells

at least 1-2 per chromosome pair

When homologous chromosomes cross over, what occurs?
A) Two chromatids get tangled, resulting in one re-sequencing its DNA.
B) Two sister chromatids exchange identical pieces of DNA.
C) Specific proteins break the two strands of nonsister chromatids and re-join them.
D) Each of the four DNA strands of a homologous pair is broken, and the pieces are mixed.
E) Maternal alleles are "corrected" to be like paternal alleles, and vice versa.

Specific proteins break the two strands of nonsister chromatids and re-join them.

Which of the life cycles is (are) typical for animals?
A) I only
B) II only
C) III only
D) I and II
E) I and III

I only

Which of the life cycles is (are) typical for plants and some algae?
A) I only
B) II only
C) III only
D) I and II
E) I and III

III only

Which of the life cycles is (are) typical for most fungi and some protists?
A) I only
B) II only
C) III only
D) I and II
E) I and III

II only

In part III of Figure 10.1, the progression of events corresponds to which of the following
series?
A) zygote, mitosis, gametophyte, mitosis, fertilization, zygote, mitosis
B) sporophyte, meiosis, spore, mitosis, gametophyte, mitosis, gametes, fertilization
C) fertilization, mitosis, multicellular haploid, mitosis, spores, sporophyte
D) gametophyte, meiosis, zygote, spores, sporophyte, zygote
E) meiosis, fertilization, zygote, mitosis, adult, meiosis

sporophyte, meiosis, spore, mitosis, gametophyte, mitosis, gametes, fertilization

In a life cycle such as that shown in part III of Figure 10.1, if the zygote's chromosome
number is 10, which of the following will be true?
A) The sporophyte's chromosome number per cell is 10 and the gametophyte's is 5.
B) The sporophyte's chromosome number per cell is 5 and the gametophyte's is 10.
C) The sporophyte and gametophyte each have 10 chromosomes per cell.
D) The sporophyte and gametophyte each have 5 chromosomes per cell.
E) The sporophyte and gametophyte each have 20 chromosomes per cell.

The sporophyte's chromosome number per cell is 10 and the gametophyte's is 5.

Which diagram represents anaphase I of meiosis?
A) I
B) II
C) IV
D) V
E) VI

I

Which diagram(s) represent(s) anaphase II of meiosis?
A) II only
B) III only
C) IV only
D) V only
E) either II or V

V only

You have isolated DNA from three different cell types of an organism, determined the relative
DNA content for each type, and plotted the results on the graph shown in Figure 10.3. Refer to
the graph to answer the following questions.

Figure 10.3
8) Which sample(s) of DNA might be from a nerve cell arrested in G0 of the cell cycle?
A) I
B) II
C) III
D) either I or II
E) either I or III

A) I

Which sample(s) might represent an animal cell in the G2 phase of the cell cycle?
A) I
B) II
C) III
D) both I and II
E) either II or III

II

Which sample(s) might represent a zygote?
A) I
B) II
C) III
D) either I or II
E) either II or III

I

A certain (hypothetical) organism is diploid, has either blue or orange wings as the consequence
of one of its genes on chromosome 12, and has either long or short antennae as the result of a
second gene on chromosome 19, as shown in Figure 10.4.

Figure 10.4
11) A certain female's number 12 chromosomes both have the blue gene and number 19
chromosomes both have the long gene. As cells in her ovaries undergo meiosis, her resulting
eggs (ova) may have which of the following?
A) either two number 12 chromosomes with blue genes or two with orange genes
B) either two number 19 chromosomes with long genes or two with short genes
C) either one blue or one orange gene in addition to either one long or one short gene
D) one chromosome 12 with one blue gene and one chromosome 19 with one long gene

one chromosome 12 with one blue gene and one chromosome 19 with one long gene

If a female of this species has one chromosome 12 with a blue gene and another chromosome
12 with an orange gene, and has both number 19 chromosomes with short genes, she will
produce which of the following egg types?
A) only blue short gene eggs
B) only orange short gene eggs
C) one-half blue short and one-half orange short gene eggs
D) three-fourths blue long and one-fourth orange short gene eggs
E) three-fourths blue short and one-fourth orange short gene eggs

one-half blue short and one-half orange short gene eggs

A female with a paternal set of one orange and one long gene chromosome and a maternal
set comprised of one blue and one short gene chromosome is expected to produce which of the
following types of eggs after meiosis?
A) All eggs will have maternal types of gene combinations.
B) All eggs will have paternal types of gene combinations.
C) Half the eggs will have maternal and half will have paternal combinations.
D) Each egg has a one-fourth chance of having either blue long, blue short, orange long, or
orange short combinations.
E) Each egg has a three-fourths chance of having blue long, one-fourth blue short, three-fourths
orange long, or one-fourth orange short combinations.

Each egg has a one-fourth chance of having either blue long, blue short, orange long, or
orange short combinations.

There is a group of invertebrate animals called rotifers, among which a particular group of
species reproduces, as far as is known, only asexually. These rotifers, however, have survived a
long evolutionary history without evidence of having been overcome by excessive mutations.
1) Because the rotifers develop from eggs, but asexually, what can you predict?
A) The eggs and the zygotes are all haploid.
B) The animals are all hermaphrodites.
C) Although asexual, both males and females are found in nature.
D) All males can produce eggs.
E) No males can be found.

No males can be found.

How is natural selection related to sexual reproduction as opposed to asexual reproduction?
A) Sexual reproduction results in many new gene combinations, some of which will lead to
differential reproduction.
B) Sexual reproduction results in the most appropriate and healthiest balance of two sexes in a
population.
C) Sexual reproduction results in the greatest number of new mutations.
D) Sexual reproduction allows the greatest number of offspring to be produced.
E) Sexual reproduction utilizes far less energy than asexual reproduction.

Sexual reproduction results in many new gene combinations, some of which will lead to
differential reproduction.

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

a sperm.

Homologous chromosomes move toward opposite poles of a dividing cell during
A) mitosis.
B) meiosis I.
C) meiosis II.
D) fertilization.
E) binary fission

meiosis I.

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
A) 0.25x.
B) 0.5x.
C) x.
D) 2x.
E) 4x.

2x.

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 = 8)?
A) 2
B) 4
C) 8
D) 16
E) 32

16