In his breeding experiments, Mendel first crossed true-breeding
plants to produce a second generation, which were then allowed to
self-pollinate to generate the offspring. How do we name these three generations?
P1 ... P2 ... P3
P1 ... P2 ... F
P ... F1 ... F2
F ... P1 ... P2
F1 ... F2 ... F3

P..F1..F2

Which of the following is true about a plant with the genotype AABbcc?
It has recessive alleles at three loci.
It is homozygous at two loci.
It is triploid.
It will not express the recessive c allele.
It is heterozygous at two loci.

It is homozygous at two loci

What is an allele?
the dominant form of a gene
the recessive form of a gene
a variety of pea plant used by Mendel
an alternative version of a gene
a type of chromosome

an alternative version of a gene

What do we mean when we use the terms monohybrid cross and
dihybrid cross?
A dihybrid cross involves organisms that are heterozygous for two
characters, and a monohybrid cross involves only one.
A monohybrid cross produces a single progeny, whereas a dihybrid
cross produces two progeny
. A monohybrid cross results in a 9:3:3:1 ratio, whereas a dihybrid
cross gives a 3:1 ratio.
A monohybrid cross is performed for one generation, whereas a
dihybrid cross is performed for two generations.
A monohybrid cross involves a single parent, whereas a dihybrid
cross involves two parents.

A dihybrid cross involves organisms that are heterozygous for two
characters and a monohybrid cross involves only one.

What was the most significant conclusion that Gregor Mendel drew from
his experiments with pea plants?
Recessive genes occur more frequently in the F1
generation than do dominant ones.
An organism that is homozygous for many recessive traits is at a disadvantage.
Traits are inherited in discrete units, and are not the results of "blending."
Genes are composed of DNA.
There is considerable genetic variation in garden peas.

traits are inherited in discrete units and are not the results of "blending".

The individual with genotype AaBbCCDdEE can make many kinds
of gametes. Which of the following is the major reason?
segregation of maternal and paternal alleles
recurrent mutations forming new alleles
different possible assortment of chromosomes into gametes
crossing over during prophase I
the tendency for dominant alleles to segregate together

different possible assortment of chromosomes into gametes.

Two plants are crossed, resulting in offspring with a 3:1 ratio for a
particular trait. What does this suggest?

the parents were both heterozygous for a single trait

A sexually reproducing animal has two unlinked genes, one for head
shape (H) and one for tail length (T). Its genotype
is HhTt. Which of the following genotypes is possible in a
gamete from this organism?

HT

When crossing an organism that is homozygous recessive for a single
trait with a heterozygote, what is the chance of producing an
offspring with the homozygous recessive phenotype?

50%

Mendel accounted for the observation that traits that had disappeared
in the F1 generation reappeared in the F2
generation by proposing that

traits can be dominant or recessive, and the recessive traits were
obscured by the dominant ones in the F1.

Mendel's observation of the segregation of alleles in gamete
formation has its basis in which of the following phases of cell division?

anaphase 1 of meiosis

Why did the F1 offspring of Mendel's classic pea cross
always look like one of the two parental varieties?

one allele was dominant

Consider pea plants with the genotypes GgTt and
ggtt . These plants can each produce how many type(s) of gametes?

four...one

You cross a true-breeding red-flowered snapdragon with a
true-breeding white-flowered one. All of the F1 are pink.
What does this say about the parental traits?
Pink is dominant, and red and white are recessive.
Red is completely dominant
. Both red and white are pleiotropic.
Red shows incomplete dominance over white.

red shows incomplete dominance over white

Height in humans generally shows a normal (bell-shaped) distribution.
What type of inheritance most likely determines height?
a combination of epistasis and environmental factors
a combination of complete dominance and environmental factors
incomplete dominance a combination of multiple alleles and codominance
a combination of polygenic inheritance and environmental factors

a combination of polygenic inheritance and environmental factors

In cattle, roan coat color (mixed red and white hairs) occurs in the
heterozygous (Rr) offspring of red (RR) and white
(rr) homozygotes. Which of the following crosses would
produce offspring in the ratio of 1 red:2 roan:1 white?
red � roan
roan � roan
red � white
white � roan
The answer cannot be determined from the information provided.

roan x roan

Which of the following is an example of polygenic inheritance?
skin pigmentation in humans
the ABO blood group in humans
pink flowers in snapdragons
Huntington's disease in humans
white and purple flower color in peas

skin pigmentation in humans

Which of the following provides an example of epistasis?
In cacti, there are several genes for the type of spines.
In rabbits and many other mammals, one genotype (ee)
prevents any fur color from developing.
Recessive genotypes for each of two genes (aabb) result in
an albino corn snake.
In Drosophila (fruit flies), white eyes can be due to an
X-linked gene or to a combination of other genes.
The allele b17 produces a dominant phenotype, although
b1 through b16 do not.

In rabbits and many other mammals, one genotype (ee)
prevents any fur color from developing

Folk singer Woody Guthrie died of Huntington's disease, an autosomal
dominant disorder. Which statement below must be true?
It is very likely that at least one of Woody Guthrie's parents also
have had the allele for Huntington's disease.
His daughters will die of Huntington's disease but not his sons.
All of his children will develop Huntington's disease
. His sons will develop Huntington's disease but not his daughters.
There is not enough information to answer the question.

it is very likely that at least one of woody's parents also have had
the allele for Huntington's disease

1. Edouard van Beneden proposed that an egg and a sperm, each
containing half the complement of chromosomes found in somatic cells,
fuse to produce a single cell called a(n) ______.A.
zygoteB. karyotypeC. embryoD. oocyte

zygote

2. ______ is a process of nuclear division which reduces the number
of chromosomes per cell from 2 sets to 1 set. A. MitosisB.
MeiosisC. Binary fissionD. Syngamy

meiosis

3. ______ cells contain one set of chromosomes. A.
Germ-lineB. SomaticC. DiploidD. Haploid

D. Haploid

4. In life cycles that alternate between haploid and diploid stages,
fertilization doubles the number of chromosomes per cell while ______
reduces it in half. A. mitosisB. meiosisC. binary
fissionD. syngamy

meiosis

5. Homologous chromosomes pair along their length during prophase I
of meiosis. While two homologues are paired, genetic exchange may
occur between them in a process called ________. A.
syngamyB. synapsisC. independent assortmentD.
crossing over

crossing over

6. Compared to asexual reproduction, the main advantage of sexual
reproduction is that it A. requires less energyB.
increases the genetic diversity of the offspringC. can produce
more complex offspringD. can produce a greater number of offspring

B. increases the genetic diversity of the offspring

7. If there were no suppression of DNA replication between meiotic
divisions but cytokinesis proceeded normally, what is the most likely
outcome of meiosis? A. 4 diploid cellsB. 2 diploid
cellsC. 4 haploid cellsD. 2 haploid cellsE. 2
diploid cells and 2 haploid cells

4 diploid cells

8. Evidence of crossing over can often be seen under the light
microscope as a structure called a _______. A.
kinetochoreB. centromereC. chiasmaD. centriole

chiasma

9. The fusion of a male gamete with a female gamete is called
A. syngamy.B. meiosis.C. mitosis.D.
recombination.E. synapsis.

syngamy

10. Diploid organisms use meiosis to produce haploid cells. Meiosis
consists of how many rounds of nuclear division? A. oneB.
twoC. threeD. fourE. none of these

two

11. The pairing of chromosomes along their lengths, which is
essential for crossing over, is referred to as A.
syngamy.B. synapsis.C. prophase.D.
recombination.E. centromere.

synapsis

12. The cell produced by the fusion of an egg and a sperm is the
A. gamete.B. oocyte.C. zygote.D. germ line
cell.E. somatic cell.

zygote

13. The zygote has A. one copy of each chromosome.B. one
full haploid complement of chromosomes.C. chromosomes identical
to those of a sperm cell.D. chromosomes identical to those of an
egg cell.E. two copies of each chromosome.

E. two copies of each chromosome.

14. All animal cells are diploid except A. gametes.B.
muscle cells.C. nerve cells.D. germ-line cells.E.
somatic cells.

gametes

16. Which of the following produces new cells that are genetically
identical to the original cell?A. meiosisB.
mitosisC. crossing overD. independent assortmentE. fertilization

mitosis

17. In animals, the cells that will eventually undergo meiosis to
produce gametes are set aside early in development. These are called
A. somatic cells.B. germ-line cells.C. sex
cells.D. gametophytes.E. reproductive cells.

germ-line cells

18. Which of the following events occurs first during meiosis?
A. homologous chromosomes separate and are pulled to opposite
poles of the cellB. sister chromatids separate and are pulled to
opposite poles of the cellC. chromosomes decondenseD.
synapsis of homologous chromosomesE. pairs of homologous
chromosomes align along the equatorial plate

D. synapsis of homologous chromosomes

19. Chromosomes exchange genetic information by A.
fertilization.B. mitosis.C. syngamy.D. DNA
replication.E. crossing over.

crossing over

20. Crossing over between homologous chromosomes takes place during
A. prophase II.B. prophase I.C. interphase
II.D. interphase I.E. metaphase II.

B. prophase I.

21. The synaptonemal complex is A. a cluster of microtubules at
each pole of the cell.B. a network of microtubules that forms
the spindle apparatus.C. a network of proteins that holds
homologues together.D. the area where microtubules attach to the
centromere of each chromosome.E. a region of highly coiled DNA.

C. a network of proteins that holds homologues together.

23. Which best describes the process of independent assortment?
A. The way one pair of homologues lines up along the metaphase
plate does not affect how any other pair lines up.B. Segregation
of chromosomes during meiosis I is independent of their segregation
during meiosis II.C. During synapsis, chromosomes pair up at
random.D. Crossing over along one pair of chromosomes is
independent of crossing over along the other pairs.E. During
synapsis, homologues pair independently of each other.

A. The way one pair of homologues lines up along the metaphase plate
does not affect how any other pair lines up.

22. At the end of meiosis II, each of the four resulting cells
contains A. one full set of chromosomes, each with 2 molecules
of DNA.B. two full sets of chromosomes, each with 2 molecules of
DNA.C. one full set of chromosomes, each with 1 molecule of
DNA.D. two full sets of chromosomes, each with 1 molecule of DNA.

C. one full set of chromosomes, each with 1 molecule of DNA.

24. In plants and animals, the zygote develops by which of the
following processes? A. mitosisB. meiosisC.
syngamyD. synapsisE. reduction division

mitosis

25. The pairing of homologous chromosomes is called A.
syngamy.B. synapsis.C. alignment.D. independent
assortment.E. crossing over.

synapsis

26. Which best explains the process of meiosis? A. The cells
that result from meiosis I are haploid, and each chromosome consists
of 1 chromatid.B. The cells that result from meiosis I are
haploid, and each chromosome consists of 2 chromatids.C. The
cells that result from meiosis II are haploid, and each chromosome
consists of 2 chromatids.D. The cells that result from meiosis I
are diploid, and each chromosome consists of 2 chromatids.E. The
cells that result from meiosis I are diploid, and each chromosome
consists of 1 chromatid.

B. The cells that result from meiosis I are haploid, and each
chromosome consists of 2 chromatids.

27. During meiosis, sister chromatids are held together by A. a
common centromere and kinetochore microtubules.B. a common
centromere and chiasmata.C. a common centromere and polar
microtubules.D. a common centromere and a protein called
cohesion.E. the kinetochores and a protein called cohesion.

D. a common centromere and a protein called cohesion.

28. What immediately follows meiosis I? A. DNA
replicationB. prophase IIC. metaphase IID. synapsis
of homologuesE. crossing over of homologues

B. prophase II

29. All of the following increase genetic variation EXCEPT A.
crossing over.B. random fertilization.C. independent
assortment.D. mitosis.E. mutation.

mitosis

30. One of a pair of chromosomes with similar genetic information and
from different sources like the sperm and egg. A.
chiasmaB. homologueC. kinetochoreD. synapsisE. synaptonemal

homologue

31. Which structures indicate where crossing over has occurred.
A. chiasmataB. centromeresC. kinetochoresD.
centriolesE. spindle fibers

chiasmata

32. Which structure holds two homologous chromosomes together?
A. centromereB. kinetochoreC. polar
microtubulesD. spindle apparatusE. synaptonemal complex

E. synaptonemal complex

33. During anaphase I, which best represents segregation of the
chromatids that make up one pair of homologues? (M represents a
maternal chromatid and P represents a paternal chromatid. Assume no
crossing over occurs.) A. M and M to one pole; P and P to the
other pole.B. M and P to one pole; M and P to the other
pole.C. M to one pole; P to the other pole.D. half of M
and half of P to each pole.E. the segregation of these
chromatids is completely random.

A. M and M to one pole; P and P to the other pole.

34. You are studying meiosis in an organism where 2n= 28. How many
chromosomes will be present in each cell after meiosis I is complete
but before meiosis II begins? A. 7B. 14C. 28D. 56

B. 14

35. You are studying meiosis in an organism where 2n=24. How many
chromosomes will each nucleus have after meiosis II is
complete?A. 24B. 12C. 6D. 48

B. 12

36. You are comparing the events of meiosis I in cells from several
different organisms. You come across one species in which you do not
observe any chiasmata. The best conclusion to make isA. there is
no crossing over between non-sister chromatidsB. kinetochores of
sister chromatids do not fuseC. the chromosome pairs will not
assort independentlyD. chiasmata will form during meiosis II

A. there is no crossing over between non-sister chromatids

22. At the end of meiosis II, each of the four resulting cells
contains A. one full set of chromosomes, each with 2 molecules
of DNA.B. two full sets of chromosomes, each with 2 molecules of
DNA.C. one full set of chromosomes, each with 1 molecule of
DNA.D. two full sets of chromosomes, each with 1 molecule of DNA.

C. one full set of chromosomes, each with 1 molecule of DNA.

37. Which statement about the reductive division of meiosis is
false?A. During the reductive division, homologues migrate to
opposite poles of the cell.B. During the reductive division,
sister chromatids migrate to opposite poles of the cell.C.
During the reductive division, centromeres do not divide.D. At
the end of the reductive division, each daughter nucleus has one-half
as many centromeres as the parental nucleus.

B. During the reductive division, sister chromatids migrate to
opposite poles of the cell.

38. The Rec8 protein holds sister chromatids together during meiosis.
If an individual has a mutation that prevents degradation of Rec8,
this would most likely preventA. normal segregation during
meiosis IB. normal segregation during meiosis IIC.
synapsis of homologous chromosomesD. crossing over during
prophase I

B. normal segregation during meiosis II

39. Which of the following is likely to occur if you were to prevent
cyclin B from associating with its cyclin-dependent kinase near the
end of meiosis I?A. failure to maintain sister chromatid
cohesion at the centromereB. failure to form initiation
complexes necessary for DNA replication to proceedC. suppression
of DNA replicationD. activation of DNA replication

D. activation of DNA replication

40. Which of the following statements about crossing over is
false?A. Crossing over takes place between non-sister
chromatids.B. Crossing over takes place between sister
chromatids.C. Crossing over occurs during prophase I.D.
Sites of crossing over are called chiasmata.E. Crossing over is
also called genetic recombination.

B. Crossing over takes place between sister chromatids.

41. A life cycle that regularly alternates between haploid and
diploid stages is found in all of the following EXCEPTA.
dogsB. the bacterium E. coliC. alfalfa plantsD. the
mold N. crassa

B. the bacterium E. coli

42. In 95% of cases of Down's syndrome, there is one extra chromosome
(number 21) in every cell. This aneuploid condition is most likely the
result ofA. failure to suppress DNA replication between meiosis
I and meiosis IIB. failure of the chromosomes to assort
independently during meiosisC. failure of 1 homologous pair to
segregate during meiosis.D. failure of 2 homologous pairs to
segregate during meiosisE. failure of the cytoplasm to divide at
the end of meiosis II

C. failure of 1 homologous pair to segregate during meiosis.

43. Why does sexual reproduction require both meiosis and
syngamy?A. The process of meiosis results in the production of
gametes in which the number of chromosomes remains the same. During
syngamy, two gametes fuse to form a new cell, and the number of
chromosomes is restored to the full amount. Therefore, by coupling
meiosis and syngamy, the organism ensures that the proper number of
chromosomes will be maintained.B. The process of meiosis results
in the production of gametes in which the number of chromosomes is
reduced by half. During syngamy, two gametes fuse to form a new cell,
and the number of chromosomes is restored to the full amount.
Therefore, by coupling meiosis and syngamy, the organism ensures that
the proper number of chromosomes will be maintained.C. The
process of meiosis results in the production of gametes in which the
number of chromosomes is doubled. During syngamy, gametes are reduced
by half, and the number of chromosomes is restored to the full amount.
Therefore, by coupling meiosis and syngamy, the organism ensures that
the proper number of chromosomes will be maintained.

B. The process of meiosis results in the production of gametes in
which the number of chromosomes is reduced by half. During syngamy,
two gametes fuse to form a new cell, and the number of chromosomes is
restored to the full amount. Therefore, by coupling meiosis and
syngamy, the organism ensures that the proper number of chromosomes
will be maintained.

44. Which cells never divide by meiosis? (Check all that
apply.)__X__ haploid cells_____ diploid cells__X__
somatic cells_____ germ-line cells__X__ zygotes

__X__ haploid cells__X__ somatic cells__X__ zygotes

45. A cell biologist examines a skin cell from a lizard during
metaphase of mitosis and determines that 20 chromatids are present.
The role of meiosis in this species is to (Check all that
apply)__X__ Produce 4 daughter cells that are genetically
different from each other__X__ Produce 4 daughter cells that are
genetically different from the original parental cell__X__
Reduce the number of chromosomes per cell from 10 to 5_____
Reduce the number of chromosomes per cell from 20 to 10

_X__ Produce 4 daughter cells that are genetically different from
each other__X__ Produce 4 daughter cells that are genetically
different from the original parental cell__X__ Reduce the number
of chromosomes per cell from 10 to 5

46. A cell biologist examines a leaf cell from an alfalfa plant
during metaphase of mitosis and determines that 32 chromatids are
present. The role of fertilization in this species is to (Check all
that apply)__X__ Produce a new cell that has a combination of
chromosomes from 2 different parents_____ Increase the number of
chromosomes per cell from 16 to 32__X__ Increase the number of
chromosomes per cell from 8 to 16__X__ Combine the chromosomes
from 2 haploid cells into a single diploid cell

__X__ Produce a new cell that has a combination of chromosomes from 2
different parents__X__ Increase the number of chromosomes per
cell from 8 to 16__X__ Combine the chromosomes from 2 haploid
cells into a single diploid cell

47. The most common form of gene therapy involves inserting a normal
gene into cells that contain a defective version of the gene. In order
to use gene therapy to prevent a man from passing a defective gene on
to future generations, you should try to insert normal copies of the
gene intoA. blood cellsB. germ-line cellsC. somatic
cells in the testesD. bone marrow cells

B. germ-line cells

48. If a germ-line cell from an owl contains 8 picograms of DNA
during G1 of interphase, how many picograms of DNA would be present in
each cell during prophase I of meiosis? (Enter the number only, not
the units.)

16

49. If a somatic cell from a cat contains 40 picograms of DNA during
G2 of interphase, how many picograms of DNA would be present in each
cell during metaphase II of meiosis? (Enter the number only, not the units.)

20

50. If a germ-line cell from a salamander contains 10 picograms of
DNA during G1 of interphase, how many picograms of DNA would be
present in each gamete produced by this species? (Enter the number
only, not the units.)

5

51. How many tetrads are present in a single elephant cell (2n=56)
during metaphase I of meiosis?

28

52. A geneticist examines a somatic cell from a fly during metaphase
of mitosis and determines that 16 chromatids are present. If a
germ-line cell from this species divides by meiosis, then at the end
of meiosis I (including the first cytokinesis) each cell will
containA. 8 chromosomes with 8 DNA moleculesB. 8
chromosomes with 16 DNA moleculesC. 4 chromosomes with 4 DNA
moleculesD. 4 chromosomes with 8 DNA molecules

D. 4 chromosomes with 8 DNA molecules

53. Nondisjunction is the failure of homologous chromosomes to
separate during meiosis I, or the failure of sister chromatids to
separate during meiosis II or mitosis. As a result, both homologous
chromosomes or both sister chromatids migrate to the same pole of the
cell. This produces daughter cells with an imbalance of chromosomes. A
cell biologist examines the final products of meiosis in an earthworm
(2n=36) and finds 2 cells with 20 chromosomes, and 2 cells with 16
chromosomes. Most likely this was becauseA. 2 pairs of sister
chromatids failed to separate during meiosis IIB. 1 pair of
sister chromatids failed to separate during meiosis IIC. 2 pairs
of homologous chromosomes failed to separate during meiosis ID.
1 pair of homologous chromosomes failed to separate during meiosis I

C. 2 pairs of homologous chromosomes failed to separate during
meiosis I

54. Nondisjunction is the failure of homologous chromosomes to
separate during meiosis I, or the failure of sister chromatids to
separate during meiosis II or mitosis. As a result, both homologous
chromosomes or both sister chromatids migrate to the same pole of the
cell. This produces daughter cells with an imbalance of chromosomes.
If 18 pairs of sister chromatids segregate normally during meiosis II
in cats (n=19) but we have nondisjunction of 1 pair, then at the end
of meiosis II we will haveA. 3 cells with 20 chromosomes and 1
cell with 18B. 2 cells with 20 chromosomes and 2 cells with
18C. 2 cells with 19 chromosomes, 1 with 20, and 1 with
18D. 3 cells with 18 chromosomes and 1 cell with 20

C. 2 cells with 19 chromosomes, 1 with 20, and 1 with 18

55. A cell biologist examines a diploid cell from a particular
species of during metaphase of mitosis and determines that 8
centromeres are present. Based on this finding, how many centromeres
should be present in a single cell from this species during anaphase
II of meiosis?

8

56. A cell biologist examines a diploid cell from a particular
species of butterfly during prometaphase of mitosis and determines
that 10 centromeres are present. Based on this finding, how many
chromatids should be present in a single cell from this species in
metaphase I of meiosis?

20

57. Meiosis results in a reassortment of maternal chromosomes
(inherited from the mother) and paternal chromosomes (inherited from
the father.) If n=4 for a given species, and ignoring the effects of
crossing over, what is the probability that a gamete will receive only
paternal chromosomes?A. 1/2B. 1/4C. 1/8D. 1/16

16-Jan

58. A cell in G2 before meiosis begins, compared with one of the four
cells produced at the end of meiosis II, hasA. twice as much DNA
and twice as many chromosomesB. four times as much DNA and twice
as many chromosomesC. twice as much DNA but the same number of
chromosomesD. four times as much DNA and four times as many
chromosomesE. twice as much DNA and half as many chromosomes

B. four times as much DNA and twice as many chromosomes

59. In meiosis, sister kinetochores are attached to the same pole of
the cell during meiosis I, and sister chromatid cohesion is released
during anaphase II. What would be the likely result if sister
kinetochores were attached to different poles of the cell during
meiosis I and sister chromatid cohesion was released during anaphase
I?A. sister chromatids would migrate to opposite poles during
anaphase IB. sister chromatids would migrate to opposite poles
during anaphase IIC. sister chromatids would migrate to the same
pole during anaphase ID. sister chromatids would migrate to the
same pole during anaphase II

A. sister chromatids would migrate to opposite poles during anaphase I

60. Sister chromatids move to opposite poles of the cell during
(Check all that apply.)_____ anaphase I of meiosis_____
metaphase I of meiosis__X__ anaphase II of meiosis__X__
anaphase of mitosis

__X__ anaphase II of meiosis__X__ anaphase of mitosis

15. The point of connection between two sister chromatids, before
anaphase II of meiosis separates them, is called the A.
centrioleB. kinetochore.C. centromere.D. spindle
apparatus.E. centrosome.

C. centromere.