Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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What
did Gregor Mendel do to study different characteristics in his genetics experiments? a. | He studied only
asexual plants. | b. | He studied only tall and short pea
plants. | c. | He cross-pollinated plants. | d. | He
cross-pollinated both plants and animals. | | |
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2.
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In
Mendel’s experiments, what proportion of the plants in the F2 generation had a trait
that had been absent in the F1 generation? a. | none | b. | one fourth | c. | half | d. | three fourths | | |
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3.
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Factors that control traits are called a. | genes. | b. | purebreds. | c. | recessives. | d. | parents. | | |
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4.
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Scientists call an organism that has two different alleles for a trait
a a. | hybrid. | b. | trait. | c. | purebred. | d. | factor. | | |
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5.
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What
does the notation TT mean to geneticists? a. | two dominant alleles | b. | heterozygous
alleles | c. | at least one dominant allele | d. | one dominant and
one recessive allele | | |
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6.
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What
does the notation Tt mean to geneticists? a. | two dominant alleles | b. | two recessive
alleles | c. | homozygous alleles | d. | one dominant
allele and one recessive allele | | |
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7.
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What
is probability? a. | the actual
results from a series of events | b. | a number that describes how likely it is that an event will
occur | c. | the way the results of one event affect the next
event | d. | the number of times a coin lands heads
up | | |
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8.
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What
is the probability of producing a tall pea plant from a genetic cross between two hybrid tall pea
plants? a. | one in
four | b. | two in
four | c. | three in
four | d. | four in
four | | |
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9.
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What
does a Punnett square show? a. | all the possible outcomes of a genetic
cross | b. | only the dominant alleles in a genetic
cross | c. | only the recessive alleles in a genetic
cross | d. | all of Mendel’s discoveries about genetic
crosses | | |
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10.
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If a
homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb),
what is the probability that an offspring will have black fur? a. | 25
percent | b. | 50 percent | c. | 75
percent | d. | 100 percent | | |
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11.
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An
organism’s physical appearance is its a. | genotype. | b. | phenotype. | c. | codominance. | d. | heterozygous. | | |
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12.
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A
purebred chicken with white feathers is crossed with a purebred chicken that has black feathers. Each
of their offspring has both black and white feathers. Why does this happen? a. | Both alleles for
feather color are dominant. | b. | Both alleles for feather color are
recessive. | c. | The alleles for feather color are neither dominant nor
recessive. | d. | Several alleles work together to determine the
trait. | | |
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13.
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What
is the chromosome theory of inheritance? a. | Chromosomes are carried from parents to offspring on
hybrids. | b. | Genes are carried from parents to offspring on
chromosomes. | c. | Hybrid pairs of chromosomes combine to form
offspring. | d. | Codominant genes combine to form new
hybrids. | | |
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14.
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Walter Sutton discovered that the sex cells of grasshoppers have a. | 12 times the
number of chromosomes found in the body cells. | b. | twice the number
of chromosomes found in the body cells. | c. | the same number of chromosomes found in the body
cells. | d. | half the number of chromosomes found in the body
cells. | | |
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15.
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What
happens during meiosis? a. | Two sex cells combine. | b. | Chromosome pairs
separate and are distributed into new sex cells. | c. | Each sex cell
copies itself to form four new chromosomes. | d. | Chromosome pairs
remain together when new sex cells are formed. | | |
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16.
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When
sex cells combine to produce offspring, each sex cell will contribute a. | one fourth the
number of chromosomes in body cells. | b. | half the number of chromosomes in body
cells. | c. | the normal number of chromosomes in body
cells. | d. | twice the number of chromosomes in body
cells. | | |
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17.
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What
determines the genetic code? a. | the order of nitrogen bases along a
gene | b. | the number of
nitrogen bases in a DNA molecule | c. | the order of amino acids in a protein | d. | the number of
guanine and cytosine bases in a chromosome | | |
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18.
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The
order of the bases along a gene determines the order in which a. | sugars are put
together to form a carbohydrate. | b. | phosphates are arranged in DNA. | c. | amino acids are
put together to form a protein. | d. | chromosomes are arranged in the
nucleus. | | |
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19.
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What
does messenger RNA do during protein synthesis? a. | copies the coded message from the DNA and carries it into the
cytoplasm | b. | copies the coded message from the DNA and carries it into the
nucleus | c. | carries amino acids and adds them to the growing
protein | d. | copies the coded message from the protein and carries it into
the nucleus | | |
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20.
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What
do transfer RNA molecules do during protein synthesis? a. | copy the coded
message from the protein and carry it into the nucleus | b. | copy the coded
message from the DNA and carry it into the nucleus | c. | carry amino
acids and add them to the growing protein | d. | copy the coded message from the DNA and carry it into the
cytoplasm | | |
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21.
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What
is a mutation? a. | any change that
is harmful to an organism | b. | any change in a gene or chromosome | c. | any change that
is helpful to an organism | d. | any change in the phenotype of a cell | | |
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22.
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A
mutation is harmful to an organism if it a. | changes the DNA of the organism. | b. | changes the
phenotype of the organism. | c. | reduces the organism’s chances for survival and
reproduction. | d. | makes the organism better able to avoid
predators. | | |
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23.
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Which
term refers to physical characteristics that are studied in genetics? a. | traits | b. | offspring | c. | generations | d. | hybrids | | |
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24.
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The
different forms of a gene are called a. | alleles. | b. | factors. | c. | masks. | d. | traits. | | |
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25.
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Where
does protein synthesis take place? a. | in the ribosomes in the nucleus of the
cell | b. | on the ribosomes
in the cytoplasm of the cell | c. | in the chromosomes in the nucleus of the
cell | d. | on the
chromosomes in the cytoplasm of the cell | | |
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26.
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An
organism’s genotype is its a. | genetic makeup. | b. | feather
color. | c. | physical appearance. | d. | stem
height. | | |
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27.
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Which
nitrogen base in RNA is NOT part of DNA? a. | adenine | b. | guanine | c. | cytosine | d. | uracil | | |
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28.
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An
organism that has two identical alleles for a trait is a. | codominant. | b. | tall. | c. | homozygous. | d. | heterozygous. | | |
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29.
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A
heterozygous organism has a. | three different alleles for a trait. | b. | two identical
alleles for a trait. | c. | only one allele for a trait. | d. | two different
alleles for a trait. | | |
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30.
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Chromosomes are made up of a. | one pair of alleles. | b. | many traits
joined together. | c. | transfer RNA. | d. | many genes
joined together. | | |
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Modified True/False
Indicate
whether the sentence or statement is true or false. If false, change the identified word or
phrase to make the sentence or statement true.
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31.
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When
Mendel crossed purebred short plants with purebred tall plants, all of the offspring were
short. _________________________
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32.
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A
hybrid is the offspring of parents that have different alleles for a trait.
_________________________
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33.
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A pea
plant that is heterozygous for tall stems has the alleles Tt.
_________________________
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34.
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A
Punnett square shows all the possible combinations of alleles resulting from a cross.
_________________________
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35.
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An
organism’s phenotype is its allele combinations. _________________________
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36.
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The
sex cells produced by meiosis have twice the number of chromosomes as the parent cells.
_________________________
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37.
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Chromosomes carry genes from parents to offspring.
_________________________
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38.
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The
number of DNA bases along a gene specifies the type of protein that will be produced.
_________________________
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39.
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Transfer RNA carries coded messages from the nucleus to the cytoplasm.
_________________________
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40.
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A
mutation in a sex cell can be passed to offspring. _________________________
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Completion
Complete each sentence or
statement.
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41.
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A(n)
____________________ organism is the offspring of many generations of organisms that have the same
trait.
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42.
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If
a(n) ____________________ allele is present, its trait will appear in the organism.
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43.
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In
pea plants, the tall-stem allele and the short-stem allele are different forms of the same
____________________.
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44.
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If
D represents the dominant allele of a gene, then ____________________ represents the recessive
allele.
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45.
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Mendel used the principles of ____________________ to predict what percent of
offspring would show a particular trait.
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46.
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If
each of ten events is equally likely to occur, the probability of each individual event occurring is
____________________ percent.
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47.
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A
chart used to predict results of genetic crosses is known as a(n) ____________________.
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48.
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In a
cross between two hybrid Tt pea plants, ____________________ percent of the offspring will
be Tt.
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49.
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An
organism that has two dominant or two recessive alleles is said to be ____________________ for that
trait.
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50.
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Alleles that are neither dominant nor recessive produce an inheritance pattern known
as ____________________.
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51.
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Genes
are carried from parents to their offspring on structures called ____________________.
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52.
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The
process in which a parent cell divides twice to produce sex cells is called
____________________.
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53.
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If
all of the sex cells of an organism have the T allele, the genotype of that organism must be
____________________.
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54.
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The
genetic code is found in the order of nitrogen ____________________ along a gene.
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55.
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A set
of three bases codes for one specific ____________________ in a protein.
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56.
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____________________ RNA adds amino acids to a growing protein.
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57.
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A
section of DNA has the base sequence TGAG. The corresponding section of a messenger RNA molecule will
have the base sequence ___________________.
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58.
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The
substitution of one base for another during DNA replication is an example of a(n)
____________________.
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59.
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An
organism can be heterozygous for some traits and ____________________ for others.
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60.
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The
chromosomes in a pair may each have different ____________________ for each gene.
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Short Answer
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Use the diagram to answer each question.
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61.
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Which
trait—white flowers or purple flowers—is controlled by a dominant allele? Which is
controlled by a recessive allele? How do you know?
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62.
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In
which generation are the parents purebred? In which generation are they hybrids?
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63.
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In
the F1 generation, what is the genotype of the offspring? What is their
phenotype?
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64.
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In
the F2 generation, what percent of the offspring have purple flowers? What is the genotype
of the purple-flowered offspring?
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65.
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In
the F2 generation, what percent of the offspring have white flowers? What are the
genotypes of the white-flowered offspring?
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66.
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Suppose one of the parents of the F2 generation had been ww instead
of Ww. What percent of the offspring would have purple flowers? What percent would have white
flowers?
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Use the diagram to answer each question.
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67.
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Identify structure A and state what it is made of.
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68.
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Identify structures B and C.
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69.
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Identify structure D and state where it is made.
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70.
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Identify structure E and describe its function.
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71.
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What
are the three nitrogen bases in transfer RNA that pair with bases A-G-U in messenger
RNA?
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72.
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If
one of the nitrogen bases on structure D were replaced by a different base, what effect might that
have on protein synthesis?
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Essay
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73.
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In
pea plants, green pod color is controlled by a dominant allele. Yellow is controlled by a recessive
allele. Explain why a plant with yellow pods can never be a hybrid.
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74.
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A
woman gives birth to a son. Two years later, she gives birth to another son. What is the probability
that her third child will be a girl? Explain your reasoning.
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75.
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Some
clover plants have leaves with a white stripe. Other clover plants have leaves with a white spot.
When these two types of plants are crossed, the leaves of the offspring have a white stripe and a
white spot. Explain how this inheritance pattern occurs.
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76.
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Explain the function of meiosis.
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77.
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Describe what messenger RNA and transfer RNA do during protein
synthesis.
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78.
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Contrast the effects of harmful and helpful mutations.
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79.
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Explain why Mendel’s cross of purebred tall and short pea plants resulted in only
tall plants.
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80.
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In
pea plants, the allele for smooth pods (S) is dominant over the allele for pinched pods
(s). Construct a Punnett square that shows a cross between an SS plant and an Ss
plant. Predict what percent of the offspring are likely to have smooth pods.
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