Multiple Choice
Identify 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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Which term refers to physical characteristics that are studied in
genetics?
a. | traits | b. | offspring | c. | generations | d. | hybrids |
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4.
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Factors that control traits are called
a. | genes. | b. | purebreds. | c. | recessives. | d. | parents. |
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5.
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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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6.
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What does the notation AA 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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7.
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What does the notation Aa 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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8.
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The different forms of a gene are called
a. | alleles. | b. | factors. | c. | masks. | d. | traits. |
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9.
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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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10.
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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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11.
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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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12.
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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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13.
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An organism’s physical appearance is its
a. | genotype. | b. | phenotype. | c. | codominance. | d. | heterozygous. |
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14.
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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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15.
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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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16.
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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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17.
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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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18.
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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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19.
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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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20.
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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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21.
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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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22.
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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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23.
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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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24.
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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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25.
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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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26.
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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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27.
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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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28.
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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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29.
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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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30.
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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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Modified True/False
Indicate
whether the statement is true or false. If false, change the identified word or phrase to make
the 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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Chromosomes carry genes from parents to offspring.
_________________________
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37.
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The sex cells produced by meiosis have twice the number of chromosomes as
the parent cells. _________________________
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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
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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An organism can be heterozygous for some traits and ____________________ for
others.
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55.
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The chromosomes in a pair may each have different ____________________ for each
gene.
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56.
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The genetic code is found in the order of nitrogen ____________________ along a
gene.
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57.
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A set of three bases codes for one specific ____________________ in a
protein.
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58.
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____________________ RNA adds amino acids to a growing protein.
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59.
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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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60.
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The substitution of one base for another during DNA replication is an example of
a(n) ____________________.
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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 F2 generation, what percent of the offspring have purple
flowers? What is the genotype of the purple-flowered offspring?
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64.
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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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65.
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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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66.
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In the F1 generation, what is the genotype of the offspring? What is
their phenotype?
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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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Explain why Mendel’s cross of purebred tall and short pea plants resulted
in only tall plants.
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74.
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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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75.
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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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76.
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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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77.
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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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78.
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Explain the function of meiosis.
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79.
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Describe what messenger RNA and transfer RNA do during protein synthesis.
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80.
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Contrast the effects of harmful and helpful mutations.
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