Honors Biology Chapter 9 – Important Answers
Answer Key
Patterns of Inheritance
1. Punnett
2. genotype, phenotype
3. probability
4. codominance, incomplete dominance, multiple, blood
Do not worry about the two Math Lab Answer Keys…the data was
too extensive to post. Focus on the Reviews, notes, and
vocabulary.
Section 9-1
VOCABULARY REVIEW
1. The F1 generation consists of the offspring of a
cross between two purebred parents; the F2
generation consists of the offspring of a cross
between two individuals in the same F1 generation.
2. A dominant factor is one that masks the effect of
another factor for the same characteristic; a recessive
factor is one whose effect is masked by another
factor for the same characteristic.
3. A gene is a segment of DNA that controls a particular
hereditary trait; an allele is one of several
alternative forms of a gene.
MULTIPLE CHOICE
1. c 2. a 3. d 4. b
SHORT ANSWER
1. A strain is a group of plants that are pure for a
specific trait.
2. In meiosis, the two alleles of each gene are segregated
when the two chromosomes in each pair of
homologues are separated into different gametes.
Alleles of genes located on different chromosomes
or far apart on the same chromosome assort independently
when homologues are randomly separated
during meiosis.
3. Orange flower color is dominant. All of the F1
plants will have orange flowers.
4. Mendel would have observed that the traits
controlled by dominant factors for these characteristics
almost always appeared together. Thus, he
might not have concluded that the factors for different
characteristics are assorted independently.
STRUCTURES AND FUNCTIONS
Possible combinations are RB, Rb, rB, and rb.
Section 9-2
VOCABULARY REVIEW
1. In complete dominance, heterozygous and dominant
homozygous individuals have the same phenotype.
For example, in pea plants, the P allele is
completely dominant over the p allele, so both PP
and Pp plants have purple flowers.
2. In incomplete dominance, neither allele is completely
dominant over the other and both influence
the phenotype. For example, in four o’clocks,
neither the R or r allele is completely dominant, so
Rr plants have pink flowers.
3. In codominance, neither allele is dominant or
recessive; both are expressed in heterozygotes.
For example, in roan horses, red hairs are produced
by the R allele and white hairs are produced
by the Rallele.
MULTIPLE CHOICE
1. b 2. a 3. c 4. d 5. c
SHORT ANSWER
1. In a homozygous individual, both alleles of a pair
are the same; in a heterozygous individual, the
two alleles of a pair are different.
2. 0.25 80 individuals 20 individuals
3. AA and Aa will result. 100% will have the dominant
phenotype.
4. In a testcross, the dominant phenotype would
appear in all of the offspring if the cow were
homozygous dominant but in only about 50% of
the offspring if the cow were heterozygous. With
only one individual per F1 generation, distinguishing
between these two possibilities would
take a long time, until a calf with the recessive
phenotype was born.
8
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Modern Biology Study Guide Answer Key
STRUCTURES AND FUNCTIONS
Arrangements of the offspring alleles will vary
according to the order of the parental alleles in the
Punnett square. 1. 9/16 2. 1/4 3. 1/16 4. 1/16