Chapter 12 Questions
Vocabulary: character, trait, hybrid, generation, allele, dominant,
recessive, genotype, phenotype, homozygous, heterozygous, Punnett Square,
probability, pedigree, Polygenic character, codominance, testcross
1. Who is Gregor Mendel and what did he do that was important for modern
genetics?
2. Why did Mendel choose garden peas for his experiments?
3. What is the difference between a trait and a character?
4. What is a monohybrid cross?
5. What was the important thing that happened between Mendel’s F1 and F2
generations?
6. What is an important feature of all organisms used for traditional
genetic studies? For instance, why are garden peas and fruit flies
often chosen for genetic studies?
7. Why did Mendel record the results of so many plant crosses?
8. What is the typical ratio seen in the F1 generation when crossing a
homozygous dominant trait with a homozygous recessive trait?
9. What is the typical ratio seen in the F2 generation when crossing two
heterozygous individuals?
10.
What patterns of heredity were explained by Mendel’s hypotheses?
11.
In pea plants, how many alleles for seed color does each parent
pass on to each offspring?
12.
What is the Law of Segregation?
13.
How does genotype relate to phenotype?
14.
What is the Law of Independent Assortment?
15.
What is a dihybrid cross?
16.
Mendel used dihybrid crosses in his second experiments. He
found that the inheritance of one character, suc has seed color, did
not affect the inheritance of another character, such as seed shape.
What law did Mendel propose to explain these findings?
17.
Describe the patterns that Mendelian theory explains.
18.
Relate genotype to phenotype using examples from Mendel’s
experiments with pea plants.
19.
What is the “blending” hypothesis?
20.
Describe the processes of replication, transcription, and
translation and how they relate to each other in molecular biology.
21.
How are Punnett Squares used in genetics?
22.
How is mathematical probability used in genetics?
23.
What do the boxes inside a Punnett Square represent?
24.
Determine the genotype and phenotype of monohybrid crosses using
a Punnett Square. Use the following information to build your Punnett
Square: The gene for plant height has two versions: T for tall and
t for short. What would happen if you crossed a homozygous dominant
plant with a homozygous recessive plant? What would the genotypes
be? What is the ratio seen in the offspring?
25.
What is a testcross, and how are they used?
26.
Now, using the same information as above, T-tall and t-short.
What would happen if you crossed two of the offspring from the above
cross? What would the genotypes be? What is the ratio seen in the
offspring?
27.
Suppose a breeder has a rabbit that has a dominant phenotype,
such as black fur (as opposed to recessive brown fur). How could the
breeder know whether the rabbit is homozygous (BB) or heterozygous
(Bb) for fur color?
a. In the space below, draw two Punnett Squares. In one of them
you will cross a homozygous dominant, black furred rabbit with a
homozygous, brown furred rabbit. In the other Punnett Square,
you will cross a heterozygous, black furred rabbit with a
homozygous recessive, brown furred rabbit.
b. Which figure represents a testcross?
c. If half of the offspring in a test cross have brown fur, what is
the genotype of the parent that has black fur?
28.
Explain the genetic basis for Mendel’s laws of segregation and
independent assortment.
29.
What is the probability that a heterozygous cross will produce
homozygous recessive offspring?
30.
How can you determine the genotype of a pea plant that has
purple flowers?
31.
How does codominance differ from incomplete dominance?
snap-dragons and ABO blood type in your explanation.
32.
Differentiate between dominant, recessive, codominant,
polygenic, and sex-linked traits.
Use pink
33.
Explain that the information passed from parents to offspring is
transmitted by means of genes that are coded in DNA molecules. These
genes contain the information for the production of proteins.
34.
The gene for colorblindness is sex-linked and found on the X
chromosome. Suppose a woman is a carrier for the colorblind allele
and she marries a man with normal color vision. What is the
probability that they will have a child that is colorblind? What is
the probability that they will have a male child that is colorblind?
What is the probability that they will have a female child that is
colorblind? Draw the Punnett Square showing this cross.