Download There are 3 “project-style” questions on the pages that follow. They

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There are 3 “project-style” questions on the
pages that follow. They are questions that
supply information first, then ask you to
answer questions using that information.
They will test the depth of your
understanding of the topic.
The scenario and the questions appear first,
then the answers are on the next page.
Good luck, even though it’s the effort you
invest . . .
Jillian is a student at McClintock High School in
Tempe. Her middle school class learned about
PTC tasting. As it turned out she is not a
taster. She asked her teacher for test strips
and found out everyone in her family is a
taster.
1. Is it possible that Jillian cannot taste PTC
when everyone in her family can?
2. What genotype for PTC tasting does Jillian
have?
3. What genotypes are possible for her
parents?
1.
Is it possible that Jillian cannot taste PTC when
everyone in her family can?
Yes, it is possible that Jillian could have a recessive
genotype as long as both of her parents have a
heterozygous (Pp) genotype. If each parent passes
the recessive allele, Jillian would not taste PTC.
2.
What genotype for PTC tasting does Jillian have?
3.
What genotypes are possible for her parents?
Jillian’s genotype is (pp). Lower case letters are
used for recessive alleles (versions of genes).
See answer to first question above. Jillian’s parent
must both have a heterozygous genotype to make
it possible to have a child who has a homozygous
recessive genotype.
A dwarf pea plant (tt) is crossed with a pea
plant of regular height (TT). All of the
offspring have the genotype Tt.
1.
2.
3.
How would you describe their phenotype?
Is the genotype of the offspring
heterozygous or homozygous?
If seeds from these plants were pollinated
by a dwarf plant, what genotypes would be
possible for the offspring?
1.
How would you describes their phenotype?
2.
Is the genotype of the offspring heterozygous or
homozygous?
For the heterozygous genotype of Tt, the plant would
have a regular height because the single dominant allele
overpowers the recessive allele.
The offspring genotype is heterozygous because it
contains one dominant allele and one recessive allele.
3.
If seeds from these plants were pollinated by a dwarf
plant, what genotypes would be possible for the
offspring?
Using a genotype of tt for the dwarf plant, the Punnett
square would look like:
T
t
So there is a 50% chance of
Regular height plants and 50%
Chance of a dwarf -size offspring
t
Tt
tt
t
Tt
tt
Steven went to a farm and picked a bright red
tomato from a broken branch on the plant. The
tomato had a rotten spot with a worm inside of
it. Instead of eating the tomato, Steven decided
to plant the seeds and grow new tomato
plants.
1. Which feature of the plant is inheritable?
2. Do we know anything about the genotype of
the plant?
3. What info would we need to predict the
traits of the offspring?
1.
Which feature of the plant is inheritable?
Only the color of the tomato skin is an inheritable
trait. The others depend on the environment
1.
Do we know anything about the genotype of
the plant?
No, we don’t know the genotype because we don’t
know the dominant color of the tomato skin.
1.
What info would we need to predict the traits of
the offspring?
In order to predict the traits of the offspring, you
need to know the genotype of the parents and the
dominant variation.