Download Sec.. .Name - Circle

Sec..
.Name:
Experiment:
_
Predicting Outcomes of Monohybrid
Crosses (8. Science 10-11-1c)
Purpose: To diagram inheritance in monohybrid
(one trait) crosses.
Methods:
1. The parent plants crossed by Mendel are
shown in the diagram in results. Axial flowers
grow along the stem. Terminal flowers develop
only at the tip of the stem. Mendel found in pea
plants that axial (A) flower position is dominant to
terminal (a) flower position. Examine the
genotypes of each parent. Which parent, in this
case, is homozygous for the dominant trait?
2. Which parent is homozygous for the recessive
trait?
3. What gene will be contained in the gamete of the male parent?
4. What gene will be contained in the gamete of the female parent?
5. Diagram the cross in the F1 Punnett square.
6. What genes were inherited by the F1 offspring?
7. When planted, what will be the position of the flowers produced by the F1 plants?
8. In the Punnett square, cross the F1 offspring with themselves to obtain the F2
generation. Why is this called a monohybrid cross?
9. What ratio do you predict for the genotype among the F2 offspring?
10. What ratio do you predict for the phenotype among the F2 offspring?
1'1. When complete dominance is involved, would the predicted ratios obtaineu in this
cross hold true for any monohybrid cross?
Results:
1.. dominant:
2. recessive:
3.. gene:
4. gene:
6. genes:
7. position:
8. why:
9. genotype:
11. true?:
10. phenotype:
p
d Axial
Female
Genes
Male
axial
terminal
(AA) X
<;>
_
terminal (aa)
F,
Axial
Female
Genes
Male
(Aa)
X
Axial (Aa)
Sec.
Name:
_
Conclusions:
1. Briefly define each of Mendel's Law and Principles that have been demonstrated in
the crosses you have completed in this investigation by filling in the blank.
a. principle of unit (individual) characters:
- for one trait there is one
_
b. principle of dominance:
- one allele is
while the other allele is
_
c. principal of segregation:
- during the formation of games the gene will
from each other.
2. In a cross of two individuals heterozygous for a single trait, what genotype ratio
would be obtained (Look at the results of this experiment to help you out)?
phenotype?
Discussion:
Mendel made the following crosses with pea plants. Complete the Punnett squares,
list the phenotype ratio for each and then answer the questions.
T is tall plant
t is short plant
T
T
T
TIT
---.I
1
1
t
t
I
I
a.
I
I
T ~I__
t ~I
b.
~__
T
_
t
_1
_
_I
_
t
t
c.
I
Id.
1. He crossed two tall plants. The results were 151 tall plants and 49 short plants.
Which Punnet square shows this cross? (Record the letter)
2. He crossed a tall plant with a short plant. His results were 101 tall plants and 99
short plants. Which Punnet square shows this?
3. He crossed a tall plant with a short plant. The results were 200 tall plants and 0
short plants. Which Punnett square shows this cross?
4. How did Mendel know for sure about the parents of each seed?
5. Is it possible for two organisms to have different genotypes but the same
phenotype? Explain.
6. Is it possible for two organisms to have different phenotypes but the same
genotype? Explain.
7. How did Mendel cross - pollinate plants with different traits?
8. Hopefully each of you were careful and did your best while doing today's
experiment. Explain how CoL 3:23 applies to daily life and even with labs &
homework. (Something to think about).