Name_____________________________Date___________________Period_____________
Seedlings for Genetics
Objective: In this lab, you will germinate and grow
F2 corn seeds to determine inheritance patterns by
following monohybrid traits and dihybrid traits.
You also will compare your results to Mendel’s
Results
Materials: Genetic Corn Seed, cups, paper towels or soil
Monohybrid:
Studying one-factor segregation, we will follow one trait characteristic (coloration) with 2 allele results
(green or albino) corn. The albino characteristic is a lethal chlorophyll mutant, so that homozygous
green and heterozygous green are normal in color. The albino strain is recessive and has almost no
pigment.
A-green pigment
a-albino pigment
P generation: If a homozygous green and a homozygous albino corn were bred, what would the F1
generation results show?
A
a
a
A
Genotype:
Phenotype:
Cross the F1 generation to get the F2
Genotype:
Phenotype:
Name_____________________________Date___________________Period_____________
Write a hypothesis: If the class grows F2 generation corn, and follows just the characteristic of color,
then__________________________________because_________________________________________
_____________________________________________________________________________________
Chi Square Analysis:
If a person were to flip a coin 100 times, how many heads and how many tails should they get?...50 heads
and 50 tails. Suppose that he got 51 heads and 49 tails….did he just disprove probability? What about
55:45? What about 60:40? At what point does one conclude that the coin is likely abnormal or that some
other aspect of the experiment is likely askew? Chi Square to the rescue! Chi square determines whether
or not results seem to confirm or call into question a hypothesis.
Null Hypothesis vs. Alternative Hypothesis
Null: no statistically significant difference between expected and observed results
Alternative: explanation (hypothesis) of why the results are so different from what’s expected
Monohybrid
Data and Calculations:
Color of
Corn
Observed
Number
Expected
Number
Green
.75 x Total
Albino
.25 x Total
Total:
Total:
Difference between
observed and expected
Difference
Squared
Squared
Difference/
expected
number
0
n/a
X2 =
Name_____________________________Date___________________Period_____________
We will use this chart: 1 degree freedom
Hypothesis is Supported
Hypothesis not supported
Differences are Insignificant
Differences are significant
p
C-1
1
2
0.99
0.95
0.80
0.50
0.30
0.20
0.10
0.05
.00016
.0201
.0039
.103
.064
.446
.455
1.386
1.074
2.408
1.642
3.219
2.706
4.605
3.841
5.991
Dihybrid
Now we will look at two-factor cross by following the characteristic of color and height. We know green is dominant
to the albino allele, but we will also follow the alleles of height. The tall allele is dominant over the recessive dwarf
allele.
D-tall height
d-dwarf height
A-green pigment
a-albino pigment
P generations: a pure bred homozygous green tall plant was pollinated with a purebred homozygous albino
dwarf plant
___ ___ ___ ___ X___ ___ ___ ___
Genotype:
Phenotype:
Name_____________________________Date___________________Period_____________
F1: Breed offspring of P generation
___ ___ ___ ___ X___ ___ ___ ___
Genotype:
Phenotype:
Write a hypothesis: If the class grows F2 generation corn, and follows the characteristics of color and
height, then ________________________________________________________________________
because___________________________________________________________________________
Dihybrid
Data and Calculations
Color and
Height
Observed
Number
Expected
Number
Green
Tall
Total x9/16
Green
Dwarf
Total x 3/16
Albino
Tall
Total x 3/16
Albino
Dwarf
Total x 1/16
Total:
Total:
Difference between
observed and expected
Difference
Squared
Squared
Difference/
expected
number
0
n/a
X2 =
Name_____________________________Date___________________Period_____________
We will use this chart: 3 degree freedom
Hypothesis is Supported
Hypothesis not supported
Differences are Insignificant
Differences are significant
p
C-1
1
2
3
0.99
0.95
0.80
0.50
0.30
0.20
0.10
0.05
.00016
.0201
.115
.0039
.103
.352
.064
.446
1.005
.455
1.386
2.366
1.074
2.408
3.665
1.642
3.219
4.642
2.706
4.605
6.251
3.841
5.991
7.815
Results:
1. Was your hypothesis in the monohybrid cross supported or rejected? Explain.
2. Was your hypothesis in the dihybrid cross supported or rejected? Explain.
3. Name 3 sources of error? Effects they had data.
Conclusion:
What did you learn from this lab?