Download Name: Corn Lab Directions: 1. Do not remove labels or plastic wrap

Name: _________________________
Corn Lab
Directions:
1.
2.
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5.
Do not remove labels or plastic wrap from ears.
Treat them gently. Do not drop, etc. They are fragile and expensive.
Do not remove any kernels from the ears.
Count the kernels of each kind in a row from end to end. Be sure you stay in the same row all
he way. One partner should be the recorder.
Get class data totals for each kind of kernel and record it on the data sheet.
MONOHYBRID: Work in pairs. Take one ear of corn and count the kernels of yellow and black. Use a five
row sample method. Count the yellows and blacks in five rows, total them, and then divide by 5 to find the
average number per row. The ear that you are using is the F2 generation.
How to calculate:
1.
The AVERAGE - Find the total of all 5 rows and divide by 5.
2.
The PERCENT - Add the totals (for yellow and black). This is the total of both.
Then, divide the number of each (yellow or black) by the total to find the percent of the
total.
**PLACE YOUR AVERAGE FOR EACH COLOR ON THE CLASS DATA SECTION OF THE BOARD.
Your average: Black ________
Your percent: Black ________
Yellow ________
Yellow ________
Class average: Black ________
Class percent: Black ________
Yellow ________
Yellow ________
1.
Based on your results, which gene is dominant? Label this with a letter.
2.
Which trait is coded by a recessive gene? Label this with a letter.
3.
What is the PHENOTYPE and GENOTYPE of the P1 generation? (The P1 generation was
homozygous.)
4.
Make the cross of the P1 to get the F1. (using the punnett square) What would be the
phenotype and genotype probabilities of the F1 generation?
5.
Now cross two individuals from the F1 generation to get the F2 generation. What is the
expected phenotype and genotype probabilities of this generation?
6.
Remember: the kernels of corn that you counted were from the F2 generation. How did your
results (from counting ) compare with the results from the punnett square? Compare
percentages in your answer below.
DIHYBRID: Now use a F2 dihybrid ear and sample it for black full, black shrunken, yellow full, and yellow
shrunken kernels. Use the same method as you did for monohybrid.
**SHOW YOUR AVERAGES ON THE BOARD TO CALCULATE CLASS AVERAGE.
Your average: Black, Full _____ Black, Shrunken _____ Yellow, Full _____ Yellow, Shrunken _____
Your percent: Black, Full _____ Black, Shrunken _____ Yellow, Full _____ Yellow, Shrunken _____
Class average: Black, Full _____ Black, Shrunken _____ Yellow, Full _____ Yellow, Shrunken _____
Class percent: Black, Full _____ Black, Shrunken _____ Yellow, Full _____ Yellow, Shrunken _____
7.
In the dihybrid cross, which traits are coded by dominant genes? Label them with letters.
8.
Which traits are coded by recessive genes? Label them with letters.
9.
What are the P1 genotypes? Assume that both of the original parents are homozygous.
10.
What are the genotypes of the gametes (sex cells) produced by the original two parents?
11.
Show the cross of the P1 generation and do a punnett square to determine the genotypes of the F1
generation. State the genotype and phenotype probabilities of the F1 generation.
12.
Cross two individuals from the F1 generation to get the F2 generation. What phenotype probabilities
would you predict from the punnett square?
13.
Compare your EXPECTED results (from the punnett square) with the actual results (from counting the
kernels). Show the comparison below.
14.
Which results were closest to the prediction based on the punnett square, your data or the class
Which would you expect to be the closest? WHY?
data?