Download Corn Crossing Handout

Corn Crossing
Name:
Date:
Pd:
The corn seedlings that you planted for this lab are products of a monohybrid cross; meaning a single gene
is responsible for the trait inherited from their parent plants. Both parents were entirely green, yet you will
notice that the offspring are both green and albino (lacking chlorophyll).
Objectives
 Observe and examine genetic biodiversity among corn plants.
 Relate the importance of genetic biodiversity to species interaction and survival.
Procedures
1. Count the number of green and albino seedlings for your group and record your data in the table.
2. Now find two other groups and collect their data and record it in the table as you did your own.
3. Then divide the number of green plants by the number of white ones to determine the ratio of
green to albino corn.
Data Table
Plant Group #
Number Green
Seedlings
#
#
#
Total:
Number of Albino
Seedlings
Ratio of Green:Albino
Determining Possible heredity: Punnett Squares
Fill in the Punnett squares by combining the above the square in the top column and the letter in the left
column of the same row. These letters represent the genotype for the parents (genetic code for a specific
trait). When the entire Punnett square as been completed, write the ratio of green to albino corn plants.
(C) represents green plants and is the dominate trait. (c) represents albino plants and is the recessive trait.
Ratio:
Ratio:
C
C
C
C
C
C
c
Ratio:
c
Ratio:
c
c
C
c
c
c
c
C
In your answers below, use (C) to represent the gene that codes for the formation of Chlorophyll (green
corn plants). Use (c) for the gene that lacks coding for the formation of chlorophyll (albino corn plants).
1. Given the overall ratio of green to albino offspring in the 1st generation, what were the genotypes of the
two green parents?
2. What is the genotype(s) of the green 1st offspring?
3. What is the genotype(s) of the albino 1st offspring?
4. If ratios differ from block to block, why is this?
5. Consider the total ratio from the observed data. What would it be theoretically?
6. Does the theoretical ratio differ from actual ratio? Why?
7. Do ratios differ from block to block and to the total? Why?
8. What can you predict about the progeny (2nd generation) of the albinos?