NAME: H/H: DATE: / 50
COLUMBIA SECONDARY SCHOOL for Math, Science & Engineering
A Public School, Community and University Partnership Challenging Academics - A Passion for Reason and Knowledge - Strength in Diversity
Predicting Tobacco Seed Phenotype Using a Pedigree Chart
Question: Can you predict the phenotypic results of the F2 generation of a tobacco seed given the available information
about the F1 and P generations (see background knowledge)? What do you predict they would be?
Background Information (9):
Sexual Reproduction and Heredity:
Drawing of the Tobacco Seed Pedigree (Family Tree) (4)
Prediction: % Green % Yellow % Other / 17
Tobacco Seeds (approximately 8) 1 germinating paper
Magnifying glass 1 dropper
1 tray 1 crucible filled halfway with water
1 clear Petri dish (with lid) Pencil
1. Use the magnifying glass to examine two seeds. Draw them in figure 1 (below)
and not e any qualitative and quantitative traits.
2. Draw eight pie slices on your germinating paper (see image to the right)
3. Place water in your crucible
4. Moisten your germinating paper in the crucible and place it in the Petri dish
5. Place one tobacco seed in the middle of each pie slice.
6. Water your tobacco seeds daily and observe the color of the leaves once the
seeds have germinated.
7. Note the color of the leaves in table 1 (results section)
8. Record the results of your class in table 2.
Figure 1: Sketch of tobacco seed phenotype before germination (to check for regularity) (4)
Seed sketches (at least 2 for comparison purposes) – Use the magnifying glass to get close
Seed 1 Seed 2
Qualitative Observations (description of traits Quantitative Observations (data about your
that cannot be or are not easily measured) organism that can be measured or counted)
Table 1: Table Data - Color of tobacco seeds grown on the classroom table (3)
Table # Number of Plants Percent Other Observations
Table 2: Class Data - Color of tobacco seeds grown out in the open
Table 1 2 3 4 5 6 7 8 Total Percent
Table 3: Comparison of color results in the light and dark growing conditions (4)
Light (Percent of Total Population) Ratio of Green : Yellow
Figure 2: Bar graph comparing the number of green and yellow tobacco
seed plants in the F2 generation (1)
(Graph notes from class):
1. Can you predict the phenotype of an F2 population of tobacco seeds?
2. What are the differences between this lab and the lab in which you predicted the phenotype of your offspring (with
a partner in class)? (3)
3. How does your confidence in these results compare to your confidence in predicting the phenotype of an offspring
based on knowing the traits of the two parents (the previous lab)? Explain (3).
4. Do you think it’s more helpful to know whether an ancestor exhibits the dominant or recessive trait (or neither).
5. What did you learn? (3)