Download "Analyzing Genetic Data" 62 Analyzing Genetic

Name ___________________________________________ Date _______________ Period _____________
62 Analyzing Genetic Data
Procedure:
1. Review the prediction(s) you made when you began Activity 55, “Plants Have Genes Too.” If you
would like to change your prediction, record your revised prediction in the space below.
Answers vary
2. Get your dish of sprouted seedlings.
3. With the lid off, examine each seedling plant carefully. With your lab group, count the number of
green seedlings and the number of yellow seedlings. (If the sprout is mixed with green and yellow,
count it as green.)
4. Use the data table in the space below to summarize your results.
Petri Dish
Number of Green
Seedlings
Number of Yellow
Seedlings
Group Totals
Class TOTALS
Group and Class Totals Vary
5. Report your results to your teacher, as directed.
6. Your teacher will display the class’s total data. Record the data in your table.
Analysis:
1. Look back to the prediction you made in Activity 55 “Plants Have Genes Too.” Was your prediction
correct? Explain.
Yes, my prediction was correct. I predicted that 2 out of 6 would have yellow leaves and that is what
happened.
No, my prediction was incorrect. I predicted that 2 out of 6 would have yellow leaves and only 1 out
of 6 had yellow leaves.
2. Compare the class’s results for seedling color to Mendel’s results for various pea plant traits. Why are
they similar? What do they suggest about the inheritance of the pale yellow and green Nicotiana
traits?
Our results are similar to Mendel’s results because we were observing a characteristic with two traits.
One was more common (green) in the third generation of plants than the other (yellow).This suggests
that the green trait is dominant to the yellow trait.
3. Do each group’s results fit Mendel’s model? Explain.
Each group’s results do not fit Mendel’s model because inheritance is random. While there might be
a 3:1 ratio of green to yellow plants in a very large group of offspring, a small group might not
demonstrate the pattern.
4. When you first set out these seeds to germinate, you were told that they were all the offspring of two
green parent plants. You were also told that each of the green parents had one green parent and one
yellow parent.
a. Based on the class’s results, what can you conclude about the color alleles of each of the
green parents of your seedlings?
The parents likely were heterozygous for the green leaf trait. (Ll)
b. How is this breeding cross similar to the one you modeled in Activity 59, “Gene Combo”?
Explain.
In activity 59 we crossbred two heterozygous parents. In this activity we did the same, but with
plants. The offspring produced in both cases were a mixture of phenotypes, with more of the
dominant trait than the recessive trait.
5. Construct a Punnett square to show what will happen if one of the green parent-generation Nicotiana
plants is crossed with a pale yellow plant. Explain the results.
L
l
l
l
Ll
ll
Ll
ll
There will be two heterozygous green plants and two homozygous yellow plants