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Internet Biolab
How can phenotypes and genotypes of plants be determined?
It's difficult to predict the traits of plants if all that you see is their seeds. But if these seeds are planted and allowed to grow, certain traits will appear. By observing these traits, you might be able to determine the possible phenotypes and genotypes of the parent plants that produced these seeds. In this lab, you will detemine the genotypes of plants that grow from two groups of tobacco seeds. Each group of seeds came from different parents. Plants will be either green or albino (white) in color. Use the following genotypes for this cross. CC=green, Cc=green, and cc=albino.
Preparation
Problem
Can the phenotypes and genotypes of the parent plants that produced two groups of seeds be determined from the phenotypes of the plants grown from the seeds?

Hypotheses
Have your group agree on a hypothesis to be tested that will answer the problem question. Record your hypothesis.

Objectives
In this BioLab, you will:

  • Analyze the results of growing two groups of seeds.
  • Draw conclusions about phenotypes and genotypes based on those results.
  • Use the Internet to collect and compare data from other students.
Possible Materials
  • Potting soil
  • Small flowerpots or seeding flats
  • Two groups of tobacco seeds
  • Hand lens
  • Light source
  • Thermometer
  • Plant watering bottle
Data Sources

Safety Precautions
Always wash your hands after handling plant materials. Always wear goggles in the lab.

Skill Handbook
Use the Skill Handbook if you need additional help with this lab.

Plan the Experiment
1. Examine the materials provided by your teacher. As a group, make a list of the possible ways you might test your hypothesis.

2. Agree on one way that your group could investigate your hypothesis.

3. Design an experiment that will allow you to collect quantitative data. For example, how many plants do you think you will need to examine?

4. Prepare a numbered list of directions. Include a list of materials and the quantities you will need.

5. Make a data table for recording your observations.

Check the Plan
1. Carefully determine what data you are going to collect. How many seeds do you think you will need? How long will you carry out the experiment?

2. What variables, if any, will have to be controlled? (Hint: Think about the growing conditions for the plants.)

3. Make sure your teacher has approved your experimental plan before you proceed.

4. Carry out your experiment. Make any needed observations, such as the numbers of green and albino plants in each group, and complete your data table.

5. Post your data in the table below.

Post Your Data

Group 1: Offspring Phenotypes

green

albino

Group 2: Offspring Phenotypes

green

albino

Possible Parent Genotype

Female Male
Experimental Design - Explain Briefly

*City
*State
*School

*Required field

Analyze and Conclude
1. Thinking Critically
Why was it necessary to grow plants from the seeds in order to determine the phenotypes of the plants that formed the seeds?

2. Drawing Conclusions
Using the information in the introduction, describe how the gene for green color (C) is inherited.

3. Making Inferences
For the group of seeds that yielded all green plants, are you able to determine exactly the genotypes of the parents that formed these seeds? Can you determine the genotype of each plant observed? Explain.

 

4. Making Inferences
For the group of seeds that yielded some green and some albino plants, are you able to determine exactly the genotypes of the plants that formed these seeds? Can you determine the genotype of each plant observed? Explain.

5. Using the Internet
Compare your experimental design with that of other students. Were your results similar? What might account for the differences?


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