Name: ______LAB: Variations in a Bean Population Ms. Czuprynski
INTRODUCTION
Evolution is a change in a population over time. In today’s lab we will be analyzing a population of beans. While you may not look at a bunch of beans as a population, they are a group of the same species, hence a population. A bean is the seed of a plant. Most of the seed is used by the developing plant as food. Beans are ideal to study as they are small and easy to gather; and when studying variations in a population it is best to examine large numbers of organisms.
In order for a population to evolve over time a mechanism, called natural selection, must be an active force.
Natural selection is the process in which organisms with favorable traits are able to survive and reproduce. We know that organisms in a population are not all alike due to differences in genetics. This variation is essential for natural selection to occur.
MATERIALS
1. Metric Ruler
2. Petri Dish
3. Kidney Beans
PROCEDURE
□ 1. Make a hypothesis about the average length of a kidney bean (in centimeters) and one reason why you think this is the average bean length.
□ 2. Measure the length (in centimeters) of 100 kidney beans. Record each length in the data table.
□ 3. Complete the tally sheet for your bean population by counting the number of beans there were for each length measurement.
□ 4. Create a Bar Graph using your data. (X-Axis = Length of Beans; Y-Axis = Number of Beans)
EXTENSION:
Question: Would the same size bean be the best choice in all environments?
Hypothesis: ______
In this part of the lab you will germinate beans to see if the size of the bean does affect the success of the plant. You must write a procedure for how you will test your hypothesis. In your procedure you must decide:
1.) How many beans you will grow in the cup
2.) How much water will you add daily
3.) How will you limit the amount of variables in the environment that the beans are exposed to
4.) What will you measure each day
Part 1: Lab write up
INTRODUCTORY PARAGRAGH
a) Start with a general introductory sentence. Use the lab handout to help, but be careful not to plagiarize.
b) Describe two or more reasons (purposes) for why we are doing this lab.
c) Explain any important background information:
a. What is natural selection?
b. Why is variation essential for natural selection to occur?
c. Why are we using beans to study populations?
d) State your hypothesis and one or more reason(s) why you believe your hypothesis is correct. (See Procedure Step #1)
CONCLUSION
1. Describe the range (distribution) of lengths you gathered by performing the experiment.
a. Explain one or more reasons why it might be beneficial for these particular beans to be the size they are?
b. Would the same size bean be the best choice in all environments? Explain why or why not.
c. What type of natural selection was seen in this population of bean? In other words was it stabilizing selection, disruptive selection or directional selection? Explain how you know
à HINT: Use your bar graph to help answer this question
2. State whether you accept or reject your hypothesis. In other words was your hypothesis correct or incorrect. Explain why you accept or reject it.
LAB REPORT CHECK OFF
□ Cover Page (Title of Lab, Name, Date, Period)
□ Introductory Paragraph
□ Materials – List
□ Procedure – Number
□ Results – Data Table, Tally Sheet, Bar Graph
□ Conclusion Paragraph