Natural Selection Lab
Tuesday – Lab Set-Up:
 Each lab table will set up the cultures listed below.
Petri Dish #
1
2
3
4
5
1.
2.
3.
4.
5.
6.
7.
8.
9.
Set-Up
0.0
0.5
1.0
1.5
2.0
Obtain 5 small petri dishes. Make sure they appear clean … wipe with a damp paper towel if necessary.
Use a Sharpie to label the SIDE of the bottom dish (the deeper half) with your table number + NaCl concentration. For example, 1-0.5, etc.
Use a graduated cylinder to measure 10 mL of the correct NaCl solution. Pour it into the deeper half of the petri dish. Be sure to rinse the
graduated cylinder between measurements to prevent contamination.
Use a paintbrush to pick up ~20 brine shrimp eggs. Transfer them into the petri dish containing 0.0 NaCl solution.
Examine the petri dish under the stereoscope. Count the number of eggs in the petri dish. Record.
Repeat steps 3 – 5 for all set-ups.
Place the lids on the petri dishes. Incubate as directed.
Formulate a hypothesis based on your research that predicts the viability of the brine shrimp in all five solutions.
Construct the data table below in your lab notebook:
Brine Shrimp Hatching Viability – Table Data
% NaCl
0.0
0.5
1.0
1.5
2.0
0 hrs
# Eggs
24 hrs
# Swimming
72 hrs
# Swimming
Hatching
Viability (%)
Block Day
Data Collection
1. Use the stereoscope to observe each petri dish.
2. Locate any hatched, viable brine shrimp. Count each brine shrimp, remove it from the petri dish, and transfer it to the container provided.
3. Record your data.
4. Construct Data Table to record class averages on Friday
Inquiry Lab - Environmental Factor Test Set-up
On Friday, you will set up brine shrimp cultures in the salt solution you determine to be most conducive to viable hatchlings to determine the effect of two
different environmental factors. Your choices are:
 Acid rain → Lower the pH of the solution by adding H2SO4
 Global warming → Increase the temperature
 Oil spill → Add oil
 Nutrient run-off → Add fertilizer pellets
 Water hardness due to erosion → Add NaBicarbonate to increase bicarbonate ion concentration
 Detergent run-off → Add detergent to sample
 Another factor??
Today you will design the experiment.
 First, decide on the factors you want to test.
 Determine how to create a set-up that most closely mimics real-life conditions.
 Summarize the procedure for your experiment. A few things to consider …
 Only one variable permitted per set-up
 Controlled variables must be addressed
 Procedure must be repeatable
 Set-up should reflect effect of factor in nature
 Record your hypothesis.
Next week, you will construct a tri-fold reporting your findings so you may want to take pictures on Friday/Monday.
Friday
Brine Shrimp Hatching Viability – Class Averages
% NaCl
Hatching Viability
(%)
0.0
0.5
1.0
1.5
2.0
Data Collection
1. Use the stereoscope to observe each petri dish.
2. Locate any hatched, viable brine shrimp.
3. Record your data.
4. Calculate the % hatched:
# hatchings on Block Day + # of hatchlings on Friday
Total # of eggs
X 100 = % Hatching Viability
Inquiry Lab Set-up
1. Set-up Environmental Factor tests according to table experimental design
Monday
Data Collection
1. Use the stereoscope to observe each petri dish.
2. Locate any hatched, viable brine shrimp. Record your data in your lab notebook
3. Calculate the % hatched:
# of hatchlings
Total # of eggs
4.
5.
X 100 = % Hatching Viability
Collect data from other tables with same set-up. Please note: You need the % Hatching Viability for the test set-up and the control.
Label trifold with table number.
Data Analysis – In your lab notebook …
1. Record your hypothesis and your null hypothesis for each test. Remember, the null hypothesis is also called “the hypothesis of no effect”.
2. Test your null hypothesis by performing a Chi Square analysis for each test, using your data plus other tables that performed the same test.
Tuesday
Trifold Guidelines
 Title
o Specific & descriptive
o Centered at the top of the trifold
 Left Panel
o Photos illustrating experimental set-up/relevance
 Center Panel
o Abstract
 Must be written collaboratively by all students
 ~250 words
 Created/completed in class
 Typed
 Format
 Three – four sentences about the topic, its importance including relevance
 One – two sentences describing the purpose, including the hypothesis
 Two – three sentences providing a general description of the procedure used
 Three - four sentences describing the data/data analysis
 Include information about initial set-up to determine optimal salinity
 Include null hypothesis, P value & interpretation
 Three - four sentences describing your conclusions
 Right Panel
o Graphical representation of data
 What type of graph best illustrates your data?
 May be constructed by hand or on computer
 Construct separate graphs to represent table data/class data
 To illustrate class data, calculate the mean value for % viability in the test set-ups/control.
Completed Table Trifold, Individual Planning Pages Due Today!