1. Serial Dilutions

2. Make a 0.2-g/mL NaCl STOCK solution
- Add 2 g of sodium chloride to beaker and add water to 10 mL
0.2 g/mL NaCl
Stock Solution

3. Get as many test tubes (minus two controls) as you have plastic jewelry bags for your experiment

4. Add 5 mL of water to each of you test tubes

5. Add 5 mL of Stock Solution to first test tube.

6. Mix the first Tube

7. Take 5 mL of first tube and add to second tube

8. Mix

9. Repeat and remove 5 ml from last tube and discard

10. Using a 5mL disposable pipette, add 3 mL from stock solution to a bag, 3 mL of water to a bag, and the 3 mL from each test to its respective bag

11. Stock Solution

14. Water

17. 0.1 g/mL Solution

20. 0.05 g/mL Solution

23. Etc.

24. Put all the bags upright in the beaker that had the stock solution.
Put in dark area for one about one week
Determine the percent dead for each concentration.
Graph with the % dead on the y-axis and concentration on the x-axis.
Determine the LD50 or the concentration where 50% of the seeds did not germinate

25. Percentage of population killed by a given dose
100 75 50 25 2 4 6 8 10 12 14 16
Percentage of population killed by a given dose
Dose (hypothetical units) LD