Serial Dilutions Get 2 x 3 inch jewelry

Serial Dilutions

Get 2 x 3 inch jewelry bags jewelry supply store. See product # 52 -002 on second table @ http: //www. aajewelry. com/ templates/product_list_dro pdown_pix. aspx? Group. Gui d=5523 Cut piece of paper towel and insert into bag Staple across the bag such that there is space for roots to grow Add 10 to 15 seeds to each bag

Make a 0. 2 -g/m. L Na. Cl STOCK solution - Add 2 g of sodium chloride to beaker and add water to 10 m. L 0. 2 g/m. L Na. Cl Stock Solution

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

Add 5 m. L of water to each of you test tubes

Add 5 m. L of Stock Solution to first test tube.

Mix the first Tube

Take 5 m. L of first tube and add to second tube

Mix

Repeat and remove 5 ml from last tube and discard

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

Stock Solution

Water

0. 1 g/m. L Solution

0. 05 g/m. L Solution

Etc.

• 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 LD 50 or the concentration where 50% of the seeds did not germinate

Percentage of population killed by a given dose 100 75 50 25 LD 0 2 4 6 8 50 10 12 Dose (hypothetical units) 14 16