Collaborators: Anna Duke, Chinonso Ejere, Darby Ford, Ahlora Gartland
Problem: What is the LD50 of salt solution on seeds?
Hypothesis: The higher the salt concentration, the less seeds will survive.
Abstract: After putting lettuce seeds into six different bags different concentrations of salt water (0, .75, 1.5, 3, 6, 12), the bags had to sit closed for five days. When the bags were opened, each group of seeds was studied. The amount of seeds germinated and the length of their radicle was recorded from each group of seeds. The salt concentrations (measured in g/L) of 6.0 and 12.0 had the least amount of seeds germinate, and their radicle lengths were the shortest. However, the salt concentration of 12.0 g/L is not the LD50, because the percent that survived was 66.25%. To reach the LD50, the concentration of salt would have to be higher.
Variables:
Independent- The amount of salt water concentrations
Dependent- The growth of the seeds
Controlled- The distilled water
Experimental- The varying salt concentrations
Materials:
· 6 test tubes
· 10 mL graduated cylinder
· “Concentrated salt solution” (12 grams of sodium chloride/1 liter of distilled water)
· 6 plastic bags
· 6 paper towels
· 60 lettuce seeds
Procedure/Methods:
· First, a serial dilution was done
· Set up 6 test tubes with the following salt concentrations: 12 g/L, 6 g/L, 3 g/L, 1.5 g/L, .75 g/L
· Add 10 mL of distilled water to test tubes #2-6
· Measure 20 mL of the concentrated solution and pour it into test tube #1
· Transfer 10 mL of salt solution from test tube #1 to test tube #2
· Swirl test tube #2 to mix the salt solution
· Repeat these past 2 steps for test tubes #3-5 measuring 10 mL each time
· Don’t add any salt solution to test tube #6
· Measure 10 mL of distilled water into test tube #6
· Place each group of seeds onto a paper towel, and pour the concentrations on them. Then, place them into the properly labeled bag.
· Incubate for 4-5 days
· When you take them out, measure the length of their stems
Data:
Problem: What is the LD50 of salt solution on seeds?
Hypothesis: The higher the salt concentration, the less seeds will survive.
Abstract: After putting lettuce seeds into six different bags different concentrations of salt water (0, .75, 1.5, 3, 6, 12), the bags had to sit closed for five days. When the bags were opened, each group of seeds was studied. The amount of seeds germinated and the length of their radicle was recorded from each group of seeds. The salt concentrations (measured in g/L) of 6.0 and 12.0 had the least amount of seeds germinate, and their radicle lengths were the shortest. However, the salt concentration of 12.0 g/L is not the LD50, because the percent that survived was 66.25%. To reach the LD50, the concentration of salt would have to be higher.
Variables:
Independent- The amount of salt water concentrations
Dependent- The growth of the seeds
Controlled- The distilled water
Experimental- The varying salt concentrations
Materials:
· 6 test tubes
· 10 mL graduated cylinder
· “Concentrated salt solution” (12 grams of sodium chloride/1 liter of distilled water)
· 6 plastic bags
· 6 paper towels
· 60 lettuce seeds
Procedure/Methods:
· First, a serial dilution was done
· Set up 6 test tubes with the following salt concentrations: 12 g/L, 6 g/L, 3 g/L, 1.5 g/L, .75 g/L
· Add 10 mL of distilled water to test tubes #2-6
· Measure 20 mL of the concentrated solution and pour it into test tube #1
· Transfer 10 mL of salt solution from test tube #1 to test tube #2
· Swirl test tube #2 to mix the salt solution
· Repeat these past 2 steps for test tubes #3-5 measuring 10 mL each time
· Don’t add any salt solution to test tube #6
· Measure 10 mL of distilled water into test tube #6
· Place each group of seeds onto a paper towel, and pour the concentrations on them. Then, place them into the properly labeled bag.
· Incubate for 4-5 days
· When you take them out, measure the length of their stems
Data:
LD50 Graph:
Data Analysis: This data shows that the more salt concentration that is used on the seeds, the less the seeds will germinate. It also shows that the LD50 of salt water on lettuce seeds is higher than 12 g/L. It shows that the radicle length is longer when there is less salt concentration. The data supports my hypothesis, and helped me figure out the LD50 of the salt concentration.
Conclusion:
For the most part, the hypothesis that the higher the concentration, the less seeds will survive. The salt concentrations of 6 g/L and 12 g/L had a survival percent of 76.25% and 66.25%. However, the percent survived for the .75 g/L concentration was 78.75%, while the other percents were in the 80’s and 90’s. The LD50 of salt concentration on the seeds is 20.77. When .5 (50%) was plugged in for Y in the equation on the “Percent Not Germinated” graph and solved, this was the result. It makes sense because at the concentration of 12 g/L, 66.25% of the seeds survived, so the LD50 has to be higher than 12 g/L. For the most part, the radicle lengths were the longest on the seeds that had less of a salt concentration, except for the control group and the salt concentration of 3 g/L. A lot of times, LD50 is tested on rats. When trying to find the LD50 of a substance on humans, it can vary because of different weights and body sizes. Ask Erowid was testing caffeine the LD50 of caffeine. He said that usually, it is tested on rats first. The LD50 of caffeine on a 1kg rat turned out to be about about 75 mg. So, to find the amount on humans, take the average body weight. (In this case, they used 60 kg which is about 130 pounds) Since the LD50 for 1 kg is known, multiply that amount by 60. The lethal dosage of caffeine for a 130 pound human would be 4500 mg.
Citation:
"Ask Erowid : ID 2954 : How Are LD50s in Humans Determined?" Ask Erowid : ID 2954 : How Are LD50s in Humans Determined? N.p., 23 Mar. 2002. Web. 13 Feb. 2014. <http://www.erowid.org/ask/ask.php?ID=2954>.