LD 50 Lab
![Picture](/uploads/3/2/3/3/32337313/4587219.jpg?389)
Collaborators: Emily Davis, Ellie Lupton, Caitlin Brennan, Devin Stafford.
Introduction
In this lab, we sought to come up with an LD50, which according to the EPA, is the lethal dose which is require to kill half of a population of test organisms. In order to observe this, we created a dose-response curve, which plots the relationship between the dose of a drug administered and its medical effect. The lab, specifically,measured the response of 10 radish seeds when exposed to 20 mL of water with varying concentrations of salt, thereby creating a serial dilution process. To observe the effects of salt on seed germination, we measures both the radical length of the sets of seeds after germination, as well as the number germinated. The data we collected after a 4 day germination period made it evident that exposure to higher concentrations of salt lead to lower numbers of germinated seeds. The control group which was exposed to 0 salt had all 10 germinated, but the seeds exposed to the 6.25% concentration still had 4 germinated, so we can conclude that this is an acceptable, tolerable concentration of salt to expose to our environments.
Problem
How does salt impact the germination of radish seeds?
Hypothesis
If radish seeds are exposed to varying concentrations of salt prior to germination, the seeds exposed to higher concentrations will have more limited germination and shorter radicle length.
Parts of the Experiment
Control Group: Seeds exposed to concentrations with 0% salt.
Experimental Group: 5 Bags of seeds with varying salt concentrations.
Independent Variable: Salt concentrations in solutions.
Dependent Variable:Radicle length and number of seeds germinated.
Controlled Variables: 2 napkins, 1 plastic bag, 20 mL of liquid, 4 days, 10 seeds
Materials
-6 ziploc bags
-60 seeds
-12 napkins
-Water
-Graduated cylinder
-Concentrated Salt Water solution
Method
1. Use the graduated cylinder to prepare the various concentrations provided in the graph below.
2. Label the six bags with group number, bag number, and percent concentration of chemical:
a. Bag #1: 0%
b. Bag #2: 6.25%
c. Bag #3: 12.5%
d. Bag #4: 25%
e. Bag #5: 50%
f. Bag #6: 100%
3. Put two napkins together and cut them to fit in the bag.
4. Put on lab goggles and gloves, and carefully pour the salt solution into the napkins to which each is assigned.
5. Count 10 seeds and place them on the moist napkins within the bag. Do this for each bag.
6. Place the seed bags in a stack, lying flat with the seeds up.
Data (see below)
Introduction
In this lab, we sought to come up with an LD50, which according to the EPA, is the lethal dose which is require to kill half of a population of test organisms. In order to observe this, we created a dose-response curve, which plots the relationship between the dose of a drug administered and its medical effect. The lab, specifically,measured the response of 10 radish seeds when exposed to 20 mL of water with varying concentrations of salt, thereby creating a serial dilution process. To observe the effects of salt on seed germination, we measures both the radical length of the sets of seeds after germination, as well as the number germinated. The data we collected after a 4 day germination period made it evident that exposure to higher concentrations of salt lead to lower numbers of germinated seeds. The control group which was exposed to 0 salt had all 10 germinated, but the seeds exposed to the 6.25% concentration still had 4 germinated, so we can conclude that this is an acceptable, tolerable concentration of salt to expose to our environments.
Problem
How does salt impact the germination of radish seeds?
Hypothesis
If radish seeds are exposed to varying concentrations of salt prior to germination, the seeds exposed to higher concentrations will have more limited germination and shorter radicle length.
Parts of the Experiment
Control Group: Seeds exposed to concentrations with 0% salt.
Experimental Group: 5 Bags of seeds with varying salt concentrations.
Independent Variable: Salt concentrations in solutions.
Dependent Variable:Radicle length and number of seeds germinated.
Controlled Variables: 2 napkins, 1 plastic bag, 20 mL of liquid, 4 days, 10 seeds
Materials
-6 ziploc bags
-60 seeds
-12 napkins
-Water
-Graduated cylinder
-Concentrated Salt Water solution
Method
1. Use the graduated cylinder to prepare the various concentrations provided in the graph below.
2. Label the six bags with group number, bag number, and percent concentration of chemical:
a. Bag #1: 0%
b. Bag #2: 6.25%
c. Bag #3: 12.5%
d. Bag #4: 25%
e. Bag #5: 50%
f. Bag #6: 100%
3. Put two napkins together and cut them to fit in the bag.
4. Put on lab goggles and gloves, and carefully pour the salt solution into the napkins to which each is assigned.
5. Count 10 seeds and place them on the moist napkins within the bag. Do this for each bag.
6. Place the seed bags in a stack, lying flat with the seeds up.
Data (see below)
Conclusion
The LD 50 for the radish seeds was around 6%, or 20 mL of liquid containing 6% salt. This was found by observing the data collection table and the responding graph of germination percentages. At 6.25% concentration, 4 seeds were germinated, or 40% of the seeds.
Inconsistencies existed in the lab because a paper towel was used to replace a napkin in one of the bags. The paper towel may have effected the seed's germination by not absorbing the solution, and could have possibly overexposed to the solution that was not absorbed by the paper towel the way it was the napkins. The salt was very harmful to the seeds germination and radicle growth. The chart of the radicle's lengths when exposed to different concentrations. The data coincides with the negative correlation of the seed's germination. My hypothesis prior to the experience was that the radish seeds would germinate less the more it is exposed to higher concentrations of salt. This proved an accurate hypothesis and is a relevant finding, as roads are regularly salted in icy weather, and thereby harming the surrounding environments through runoff. Minnestota alone, which experiences frequent icy weather, uses an average amount 225,000 tons of salt, according a report by USA Today.
Citations
Copel, Larry. "Communities Seek a Substitute for Road Salt." USA Today. Gannett, 23 Feb. 2013. Web. 06 Feb. 2015.
The LD 50 for the radish seeds was around 6%, or 20 mL of liquid containing 6% salt. This was found by observing the data collection table and the responding graph of germination percentages. At 6.25% concentration, 4 seeds were germinated, or 40% of the seeds.
Inconsistencies existed in the lab because a paper towel was used to replace a napkin in one of the bags. The paper towel may have effected the seed's germination by not absorbing the solution, and could have possibly overexposed to the solution that was not absorbed by the paper towel the way it was the napkins. The salt was very harmful to the seeds germination and radicle growth. The chart of the radicle's lengths when exposed to different concentrations. The data coincides with the negative correlation of the seed's germination. My hypothesis prior to the experience was that the radish seeds would germinate less the more it is exposed to higher concentrations of salt. This proved an accurate hypothesis and is a relevant finding, as roads are regularly salted in icy weather, and thereby harming the surrounding environments through runoff. Minnestota alone, which experiences frequent icy weather, uses an average amount 225,000 tons of salt, according a report by USA Today.
Citations
Copel, Larry. "Communities Seek a Substitute for Road Salt." USA Today. Gannett, 23 Feb. 2013. Web. 06 Feb. 2015.