LD50 Lab
Collaborators- Julia, Skippy, Riley
Abstract- we took six petri dishes and filled each with two napkins. Once we did we filled each of them with different amounts of saltwater mixed into regular water. Then, we placed ten radish seeds in the petri dishes. After that we waited a week to germinate. After the week had gone, the seeds were germinated, but some were not germinated at all. We then measured all of the seeds that had been germinated, and we got our results to figure out how much salt water it takes to kill half of the seedlings.
Problem- How much salt water would it take to kill half of the seedlings
Hypothesis- If half of the water is salt water then half of the seedlings will die
Parts of the experiment- The control group is the petri dish with no salt water in it, and the experimental group is all the other petri dishes will slat water in them. The controlled variables would be how much salt water we put in the dishes, the independent variable is also how much salt water we put in the dishes, and the dependent variable would be how many seeds germinated.
Materials- 6 petri dishes, 6 seeds, 12 napkins, Water, Graduated cylinder, and Concentrated Salt Water solution
Procedure-
You will measure the response of the radish seeds at various salt concentrations. After the seeds have germinated, count the number of seeds that germinated and measure the length of each radical (embryonic root). After recording your results, you will create two graphs (% seed germination and dose-response curve) to help you analyze the data collected.
Data-
Abstract- we took six petri dishes and filled each with two napkins. Once we did we filled each of them with different amounts of saltwater mixed into regular water. Then, we placed ten radish seeds in the petri dishes. After that we waited a week to germinate. After the week had gone, the seeds were germinated, but some were not germinated at all. We then measured all of the seeds that had been germinated, and we got our results to figure out how much salt water it takes to kill half of the seedlings.
Problem- How much salt water would it take to kill half of the seedlings
Hypothesis- If half of the water is salt water then half of the seedlings will die
Parts of the experiment- The control group is the petri dish with no salt water in it, and the experimental group is all the other petri dishes will slat water in them. The controlled variables would be how much salt water we put in the dishes, the independent variable is also how much salt water we put in the dishes, and the dependent variable would be how many seeds germinated.
Materials- 6 petri dishes, 6 seeds, 12 napkins, Water, Graduated cylinder, and Concentrated Salt Water solution
Procedure-
- Use the graduated cylinders and test tubes to prepare the various concentrations
- Label all six petri dishes with your group number, the dish #, and a percent concentration of chemical:
- Dish #1: 0%
- Dish #2: 6.25%
- Dish #3: 12.5%
- Dish #4: 25%
- Dish #5: 50%
- Dish #6: 100%
- Put two napkins together and cut them so that they fit into the petri dish.
- Put on the safety goggles and latex gloves. Carefully pour the chemical solutions onto the napkins, making sure to match the numbers and concentration percentages of the dish.
- Count out 10 seeds. Carefully place the seeds on the moist napkins in the petri dish.
- Repeat steps 3-5 for the other dishes.
- Place the seed dishes in a stack, lying flat with the seeds up. Put the seeds in the spot designated by your teacher.
You will measure the response of the radish seeds at various salt concentrations. After the seeds have germinated, count the number of seeds that germinated and measure the length of each radical (embryonic root). After recording your results, you will create two graphs (% seed germination and dose-response curve) to help you analyze the data collected.
- Remove the lid of the control dish. Count the number of seeds that germinated. Calculate the percentage of seeds that germinated and record in Table 2. Note: if fewer than 80% of the seeds in this control sample germinate, this indicates a problem with the experiment.
- Measure the length of the radical for each of the germinating lettuce seeds to the nearest millimeter (mm). Look carefully at each sprout to make sure you are measuring just the root, not the shoot as well. In the picture below, you would measure just the part between the two arrows, not the shoot and cotyledons to the left.
- Repeat steps 1-2 for each petri dish.
- For each treatment, calculate the mean radical length for each salt solution. Add the total radical lengths for each salt solution and divide by the total number of seeds that germinated. Do not include data from seeds that did not germinate. Record data in column labeled, “Mean Radicle Length (mm).”
Data-
Questions- 1. What appears to be the LD50 for salt for radish
seeds? Support your answer with data.
- According to this
- According to this
The LD50 for the radish seeds is about a 18% salt concentration
2. Is your radicle data supported by your germination data? Support your answer with data.
- No, we measures the growth of the seeds that did germinate and used the average length of every concentration for my radical data.
Conclusion- It turns out my hypothesis was wrong. I assumed that a half concentration would kill half of the population, when in fact, it was much less. It just goes to show how delicate the environment really is. A little salt water helped the seeds, but after that it just started to hurt them. There is such a thing as too much of a good thing. The best example would be overdosing. People take more medication than they should because they hurt a little more or they need it to work faster, but it only ends up hurting them. However, this lab mainly shows how pharmaceuticals are tested in order to make sure no one gets hurt. The whole point of an LD50 is to make sure people or plants are safe. LD50 is not the only way to make sure drugs and other chemicals safe, but in the article listed at the top of the screen there are more ways to make sure a chemical is safe.
2. Is your radicle data supported by your germination data? Support your answer with data.
- No, we measures the growth of the seeds that did germinate and used the average length of every concentration for my radical data.
Conclusion- It turns out my hypothesis was wrong. I assumed that a half concentration would kill half of the population, when in fact, it was much less. It just goes to show how delicate the environment really is. A little salt water helped the seeds, but after that it just started to hurt them. There is such a thing as too much of a good thing. The best example would be overdosing. People take more medication than they should because they hurt a little more or they need it to work faster, but it only ends up hurting them. However, this lab mainly shows how pharmaceuticals are tested in order to make sure no one gets hurt. The whole point of an LD50 is to make sure people or plants are safe. LD50 is not the only way to make sure drugs and other chemicals safe, but in the article listed at the top of the screen there are more ways to make sure a chemical is safe.