The question
Name: ______________________ Date: ____________ A new pesticide: toxicity and how long it lasts (10 points)
Data
Toxicity test of a new insecticide in rats
| Dose (mg/kg) | Rats killed (%) |
|---|---|
| 0 | 0 |
| 5 | 4 |
| 10 | 16 |
| 15 | 38 |
| 20 | 62 |
| 25 | 80 |
| 30 | 92 |
(a) A farm cooperative is considering insecticide Z for its orchards, which drain into a creek. The table shows a toxicity test in rats. Identify the LD50 of insecticide Z from the data, with its unit. [1 point]
(b) Rats in the orchard have an average mass of 0.40 kg. Calculate the dose of insecticide Z, in milligrams, expected to kill half of a group of these rats. Show your setup with units. [2 points]
(c) Insecticide Z has a half-life of 15 days in orchard soil. The cooperative applies 400 kg of it across its orchards. Calculate the mass of insecticide Z left in the soil 60 days later. Show your setup. [2 points]
(d) Insecticide Z dissolves in fat and breaks down slowly. Explain how its use in the orchards could lead to high concentrations in hawks that eat rodents and small birds. [2 points]
(e) Propose a solution, other than switching to a different chemical, that would reduce the amount of insecticide Z reaching the creek. Justify it by explaining how it works. [2 points]
(f) Describe one reason the LD50 measured in rats may not show how harmful insecticide Z is to people. [1 point]