Lessons 7 and 8

In lesson 7 we learned about lethal doses. A lethal dose is an amount of an ingested substance that kills 50% of a test sample of animals. This is expressed in mg/kg. The lethal dose depends on the amount of a substance and the mass of the organism. The smaller the amount the more toxic it is.

Practice Problems

1. The toxicity of different substances is usually measured by exposing lab animals to the substance in different amounts.

 

Lesson 8

In lesson eight we learned about percent error. We did a lab where we had to try and figure out how many small objects were in a Baggie. Then when we learned the correct method we we taught the equation for percent error. This equation is pictured below.

Practice Problems

5. The marbles will have a greater mass because the mass of a marble is greater than the mass of a plastic bead.

 

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