Mid-Unit Assessment, Part 2: The Chemistry of Life Complete this teacher-scored portion of the assessment and submit it to your teacher.

Total score:

_ of [9] points

(Score for Question 1: _ of [3] points)

1. Discuss the types of trace elements in organic compounds.

Answer:

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(Score for Question 2: _ of (3] points)

2. Discuss how compounds in different types of organisms can be used to benefit people.

Answer:

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(Score for Question 3: _ of [3] points)

3. Describe what is meant when water is called a polar molecule.

Answer:

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1. At Thanksgiving dinner, your great aunt refuses to eat with plastic silverware and proudly exclaims that she has discarded all plastics because “they cause cancer.” You wonder if chemicals you commonly use are mutagenic. You recall your time in BY 331, Genetics, and realize that you can use the Ames test to test for reversion of a point mutation in the HisG gene in the bacteria S. typhimurium. You added the chemical you wish to test into the growth medium for the bacteria. You carefully plated an equal number of cells on each mutagenesis plate. You also calculated percent survival for chemical treated cells relative to untreated cells. Remember that the plate media for survival is not selective. A summary of the results is shown below.

A. What medium must be used in the selective plate as part of the Ames test? Explain how a mutation gives rise to a revertant in this experiment.

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B. You are initially surprised to see revertants in the absence of any chemical that you are testing, but you realize that this is normal. Explain a specific way in which a revertant can arise in the absence of an added mutagen.

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C. Which chemicals would you identify as containing a mutagen? Explain your reasoning.

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D. Which chemicals would you identify as possibly antimutagenic? Explain your reasoning.

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