What is a Bioassay?

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What is a Bioassay?
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Bioassay

• A bioassay involves the use of biological
  organism to test for chemical toxicity.

Canaries are used by coal miners as a way to test
for high levels of methane (an odorless gas)
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Used by the FDA

• Bioassays are used to test drugs and skin care
  products before being okayed by the FDA.

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QoD In Science Notebooks

• 1. What is a bioassay? Use complete sentences.
• 2. What do we always wear for safety in the
  laboratory?

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BIOASSAYS

• Dose/Response Bioassays are used to
• Estimate toxicity to humans and other organisms.
• Estimate maximum concentrations of specific
  chemicals allowed to discharge into bodies of
  water.
• Investigate hazardous waste sites.

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Bioassay Species

• 3 organisms are often used
• Daphnia
• Duckweed
• Lettuce Seeds
• Expose organisms to chemicals and measure how
  they respond.

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Bioassay Species

• Lettuce Seeds
• In Petri dishes with test samples
• After 5 day check for
• germination (sprouting)
• radicle length (length of the sprout)

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CONCENTRATION VS. DOSE

• LD50 the Dose that is Lethal for 50 of the test
  organisms.
• Used for Daphnia
• TC50 the Concentration that causes a 50 drop in
  growth or health of the test organisms (Toxic
  Concentration).
• Used for seeds (they may not die, just not
  sprout)

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An Introduction To Experimental Design

• The Manipulated Variable in an experiment
  represents the factor that you vary while keeping
  everything else constant.

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An Introduction To Experimental Design

• The Responding Variable (Dependent Variable) in
  an experiment represents what we measure (what we
  expect to vary depending on the manipulated
  variable).

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Radicle Length
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An Introduction To Experimental Design

• The control is the untreated group, used for
  comparison with the treatment groups.

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An Introduction To Experimental Design

• Replicates (trials) are groups of organisms
  exposed to identical conditions.
• The more replicates the better.

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Safety

• Always wear your gloves and glasses
• No eating or drinking
• No horseplay!