Respirometers

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  • Created by: Lotto65
  • Created on: 20-03-17 18:35
What is a respirometer?
A device that allows you to measure respiration rates
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What three main parts are involved in a respirometer set up?
A glass/plastic sealed container; An alkali; A capillary tube
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What is put into the sealed glass/ plastic container?
The organism or tissue
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Which alkali is normally used?
Sodium hydroxide
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What is the purpose of the alkali?
To absorb carbon dioxide
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What does the capillary tube contain?
Fluid
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What is the purpose of the capillary tube?
Connects to the container to allow the volume of air inside the respirometer to monitored
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What would you expect to happen to the volume of air in the respirometer? Why?
It would decrease because carbon dioxide is being absorbed by the alkali and oxygen is being taken in by the organism or tissue for cell respiration
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What is the purpose of a water bath?
Allows a constant temperature to avoid volume changes due to temperature fluctuations
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What size graduated syringe is used?
1cm3
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Give examples of organisms/ tissues used in the respirometer
Invertebrates like fly larvae or seeds
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What do you do with filter paper?
Roll it up to form a wick
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If animals will be in pain or harm during an experiment, should it be performed in an IB school?
No
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If animals will be under unacceptable risks e.g. in contact with the alkali, should the experiment still go ahead
No
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Give other ethical questions that should be asked when using animals in an experiment
Is it necessary to use animals or can you use something else e.g. germinating seeds? If animals were removed form their habitat, can the animals be returned to their natural habitat safely and continue to live a natural life?
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There are strict restrictions with using ... in research
Vertebrates
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If you have repeats in your results, what should you calculate?
The mean value
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When drawing a graph, what goes along the x axis and what goes along the y axis?
X axis = Independent variable y axis = dependent variable
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What is the independent variable with this experiment?
E.g. temperature
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What is the dependent variable with this experiment?
E.g. distance moved by the fluid in the capillary tube per minute
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What do range bars show?
The lowest and highest individual results for that reading
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What other type of bar can show the range of repeat results?
Error bars
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How can you statistically show an error bar?
Standard deviation or standard error values
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What does an error bar show?
The standard deviation above and below the line
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What is another name for the capillary tube set up?
Manometer
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Which direction would you expect the manometer fluid to move in?
Towards the organisms because oxygen is used up and the volume of air is decreasing
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If the rate of movement of fluid in the manometer is even, the results are...
Reliable
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How could you extend this investigation?
Use different organisms to compare; Change the temperature to see the effect; Compare the rates for active and inactive organisms
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Other cards in this set

Card 2

Front

What three main parts are involved in a respirometer set up?

Back

A glass/plastic sealed container; An alkali; A capillary tube

Card 3

Front

What is put into the sealed glass/ plastic container?

Back

Preview of the front of card 3

Card 4

Front

Which alkali is normally used?

Back

Preview of the front of card 4

Card 5

Front

What is the purpose of the alkali?

Back

Preview of the front of card 5
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