Activity Book

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Activity Book
ANSWER
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Practical 8.1 Investigation of carbon dioxide
production in a living mouse Practical
8.2 Investigation of carbon dioxide production in
living germinating seeds Practical
8.3 Investigation of heat production in a living
mouse Practical 8.4 Design an investigation of
heat production in living germinating seeds
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Practical 8.5 Demonstration of anaerobic
respiration in germinating seeds Practical
8.6 Design an investigation of alcoholic
fermentation in yeast STS connection 8.2 Degree
of dependence on anaerobic respiration of
different sports Exercise 8
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8.1
Investigation of carbon dioxide production in a
living mouse
Questions
1 Why is potassium hydroxide solution used in
flask A?
ANS ?
To absorb carbon dioxide from the incoming air.
One can deduce ?? that any carbon dioxide
detected in flask C is due to the mouse.
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8.1
Investigation of carbon dioxide production in a
living mouse
2 What are the functions of the red
hydrogencarbonate indicator in flasks B and C?
Flask B To test whether there is any carbon
dioxide in the air entering the bell jar. Flask
C To test whether there is any carbon dioxide in
the air leaving the bell jar.
ANS ?
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8.1
Investigation of carbon dioxide production in a
living mouse
3 What can you tell from the result of flask B?
Carbon dioxide is absent in the air entering the
bell jar.
ANS ?
4 What can you tell from the result of flask C?
ANS ?
Carbon dioxide is released ( given out) by the
mouse.
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8.1
Investigation of carbon dioxide production in a
living mouse
5 How would you set up a control for this
practical? ????????
Set up a similar apparatus (i.e. that is the same
in all ways except one aspect / factor) without
putting a mouse in the bell jar.
ANS ?
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???? Control experiment (We must learn how to
design it when a real context ???? is given.)
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8.1
Investigation of carbon dioxide production in a
living mouse
6 What precautions should be taken if the mouse
is replaced by a potted plant? Explain.
Wrap the pot with a plastic bag. Otherwise,
carbon dioxide released by the micro-organisms in
the soil will affect the results. (To be
continued.)
ANS ?
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8.1
Investigation of carbon dioxide production in a
living mouse
continued from previous page
Cover the bell jar with a black cloth. Otherwise,
the plant will absorb carbon dioxide for
photosynthesis and this will affect the results
of the respiration experiment.
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8.1
Investigation of carbon dioxide production in a
living mouse
Conclusion
What conclusion can you draw from this practical?
The living mouse gives out carbon dioxide. ??
?????????
ANS ?
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8.2
Investigation of carbon dioxide production in
living germinating seeds
Questions
1 What is the function of the moist cotton wool?
ANS ?
To provide the necessary amount of water for
germination (????)
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8.2
Investigation of carbon dioxide production in
living germinating seeds
2 Why should the surface of the seeds be
sterilized?
To kill the micro-organisms on the surface of the
seeds. Otherwise, carbon dioxide released by them
during respiration will affect the results.
ANS ?
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8.2
Investigation of carbon dioxide production in
living germinating seeds
3 What is the reason for having a tube with
boiled seeds?
As a control (or control experiment) to show
that only living seeds release carbon dioxide.
ANS ?
?????? control
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8.2
Investigation of carbon dioxide production in
living germinating seeds
Conclusion
What conclusion can you draw from this practical?
The living seeds give out carbon dioxide.
ANS ?
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8.3
Investigation of heat production in a living mouse
Questions
1 What is the function of the cotton wool?
To prevent heat loss from the chambers. ? to
trap heat inside the chambers.
ANS ?
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8.3
Investigation of heat production in a living mouse
2 Why are the two clips opened at the start of
the practical?
To equalize the air pressure on both sides of the
U-shaped capillary tube. This ensures that both
liquid levels are the SAME ( atmospheric
pressure) at the start of the practical.
ANS ?
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8.3
Investigation of heat production in a living mouse
3 Explain the results.
? Heat is produced by the mouse and it warms up
the air in the thin-walled test tube. ? The air
in the test tube expands and results in an
increase in air pressure. ? This pushes the air
out of the test tube and hence forces the liquid
level in arm B downwards. (To be continued.)
ANS ?
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8.3
Investigation of heat production in a living mouse
continued from previous page
Since there is no temperature change in the
control (the side without the mouse), the falling
of the liquid level in arm B leads to a rise of
the liquid level in arm A. ????
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8.3
Investigation of heat production in a living mouse
4 Can the practical be carried out for a long
time? Why?
No. It is because the mouse will use up all the
oxygen inside the chamber and die.
ANS ?
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8.3
Investigation of heat production in a living mouse
5 Which capillary tube, one with a wide bore
(???) or a narrow bore, is more suitable for this
practical? Why?
A capillary tube with a narrow bore is more
suitable for this practical because small change
can be obviously recorded.
ANS ?
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8.3
Investigation of heat production in a living mouse
6 How will the results differ if the mouse is
replaced by a frog of the same size?
The change in liquid level is smaller. The frog,
being a poikilotherm, has a lower metabolic rate
and less heat is released from its body.
ANS ?
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8.3
Investigation of heat production in a living mouse
Conclusion
What conclusion can you draw from this practical?
Heat is produced by the living mouse.
ANS ?
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