|
Experiment 7.5A: Gaseous exchange (氣體交換) of
Objective:
To study the gaseous exchange of mealworms in
bright and dark
conditions.
Results:
|
Set-up
|
Distance between the stopper and
the red ink marker (cm)
|
|
|
Just after setting up
|
After 5 minutes
|
|
|
A
|
|
Shorter
|
|
B
|
|
No change
|
Discussion:
(a) Explain the results in set-up A.
The mealworms
take in oxygen
from the air in the boiling tube and releases carbon dioxide.
Soda lime absorbs (吸收) carbon dioxide
from the air in the boiling tube.
The total amount of the gas inside the boiling tube
decreases (increases
/ decreases).
As a result, the red ink marker moves towards (towards / away from) the boiling tube.
(b) What is the use of set-up B?
There is no mealworm in
set-up B. If there is any change in
the position of its red ink marker,
it means there are changes in other factors, e.g. temperature and air
pressure. These factors
will also (not / also) affect set-up A.
By comparing the results in set-ups A
and B, we can know the actual effect
(真正影響) brought
about by the
mealworms
in set-up A.
Set-up B is known as the control experiment for set-up A.
What condition does set-up C simulate
(模擬), compared with set-up A?
Set-up C simulates
the condition at night
(in the
daytime / at night) while
set-up A simulates
the condition in the daytime.
Design a control experiment (對照實驗) for set-up C. Draw a labelled diagram
to show it and call it set-up D
below.
|
Similar with set-up
C but no mealworms in the boiling tube
|
The following table shows the results of set-up A and B.
|
Set-up
|
Distance between the stopper and
the red ink marker (cm)
|
|
|
Just after setting up
|
After 5 minutes
|
|
|
A
|
9
|
2
|
|
C
|
8
|
1
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(a) Explain the results in set-up C.
The mealworms
takes in oxygen
from the air in the boiling tube and releases
carbon dioxide which is absorbed by soda lime.
The total amount of the gas inside the boiling tube
decreases.
As a result, the red ink marker moves towards the
boiling tube.
(b) What is the use of set-up D?
There is no mealworm in
set-up D. If there is any change in
the position of its red ink marker, it means there are changes in other factors,
e.g. temperature and air pressure. These factors
will also affect set-up C.
By comparing the results in set-ups C
and D, we can know the actual effect brought about by the
mealworms
in set-up C.
Set-up D is known as the control
experiment
for set-up C.
Conclusion:
Ø
The mealworm takes in oxygen and releases carbon dioxide
in both bright and dark conditions.
Ø
The gaseous exchange of the mealworm is similar / the
same in both bright and dark
conditions.
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