Experiment WS 6: 7.5A

Kowloon Tong School (Secondary Section)

F.2 Integrated Science

Experiment Worksheets 6

Name: _________________ (    )                                                               Date: __________________

Class: 2 _______

Experiment 7.5A: Gaseous exchange氣體交換 of mealworms麥皮蟲 grasshopper草蜢 (P.48-50)

Objective:       To study the gaseous exchange of mealworms in bright and dark conditions.

1.      Study the design of set-up C as shown below. 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 day time (in the daytime / at night). 2.      Set up 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. (Drawing should be the same as set-up C except that the mealworm is absent) 3.      Prepare set-ups C and D. Repeat step 2 with them.

Discussion:

(a)    Explain the results in set-up A.

The mealworms grasshopper takes in oxygen from the air in the boiling tube and releases carbon dioxide.

Soda lime absorbs 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 grasshopper 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.

(c)    Explain the results in set-up C.

The mealworms grasshopper takes in oxygen from the air in the boiling tube and releases carbon dioxide.

Soda lime absorbs carbon dioxide.

The total amount of the gas inside the boiling tube decreases.

As a result, the red ink marker moves towards the boiling tube.

(d)   What is the use of set-up D?

There is no mealworm grasshopper 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 grasshopper takes in oxygen and releases carbon dioxide in both bright and dark conditions.

Ø   The gaseous exchange of the mealworm grasshopper is similar / the same in both bright and dark conditions.