Water temperature
/°C

Amount of dissolved oxygen (in cm³)
/dm³  of water

Number of gill beats per minute

5

9,15

20

10

8,02

28

15

7,22

33

20

6,57

36

25

6,06

41

30

5,57

44

Questions

1. What happens to the amount of oxygen dissolved in the water as the temperature rises?

2. What happens to the number of gill beats of the fish as the amount of oxygen decreases?

3. Why does the fish beat its gills?

4. Calculate how much oxygen is dissolved in 100dm³ of water at 20°C. (Use the figures in the table above).

5. In 100dm³ of air there are about 21dm³ of oxygen at 20°C.
Now compare the amount of oxygen in air with the amount of oxygen in water. How much more oxygen is there in air than in water? Give your answer as a percentage.