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Breathing Underwater : Question 1
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A fish was placed in water at different temperatures.

The amount of oxygen dissolved in the water was measured at each temperature and the number of gill beats was counted by carefully observing the fish.

The results are shown in the table below:

 Water temperature /°C Amount of dissolved oxygen cm3 of oxygen/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 Answers 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). Space for calculation Answer 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. Space for calculation Answer