1 markA student investigated respiration in yeast. They set up the experiment as shown in the diagram below.
Every 30 minutes they replaced the water with the same volume but it was 10 oC warmer and counted the bubbles given off in 2 minutes.Â
What are the independent and dependent variables in this experiment?
| Â | independent | dependent |
| A | number of bubbles | time |
| B | time | number of bubbles |
| C | water temperature | number of bubbles |
| D | water temperature | volume of water |
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1 markWhich of the following do humans require energy for?
1 & 3
2, 3 & 4
4 only
All of the above
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1 markThe graph below shows the results of an investigation into how the rate of respiration of an organism is affected by changing the temperature.
Which of the following statements would explain the difference between the rate of respiration at 10 °C and that at 30 °C?
Enzyme activity is higher at 30 °C because more frequent collisions are occurring than at 10 °C.
Enzyme activity at 30 °C is lower because the bonds holding an enzyme together are altered at higher temperatures.
Enzyme activity is at its optimum at 30 °C, meaning the rate is at its highest.
Enzyme activity is lower at 10 °C because the enzymes are denatured and therefore unable to bind to their substrates.
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