BI-1382
Effect of temperature and pH on enzymes
Biology · Secondary 4 · Hard · Effect of temperature and pH on enzymes
In an experiment, a student investigates how temperature affects the rate of aerobic respiration in plant compost. She measures the temperature inside a compost heap and finds that it rises from 25 °C to 55 °C as bacteria respire. Which statement best explains why the temperature increase affects the bacteria’s respiration rate?
- Higher temperature permanently changes the shape of all bacterial enzymes so respiration stops.
- Higher temperature increases the kinetic energy of molecules, causing more frequent enzyme–substrate collisions.
- Higher temperature decreases the kinetic energy of molecules, so fewer enzyme–substrate complexes form.
- Higher temperature increases the size of the active site so substrates can no longer fit.
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