Cellular Respiration

AP Biology· difficulty 2/5

Germinating pea seeds were placed in respirometers held in water baths at 5, 15, 25, and 35 degrees C. Volume of O2 consumed per gram of seed per minute was recorded after a 5-minute equilibration.

Temperature (deg C) O2 used (mL/g/min) 5 15 25 35

Which biological reasoning best explains the trend?

  • A

    Seeds at higher temperature reproduce faster, increasing biomass.

  • B

    Higher temperature increases molecular kinetic energy and enzyme-substrate collisions, raising respiration rate.

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  • C

    Oxygen solubility increases at higher temperature.

  • D

    Cold temperatures denature respiration enzymes.

Explanation

Within tolerance limits, raising temperature accelerates enzyme-catalyzed reactions because molecules collide more frequently and forcefully.

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