Biology (Mader), 10th Edition

Chapter 6: Metabolism: Energy and Enzymes

Food Pathogens and Temperature

Why does temperature affect biological processes? Most biological processes, including bacterial reproduction occur more rapidly at higher temperatures than at lower temperatures. Temperatures that exceed some maximum temperature result in reduced performance of the process and often complete failure. Bacterial reproduction and other biological events are series of chemical reactions known as biochemical pathways. The rate of reaction generally increases with temperature. The warmer the environment the faster the reaction proceeds. However, biochemical pathways involve proteins; large complex molecules that often denature at high temperatures. Therefore biochemical pathways generally run faster as the temperature warms until a point is reached at which one or more proteins begin to break down.

View the animation below, then complete the quiz to test your knowledge of the concept.



1.

The main environmental factors that affect microorganism growth include chemical inhibitors, oxygen, pH, nutrients, moisture and
A)food texture.
B)time.
C)temperature.
D)cleaning agents.
2.

With ideal environmental factors, the reproduction rate of bacteria is
A)extremely slow.
B)somewhat slow.
C)somewhat rapid.
D)extremely rapid.
3.

What is the most important environmental factor influencing bacterial growth?
A)food texture
B)time
C)temperature
D)cleaning agents
4.

Above 100° C (212°F) most bacteria
A)are destroyed.
B)stop growing, but are not dead.
C)are not affected by the heat.
D)grow rapidly.
5.

At freezing temperatures, most bacteria
A)are destroyed.
B)stop growing, but are not dead.
C)are not affected by the cold.
D)grow rapidly.
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