Bacteriology: Test Your Understanding
Teacher's Guide
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Why are bacteria ecologically important?
Sample answer: Bacteria are important in the recycling of materials essential to plants and animals.
Bacteria also help plants by breaking down complex substances to carbon dioxide, which plants need
to grow. Further, bacteria convert certain nitrogenous substances into forms that plants can use.
How do bacterial cells differ from plant and animal cells?
Bacterial cells are simpler than plant and animal cells. Bacteria have no discrete, membrane-bound
nucleus and no membrane-bound organelles. Bacteria also possess small pieces of DNA called
plasmids, which plant and animal cells do not have.
What was the significance of the discoveries by Robert Koch and Louis Pasteur in the late 1800s?
Koch's discovery that bacteria can cause disease, along with Pasteur's discovery that bacteria can
create immunity to disease, led to a golden era of study of the cause and control of bacterial disease
among humans, and of immunization as a means to combat disease.
What are some common products that rely on bacteria?
Some common products that rely on bacteria include cheese, sauerkraut, pickles, sausage,
and antibiotics.
Critical Thinking: What does "physiological diversity" mean in the context of bacteria? Provide examples in
your answer.
Sample answer: Physiological diversity means that different species of bacteria survive, grow, and
obtain energy in a variety of ways. For example, some bacteria photosynthesize in the presence of
oxygen, whereas others survive in oxygen-free environments and use fermentation to obtain energy.
