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07:27
03:26Streptococcus mutans obtains energy by oxidizing sucrose. This bacterium is abundant in the mouths of Western European and North American children and is a prominent cause of cavities. The organism is virtually absent in children from East Africa, where tooth decay is rare. Propose a hypothesis to explain this observation. Outline the design of a study that would test your hypothesis.
Suppose that you've been hired by a firm interested in using bacteria to clean up organic solvents found in toxic waste dumps. Your new employer is particularly interested in finding cells that are capable of breaking a molecule called benzene into less-toxic compounds. Where would you go to look for bacteria that can metabolize benzene as an energy or carbon source? How would you design an enrichment culture capable of isolating benzene-metabolizing species?
Evaluate these statements about Koch's postulates, which are used to establish a causative link between a specific microbe and a specific disease. Select True or False for each statement.
T/FThe microbe must be present in individuals suffering from the disease and absent from healthy individuals.
T/FThe microbe must be isolated and grown in pure culture.
T/FIf organisms from the pure culture are injected into a healthy experimental animal, the disease symptoms should appear.
T/FThe microbe does not have to be isolated from the experimental animal as long as the disease is present.
Biologists often use the term 'energy source' as a synonym for 'electron donor.' Why?
What has metagenomic analysis allowed researchers to do for the first time? a. sample organisms from an environment and grow them under defined conditions in the lab b. isolate organisms from an environment and sequence their entire genome c. study organisms that cannot be cultured (grown in the lab) d. identify important morphological differences among species
