Escherichia coli bacteria can use the enzyme lactase to digest lactose and use it as an energy source. However, it is more efficient for bacteria to use glucose as an energy source if it is present. Which of the methods of regulating enzyme activity would be most energy efficient for a bacterium that has plenty of glucose?

A. The bacterium should produce an irreversible, allosteric inhibitor of lactase.
B. The bacterium should produce a reversible, competitive inhibitor of lactase.
C. The bacterium should produce a reversible, allosteric inhibitor of lactase.
D. The bacterium should produce an irreversible, competitive inhibitor of lactase.
E. The bacterium should stop production of lactase.
F. The bacterium should use feedback inhibition to stop the metabolic pathway that lactase starts.

E. The bacterium should stop production of lactase.

Explanation:

E. coli bacteria can degrade lactose, but lactose is not preferred as source of fuel or energy to glucose. If glucose is present, E. coli would preferably employ it over lactose as Glucose needs little process and minimal energy to degrade when compared to lactose. Although, if lactose is the major sugar that is present, the E. coli will have no option than to employ it as it's source of fuel or energy.

The formation of lactase enzyme utilizes energy, which cannot be utilised in the presence of high level glucose.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.