Final answer:
Bacteria perform 'run' for several seconds moving in a straight line, and 'tumble' briefly to change direction. During chemotaxis, runs are extended, and tumbles are reduced to move toward an attractant.
Step-by-step explanation:
The question asks about the duration of bacterial movement behaviors known as tumbling and running. In bacteria with peritrichous flagella, a run occurs when the flagella bundle as they rotate in a counterclockwise direction, propelling the bacterium forward in a more or less straight line. A tumble, on the other hand, occurs when the flagella rotate in a clockwise direction, become splayed out, and cause the bacterium to loop or change direction without meaningful forward movement. This behavior is instrumental for bacteria to move in response to environmental signals, a process known as chemotaxis. The correct answer to the question is c) Run: Several seconds; Tumble: Brief, based on the information that when an attractant is present, bacteria tend to extend the length of runs and decrease the length of tumbles to move more purposefully toward higher attractant concentrations.