Question

Ticks carry bacteria that cause Lyme disease. Ticks do not get Lyme disease, but they can transfer the bacteria to humans, who can get the disease. Which of the following statements best describes the relationships among the bacteria, the ticks, and the humans?
a. The relationship between the bacteria and the ticks is competition, and the relationship between the ticks and the humans is predation.
b. The relationship between the bacteria and the ticks is competition, and the relationship between the ticks and the humans is parasitism.
c. The relationship between the bacteria and the ticks is commensalism, and the relationship between the ticks and the humans is parasitism.
d. The relationship between the bacteria and the ticks is commensalism, and the relationship between the ticks and the humans is predation.

Answer 1

The answer is c. The relationship between the bacteria and the ticks is commensalism, and the relationship between the ticks and the humans is parasitism.

Commensalism is a relationship between two organisms in which only one of them has benefit, and the other one is not affected. Bacteria are carried by ticks, so bacteria have a benefit from the relationship. Tick is not affected by bacteria, it does not get Lyme disease. Therefore, the relationship between ticks and bacteria is commensalism.

The relationship between ticks and humans is parasitism. Parasitism is non-mutual relationship between two organisms in which one of them (tick) benefits at the expense of the host organism (human).