A large percentage of bacteria are harmful to humans and cause disease.

a. True

b. False

The correct answer is b. False

Explanation:

More than 90% of bacteria present in the world is not harmful to human beings. Human body contains trillions of bacteria in their intestine which play important role digestion of food absorption of nutrients inside the small intestine.

Human gut contains 10 times more bacteria than the cells present in human body. This proves that bacteria lives in symbiotic association with humans and human body cannot survive without them.

Thus a large percentage of bacteria are not harmful to humans rather they are important part of human body and these bacteria are called human microbiota.