MICROBES IN HUMAN HEALTH:
There are 10 times more microbes than human cells in the human body. Scientists have long known that the human body hosts a staggering number of microorganisms. Recent discoveries, however, are shedding light on how pivotal these bacteria are in the development of the human immune system. The body supports a wide array of microorganisms specially adapted to survive in particular regions. Remarkably, there is such variation in these microorganisms that few people share the same strains in the same quantities.
The colonization of microbes begins at birth. A newborn infant, emerging from the germ-free environment of the womb, is immediately exposed to germs from its mother's birth canal. These bacteria swiftly begin to breed and colonize the infant's body, which becomes their new host. The most fascinating discovery is not just that the immune system tolerates these millions of harmless organisms, but that it may actually rely on their presence to function properly.
For example, laboratory mice unable to produce a specific inflammation-reducing molecule were injected with a particular strain of bacteria. After the bacteria colonized, the mice's immune systems developed the ability to synthesize the molecule. Essentially, the mice needed the bacteria for their immune systems to function correctly.
This concept is also being applied to humans through a relatively experimental procedure known as fecal bacteriotherapy. This treatment reintroduces healthy bacteria into a colon that has lost its ability to defend against pathogens. While scientists are only beginning to understand the critical role these microorganisms play in human health, early research has yielded remarkable discoveries.
Choose the best summary of the passage about microbes.
Correct Answer: C
Rationale: The correct answer is C. The passage emphasizes the importance of certain bacteria for a properly functioning immune system. It discusses how harmless bacteria play a crucial role in defending the body against pathogens. Choice A is incorrect as it focuses on the immune system's response to certain types of bacteria in lower organisms, not the overall importance of bacteria for immunity. Choice B is incorrect as it mainly discusses bacteriotherapy in relation to the reconstruction of a damaged colon, rather than the broader role of bacteria in immune system health. Choice D is incorrect as it only talks about the process of replacing harmful bacteria with harmless ones, missing the key point about the necessity of certain bacteria for immune system function.
Nokea