Final answer:
Mutualism is a symbiotic relationship that benefits all involved species. Examples include the interaction between legumes and nitrogen-fixing bacteria, and gut bacteria like Bacteroides assisting in the human digestive process.
Step-by-step explanation:
Mutualism is a type of symbiotic relationship where two species interact and both benefit from the relationship. An example of mutualism that involves bacteria is the relationship between legumes, such as pea plants, and nitrogen-fixing bacteria.
These bacteria live in the roots of the legume plants and convert nitrogen-containing molecules into a form of nitrogen that the plant can use. Meanwhile, the plant provides essential nutrients to the bacteria, sustaining their survival.
This interaction enhances the growth of the plant by increasing the availability of essential nutrients while also supporting the bacterial population, exemplifying a mutualistic relationship.
Another classic example involves gut bacteria and humans. Bacteria such as Bacteroides thetaiotaomicron and certain strains of Escherichia coli live in the human intestinal tract, where they play a key role in digesting complex polysaccharides, producing vitamin K, and protecting against pathogens. Both humans and bacteria gain advantages, cementing this as a mutualistic relationship.