Final answer:
Rhizobium bacteria engage in a symbiotic relationship with pea plants, fixing nitrogen in exchange for carbohydrates and a protective environment, beneficial for both organisms and the soil.
Step-by-step explanation:
The bacteria that lives symbiotically in pea plants is Rhizobium. Rhizobium bacteria form a mutualistic relationship with legumes like pea plants by fixing nitrogen. These bacteria inhabit root nodules of the plant and convert atmospheric nitrogen into ammonia, which is then used by the plant for growth. In return, the plant supplies the bacteria with carbohydrates and a protected environment. This symbiotic relationship is beneficial for both the bacteria and the plants and also contributes to soil enrichment. Rhizobia is a term that collectively describes soil bacteria capable of entering into a symbiotic relationship with leguminous plants to fix nitrogen, which is then accessible to the plants. This process is not only crucial for the growth of the plants but also enhances soil fertility without the need for chemical fertilizers, making it a sustainable agricultural practice.