AP BIOLOGY

Detailed explanation-1: -Legumes are able to form a symbiotic relationship with nitrogen-fixing soil bacteria called rhizobia. The result of this symbiosis is to form nodules on the plant root, within which the bacteria can convert atmospheric nitrogen into ammonia that can be used by the plant.

Detailed explanation-2: -The rhizobia are soil microorganisms that can interact with leguminous plants to form root nodules within which conditions are favourable for bacterial nitrogen fixation. Legumes allow the development of very large rhizobial populations in the vicinity of their roots.

Detailed explanation-3: -The symbiosis between rhizobia soil bacteria and legumes is facultative and initiated by nitrogen starvation of the host plant. Exchange of signal molecules between the partners leads to the formation of root nodules where bacteria are converted to nitrogen-fixing bacteroids.

Detailed explanation-4: -Rhizobia are nitrogen-fixing bacteria which invade root hairs of leguminous plants and induce, in a specific manner, the formation of root nodules in which they fix nitrogen. The early steps of the symbiosis can be considered as a reciprocal molecular communication between the two partners.

Detailed explanation-5: -Answer: Rhizobium is a bacteria which live in the nodules of roots and fix nitrogen for the plants. Such a type of relationship between two organisms where both of them benefit from each other is called a symbiotic relationship.