Question

Which statement(s) is/are false? (Simms] legumes and rhizobia participate in a mutually beneficial symbiosis native and introduced legumes use different rhizobia none are false rhizobia never live outside their host legume legumes change the community of soil rhizobia

Answer 1

d) Rhizobia is free to reside in the soil before they can detect flavonoids, derivatives of 2-phenyl-1.4-benzopyrone, which are secreted by the roots of their host plant, causing the aggregation of a wide population of cells and ultimately attachment to root hair.Such flavonoids then facilitate the DNA-binding behavior of NodD which belongs to the transcriptional regula family of LysR.Nod factors cause a sequence of complicated developmental changes within the root hair, beginning with root hair curling and accompanied by infection thread forming, a cellulose-lined path that the bacteria use to migrate down through the root hair into the root cells. This is followed by continuous proliferation of cells resulting in root nodule formation. A second mechanism, particularly used by rhizobia which infects aquatic hosts, is called crack entry. In this case no deformation of the root hair is observed. Instead, the bacteria enter the cells through cracks created by the lateral root formation.