Bacteria may affect plants in a number of ways. Diseases have been mentioned, but most bacteria co-exist with plants quite easily. Several bacteria are involved with the transitions of nutrients and make nutrients such as nitrogen plant available (the plant is only able to absorb some nutrients in certain molecular forms). While other bacteria convert nutrients and toxins into forms unavailable to the plant.
Other bacteria make Some bacteria, Rhizobia in particular, develop symbiotic relationships with some plants. Rhizobia convert atmospheric nitrogen into ammonium which is plant available. In exchange, the plant provides Rhizobia with shelter (a root nodule) and food (photosynthates).
These are large molecules which are formed from the union of many monosaccharides units through condensation. Excess glucose in the body is stored in form of glycogen and can be hydrolyzed when glucose levels go down. Glucagon stimulates liver cells to break down glycogen into glucose.