Each sieve tube element is normally associated with one or more nucleated companion cells, to which they are connected by plasnodesmata (channels between the cells). Each companion cell is derived from the same mother cell as its associated sieve tube member. Sieve tube members have no cell nucleus, ribosomes, or vacues. Thus, they depend on companion cells to provide proteins, ATP, and signalling molecules
Starch is stored in plants and is present in Amylose and Amylopectin while glycogen is found in animals and is stored in the liver. Glycogen is an extensively branched chain of glucose molecule.
By sodium and potassium pump.
The sodium-potassium pump is observed in various cellular membranes. They are fueled by ATP, the pump moves potassium and sodium ions in reverse orientation, each against its concentration gradient. In a single cycle, two potassium ions are imported into the cell, and three sodium ions are extruded out.
These pumps are utilized to produce gradients of sodium and potassium ions. These gradients are used to proliferate electrical signals, which travel along the nerves.
