The reference point = a object used for comparison to determine if something is in motion.
An object is in motion if it changes position relative to a reference point.
You assume that the reference point is stationary, or not moving.
Glucose gets into the cells through a process called facilitated diffusion. This is a transport mechanism in which carrier proteins shuttle molecules across the cell membrane without using the cell's energy supplies and so it is called passive transport. The carrier proteins bind to glucose, which causes them to change shape and translocate the glucose from outside of the cell membrane and into the cell.
(a) glucose is important because it is the primary source of energy for the cell.
(b) Glucose is 6 - carbon monomer of starch. It is a sugar.
(c) Glucose is broken down to pyruvate through the process of glycolysis.