AP BIOLOGY

Detailed explanation-1: -During glycolysis, a glucose molecule with six carbon atoms is converted into two molecules of pyruvate, each of which contains three carbon atoms. For each molecule of glucose, two molecules of ATP are hydrolyzed to provide energy to drive the early steps, but four molecules of ATP are produced in the later steps.

Detailed explanation-2: -Glucose cannot cross cell membranes without using transport proteins and insulin is required to facilitate the removal of glucose from the blood stream so that it enters cells. When glucose is in excess, the body stores it away in the form of glycogen in a process stimulated by insulin.

Detailed explanation-3: -Plants form glucose by photosynthesis and animals get glucose by breaking down the food they eat. During cellular respiration, glucose combines with oxygen to release energy and to form carbon dioxide and water. Most of the carbon dioxide in animals is released into the air when the animal breathes.

Detailed explanation-4: -Atomic-molecular scale: The brain, nerve cells, and muscle cells all need energy to do their work. All the other living cells in an animal need energy, too. The cells all rely on the same process to get their energy: cellular respiration, a process that releases energy by combining glucose and oxygen.