Answer:
The answer is GLUCOSE.
Explanation:
Glucose is the main sugar used by cells for energy. Glucose is derived from the digestion of carbohydrates. In humans, glucose is usually absorbed into the blood from the small intestine, the blood then carry the blood around the body, allowing each cell to have access to the glucose it needs.
If the quantity of glucose in the blood is more than needed per time, the body usually store the excess glucose as glycogen, the glycogen will be turned to glucose and release for cell use when the quantity of sugar in the blood is low. In the absence of glycogen, other macro nutrients such as lipids and proteins can also be converted to glucose via gluconeogenesis when the concentration of glucose in the blood is low.
The cells oxidize the glucose and convert it to energy in form of ATP, which they use to carry out their life activities.
A single molecule is the one that is responsible for initiating a signal transduction pathway. The answer in this question is a single molecule. Molecule is defined as an electrically neutral group of two atoms or more held together by a chemical bonds.
The simplest organisms are cells.
A cell is: The smallest structural and functional unit of an organism.
