Answer: Specie
Explanation:
The basic unit of classification of living things is species. species is the smallest unit containing members which have the largest number of features in common and usually interbreed among themselves.
Thus, the group of deer describes a specie since they can interbreed freely and are similar in characteristic features.
For most organism (animals and humans) glucogen is stored in the liver. Glycogen in basically a bundle of glucose. This is like storing energy as the glucogen can be changed back into glucose by a hormone by Glucagon. It breaks down the insoluble glycogen into glucose that can be used in respiration which creates energy.
Respiraton
Glucose+ Oxygen = Water + Carbon Dioxide + ENERGY
The heart is an example of an organ.