Final answer:
The subject of this question is biology, and the characteristics described in the question point towards bacteria, specifically their flagella.
Step-by-step explanation:
The subject of this question is biology. The characteristics mentioned in the question, such as a sharp edge, smooth cut, and ability to glide through hair easily, are indicative of bacteria. Bacteria have structures called flagella that allow them to move smoothly and quietly through their surroundings. These flagella are made up of proteins and provide bacteria with the ability to move and interact with their environment.