One muscle can produce a variation of smooth forces called . And they're generally affected by both the and with which they're stimulated

One muscle can produce a variation of smooth forces, called graded muscle responses. And they’re generally affected by both the frequency and strength with which they’re stimulated

Explanation: Muscle fibers are a collection thousands of fibers responding to a single action from a neuron to form a motor unit which can  either be large motor units controlling activities like walking and small motor units controlling activities like blinking the eye. These muscle movements are smooth and produce smooth forces called  The graded muscle responses which depends on the magnitude of forces  in  releasing and contracting of muscles when carrying out an activity. The force exerted by the  graded muscles responses depends on the energy exerted ---strength and number of times, such muscle is used ---frequency.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme