Final answer:
Large motor units consist of a single motor neuron supplying a large number of muscle fibers, allowing for powerful movements.
Step-by-step explanation:
A large motor unit is an arrangement where a single motor neuron supplies a large number of muscle fibers in a muscle. Large motor units are concerned with simple, or 'gross,' movements, such as powerfully extending the knee joint. The best example is the large motor units of the thigh muscles or back muscles, where a single motor neuron will supply thousands of muscle fibers in a muscle, as its axon splits into thousands of branches.