Discontinuous variation is when a trait is seen in a population in two or more different forms and there is no continuation along a gradient. A good example that Mendel studied is flower color. The flowers were either white or purple. There was no in between color. This is caused by an allele for purple or a lack of an allele for purple, which produces no pigment, or white.
By moving substances across membranes, transport proteins make everything from nerve impulses to cellular metabolism possible. Without transport proteins, for example, the sodium-potassium gradient that allows our nerves to fire would not exist.
Fred must have suffered muscle atrophy.
Explanation:
Since Fred broke his leg and a cast was put around his leg,his orthopedic must have suggested restricted movement of his leg as a part of treatment.. Due to this immobilization the muscle mass of his leg may have got wasted and his leg became weak. Being too weak the leg may not have supported the body weight and Fred fell.