Question

Choose the TRUE statement for how a heavier weight can be lifted.

A. more calcium enters the cell from the motor nerve
B. the sarcoplasmic calcium ATPase is more strongly activated
C. more motor neurons are activated
D. larger action potentials occur in each muscle cell

Answer 1

The true statement for lifting heavier weight is that more motor neurons are activated to involve more muscle fibers in the effort, which generates greater force. Increased frequency of action potentials can also slightly enhance this force.

Step-by-step explanation:

The true statement for how a heavier weight can be lifted is that more motor neurons are activated. When lifting a heavier object, like picking up a piano instead of a pencil, the motor cortex of the brain signals all of the neurons in the muscles involved, such as the biceps, so every muscle fiber (myofiber) participates in the effort. This acts to generate nearly the maximum force the muscle can produce. Additionally, increasing the frequency of action potentials (the number of signals per second) can slightly increase the force, as this results in the muscle's regulatory proteins being saturated with calcium ions (Ca++), allowing for continuous contraction as long as ATP is present.