During the contraction of a vertebrate skeletal muscle fiber, calcium ions
a. break cross-bridges by acting as a cofactor in the hydrolysis of ATP.
b. spread action potentials through the T tubules.
c. re-establish the polarization of the plasma membrane following an action potential.
d. transmit action potentials from the motor neuron to the muscle fiber.
e. bind with troponin, changing its shape so that the myosin-binding sites on actin are exposed.

Suppose that on a small island off the coast of scotland, 32 percent of the population has blue eyes, which means that these individuals must be homozygous for the blue eye color gene (bb). the only other eye color found on the island is brown, and individuals that are homozygous for the brown eye color gene (bb) or heterozygous (bb) will have brown eyes because brown is the dominant gene. assume this population is in hardy-weinberg equilibrium. if 100 babies are born next year, how many of these would you expect to have brown eyes and be heterozygous? a. 58 b. 49 c. 29 d. 43