Choose the correct order of steps for the synthesis of vitamin d.

a. inactive vitamin d is transported to the liver where it is modified.
b. inactive, chemically altered vitamin d is transported to the kidneys.
c. uv light strikes the skin and converts a steroid molecule into an inactive form of vitamin d.
d. vitamin d is activated under the influence of pth.

a. d, a, c, b
b. a, c,b, d
c. a, b, c, d
d. c, a, b, d
e. c, b, a, d

Choose the incorrect statement (a) the motor end plate membrane is only capable of generating graded potentials, but it is contiguous with the skeletal muscle sarcolemma, which can generate action potentials. (b) propagation of an action potential through the t-tubules into the sarcoplasmic reticulum triggers the release of ca++ into the cytoplasm of a skeletal muscle fiber. (c) the generation of suprathreshold endplate potentials in multiple muscle fibers could be due to the increased frequency of action potential generation at the axon hillock of a single motor neuron. (d) a greater amount of ach would be found in the presynaptic vesicles of a motor unit that fired several action potentials after exposure to botulinum toxin, than in a motor unit that fired several action potentials after exposure to the venom of the krait snake (which contains α-bungarotoxin).