Which best explains how and why scientific knowledge is continually expanded and improved?
the scientific process flows in one direction and finds only facts that support a scientist's original idea.
the scientific process is cyclical so that new facts inspire questions that lead to new studies.
once explanations are found to be true, they do not need to be questioned; then scientists can stop studying the topic.
once facts are found through experiments and observations, other scientists do not need to repeat the experiments

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).