Which of the following best describes the air particles inside an air-filled balloon and the water particles inside a water-filled balloon? a) both have particles that bounce far off and collide. b) both have particles that separate to fill up all the space inside the balloon. c) the particles in air-filled balloon bounce off and collide, and water particles in water-filled balloon easily slide against one another. d) the particles in air-filled balloon take up limited space, and water particles inside water-filled balloon take up the entire space available.

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).