Some migratory birds are heterothermic, meaning they sometimes maintain a constant body temperature and other times allow their body temperature to vary. For example, on cold nights, they sometimes reduce their metabolic rate and allow their body temperature to drop as the air temperature falls. Which of the following hypotheses about this unusual strategy is consistent with what you learned in this section? A. Birds allow their temperature to drop in order to increase their assimilation efficiency.
B. Birds allow their temperature drop in order to increase their production efficiency.
C. Birds allow their temperature to drds in order to increase their consumption efficiency.

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).