Lions are a large, cat species that live in the savannahs of Africa. As carnivores, they hunt and feed upon herds of zebra. Zebras are also hunted by groups of cheetah, which are another species of cat. Groups of lions and cheetah will often hunt and drive off each other when zebra populations get too low. The relationship between lions and cheetahs is best defined as which of the following? competition

mutualism

parasitism

predation

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).