Complex organisms contain different levels of organizations that work together to maintain homeostasis. Which statements correctly describe the roles of stem cells in maintaining a complex organism? Select ALL that apply. A An adult red blood stem cell can easily differentiate to become a nerve cell. B Stem cells are unspecialized cells that can become specialized during differentiation. C Stem cell differentiation is the only process needed to maintain a complex organism. D Stem cells become differentiated based on the different genes inherited by the organism. E Adult stem cells can replenish themselves with identical copies formed during cell division. F Adult stem cells are totipotent cells that can differentiate into any cell type needed for repair.

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).