Think about the three major types of soil: sand, silt, and clay. The diagram shows a comparison of these three particles, as well as a piece of gravel to show size differences. Which of these soils is best for supporting plant life and why?

A) Silt is best for most plants because roots are able to access air and water easily.
B) The large particle size of sand allows it to hold more water, making it best for plants.
C) Clay has the smallest particle size, allowing roots to grow further down than other soils.
D) Due to its small particle size, clay is sticky, and holds plants more securely than other soils.

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).