Which is not a protein found in thin filaments? a. Tropomyosin b. Actin c. Troponin d. Myosin e. No exceptions; all are found in thin filaments.

In what type of muscle would the structure illustrated in the image at right be found? A. The flight muscle of a bumblebee B. The longitudinal muscles underlying the cuticle in C. elegans C. The longitudinal muscles of the vertebrate intestine D. The cardiac muscle of mammals E. None of the above actin filament Dense body Relaxed myosin filament Contracted

Which statement about striated skeletal muscle is true?   A. The tension generated by a muscle is invariable.   B. Mechanical summation of twitches in a muscle fiber leads to a graded increase in the tension that is above that generated by a single twitch.   C. A single action potential arriving at the neuromuscular junction is not sufficient to cause a muscle fiber to twitch.   D. Muscle twitches are able to mechanically sum when Ca2+ is quickly and completely removed from the sarcoplasm between action potentials.   E. An action potential in the muscle cell activates contraction by releasing Na+ into the sarcoplasm.

Which of the following statements is true of the chameleon tongue but not of the human tongue? A. It is a muscular hydrostat. B. Force generation reflects the binding of myosin crossbridges to actin thin filaments. C. The organization of the actin and myosin filaments produces a regular pattern of bands, or striations. D. Gaps or holes in the Z-discs allow supercontraction (shortening beyond the normal limit). E. All of the above statements are true of both the chameleon tongue and the human tongue.