7. The sarcolemma is the A. storage site for calcium ions in myofibers B. plasma

Question

7. The sarcolemma is the A. storage site for calcium ions in myofibers B. plasma membrane of a myofiber C. protein that binds oxygen D. separation between sarcomeres in a myofiber E. all of the above 8. The only non striated muscle tissue ismuscle? A. cardiac B. skeletal C. smooth D. fast 9. A sarcomere A. contains actin and myosin proteins B. located within the myofilaments C. is the functional contractile unit of the muscle fiber D. shortens during muscle contraction due to the sliding of actin and myosin proteins E. all of the above are true 10. All these proteins are contained in the thin filament EXECPT? A. troponin B. tropomyosin C. actin D. myosin light chain I1. In relaxed skeletal muscle fibers, myosin is prevented from binding "active sites" by A. tropomyosin. B. troponin C. dystrophin. D. actin. E. myosin. 12. When a cell is at rest, it still has a charge across its membrane. Which of the following statements is FALSE about a neuron at rest? A. the cell is said to be at "resting membrane potential B. the cell has more sodium outside the cell C. the cell has more potassium outside the cell D. the cell has a charge of about-70 mV 13. What is the best definition of an "action potential"? A. opening and closing of sodium and potassium channels B. short-range change in voltage across plasma membrane caused by ligand-gated channels C. a rapid up-and-down shift in the voltage of the plasma membrane caused by voltage-gated sodium and potassium channels D. the -70V charge across the plasma membrane when the cell is at rest

Explanation / Answer

7.Sarcolemma is the plasma membrane of a myofiber. B

8. Smooth muscles do not show any striations on them. they are uninucleate and are spindle shape and elongated.

9.All of the above , A sarcomere contains all the features mentioned above.

10. Option D is not present i.e myosin light chain , other three actin , troponin , tropomyosin are present.

11.Tropomyosin is the answer , reason is it blocks the active sites on the myosin binding site , preventing cross bridge formation and contraction.

12. option C is the answer , The cell has more potassium inside the cell , not outside , outside sodium is high , so this option is wrong.

13. option B Change in the voltage across the membrane with opening of ligand gated channels is called as action potential

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