Question

1.

The striated appearance ofskeletal muscle is due to the

A.	dark color of myosin.
B.	multiple nuclei per fiber.
C.	regular arrangement of filaments.
D.	dense array of microtubules.
E.	dense packing of ATP molecules.

Your Response:

2.

How do muscle fibersshorten during contraction?

A.	Individual protein filaments contract.
B.	More cross-bridges are formed betweenfilaments.
C.	Arrays of filaments overlap each other.
D.	Protein filaments coil more tightly.
E.	Subunits of protein polymers detach.

Your Response:

3.

How do actin and myosinmolecules interact?

A.	Globular myosin heads bind to actin filaments.
B.	Globular actin heads bind to myosin filaments.
C.	Other proteins connect the two.
D.	Myosin filaments bend to connect to actin.
E.	Actin filaments bend to connect to myosin.

Your Response:

4.

When animals die, musclesstiffen in rigor mortis because

A.	muscles cannot contract without ATP.
B.	actin and myosin cannot bind without ATP.
C.	actin and myosin cannot separate without ATP.
D.	ATP is required for synthesis of proteinfilaments.
E.	ATP forms cross-bridges between filaments.

Your Response:

5.

Vertebrate skeletalmuscles are excitable cells because they

A.	can be stimulated by ATP.
B.	can be stimulated by an electric charge.
C.	can secrete neurotransmitter.
D.	possess voltage-gated sodium channels.
E.	can attain a high level of activity.

Your Response:

6.

Starting with the arrivalof an action potential at the neuromuscular junction, which of thefollowing is the correct order of events?

A.	Calcium is released from the sarcoplasmic reticulum,an action potential travels down the T tubules, depolarizationspreads through the T tubule, and myosin binds actin.
B.	An action potential travels down the T tubules,depolarization spreads through the T tubule, calcium is releasedfrom the sarcoplasmic reticulum, and myosin binds actin.
C.	An action potential travels down the T tubules,depolarization spreads through the T tubule, calcium is taken up bythe sarcoplasmic reticulum, and myosin binds actin.
D.	An action potential travels down the T tubules,depolarization spreads through the T tubule, ATP binds to myosin,and myosin binds actin.
E.	A T tubule is depolarized, calcium is released fromthe sarcoplasmic reticulum, an action potential is created in themuscle cell, and myosin binds actin.

Your Response:

7.

How does tropomyosincontrol muscle contraction?

A.	It provides a bridge between actin and myosin.
B.	It provides a site where ATP can be utilized.
C.	Changes in its position expose actin