Biology 103A - Comprehensive / Final Exam (sample exam only) (version 3)

Biology 103A - Professor Kauffman Comprehensive Exam


1. Which of the following is only found in cardiac and skeletal muscle fibers, but not in smooth?
a. myosin
b. aerobic respiration 
c T tubules 
d. actin
e. Ca++ pumps in the sarcoplasmic reticulum

2. Which of the following is not found in smooth muscle?
a. calmodulin
b. anaerobic resporation
c. actin
e. a and c

3. Creatine phosphate:
a. binds oxygen with greater affinity then hemoglobin
b. stores glucose for energy
c. stores high energy phosphate bonds
d. binds Ca++ to maintain low concentration in the sarcoplasm
e. split ATP to alter the myosin head

4. If T tubules were no longer functional what would not happen in a skeletal muscle fiber?
a. chemical gates would not open at the NMJ
b. voltage sensitive Ca++ gates would not open in the terminal cisternae
c. relaxation of the muscle could not happen
d. the high energy head position of the myosin couls not re-set
e. none of the above could occur

5. Why do slow oxidative skeletal muscle fibers and smooth muscle both contract slowly?
a. they both primarily use anaerobic respiration
b. they both have slow myosin ATPase enzymes
c. they both have voltage sensitive Ca++ channels in their sarcolemma
d. they both contain very large amounts of glycogen compared to other fibers types
e. all of the above 

6. Which of the following form fascicles?
a. epimysium
b. perimysium
c. endomysium
d. sarcolemma
e. actin and myosin


7. In a fully relaxed muscle fiber what is the state of the myosin head and its position?
a. low energy and more vertical relative to the tail part of the molecule
b. low ebergy and bent reative to the tail part of the molecule
c. high energy and more vertical relative to the tail part of the molecule
d. high energy and bent relative to the tail part of the molecule
e. none of the above, the myosin head does not move.

8. Which of the following neutotransmitters opens chemically gated channels in both smooth and cardiac muscle?
a. Ca++
b. acetylcholine
c. norepinephrine
d. b and c
e. a, b and c

9. Which of the following is a feature of graded potentials?
a. they can be of any value
b. they can be both depolarizing and hyperpolarizing
c. they are highly localized
d. they decrease in size with distance 
e. all of the above

10. ATP is used by skeletal muscle fibers to:
a. energize the myosin head
b. unbind the myosin head from actin
c. pump Ca++ back into the sarcoplasmic reticulum
d. maintain the membrane potential via the Na+/K+ pump
e. all of the above

11. The refractory period causes: 
a. the same number of Na+ voltage gates to open
b. the same amount of Na+ and K+ ions to move
c. enough gates to open to reach Na+’s equilibrium potential
d. the membrane to be able to bind Ach
e. the action potential to move in one direction away from the point of excitation

12. Membrane resistance:
a. moves ions across the membrane 
b. limits the spread of current during an action potential 
c. changes when Ach binds
d. determines the height of the action potential 
e. limits the action potential to 1-2ms in length


Fill in the blanks

Compared to normal cells skeletal muscle fibers can generate more ATP due to having ____________ and ____________.

When Ach binds to its receptor at the NMJ chemical gates open and _______________ enters the fibers causing a __________ potential. 

When Ca++ concentration is very low in the cytoplasm the myosin head is in the 
________ energy position and __________ prevents myosin and actin from binding. 

Contraction is ened when Ca++ levels fall in the cytoplasm due to _____________ in the sarcomplasmic reticulum and the sarcomere returns to its original length due to _________.

The role of troponin is to bind ________ and to move ____________.

During contration the length of the thin and thick filaments _______________ while the length of the sarcomere ____________.

If membrane resistance decreased the speed of action propagation would ___________ and the electrical currents would spread over a ___________ distance along the sarcrolemma.

Sarcomeres are linked end to end by the _____ disc and these dics are aligned in perfect register with each other and llinked to the sarcolemma by the protein ___________. 

If ATP is used up before Ca++ levels decrease in the muscle fiber, the myosin head will not be able to ___________. After death this is know as __________.

In skeletal muscle the role of Ca++ is to permit ___________ binding, while in smooth muscle the role of Ca++ is to bind ________________ to activate myosin ATPase.

The cardiac action potential has three types of voltage sensitive ion channels: _______, ________ and ________.

Skeletal muscle action potential last 1-2mc, while cardiac action potential last ____ms, nearly as long as the fiber contration. This means that ____________ is not possible in cardiac muscle.


Correct the FALSE statements

Each sarcomere shortens at a different time then neightboring sarcomeres.

Sarcomeres in cardiac muscle fibers are at near optimal length prior to contration.

Postural muscles are primaril made up of fast oxidative skeletal muscle fibers. 

Recruitment increases the concentration of Ca++ in the cytoplasm, resulting in greater tension in that muscle fiber.

Voltage gated Ca++ channels are found in the sarcoplasmic reticulum and sarcolemma of smooth, cardiac and skeletal muscle fibers. 

Thin filaments are made up of troponin, tropomyosin and myosin


Short Answers

Briefly describe three morphological differences and two biochemical between an average cell and a skeletal muscle fiber and give an explanation for why each of these differences exist. 

Explain how the action potential is propagated in terms of electrical currents, membrane resistance and voltage activated ion channels.

Explain how muscle tone arises and explain how tome affects the muscle fibers ability to develop tension when it contracts.

Contrast wave summation and recruitment using three differences between how these mechanisms control the amount of tension developed by the whole muscle.