Muscle 2001
Choose the correct answer for each question.
1
Contractions of the human arm can be modeled as a simple lever system with the pivot (fulcrum) at the elbow). An increase in the length of the out lever (the ulna) will lead to:
an increase in out force (Fo).
an increase in the in lever length (Li).
an increase in the out velocity (Vo).
an increase in the sarcoplasmic reticulum.
none of the above.
2
In a positive feedback loop,
the response returns a regulated variable to a set point.
the set point changes extremely quickly, enabling fast responses by the body.
a stimulus that decreases a variable would elicit a response that cause a further decrease in that variable.
homeostasis is maintained because the positive impact of the feedback response.
none of the above.
3
Which of the following accurately describes expected differences between the muscles of a sprinter and a marathoner?
the sprinter will have less actin.
the marathoner will have more mitochondria.
the sprinter will have fewer sarcoplasmic reticulum calcium pumps.
the marathoner will have more fast myosin heavy chain.
none of the above.
4
The three-dimensional shape of a protein molecule.
is called the primary structure.
never changes during normal cellular function.
is completely independent of the linear sequence of amino acids that makes up the protein.
is called the quaternary structure.
none of the above
5
Which of the following accurately describes a function of ATP during muscle contraction.
ATP binds to the calcium channels initiating the release of calcium by the sarcoplasmic reticulum.
ATP binds to troponin, causing a change in tropomyosin structure that allows contraction to begin.
ATP is split to ADP and P by the calcium pump, this causes calcium to be pumped out of the sarcoplasmic reticulum where it stimulates contraction.
ATP binds to myosin but is not split to ADP and P, this allows myosin to detach from actin.
none of the above.
6
When a muscle contracts at its maximal contraction velocity,
force generation is also maximal.
power generation is also maximal.
the contraction is isometric.
no force at all is generated.
none of the above.
7
A major consequence of the series arrangement of sarcomeres within a muscle fiber is
contraction velocity of the whole muscle is increased.
contraction strength of the whole muscle is increased.
the speed of myosin head ratcheting is increased.
each sarcomere will contract a greater amount.
none of the above
8
Rattlesnakes have "shaker" muscles that enable them to shake their rattles very rapidly (about 60 times per second) for extended periods (up to three hours). However, force production is low. Which of the following is NOT a property of rattlesnake shaker muscles?
High level of sarcoplasmic reticulum calcium pumps.
High level of sarcoplasmic reticulum calcium channels.
Moderate levels of mitochondria.
High levels of actin and myosin.
All of the above are properties of rattlesnake shaker muscle.
9
Which of the following functions of muscle proteins is NOT mediated by a change in the 3-dimensional shape of the protein?
The energizing of the myosin head due to the splitting of ATP to ADP and P.
The activation of muscle contraction due to the binding of calcium to troponin.
The detachment of myosin from actin due to the binding of ATP to myosin.
The covering of myosin-actin binding sites by tropomyosin when calcium is released from troponin.
All of the above are mediated by changes in protein 3-D shape.
10
During a muscle contraction, which of the following steps occurs first?
Calcium binds to troponin.
An electrical impulse travels along the muscle cell membrane.
Acetylcholine receptors on the muscle cell bind to acetycholine molecules.
Tropomyosin structure changes, allowing actin and myosin to interact.
ATP binds to troponin in the nerve cell membrane.