21 Motor Mechanisms

Question 1

The function of ATP during muscle contraction is to
Select one:
A. Causes a conformational change in myosin so that it detaches from actin
B. Provide the energy necessary to release calcium from the sarcoplasmic reticulum
C. Expose the myosin-binding sites on the filaments
D. Cause shortening of the H zone of the sarcomere

Answer 1

Causes a conformational change in myosin so that it detaches from actin

Question 2

The role of calcium in skeletal muscle contraction is to

Select one:
A. Cause a conformational change in myosin so that it releases from actin
B. Expose the myosin binding site
C. Promote the repolarization of the nerve cell after it has depolarized the muscle cell.
D. Activate the ATPase in the sarcoplasmic reticulum.

Answer 2

Expose the myosin binding site

Question 3

The marrow cavity of an adult bone may contain
Select one:
A. Hyaline cartilage
B. Periosteum
C. Blood forming tissue
D. Myocytes
E. Epiphyseal cartilage

Answer 3

Blood forming tissue

Question 4

Stimulation of a muscle fiber by a motor neuron occurs at
Select one:
A. The neuromuscular junction
B. The transverse tubules
C. The myofibril
D. The sarcoplasmic reticulum

Answer 4

The neuromuscular junction

Question 5

When I make chicken soup, I always put a bit of vinegar in it, which helps to release Ca2+ from the bones. How does this work?
Select one:
A. it activates osteoclasts.
B. it activates osteoblasts.
C. it dissolves the bone minerals.
D. it opens Ca2+ channels in the sarcoplasmic reticulum

Answer 5

it dissolves the bone minerals.

Question 6

Curare, a substance that blocks the acetylcholine receptors on skeletal muscle, will cause
Select one:
A. Rapid muscle twitches
B. Sustained muscle contraction
C. Muscle relaxation
D. Disruption of blood pressure and digestive functions
E. No effect, as acetylcholinesterase will degrade it

Answer 6

Muscle relaxation

Question 7

Slow twitch fibers have all of the following EXCEPT
Select one:
A. An abundance of myoglobin
B. A well-developed glycolysis/lactic acid system
C. High fatigue resistance
D. A red color
E. A high capacity to synthesize ATP aerobically

Answer 7

A well-developed glycolysis/lactic acid system

Question 8

A boy takes a ski jump and lands on hard ice. The reason his bones do no€™t shatter is because they contain

Select one:
A. An abundance of calcium phosphate
B. Young, resilient osteocytes
C. Myosin fibers
D. Collagen fibers
E. Elastin fibers

Answer 8

Collagen fibers

Question 9

which of the following decreases in size during muscle contraction

• I Band
• A Band
• H zone
• Z line

Answer 9

H zone

I band

Question 10

Does the length of myosin and actin decrease when a muscle contracts

Answer 10

no they overlap

Question 11

Where is the sorage of O₂ in the muscle

Answer 11

in the myoglobin