Sliding Filament Theory Quiz

Which of the following best describes the structure of an actin filament?

• A thin filament that is made up of two molecules twisted around each other

• A thick filament with a globular head and a cylindrical tail

In the sliding filament theory of muscle contraction, what initiates the detachment of the myosin head from the binding site on the actin filament?

• A molecule of ATP binding to the myosin head

• The hydrolysis of an ADP molecule on the actin filament

• Calcium ions binding to tropomyosin

• A molecule of ADP being released from the myosin head

The flowchart provided describes the events that occur at a neuromuscular junction, with each step assigned a number. State the number sequence that would give the correct order of events.

• 6, 2, 1, 4, 3, 5

• 5, 2, 1, 4, 3, 6

• 6,2,4,3,1,5

• 1,2,6,4,3,5

• 3, 4, 6, 2, 1, 5

Where does a neuromuscular junction form?

• Between the axon of a motor neuron and a muscle fiber

• Between the axon of a motor neuron and the dendrite of another neuron

• Between the axon of a motor neuron and the dendrite of a sensory neuron

• Between the dendrite of a sensory neuron and muscle fiber

Which of the following best describes the structure of a myosin filament?

• A thin filament that is made up of two molecules twisted around each other

• A thick filament with a globular head and a cylindrical tail

In the sliding filament theory of muscle contraction, how does the myosin head resume its normal position?

• Using energy from the breakdown of ADP

• Using the electrical stimulation of the influx of calcium ions

• Using energy from the hydrolysis of ATP

In the sliding filament theory of muscle contraction, what is the primary role of calcium ions?

• To provide the energy required to return the myosin heads back to their normal position

• To initiate the release of a molecule of ADP as the myosin heads pull the actin filament along

• To stimulate the detachment of the myosin heads from the actin binding sites

• To bind to tropomyosin, changing its shape and moving it away from myosin binding sites

The diagram provided shows the stages of the sliding filament theory. State the correct order.

• 5, 3, 2, 7, 8, 6, 4, 1

• 3, 2, 5, 6, 8, 7, 4, 1

• 3, 2, 5, 7, 8, 6, 4, 1

• 8, 6, 4, 1, 3, 2, 5, 7

The diagram provided shows a basic outline of a neuromuscular junction.What is the role of acetylcholine at a neuromuscular junction?

• To open the voltage-gated calcium channels on the presynaptic neuron

• To act as a biological catalyst

• To act as a chemical neurotransmitter

• To move tropomyosin away from the myosin-binding sites on actin filaments

The diagram provided shows how a sarcomere changes when a muscle fiber contracts. Which of the following best describes how the sarcomere changes?

• The sarcomere extends as the actin filaments pull the myosin away from the M line.

• The sarcomere shortens as the myosin pulls the actin filaments toward the M line.