Practice Quiz Questions Ch. 11 – Muscle Contraction

Sep 21st, 2023

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28 test answers

question

An action potential enters the depths of a muscle fiber by way of __________. (11)

answer

T tubules

question

Which structure do the calcium ions bind to when muscle contraction is initiated? (11)

answer

The troponin molecule

question

Cross-bridges form between the __________ and the __________. (11)

answer

actin filaments; myosin head

question

An action potential introduced at the neuromuscular junction is propagated along the sarcoplasmic reticulum. (11)

answer

False

question

In response to an action potential entering the neuron, calcium ions diffuse from the sarcolemma into the sarcoplasm. (11)

answer

False

question

An action potential causes calcium ions to diffuse from the ________ into the ________.

answer

sarcoplasmic reticulum; sarcoplasm

question

Which of the following best describes the role of Ca2+ in muscle contraction?

answer

It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.

question

Which of the following is not a filamentous protein?

answer

ActinMyosinTroponinTropomyosinToponi

question

An action potential causes depolarization of the T tubule membrane.

answer

True

question

T tubules are invaginations of the sarcolemma of a muscle cell.

answer

True

question

Correct sequence of smooth muscle contraction

answer

An increase in cytosolic calcium binds to calmodulin in the cytosol. This complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross-bridges, which bind to the actin filaments' active sites, resulting in contraction.

question

Correct sequence for skeletal muscle contraction

answer

An increase in cytosolic calcium binds to troponin, which moves tropomyosin from blocking the active sites on the actin filament, which binds with myosin, forming cross-bridges, resulting in contraction.

question

Smooth muscle and skeletal muscle fibers both have their contractions triggered by calcium ions.

answer

True

question

Both smooth muscle contractions and skeletal muscle contractions involve thin (actin) filaments sliding over the thick (myosin) filaments.

answer

True

question

During contraction of a muscle, calcium ions bind to the __________.

answer

Troponin

question

The bond between the active site on actin and the myosin head is broken when an __________.

answer

ATP molecule binds to the myosin head

question

The sequence of cross-bridge formation and myofilament movement will be repeated as long as calcium ions and ATP are present.

answer

True

question

When cross-bridges form, and the muscle fibers contract, the actin myofilament slides past the myosin myofilament.

answer

True

question

Muscle contractions are initiated by the binding of __________ to __________.

answer

calcium ions, troponin

question

During muscle contractions, cross-bridges form between the _________ and the __________.

answer

myosin heads; actin filaments

question

Which of the following is the site of ATP binding and hydrolysis?

answer

myosin

question

The binding of ATP immeditely initiates the sliding of muscle filaments past one another.

answer

false

question

After cross-bridges form, phosphate is released, followed by ADP.

answer

true

question

The __________ is described as two strands of actin molecules wrapped together.

answer

thin filaments

question

Which of the following happens as actin and myosin filaments slide past each other during muscle contraction?

answer

neither action or myosin shorten

question

Which of the following statements about the heads of the myosin molecules is true?

answer

they can attach to different actin sites

question

Each myosin protein has a globular head that extends outward from the myosin filament.

answer

true

question

Unflexing of the myosin head requires ATP.

answer

true

1 of 28

question

An action potential enters the depths of a muscle fiber by way of __________. (11)

answer

T tubules

question

Which structure do the calcium ions bind to when muscle contraction is initiated? (11)

answer

The troponin molecule

question

Cross-bridges form between the __________ and the __________. (11)

answer

actin filaments; myosin head

question

An action potential introduced at the neuromuscular junction is propagated along the sarcoplasmic reticulum. (11)

answer

False

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question

In response to an action potential entering the neuron, calcium ions diffuse from the sarcolemma into the sarcoplasm. (11)

answer

False

question

An action potential causes calcium ions to diffuse from the ________ into the ________.

answer

sarcoplasmic reticulum; sarcoplasm

question

Which of the following best describes the role of Ca2+ in muscle contraction?

answer

It binds to troponin, moving tropomyosin, so that myosin heads can bind to actin.

question

Which of the following is not a filamentous protein?

answer

ActinMyosinTroponinTropomyosinToponi

question

An action potential causes depolarization of the T tubule membrane.

answer

True

question

T tubules are invaginations of the sarcolemma of a muscle cell.

answer

True

question

Correct sequence of smooth muscle contraction

answer

question

Correct sequence for skeletal muscle contraction

answer

question

Smooth muscle and skeletal muscle fibers both have their contractions triggered by calcium ions.

answer

True

question

Both smooth muscle contractions and skeletal muscle contractions involve thin (actin) filaments sliding over the thick (myosin) filaments.

answer

True

question

During contraction of a muscle, calcium ions bind to the __________.

answer

Troponin

question

The bond between the active site on actin and the myosin head is broken when an __________.

answer

ATP molecule binds to the myosin head

question

The sequence of cross-bridge formation and myofilament movement will be repeated as long as calcium ions and ATP are present.

answer

True

question

When cross-bridges form, and the muscle fibers contract, the actin myofilament slides past the myosin myofilament.

answer

True

question

Muscle contractions are initiated by the binding of __________ to __________.

answer

calcium ions, troponin

question

During muscle contractions, cross-bridges form between the _________ and the __________.

answer

myosin heads; actin filaments

question

Which of the following is the site of ATP binding and hydrolysis?

answer

myosin

question

The binding of ATP immeditely initiates the sliding of muscle filaments past one another.

answer

false

question

After cross-bridges form, phosphate is released, followed by ADP.

answer

true

question

The __________ is described as two strands of actin molecules wrapped together.

answer

thin filaments

question

Which of the following happens as actin and myosin filaments slide past each other during muscle contraction?

answer

neither action or myosin shorten

question

Which of the following statements about the heads of the myosin molecules is true?

answer

they can attach to different actin sites

question

Each myosin protein has a globular head that extends outward from the myosin filament.

answer

true

question

Unflexing of the myosin head requires ATP.

answer

true

Practice Quiz Questions Ch. 11 – Muscle Contraction

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