Question 1

The diagram below represents the ultrastructure of a single sarcomere in skeletal muscle.

Three features of the sarcomere are labelled P, Q, and R.

Here are three statements about the diagram:

   1 - during muscle contraction, R slides along P

   2 - P is responsive to calcium ions

   3 - Q is responsive to ATP molecules

Which of the statements is/are correct?

  A  

1, 2, and 3 are correct

  B  

only 1 and 2 are correct

  C  

only 2 and 3 are correct

  D  

only 1 is correct


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Question 2

ATP is required for the contraction of skeletal muscle.

What is the result of ATP binding to the myosin head?

  A  

attachment of the myosin head to actin


  B  

detachment of the myosin head from actin

  C  

return of the myosin head to the original (cocked) position


  D  

tilting of the myosin head

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Question 3

Students prepared a section of muscle tissue and added drops of ATP solution to the tissue.

The students observed changes in the muscle tissue.

What would happen to the length of the sarcomere?

  A  

no change

  B  

shortens

  C  

lengthens

  D  

disappears

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Question 4

What is the role of myosin in muscle contraction?

  A  

to form the Z-lines

  B  

to bind with calcium ions

  C  

to block the active sites on actin

  D  

to form cross-bridges with actin filaments

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Question 5

What is a sarcomere?

  A  

a type of muscle fibre

  B  

the functional unit of a myofibril

  C  

a protein that binds calcium

  D  

the cell-surface membrane of a muscle cell

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Question 6

What best describes the structure of a myosin molecule?

  A  

a single globular protein

  B  

a fibrous protein with a tail and two bulbous structures at one end

  C  

a helical strand made of long threads

  D  

a molecule that blocks binding sites

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Question 7

During muscle contraction, what happens to the I-band?

  A  

it becomes wider

  B  

it remains the same width

  C  

it becomes narrower

  D  

it disappears completely

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Question 8

What is the significance of the Z-line in muscle anatomy?

  A  

it is the site of ATP synthesis

  B  

it marks the boundary of a sarcomere

  C  

it is the location where myosin binds to actin

  D  

it stores calcium ions for muscle contraction

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Question 9

What is the function of troponin in muscle contraction?

  A  

it forms the thin filaments

  B  

it binds calcium and helps position tropomyosin to expose binding sites on actin

  C  

it generates the action potential

  D  

it transports ATP to the myosin heads

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Question 10

What is the role of the sarcoplasmic reticulum during muscle contraction?

  A  

it synthesises new protein filaments for muscle repair

  B  

it releases calcium ions to initiate contraction

  C  

it conducts the electrical signal along the muscle fibre

  D  

it stores ATP for muscle contractions

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