11.2 Movement

The smallest unit of organisation in most tissues is the cell. However, the term 'muscle fibre' is used to describe the smallest unit of skeletal muscle. 

Explain why. 

[2 marks]

Name the bundles of actin and myosin fibres. 

[1 mark]

Place the four words above into descending order of size in the table below:

[2 marks]

Define the term, sarcolemma. 

[1 mark]

Myosin is a protein that has two different kinds of protein structure, fibrous and globular, in its molecule.

State where these two types of structure are found within the myosin molecule. 

[2 marks]

Explain how actin filaments are formed.  

[2 marks]

Complete the table to identify the molecules that carry out the following functions of muscular contraction. 

[3 marks]

State the role of calcium ions during muscle contraction. 

[2 marks]

The power stroke of muscle contraction is a short, sharp movement as a myosin head flexes and slides over an actin filament. 

Suggest why a muscle movement is a smooth process, rather than a series of short, jerky movements as this model might indicate. 

[2 marks]

Identify the two successive events that cause a contracting muscle to stop contracting when the motor neurone stops sending impulses to the muscle fibre. 

[2 marks]

Identify parts A - E on the diagram of a sarcomere below. 

[5 marks]

One mark is available for clarity of communication throughout this question.

Whilst making a school poster of the human elbow, a student dropped his annotation cards. He gathered them up and randomly allocated an annotation to each part of the elbow but many got mixed up, as shown in the table below. 

Re-sort the annotations to match the correct parts of the elbow joint below. 

[8 marks]

Explain the advantages of using an electron microscope to analyse muscle tissue. 

[3 marks]

Distinguish between the following pairs of terms about joint movement:

• Abduction and adduction
• Flexion and extension

You may use examples to clarify your answers. 

[4 marks]