7.1 Muscles & Movement

Slow and fast twitch skeletal muscle fibres differ in a number of ways.

Compare and contrast slow and fast twitch muscle fibres.

A scientist investigated the proportions of slow and fast twitch muscle fibres in athletes and non-athletes.

The percentage of fast and slow twitch muscle fibres was analysed. The results are shown in the graph below.

Explain which athlete you would expect to find the greater density of mitochondria with their muscle fibre cells.

Elite sprinters tend to be bulkier and more muscular than long distance runners. 

Use your knowledge of fast and slow twitch muscle fibre to explain why.

Muscles generate movement by antagonistic muscle action. 

Describe the action taken by muscles when a pair of antagonistic muscles work together.

Give a named example from human muscles as part of your answer.

Muscle work together with tendons and ligaments

Which statements below describe the difference between tendons and ligaments? 

Explain how muscles maintain posture.

The mass of muscle changes with age. Between the ages of 20 and 60, 15% of total muscle mass is lost. Between the ages of 60 and 80, a further 35% of the original total muscle mass is lost.

Plot a graph on the grid below to show the percentage of muscle mass remaining between the ages of 20 and 80. Assume that the rate of muscle loss in each age range is constant.

The diagram shows part of a relaxed myofibril. 

When the myofibril contracts, state which of the A-band, I-band and H-zone will decrease in length.

(1)

When the myofibril contracts, state which of the A-band, I-band and H-zone will remain the same in length.

(1)

The structure of a muscle is often referred to as light and dark. 

Identify and name the light and dark bands in the diagram from part (a).

(2)

Describe the structure of the light and dark bands of a muscle.

(2)

Explain the reason for your answer to part (a) (i)

The whole myofibril is 21 mm long when relaxed.

Use the information given in the diagram in part (a) to calculate how many sarcomeres are in a myofibril. Give your answer to four significant figures.

Which of the statements regarding the relationship between force and length is false? 

Skeletal muscle is also known as striated muscle due to its striped appearance.

Use your knowledge of the protein filaments in muscle tissue to explain the striped appearance of skeletal muscle.

Several different drugs exist that reduce the contraction of skeletal muscles. Two of these drugs are described in the table below.

Explain how each of the drugs in the table reduce the contraction of skeletal muscles.

A type of muscle disease is caused by a gene mutation. This leads to the production of disfigured myosin molecules that are unable to bind to other myosin molecules.

Use your knowledge of how muscles contract to predict the effect of this gene mutation.