Describe the following types of muscle contraction:

concentric

Describe the following types of muscle contraction:

eccentric

Explain the role of ATP in muscle contraction.

Construct a diagram showing a closed loop motor programme.

Concentric contraction:
the muscle shortens while developing tension✔

biceps during a bicep curl when the forearm comes up toward the upper arm✔

Eccentric contraction:
the muscle lengthens while developing tension ✔

biceps when lowering a weight during the curl – the forearm is moved away from the upper arm✔

ATP is the only usable source of energy by the cell/ releases energy for muscle contraction✔

ATP is present at the myosin head <ready to be used>✔

ATP gets broken down to ADP/ loss of Pi initiates power stroke✔

ADP can be re-joined with P which can be achieved from the use of more ATP / the breakdown of CP / PC / ATP / ADP P is reversible✔

The sketch needs to show that the components are linked in an enclosed loop.

Award [1] for loop from brain to movement.

Award [1] for movement/ output to feedback to brain.

Candidates struggled to describe the two muscle contractions correctly. Commonly there was a lack of reference to load or tension with the movement.

Candidates struggled to describe the two muscle contractions correctly. Commonly there was a lack of reference to load or tension with the movement.

Overall this was a positive question for many candidates. Many candidates were able to achieve at least 1 mark, identifying the role ATP had in providing energy for muscular contraction, however fewer candidates were able to link the role of ATP into the sliding filament theory.

This was a very challenging question. Some students referred to the Welford’s model of information processing and others used Adam’s closed loop theory.