Question 17N.2.HL.TZ0.d.ii
| Date | November 2017 | Marks available | [Maximum mark: 1] | Reference code | 17N.2.HL.TZ0.d.ii |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Suggest | Question number | d.ii | Adapted from | N/A |
The sodium–potassium pump plays a role in muscle activity. Nitric oxide may have a role in the recovery of hypoxic muscles. The production of nitric oxide can be blocked with an inhibitor of the enzyme nitric oxide synthase. The graph shows the concentration of sodium–potassium pumps in the diaphragm of control and hypoxic rats without and with nitric oxide synthase inhibitor.
[Source: Reproduced with permission of the © ERS 2011. European Respiratory Journal June 2011, 37 (6) 1474–1481; DOI: 10.1183/09031936.00079810]
Muscle fibres are stimulated to contract by the binding of acetylcholine to receptors in their membranes and the subsequent depolarization.
Suggest a reason for increasing the concentration of sodium–potassium pumps in the membranes of diaphragm muscle fibres.
[1]
a. resting potential restored faster
b. increases the «maximum» frequency/rate of contractions
OR
can contract again sooner
Accept shorter refractory period for mpa
Do not accept faster contraction/depolarization/ repolarization
[Max 1 Mark]
