Date | November 2018 | Marks available | 3 | Reference code | 18N.2.SL.tz0.5 |
Level | Standard Level | Paper | Paper 2 | Time zone | time zone 0 |
Command term | Describe | Question number | 5 | Adapted from | N/A |
Question
Outline the chemical control of ventilation during exercise.
Describe the phenomenon of oxygen deficit.
Outline two named methods of memory improvement.
Using a sporting example, predict how a change in radius affects speed of rotation.
Explain sliding filament theory after acetylcholine (ACh) increases muscle membrane permeability.
Markscheme
ventilation is «chemically» regulated by blood acidity levels/low pH ✔
blood acidity levels increase/pH drops due to an increase in carbon dioxide levels ✔
blood acidity levels are detected by chemoreceptors ✔
medulla oblongata/ANS/respiratory control centre receive information from receptors ✔
increased blood acidity «and information from the proprioceptors» increases the depth / rate of ventilation ✔
Accept appropriately labelled diagram.
deficit is calculated as the difference between the oxygen required for a given rate of work and the oxygen actually consumed ✔
deficit takes place during the initial stages of exercise ✔
muscles generate ATP through anaerobic pathways ✔
oxygen transport system is not immediately able to supply the needed quantity of oxygen to the active muscles
OR
oxygen consumption requires several minutes/time before a homeostatic level is reached ✔
homeostatic level is reached when the aerobic system meets the demands ✔
is repaid after exercise is finished✔
rehearsal ✔
information is processed mentally or physically ✔
coding ✔
labelling sets of information to make it easier to access ✔
brevity ✔
giving a learner a small amount of information at a time to avoid overload ✔
clarity ✔
keeping learning / teaching simple at the beginning ✔
avoiding to teach / learn similar but distinct items in the same session «to avoid interference with the memory of the other» ✔
chunking ✔
learners retain more if the information is chunked «instead of being presented as individual items» ✔
organization ✔
we remember more easily if we organize the way in which we are to learn and ensure that the information is meaningful ✔
association ✔
ensuring that new learning is linked to what players already know ✔
practice ✔
establishes memory trace/pathway ✔
Award [1 max] for a list of methods.
Award [2 max] per memory aid.
Description must correspond to the named method to obtain the mark.
Angular momentum=moment of inertia x angular velocity ✔
angular momentum is conserved after push off/take off
OR
the magnitude of angular momentum remains constant ✔
with decrease in radius the body has lower moment of inertia ✔
the speed of rotation/rotational velocity increases with decreased radius/body being in a compact shape
OR
eg moving arms/legs closer in will increase the speed of rotation ✔
when an athlete wants to stop the spin, they increase the radius to decrease the rotational velocity ✔
Award [2 max] if no reference to an example is included.
sodium ions/Na+ enter the muscle and change the polarization in the myofibril ✔
the sarcoplasmic reticulum releases calcium ions ✔
calcium ions bind to troponin ✔
Tropomyosin/troponin complex exposes the binding site «on actin» ✔
myosin «head» creates a cross-bridge with the actin ✔
power stroke takes place ✔
z lines come closer together / H zone gets smaller✔
myosin releases actin if new ATP appears ✔
myosin head reattached further down the actin filament repeating the cycle < called the ratchet mechanism>✔
process goes on until acetylcholine-esterase breaks the acetylcholine down ✔
Examiners report
Most candidates managed to articulate that an increase in CO2 changes the pH which is detected by chemoreceptors.
Overall a good understanding was shown here with very few getting this mixed up with oxygen debt.
Very well articulated.
Generally well done and understood and able to use a relevant example from sport to show understanding.
Very well articulated. Candidates clearly know the sliding filament theory and the associated steps.