Date | May 2011 | Marks available | 2 | Reference code | 11M.3.SL.TZ1.14 |
Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
Command term | Outline | Question number | 14 | Adapted from | N/A |
Question
Define the term reflex.
Draw a labelled diagram of a reflex arc for a pain withdrawal reflex.
Outline Pavlov’s experiments into conditioning in dogs.
Markscheme
rapid and unconscious/automatic response (to a stimulus)
Example of diagram.
sensory neuron shown connecting site of stimulus/receptor to relay neuron;
relay neuron shown in grey matter, connecting sensory neuron to motor neuron;
motor neuron shown connecting relay neuron to effector/muscle / cell body of motor neuron shown in grey matter;
cell body of sensory neuron shown outside spinal cord/in dorsal root;
spinal cord shown with grey and white matter;
unconditioned stimulus is smell/sight of food and unconditioned response is salivation;
conditioned stimulus is sound of a bell and conditioned response is salivation at sound of bell;
bell/other stimulus is repeatedly applied just before food;
after several repeats the response can be seen without the food/when only the bell is rung/other stimulus;
Examiners report
Many could not give a full correct definition of a reflex, often omitting the fact that it is a rapid response.
Many candidates did not attempt to draw a diagram, and those that were drawn were of very poor quality, gaining no marks. There were often no distinct neurons shown, and the division of the spinal cord into white and grey matter was generally inaccurate. Some diagrams were unrecognisable as a reflex arc.
There were some good, clearly explained descriptions of Pavlov‟s experiments, and most candidates gained the two marks.