| Date | November 2009 | Marks available | 3 | Reference code | 09N.3.SL.TZ0.14 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Explain | Question number | 14 | Adapted from | N/A |
Question
Compare rods and cones.
Explain the role of receptors, sensory neurons and motor neurons in the response of animals to stimuli.
List four general kinds of sensory receptor.
1.
2.
3.
4.
Markscheme
receptors detect stimuli;
transmit information regarding stimuli to the central nervous system;
via sensory neurons;
central nervous system sends impulse to effector;
via motor neuron;
Award [1] for every two correct answers.
thermoreceptor / chemoreceptor / photoreceptor / mechanoreceptor / baroreceptor / propioceptor
Examiners report
This was answered well by a few candidates who adequately compared rod cells with cone cells. A frequent misconception among some candidates was that each cone cell is sensitive to all three colours (red, green and blue).
Most candidates answered this question correctly.
Most candidates knew four examples of sensory receptors.
