Simple reflex arc (WJEC A-level biology)

This lesson describes the simple reflex arc as a basis for rapid, involuntary and protective actions. The PowerPoint and accompanying resources have been designed to cover the content of point (d) of topic 8 of A2 unit 3 of the WJEC A-level biology specification.

At the start of the lesson, the students are challenged to recognise the connections between three groups of key terms, and this acts to remind them of the sensory, motor and relay neurone, different types of muscle tissue and some reflexes. Time is taken to ensure that students understand that a simple spinal reflex arc is a direct neural pathway through the spinal cord and does not involve processing by the brain. Some of the content was covered at GCSE and in the first lessons of topic 8, so this lesson has been specifically planned to challenge their recall of this content and then to build upon it, and understanding and prior knowledge checks are used throughout to allow them to assess their progress. The students will be able to recognise the different matter of the spinal cord, which is named according to the presence of myelinated or unmyelinated neurones and they will also understand how sensory neurones enter via the dorsal root and motor neurones exit via the ventral root. Moving forwards, two examples of real biological reflexes are used to increase relevance, and students will see how the knee jerk reflex is unusual as it doesn’t contain a relay neurone.

References to synapses, myelination and saltatory conduction are included in the lesson and brief details provided before these are covered in upcoming topic 8 lessons.