K.C.S.E Biology Q & A - MODEL 2012PP2QN07
Using a relevant example in each case, describe simple and conditional reflex actions.
Simple reflex action - withdrawal of finger from a sharp object.
Is an automatic response to a specific stimulus;
When the finger touches a sharp object, pain receptors in the skin; are stimulated and trigger off a nerve impulse;
The nerve impulse is transmitted via the sensory neuron; to the grey matter of the spinal cord;
The impulse is then transmitted via a synapse; to the relay neuron; and then through another synapse; to the motor neuron;
The impulse is then transmitted to the effector muscles in the hand;
These effector muscles contract; and the finger is withdrawn from the hot object;
Conditioned reflex action
Is an automatic response evoked from an animal by unrelated stimulus; substituted for the one which normally elicits the response;
It develops from past experience; and involves modification of behaviour through learning; It weakens with time; and must be reinforced by repeating the unrelated stimulus;
Students salivate when the bell for lunch rings; because they have learned to associate the
ringing of the bell at lunchtime with food; from experience; every time it rings, they are offered food;