IGCSE Biology

Explain the pupil reflex in terms of the antagonistic action of circular and radial muscles in the iris

Explain the pupil reflex, limited to changes in light intensity and pupil diameter

Describe the function of each part of the eye, limited to: (a) cornea – refracts light (b) iris – controls how much light enters the pupil (c) lens – focuses light on to the retina (d) retina – contains light receptors, some sensitive to light of different colours (e) optic nerve – carries impulses to … Read more

Identify in diagrams and images the structures of the eye, limited to: cornea, iris, pupil, lens, retina, optic nerve and blind spot

Describe sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals

State that synapses ensure that impulses travel in one direction only

Describe the events at a synapse as: (a) an impulse stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap (b) the neurotransmitter molecules diffuse across the gap (c) neurotransmitter molecules bind with receptor proteins on the next neurone (d) an impulse is then stimulated in the next neurone

Describe the structure of a synapse, including the presence of vesicles containing neurotransmitter molecules, the synaptic gap and receptor proteins

Describe a synapse as a junction between two neurones

Describe a reflex action as a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)