Essential idea: Living organisms are able to detect changes in the environment.
The image show the delicate sensory hairs in the (rat's) inner ear. Sound causes vibrations in the air, which in turn causes the sensory hairs to move. The movement of sensory cells stimulates impulses in neurons which the brain interprets as sound.
Understandings, Applications and Skills
|A.3.U1||Receptors detect changes in the environment. [Humans’ sensory receptors should include mechanoreceptors, chemoreceptors, thermoreceptors and photoreceptors.]|
|A.3.U2||Rods and cones are photoreceptors located in the retina.|
|A.3.U3||Rods and cones differ in their sensitivities to light intensities and wavelengths.|
|A.3.U4||Bipolar cells send the impulses from rods and cones to ganglion cells.|
|A.3.U5||Ganglion cells send messages to the brain via the optic nerve.|
|A.3.U6||The information from the right field of vision from both eyes is sent to the left part of the visual cortex and vice versa.|
|A.3.U7||Structures in the middle ear transmit and amplify sound.|
|A.3.U8||Sensory hairs of the cochlea detect sounds of specific wavelengths.|
|A.3.U9||Impulses caused by sound perception are transmitted to the brain via the auditory nerve.|
|A.3.U10||Hair cells in the semicircular canals detect movement of the head.|
|A.3.A1||Red-green colour-blindness as a variant of normal trichromatic vision.|
|A.3.A2||Detection of chemicals in the air by the many different olfactory receptors.|
|A.3.A3||Use of cochlear implants in deaf patients.|
|A.3.S1||Labelling a diagram of the structure of the human eye. [Diagram of human eye should include the sclera, cornea, conjunctiva, eyelid, choroid, aqueous humour, pupil, lens, iris, vitreous humour, retina, fovea, optic nerve and blind spot.]|
|A.3.S2||Annotation of a diagram of the retina to show the cell types and the direction in which light moves. [Diagram of retina should include rod and cone cells, bipolar neurons and ganglion cells.]|
|A.3.S3||Labelling a diagram of the structure of the human ear. [Diagram of ear should include pinna, eardrum, bones of the middle ear, oval window, round window, semicircular canals, auditory nerve and cochlea.]|
[Text in square brackets indicates guidance notes]
Nature of science
Understanding of the underlying science is the basis for technological developments - the discovery that electrical stimulation in the auditory system can create a perception of sound resulted in the development of electrical hearing aids and ultimately cochlear implants. (1.2)
Theory of knowledge
Other organisms can detect stimuli that humans cannot. For example, some pollinators can detect electromagnetic radiation in the non-visible range. As a consequence, they might perceive a flower as patterned when we perceive it as plain. To what extent, therefore, is what we perceive merely an individual construction of reality?