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A.3 Perception of stimuli

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Description

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)
Understandings:
  • Receptors detect changes in the environment.
  • Rods and cones are photoreceptors located in the retina.
  • Rods and cones differ in their sensitivities to light intensities and wavelengths.
  • Bipolar cells send the impulses from rods and cones to ganglion cells.
  • Ganglion cells send messages to the brain via the optic nerve.
  • The information from the right field of vision from both eyes is sent to the left part of the visual cortex and vice versa.
  • Structures in the middle ear transmit and amplify sound.
  • Sensory hairs of the cochlea detect sounds of specific frequency.
  • Impulses caused by sound perception are transmitted to the brain via the auditory nerve.
  • Hair cells in the semicircular canals detect movement of the head.
Applications and skills:
  • Application: Red-green colour-blindness as a variant of normal trichromatic vision.
  • Application: Detection of chemicals in the air by the many different olfactory receptors.
  • Application: Use of cochlear implants in deaf patients.
  • Skill: Labelling a diagram of the structure of the human eye.
  • Skill: Annotation of a diagram of the retina to show the cell types and the direction in which light moves.
  • Skill: Labelling a diagram of the structure of the human ear.
Guidance:
  • Humans’ sensory receptors should include mechanoreceptors, chemoreceptors, thermoreceptors and photoreceptors.
  • 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.
  • Diagram of retina should include rod and cone cells, bipolar neurons and ganglion cells.
  • Diagram of ear should include pinna, eardrum, bones of the middle ear, oval window, round window, semicircular canals, auditory nerve and cochlea.
  • 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?
Utilization:
Syllabus and cross-curricular links:
Biology
Topic 3.4 Inheritance
Physics
Topic 4.2 Travelling waves

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