Question 32 — Communication (25 marks) Answer parts (a), (b) and (c) of the question on pages 2–4 of the Section II Writing Booklet - HSC - SSCE Biology - Question 32 - 2015 - Paper 1

In the given diagram, some stimuli may not generate an action potential because they do not reach the threshold potential, which is the minimum level of depolarization required to trigger the action potential. During the refractory period, for instance, even if stimuli are applied, they can be too weak to reach this threshold. Therefore, such weak stimuli would not lead to the rapid rise in membrane potential needed to initiate an action potential.

Different species of animals perceive their environments based on the wavelengths of light they can detect. For example, some insects can see ultraviolet light, which is invisible to humans. This ability allows them to see patterns on flowers that guide them to nectar, significantly impacting their foraging behavior. On the other hand, many mammals, including humans, primarily see in the visible spectrum (approximately 380 to 700 nm). This difference highlights how visual perception varies among species based on their evolutionary adaptations.

Humans exhibit a diverse range of senses due to various types of receptors that are specialized for specific stimuli. For instance, photoreceptors in the eyes (rods and cones) are responsible for vision and are linked to the occipital lobe of the brain, where visual information is processed. Another example is the receptors in the ears, which allow for the detection of sound waves; these receptors connect to the auditory cortex in the temporal lobe, facilitating hearing. This division of sensory receptors and corresponding brain regions results in the complex sensory experiences humans possess.