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Communication
Alissa chaitarvornkit

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Sight is a common form of communication
Most animals that use sound as a form of communication make calls or sound for identification purposes
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Stimulus​ a change in the internal or external environment for an organism
is
The sense organs contain non-sensory tissue aside from the special sensory cells that can monitor stimuli
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response​ a reaction in an organism or its tissues as a result of receiving a stimulus
is
Photoreceptors are sensitive to light energy
Mechanoreceptors respond to mechanical energy
Thermoreceptors respond to heat and cold

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Explain that the response to a stimulus involves:
● Stimulus
● Receptor
● Messenger
● Effector
● Response
● Central Nervous system consists of the brain and spinal cord, triggers the response
● Receptors such as the CNS means of nerves
● Sense organs change the stimuli received by a sense organ into electrochemical signals called nerve impulses
● Impulses travel along nerves which as as messengers
● The brain and spinal cord interpret and make sense of the messages they receive, either by taking into account
past experience or as inherited reflex
● The result of this pathway is what we term animal behaviour

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Mechanoreceptors ​
detect mechanical energy
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touch, pressure, gravity or bending and strechting caused by movement
● Taste - ​
Chemoreceptors​
detect different chemicals
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Visual signals can be given between animals and sometimes sight provides the
majority of information about the environment
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g Blue- ringed octopus signals an intention to attack by glowing blue rings on their bodies
● Hearing - ​
Some animals use sound to communicate, but many species cannot detect a wide range of sound
frequencies
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Crickets use sound as a warning and attract mates
● We are blind at wavelengths less than 400nm (UVA and UVB rays)
The range of wavelengths detected by invertebrates and other vertebrates
● Invertebrates
○ Insects are able to detect wavelengths in the ultraviolet range of the spectrum, there is their light
sensitive cells can detect the shorter wavelengths present in the UV range
● Vertebrates

○ many bird species are able to detect light well into the ultraviolet range
○ Able to detect light in the blue range, suggesting tetrachromatic vision
Describe the anatomy and function of the human eye, including the:
● Conjunctiva
● Cornea
● Sclera
● Chlorid
● Retina
● Iris
● Lens
● Aqueous and vitreous humor
● Ciliary body
● Optic nerve

● Visual stimuli in the form of light, are detected by
sensory cells called photoreceptor cells in the
eye
● An eye should:
○ Allow light to enter
○ Organise the light rays to form a picture
○ Convert the light signal into nerve impulses
○ Prevent leakage or the scattering or reflection of light

 
 
 
 
 
 
 
 
 
 
 
 
 
 

Identify the limited range of wavelengths of the electromagnetic spectrum detected humans and compare this
range with those of other vertebrates and invertebrates

Plan, choose equipment or resources and perform a first-hand investigation of a mammalian eye to gather
first-hand data to relate structures to function

Use available evidence to suggest reasons for the differences in range of electromagnetic radiation detected by
humans and other animals

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The light signal reaching the retina is transformed into an electrical
impulse
Identify photoreceptor cells as those containing light-sensitive pigments and explain that these cells convert
light images into electrochemical signals that the brain can interpret
● Photoreceptor cells contain light-sensitive pigments in retina such as rhodopsin and photopsin
● Photoreceptors convert light images into electrochemical signals that the brain can interpret
● The steps involved in the transformation of the light in the retina:
○ Light images strikes the retina
○ Photosensitive pigments in rods and cones absorb
○ Photochemical change in the rods and cones, involving visual pigments generate electrochemical
impulse
○ Impulse is transmitted to bipolar cells in the retina
○ Bipolar cells stimulate ganglion cells whose processes make up the optic nerve
○ Fibres of the optic nerve carry partly processed information to the brain
Position of photoreceptors in the retina
● LIght coming into the eye passes through the entire retina before striking the rods and cones, which are
situated closest to the choroid layer
● THe photoreceptor cell layer, bipolar layer and ganglion cell layer, as well as associated horizontal cells and
amacrine cells

Describe the difference in the structure, distribution and function of the photoreceptor cells in the human eye

Structure
● Rhodopsin ​the only pigment present in rods
is
● Cones contain ​
iodopsins
● there are three different types of iodopsins, each are sensitive to a different wavelength of light
● Rod and cone cell then converts into an electrochemical signal that the brain can interpret
Distribution and function
Rods
● Rods are responsible for most peripheral vision including the detection of movement
● Rods are extremely sensitive to light responding best to low light intensities
● Are used for night vision and to detect light and shadow contrasts
● Fovea is a small pit in the middle of the macula and contains cones
Cones
● Cones in the fovea are very densely packed and show no retinal convergence
● Absence of blood vessels, neuron fibres and rod cells in the fovea lead to it being the are of most acute vision
● Cones are responsible for colour vision
● Each type of iodopsin is sensitive to one of the primary colours of light
● Three basic colours, red, green and blue

● Cones are less sensitive to light than rods are
● Require larger quantities of light to stimulate or bleach them
● Cones function best in high intensity or bright light giving daytime vision
Outline the role of rhodopsin in rods
● Rhodopsin-​ photosensitive pigment that absorbs light waves in the rods
the
● Consists of opsin and retinal which is from Vitamin A
● Sensitive to blue-green light with peak sensitivity around 500 nm
● When light is absorb it begins a series of chemical reactions
● The reaction produces a nerve impulse, then a sequence more rhodopsin can be synthesised using ATP
Identify that there are three types of cones, each containing a separate pigment sensitive to either blue, red or
green light
● Each cone contains one of the three types of iodopsin pigments and is therefore most sensitive to light in one of
three wavelengths
● They are sensitive to:
○ Short wavelengths of blue light containing ​
cyanolabe
○ Medium wavelengths of green light containing ​
chlorolabe
○ Long wavelengths of red light containing ​
erythrolabe
● Red cones are actually more sensitive to yellow light (560-565 nm)
● To see colour impulses from red, blue and green cones are sent to the brain and is interpreted
● Rods allow you to see grey, black and white
Explain that colour blindness in humans results from the lack of one or more of the colour sensitive pigments in
the cones
● Colour Blindness ​
- means person is unable to see certain colours and is colour vision deficient rather than
blind
Causes of colour blindness
● A mutation in a gene that codes for a cone pigment leads to the inability of this pigment to function correctly
● Person is unable to perceive colour in the normal trichromatic manner
● Genes coding for red and green pigments are located at the X chromosome
● Colorblindness is recessive
● Colour blindness is a sex-linked disorder
● Mutations in the gene for the blue cone pigment are extremely rare
● Such colorblindness may arise from a diseased condition of the macula or optic nerve
Visual Defects as a result of colorblindness
● People who are red-green colorblind find it difficult to distinguish between red and green objects placed
adjacent to each other
● Person is a monochromat unable to distinguish colours and seeing most things in shades of black, white or grey
● Colour deficient is a mutation in a gene for any cone
● May simply cause a change in the peak of spectral sensitivity of that one
● Ishihara plates helps identify colour blindness

Process and analyse information from secondary sources to compare and describe the nature and function of
photoreceptor cells in mammals, insects and in one other animal

Process and analyse information from secondary sources to describe and analyse the use of colour for
communication in animals and relate this to occurrence of colour vision in animals
● Animals use colours to communicate e
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fish, amphibians, reptiles and birds
● Animals use colour communication for a variety of reasons including:
○ Signal their availability to mate - courtship
○ Warn off predators
○ Protective colouration and camouflage
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○ Camouflage​
- hiding by blending into the environment, some change the colour of their skins to match
wherever they are
■ Chameleons and octopus
○ Sexual dimorphism - ​
different appearance between the sexes, genders are distinguished by their
colour and sizes
■ Male lion develops the mane, male birds are more brightly coloured than female
○ Warning colours - ​ animals change colours to give warning that they are about to attack
some
■ Blue ringed octopus when threatened blue rings appear all over the surface of skin
○ Breeding colours -​
Birds take a different colours during breeding season
■ Male puffin during breeding season the bands on the beak are bright while outside season the
bands fade

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Play a pure note repeatedly on a
musical instrument into the
microphone attached to the CRO and you should be able to produce a simple waveform (Control)
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Play different notes on your instrument until you find one that changes just the wavelength of the control note
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Find a note that changes just the pitch of the control note
Outline the structure of the human larynx and the associated structures that assist the production of sound
The Larynx

● Larynx is positioned in the throat where the pharynx divides into the
respiratory tract and digestive tract
● Functions:
○ Provide an open airway
○ Mechanism for sound production
○ Ensure a closed air channel during swallowing
● Larynx is a hollow box which houses the vocal folds/vocal cords
● Framework of nine cartilages joined by membranes and ligaments
● The upper opening of this box - glottis - is often covered by the
epiglottis, which extends from the posterior of the tongue to its anchor
point on the anterior rim of the thyroid cartilage
● Large cartilage ring - the thyroid cartilage is known as the Adam’s apple
● The interior of the larynx has a mucous coated lining - Cilia
● Lying under the mucous lining, on each side are the vocal ligaments
● The vocal folds or true vocal cords
Phonation
● Phonation is the name given to the complicated process of
producing intelligible sounds and speech
● Stages:
○ Production of airflow
○ Production of sound
○ Articulation of the voice
● Production of airflow
○ Force of air must be enough to push open the vocal
cords
○ the Diaphragm muscle and the external intercostal
muscle
● Production of sound
○ Rapid opening and closing of the glottis set up the
vibration pattern, which produces sound
○ Length of the vocal folds/cords, therefore the size of
the
glottis is controlled by the vagus nerve
○ Nerve functions is the contraction and relaxation of
the
muscles
○ The glottis is wide open when we produce deep notes and narrow slit for high-pitched sounds
○ Loudness of the voice is controlled by the strength of the airflow
● Articulation of the voice
○ Sinuses are air-filled cavities which are lined with a mucous membrane
○ The sound must be shaped into vowels and consonants by the muscles of the tongue, soft palate,
cheeks and lips
Gather and process information from secondary sources to outline and compare some of the structures used by
animals other than humans to produce sound

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Turning head increases the
difference in time of arrival at each ear and increases the ability to determine location
Process information from secondary sources to outline the range of frequencies detected by humans as sound
and compare this range with two other mammals, discussing possible reasons for the differences identified

Process information from secondary sources to evaluate a hearing aid and a cochlear implant in terms of

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Examine the sheep brain externally noting the appearance and
location of the cerebrum, cerebellum and medulla oblongata
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Cut the brain in half lengthways and identify the areas for
speech, sight and sound perception
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The blades are extremely sharp and may cause injury

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