Option: Communication

Question 1

Identify the role of receptors in detecting stimuli

Answer 1

Stimulus: Change in internal/external environment; detected by receptors & response triggered

Receptors: Single cells or concentrated in areas to form sense organs (ear, eye)

Photoreceptor: Sensitive to light energy (UV, visible
light)

Mechanoreceptor: Mechanical energy (tough, pressure, gravity)

Thermoreceptor: Heat and cold

E.g. Tough hot plate; thermoreceptors in skin; detect heat and pain→ withdraw fingers

Coordination needs link between receptors and effectors (muscles/glands)
Link carried out by nervous system

Question 2

Identify data sources, gather and process information from secondary sources to identify the range of senses involved in communication

Answer 2

Communication: Sending and receiving meaningful info

Communicator (sending info) needs to have signalling device. E.g. voice box

Recipient needs structure to detect. E.g. Ears to hear

Sight
Lion: Hairs on mane stand up (larger) when another male in environment

Sound
Lion: Roar to intimidate other male; aggressive warning

Taste
Ants follow pheromone markers (left by others) to find food

Smell
Fish emit odours→ establish rank in social group

Touch
Humans hug and shake hands to greet

Question 3

Explain that the response to stimuli involves:

Answer 3

Stimulus, Receptor, Messenger, Effector, Response

CNS→ triggers response to stimulus (receptors change stimuli into electrochemical signals)

Electrochemical travel along nerves; transmit info to
CNS; processed/interpreted→ response initiated

CNS→ impulses along nerves to effector organs (carry out response)

Question 4

Describe the anatomy and function of the human eye, including the:

CONJUNCTIVA

Answer 4

Thin transparent membrane→ protects front of eye

Question 5

Describe the anatomy and function of the human eye, including the:

CORNEA

Answer 5

Transparent→ light can enter (no blood vessels)

Curvature→ bends/refract incoming light rays to converge & land at back of eyeball

Question 6

Describe the anatomy and function of the human eye, including the:

SCLERA

Answer 6

Outermost layer; non-elastic, tough tissue→ protects inner layers & maintains shape of eye

Site of muscle attachment→ eye movement in socket

Question 7

Describe the anatomy and function of the human eye, including the:

CHOROID

Answer 7

Middle coat; most of blood vessels

Back layer→ black to reduce scattering of light

Question 8

Describe the anatomy and function of the human eye, including the:

RETINA

Answer 8

Thin, delicate→ contains photoreceptors (rods/cones) → responds to light

Question 9

Describe the anatomy and function of the human eye, including the:

IRIS

Answer 9

Coloured part of eye; smooth muscle→ control size of pupil

Question 10

Describe the anatomy and function of the human eye, including the:

LENS

Answer 10

Transparent, biconvex (bulges outwards)→ refracts light rays; directs onto retina (focused image formed)

Elastic; round to flatter surface→ accommodates near and far vision

Question 11

Describe the anatomy and function of the human eye, including the:

AQUEOUS AND VITREOUS HUMOUR

Answer 11

Transparent, watery liquid→ contains dissolved nutrients

Aqueous; Provides nutrients for cornea and lens (that don’t have own supply)

Vitreous; Material fills remainder of eyeball; maintains shape and provide nutrients

Question 12

Describe the anatomy and function of the human eye, including the:

CILIARY BODY

Answer 12

Muscles and ligaments→ adjust curvature of lens

Ciliary muscles relax→ lens flat → distant vision

Muscles contract→ lens round→ near vision

Question 13

Describe the anatomy and function of the human eye, including the:

OPTIC NERVE

Answer 13

Nerves pass through skull→ carry electrochemical signals from retina to brain

Question 14

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

HUMANS

Answer 14

380-760 nm

All colours in visible light (no UV)

Active during day→ Need to distinguish colours in environment

Question 15

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

INSECTS (BEES)

Answer 15

300-650 nm

UV range, blue, green (NO RED)

UV patterns on flowers→ attract bees to pollen and nectar

Question 16

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

VERTEBRATES (BIRD AND SNAKE)

Answer 16

SNAKE
400- 850 nm
Blue, green, red, UV
Relies on infrared→ locate prey in dark burrows

BIRD
460-700 nm
Blue, green, red
Distinguish environment when flying

Question 17

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

Answer 17

Humans visible wavelength; 380-760nm) → only small part of spectrum (No UV light)

Flying animals detect polarised light→ for navigation in flight

Objects absorb some wavelengths; reflect other→ Colour is light reflected

Question 18

Identify the conditions under which the refraction of light occurs

Answer 18

Refraction: Bending light as it travels from one medium to another (air to water)

Move through dense medium→ slows down and bends towards normal

Pass through biconvex (eye lens) → light rays refracted to focal point (retina on back of eye)

Eye lens→ changes shape; form image of near and far objects

Question 19

Plan, choose equipment or resources and perform a first hand investigation to model the process of accommodation by passing rays of light through convex lenses of different focal lengths

Answer 19

Lightbox; different focal lengths from concave and convex

Convex→ Rays converge

Concave→ Rays diverge

Question 20

Identify the cornea, aqueous humor, lens and vitreous humor as refractive media

Answer 20

Density→ All similar (close to water) → refract light passing through

Refractive power of air→ Lower than power of eye
Light passes from air to refractive surfaces

Greatest degree of refraction in eye occurs at boundary of air and cornea

Question 21

Analyse information from secondary sources to describe changes in the shape of the eye’s lens when focusing on near and far objects

Answer 21

Distant vision→ Flat (muscles relax; pull ligaments taut)

Near vision→ Increased curvature (muscles contract; ligaments slacken) → lens becomes round

Question 22

What are cataracts?

Answer 22

Clouding of lens; obstructs path of light into eye→ blurred vision; looking through ‘veil’

Due to ageing or injury to eye

When proteins build up in lens; new and old cells compacted into centre

Question 23

Technology for cataracts and implications for society

Answer 23

TECH
Phacoemulsification: Probe inserted (tiny incision) cataract broken into pieces; suctioned out

Lens implant; permanent into eye→ focuses light on retina

Extracapsular extraction: Large incision; removes centre in one piece; (NEEDS STITCHES)

IMPLICATIONS FOR SOCIETY
Millions have vision restored; ends avoidable blindness→ return to daily activities

Increases life expectancy; gives more independence (patients and caregivers return to work)

Question 24

Compare the change in refractive power of the lens from rest to maximum accommodation AND

Identify accomodation as the focusing on objects at different distances, describe its achievement through the change in curvature of the lens and explain its importance

Answer 24

Change in curvature of lens→ accommodation

Increased lens curvature→ Thick lens; decrease focal length (increase refraction)

Decreased curvature→ thin lens; increases focal length (decrease refraction)

Low refractive power at rest→ distant objects (thin/flat lens)

High refractive power at max accomodation→ Near objects (round lens)

Question 25

What is Myopia?

Answer 25

Shortsightedness Distant objects unclear→ Near objects well Distant objects fall in front of retina (not on it) → Light rays bent incorrectly→ Blurred vision When eyeball too LONG for lens or cornea too CURVED

Question 26

What is Hyperopia?

Answer 26

Long sightedness Close up objects unclear→ Distant objects well Image falls behind retina (not on it) → Light rays diverge → blurred vision When eyeball is too rounded or lens too FLAT to alter light

Question 27

Technologies to correct Myopia

Answer 27

Orthokeratology; Special lenses at night→ reshape cornea while asleep; in morning temporarily retains new shape Contact lenses or glasses Myopia→ CONCAVE (Thicker outwards, thinner inwards) Bends light outwards to diverge before meets eye (extends focal length) Laser surgery to change cornea curvature PRK→ Outer cornea surface removed; laser shapes cornea LASIK→ Cut and lift flap of cornea and reshape

Question 28

Technologies to correct Hyperopia

Answer 28

Orthokeratology; Special lenses at night→ reshape cornea while asleep; in morning temporarily retains new shape Contact lenses or glasses Hyperopia→ CONVEX (Thinner outwards, thicker inwards) Bends light inwards to converge before meets eye (shortens focal length) Laser surgery to change cornea curvature PRK→ Outer cornea surface removed; laser shapes cornea LASIK→ Cut and lift flap of cornea and reshape

Question 29

Explain how the production of two different images of a view can result in depth perception

Answer 29

Depth perception: Ability to determine distances between objects & see in 3D 2 eyes at different positions; View from each eye slightly different Images fused together in brain→ one 3D image produced Brain calculates depth from slight differences in 2 images

Question 30

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

Answer 30

Light focuses on retina→ Photosensitive pigments in rods and cones absorb light→ generate electrochemical impulse→ Sent to brain via optic nerve Rods and cones→ contain light sensitive pigments→ convert light to electrochemical signals Acuity→ ability to see clear and precise image Low visual acuity when high retinal convergence (more rods to one bipolar neuron) High visual acuity when less convergence (less rods to one bipolar neuron)

Question 31

RODS

Answer 31

Effective in low light (night vision) Evenly distributed throughout retina Sensitive to all wavelengths One type of pigment (rhodopsin) Poor visual acuity (Coarse detail) Black and white 120 million cells More sensitive to low light Peripheral and vision vision

Question 32

CONES

Answer 32

Bright light (day vision) Concentrated in fovea Sensitive to 3 wavelengths 3 types of pigment (iodopsin) High visual acuity (Fine detail) Colour 6-7 million cells Less sensitive to low light Central and detailed vision

Question 33

Process and analyse information from secondary sources to compare and describe the nature and functioning of photoreceptor cells in mammals, insects and in one other animal Planaria (Aquatic Flatworm)

Answer 33

``` Description of eye structure Simple eyespots (resemble eyes) → can’t produce images; just tell light from dark No lens to focus images ``` Refractive surface No lens→ single layer of photosensitive cells respond to light Photoreceptor cells Little photoreceptor cells Visual acuity No image produced→ few photoreceptor cells Image formed No image→ just used to tell light from dark (for direction) Role of photoreceptor cells Determine direction/intensity of light Response time Flatworms move away from light source quickly after detection

Question 34

Process and analyse information from secondary sources to compare and describe the nature and functioning of photoreceptor cells in mammals, insects and in one other animal Insect (Bee)

Answer 34

``` Description of eye structure Compound eyes (8000 light detecting units→ ommatidium) Each ommatidium→ own lens to focus light onto photoreceptors ``` Refractive surface Light passes through lens of ommatidium and cornea refracts incoming rays Photoreceptor cells 16,000 light sensitive retinal cells Visual acuity Better than simple planaria but not as good as humans Clearer images produced (Judge distances & see flowers when flying) Image formed Clearer than simple eyes but blurred in comparison to mammals Role of photoreceptor cells Detect movements in large FOV Identify flower patterns from UV light Response time Quicker than mammals→ need to see clearly at speeds even when flying

Question 35

Process and analyse information from secondary sources to compare and describe the nature and functioning of photoreceptor cells in mammals, insects and in one other animal Mammal (Human)

Answer 35

Description of eye structure Lens→ Behind pupil and iris (focuses light) Retina→ Converts light into electrical impulses → carried to brain via optic nerve Refractive surface 80% occurs in cornea (from air to eye) Many refractive surfaces (cornea, aqueous/vitreous humor, lens) Photoreceptor cells 6-7 million rods and cones Visual acuity Clear and precise in day (cones) → High acuity Unclear at night (rods) → Low acuity Image formed Clear and inverted Role of photoreceptor cells Rods→ Peripheral and night vision Cones→ Central and detailed colour vision Detect light/movement Response time Rods→ Slow response, long integration time Cones→ fast response, short integration time

Question 36

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

Answer 36

Distribution: Evenly distributed across most of retina (absent from fovea) Structure: Elongated cells→ outer segment is long and narrow Contains visual pigments→ stacked in layers of flattened membranes Pigments: Only Rhodopsin Function: Responsible for most of peripheral vision (detects movement) Night vision; detect light and shadow contrasts Sensitive to light so can operate in semi-darkness Colour and wavelength of light to which cell is sensitive: See in shades of black, white and grey

Question 37

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

Answer 37

Distribution: Most concentrated in fovea Structure: Elongated cells→Outer segment is short and conical. Broader than rods Contains visual pigments→ stacked in layers of flattened membranes Pigments: Cones contain iodopsins (3 different types; one in each type of cone cell) Function: Responsible for colour vision- (each iodopsin is sensitive to primary colours) Function best in daytime vision Colour and wavelength of light to which the cell is sensitive See in red, blue and green and other colours (combo of different cones)

Question 38

Process and analyse information from secondary sources to describe and analyse the use of colour for communication in animals and relate this to the occurrence of colour vision in animals

Answer 38

Colour→ Warning to rivals, displays for mate attraction, E.g. Male Peacocks feathers→ mate attraction and sign of being threatened Food recognition→ Bird-pollinated flowers often red (sensitive to red) Monarch butterfly→ yellow/black markings→ indicate poisonous Birds→ Don’t use odour for territories or mates→ color is important

Question 39

Outline the role of rhodopsin in rods

Answer 39

Rhodopsin (visual pigment) → protein molecule (opsin) + retinal (light absorbing part) Main function→ To absorb light Light strikes rhodopsin→ light energy absorbed→ rhodopsin changes from resting to excited state Retinal becomes activated→ splits into free retinal part and protein opsin part Activated pigment→ causes change in electrical impulse→ triggers release of neurotransmitter Neurotransmitter stimulates bipolar cell→ generates cell impulse Bipolar cell→ transmits electrochemical signal to ganglion cells→ carry signal to brain Rhodopsin (temporarily bleached in presence of light) regenerated for reuse → recombine by enzymes

Question 40

Identify that there are three types of cones, each containing a separate pigment sensitive to either blue, red or green light

Answer 40

Cone pigment→ iodopsin (3 different types→ each sensitive to 1 primary colour of light) See in colour→ red, green, blue cone impulses sent to brain, interprets signals as colour perception All colours seen are combination of colours Overlap in light range absorbed by 3 cone pigments (particularly red and green) → In absence of red cones, green will detect red light

Question 41

Identify that there are three types of cones, each containing a separate pigment sensitive to either blue, red or green light Blue

Answer 41

Cone stimulated by light colour Blue Colour detected by cone Blue Pigment present Opsin Blue Wavelength of light cone sensitive to (nm) Approx 380-510 Peak wavelength Sensitivity (nm) 455

Question 42

Identify that there are three types of cones, each containing a separate pigment sensitive to either blue, red or green light RED

Answer 42

Cone stimulated by light colour Red Colour detected by cone Red Pigment present Opsin Red Wavelength of light cone sensitive to (nm) Approx 485-640 Peak wavelength Sensitivity (nm) 625

Question 43

Identify that there are three types of cones, each containing a separate pigment sensitive to either blue, red or green light GREEN

Answer 43

Cone stimulated by light colour Green Colour detected by cone Green Pigment present Opsin Green Wavelength of light cone sensitive to (nm) Approx 440-600 Peak wavelength Sensitivity (nm) 530

Question 44

Explain that colour blindness in humans results from the lack of one or more of the colour sensitive pigments in the cones

Answer 44

Most CB→ see clearly but not fully able to see red, blue, green light Most common; red/green→ Mix up all colours that have some red and green in colour. E.g. Confuse blue and purple (can’t see red element of purple) Red/green deficiencies→ murky green world→ red, brown, orange easily confused Red/green→ from inheritance of defective allele of colour vision gene (carried on X-chromosome)

Question 45

Explain why sound is a useful and versatile form of communication

Answer 45

Sound bends around objects and travels around corners→ don’t need to be visible to communicate Travels through solids/liquids/gases Used in dark environment and at night (E.g. Bats) Provide directional info On off rapid advantage Advantage for communication of long distances→ E.g. Humpback whales; sounds produced at certain depths→ can be heard 100’s km away

Question 46

Plan and perform a first hand investigation to gather data to identify the relationship between wavelengths, frequency and pitch of a sound

Answer 46

Equipment: Cathode ray Oscilloscope (CRO), Audio oscillator/amplifier, speaker, tuning fork, sound boxes Select wave output on audio oscillator and connect directly to CRO. Change wavelength and observe image produced Conclusion: Wavelength increases and pitch increases but frequency does not If frequency decreases, amplitude stays the same

Question 47

Explain that sound is produced by vibrating objects and that the frequency of sound is the same as the frequency of the vibration of the source of the sound

Answer 47

When vibrates rapidly enough for molecule movements to send compression wave through medium Wave only travels through medium containing particles that can be compressed or spread Frequency: Number of waves which pass a given point in 1 sec (determines pitch) Amplitude; Max distance a particle moves away from original position (determines volume) Wavelength: Distance between centres of 2 adjacent compressions or refractions High freq vibrations→ high pitched sounds, short wavelengths Low freq vibrations→ low pitched sounds, long wavelengths

Question 48

What is Frequency?

Answer 48

Number of waves which pass a given point in 1 sec (determines pitch)

Question 49

What is amplitude?

Answer 49

Max distance a particle moves away from original position (determines volume)

Question 50

What is wavelength?

Answer 50

Distance between centres of 2 adjacent compressions or refractions

Question 51

Gather and process information from secondary sources to outline and compare some of the structures used by animals other than humans to produce sound INSECTS, FISH, MAMMALS, BIRDS

Answer 51

INSECTS Crickets→ Produce sound by lifting wing 45° and rub front wing cover over rough other wing (Mating) Grasshoppers→ Scrape row of pegs on back legs along hard edges of front legs FISH Catfish→ Vibrates bone on swim bladder→ noise similar to giant aerator bubbler on fish tank (when alarmed or travelling in shoal) ``` BIRDS Use organ (syrinx) at base of trachea where bronchi branch off→ songs produced by forcing air through membranes of syrinx ``` Some birds mute (E.g. Pelicans, vultures) MAMMALS Easter horseshoe bat→ Uses nose→ emits high pitched echolocation and use area around nose to detect sound Dolphin→ Larynx doesn’t have vocal cords→ whistles, clicks through tissue in nose→ sound from air movement in trachea and release of air in blowhole

Question 52

Main functions of larynx

Answer 52

Larynx (voice box) in throat where pharynx divides respiratory and digestive tract Main functions: Provide open airway (when breathing) Provide mechanism for sound production Ensure closed air channel during swallowing→ prevents food entering trachea

Question 53

Structure of larynx

Answer 53

9 cartilages joined by membranes→ form box→ holds vocal cords Upper opening→ glottis→ covered by epiglottis (uppermost cartilage) Epiglottis→ flexible→ tips forwards during swallowing→ prevents food entry Thyroid cartilage→ 2 bands form Adam's apple when joint 3 pairs smaller cartilages→ for, lateral and posterior walls (arytemoid most important→ anchor vocal cords) Muscles connect cartilages to head or alter position, tension, shape of vocal cords Interior→ mucous coated lining (cilia push substances towards pharynx) Under lining→ vocal ligaments (join cartilages and draw lining up to form true cords) True vocal cords→ vibrate and produce sound (as air passes between them) Above true cords→ more mucous folds (false vocal cords) don't help sound; but lubricate true vocal cords and snap shut if liquids → prevents entry to breathing passages if drinking

Question 54

Phonation:

Answer 54

Process of producing intelligible sounds/speech 3 stages: production of airflow and sound and articulation of voice

Question 55

Articulation of the voice

Answer 55

Vibration of vocal cords→ only produces buzzing sound Quality of voice→ determined by other structures above larynx (pharynx and sinuses) Sinuses→ air filled cavities lined with mucous membrane Change in voice when person has blocked nose, sore throat In speech→ sounds must be ‘shaped’ into vowels/consonants by tongue, cheek, lips

Question 56

Production of Sound

Answer 56

Rapid opening and closing of glottis→ sets up vibration pattern (produces sound) From release of air in lungs and vibration of vocal cords Length of vocal cords and size of glottis→ controlled by vagus nerve→ function is contraction/relaxation of muscles→ moves attached ligaments and cartilage Volume of voice→ controlled by strength of airflow (greater airflow; strong vibration, louder sound)

Question 57

Production of airflow

Answer 57

Air expelled from lungs automatically as breathe/speak Force of air must be great enough to push open vocal cords (by relaxing diaphragm so pressure in chest is higher than outside body) Air forced out → to equalise air pressure inside and outside

Question 58

Outline and compare the detection of vibrations by insects, fish and mammals INSECTS

Answer 58

Receive sound and vibrations at same frequency of sound detected Bristles on insect cuticle and antennae→ respond to low freq vibrations Crickets→ tympanum (drum) on leg below knee→ enclosed by eardrum; nerve fibres pick up vibrations Butterflies/moths→ Have tympani at base of wings Pair of membranes in tympana; connected to auditory organ by short tendon at base of abdomen

Question 59

Outline and compare the detection of vibrations by insects, fish and mammals FISH

Answer 59

Hearing abilities vary between species All fish→ Lateral line, pronounced pair of sensory organs, pair of sensory canals→ run each side of animal Surrounding water; pressure waves→ distort sensory cells in canals→ Send message to nerves Some fish→ sound waves by inner ear (with sensory chamber→ contains ear stone and lined with hair cells) Auditory nerves→ detect differences in vibrations between hair cells and ear stones

Question 60

Outline and compare the detection of vibrations by insects, fish and mammals MAMMALS

Answer 60

Ear→ detect vibrations of air particles within ecosystems Killer whale→ receive sound by lower jawbones (fat filled cavity extends back to ear-bone complex) Sound waves received and conducted by jaw (thin, hollow bone), middle ear, inner ear and auditory nerve→ brain Dolphins→ close ear canals when diving→ detect vibrations through head and some frequency through

Question 61

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions PINNA/AURICLE

Answer 61

Structure: Outer ear (with auditory canal and outer eardrum) Either side of head (cartilage) → Low blood supply Function: Helps localise sound waves coming to ears Glands in cartilage→ produce earwax (traps dust→ prevents reaching eardrum) Relate structure to function: Either side of head→ localise sound waves Glands produce earwax→ protect ear

Question 62

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions TYMPANIC MEMBRANE/EARDRUM

Answer 62

``` Structure: Taunt membrane (3 layers) → continuous with auditory canal ``` Function: Airborne sound waves→ vibrations in tight membranes Membrane grows continuously→ allows self repair after damage Relate structure to function: Taunt membrane→ wave vibration; response to sound

Question 63

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions OSSICLES (BONES)

Answer 63

Structure: 3 small bones (middle ear) Malleus; (Hammer) → lies towards side of head; ‘handle’ attached to inner layer of eardrum Incus; (Anvil) → Attached to hammer; long process attached to stapes Stapes; (Stirrup) → Footplate rests on oval window Function: When eardrum vibrates→ malleus vibrates→ passes vibrations to incus Incoming sound given boost→ (long process of incus shorter than long process of malleus) As incus vibrates→ footplate of stapes→ vibrating area of eardrum larger than vibrating area of stapes Relate structure to function: Bones vibrate and pass onto next→ sound travel

Question 64

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions OVAL WINDOW

Answer 64

Structure: Membrane between middle and inner ear (cover opening in cochlea case) Function: Separates middle ear from inner ear fluid (holds it in cochlea) As stapes vibrates→ window vibrates→ sends waves through fluid Relate structure to function: Membrane separates middle ear and inner ear fluid, holds fluid in for vibrations

Question 65

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions ROUND WINDOW

Answer 65

Structure: Membrane; base of lower canal of cochlea Function: Allows release of hydraulic pressure of fluid; caused by vibrations of stapes in oval window Relate structure to function: Membrane allowing for release of pressure from fluid by vibrations

Question 66

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions COCHLEA

Answer 66

Structure: 3 canals filled with fluid; separated by 2 membranes Upper canal; begins at oval window→ filled with fluid (perilymph) Lower canal; base of cochlea→ continuous with upper canal and ends at round window Middle canal→ contains endolymph→ separated from upper canal (Reissner's membrane) and lower canal (Basilar membrane) Function: Vibration wave patterns from stapes→ set up vibration in membranes and perilymph/endolymph Middle canal→ Holds organ of corti Relate structure to function: 3 canals→ vibrational waves travel to membrane→ travel through cochlea

Question 67

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions ORGAN OF CORTI

Answer 67

Structure: Tectorial membrane→ covers inner and outer hair cells (outer hair→ muscle like filament. Inner hair→ Nerve fibre attached) Basilar membrane→ Separates middle and lowest canal→ ribbon like structure; broader end towards oval window Pillars of Corti→ Cells bind tunnel and run entire cochlear length Function: Sense organ of hearing→ changes mechanical energy to electrochemical energy Sends messages to brain (vibration frequency, intensity, duration of sound) Tectorial membrane→holds cilia of outer hair cells Basilar membrane→ changes position in response to wave causing cilia movement Produce sensation of hearing High frequencies coded at end of basilar membrane (near oval window) Low frequencies at narrow end Relate structure to function: Middle canal→ convert to electrochemical energy; send messages to brain→ sensation of hearing

Question 68

Gather process and analyse information from secondary sources on the structure of a mammalian ear to relate structures to functions AUDITORY NERVE

Answer 68

Structure: Leads from cochlea and organ of balance→ correct perception centre of brain Function: Transmits neural energy from cochlea to brain

Question 69

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 HUMANS, DOLPHINS, BATS

Answer 69

HUMANS Range of detected sounds (hZ) → 20-20,000 Reasons: Basilar membrane flexibility→ limits freq range of human hearing Evolution→ less reliance on hearing for survival Humans→ 3D vision→ eliminates need for echolocation DOLPHINS Range of detected sounds (hZ) → 150-150,000 Reasons: Dolphins can’t rely on sight all the time High freq clicking sound→ shorter wave; used in dark waters→ locate food Low freq sounds travel further in water→ whistles to communicate BATS Range of detected sounds (hZ) → 1.0- 120,000 Reasons: Active in dawn/dusk and night→ dark→ rely on echolocation for navigation/prey Higher freq→ more detailed messages about surroundings

Question 70

Hearing Aid and Cochlear Implant: CANDIDATES

Answer 70

HA All ages→ some residual hearing Success→ depends on how individual processes sound (differs for each person) CI Severe to profound hearing loss No minimum age; (Youngest; 5 months. Oldest: 91 years)

Question 71

Hearing Aid and Cochlear Implant: DESCRIPTION

Answer 71

HA: Artificial device; battery operated (5 parts) Digital sound processor, converter, amplifier, microphone, earphone Amplifies vibrations→ physically stimulates cochlea nerves CI: Artificial device; battery operated (3 parts): Headset (microphone and coil) Speech processor and the implant Electronically stimulates cochlea nerves

Question 72

Hearing Aid and Cochlear Implant: POSITIONING

Answer 72

HA: Miniaturized; sits inside curve of pinna and ear canal Worn externally CI: Speech processor and microphone worn externally Implant (receiver package and electron array) surgically placed inside skull and inner ear as cochlea

Question 73

Hearing Aid and Cochlear Implant: ENERGY TRANSFER

Answer 73

HA: Sound waves picked up by microphone→ magnified by amplifier Channeled into auditory canal by earphone→ then normal pathway to eardrum, ossicles, cochlea, auditory nerve CI: Sound waves; picked up by microphone→ converted to electrical code (speech processor) → transmitted to implant Transfers signal to electrical pulses→ stimulate cochlea nerve Electrochemical messages to brain; decoded

Question 74

Hearing Aid and Cochlear Implant: CONDITIONS OF TECH ASSISTING HEARING

Answer 74

HA: Middle ear; damaged eardrum or ossicles People with residual hearing Sensorineural and conductive hearing loss; bypasses middle ear CI: Inner ear; damaged hair cells in cochlea Bypasses eardrum, middle ear, cochlea For totally deaf→ no benefit from hearing aids

Question 75

Hearing Aid and Cochlear Implant: LIMITATIONS

Answer 75

HA: No surgery, no side effects Inexpensive Programmable, background noise amplified Distance limited to less than 3m Doesn't work if damage to inner ear, or auditory nerve Used at any age Wearer may still depend on lip reading CI: Requires surgery, side effects Expensive with ongoing costs Programming needs to be adjusted for on phone, dining with friends etc Background noise amplified Distance limited; effective over 15m Deaf when not wearing Works best before age of 5 years; harder to teach older people to interpret sounds Wearer may still depend on lip reading

Question 76

Outline the role of the Eustachian tube

Answer 76

Middle ear opens in the Eustachian tube→ leads to pharynx, equalises pressure on either side of eardrum Tube usually closed and flattened by swallowing. Yawning opens it for sufficient time to equalise pressure between middle ear and external environment

Question 77

Outline the path of a sound wave through the external, middle and inner ear and identify the energy transformations that occur

Answer 77

Sound energy→ wave through air into auditory canal to outer eardrum Kinetic energy→ vibrations from eardrum→ ossicles→ oval window Stapes vibrate oval window→ pressure in perilymph (upper canal) Residents membrane moves→ kinetic energy to endolymph Vibrates basilar membrane→ stimulates hair cells in organ of Corti (send messages on nerves) Kinetic energy now converted to electrochemical energy as info is transmitted→ nerve impulses from bakes to auditory nerve to brain Sound emitted→ vibrating air enters outer ear [SOUND ENERGY] Eardrum vibrates at same frequency → ossicles vibrate→ fluids in inner ear vibrate, then membranes→ tension on hair cells in organ of Corti [KINETIC ENERGY] Neurons transfer nerve impulses to brain→ interpreted as sound [ELECTRO- CHEMICAL ENERGY]

Question 78

Describe the relationship between the distribution of the hair cells in the organ of Corti and the detection of sounds of different frequencies

Answer 78

Organ of Corti→ On top of basilar membrane (made of supporting cells and 15,500 hearing receptor cells- cochlea hair cells) Not replaced as they die. One row of inner hair cells and 3 outer rows Fibres of cochlea nerve coiled around bases of hair cells Activation of hair cells at points of high vibration of basilar membrane Hair cells at base (oval window) stimulated by high pitch sound. At narrow end of cochlea (apex) need low pitched sound Inner hair cells responsible for sending most of auditory messages to brain

Question 79

Outline the role of the sound shadow cast by the head in the location of the sound

Answer 79

Noise coming from right→ reaches right ear first To reach left ear→ must travel around head or through head Head absorbs high frequencies easier than low→ causes sound shadow cast over ear furthest away from sound source Sound shadow enables humans to determine direction of the sound

Question 80

Identify that a nerve is a bundle of neuronal fibres

Answer 80

No neurons exactly alike, but all have three parts: Cell body, dendrites (extension that conduct nerve impulses to cell body) and axon (extension that conducts impulses away from cell body) Nerve fibres transmit info rapidly along entire length, pass onto successive neurons Dendrites, axons → fluid filled tubes, surrounded by fatty insulating layer (myelin sheath) Myelin sheath: built as layers, supported by Schwann cells on outside Cell body of neuron→ usually in brain or spinal cord→ axons/densities extend towards organ Ion channels function in action potential→ concentrated in node regions of axons Action potential jumps from node to node→ skips insulated region in membrane between node If impulse travels from sensory organ to CNS→ dendron called sensory fibre If impulse passes from CNS to muscle or gland→ axon called motor fibre

Question 81

3 types of nerve cells: (make up nervous system)

Answer 81

Sensory neurons→ Transmit impulses from sense organs to other neurons in CNS Motor neurons→ Transmit impulses from CNS to muscles and glands Connector neurons→ Connect sensory and motor, (usually in brain/spinal cord)

Question 82

Perform a first hand investigation using stained prepared slides and/or electron micrographs to gather information about the structure of neurones and nerves (NERVE CELL)

Answer 82

Cell body is central structure with neuritis (long, thin structures) radiating outwards from it Neurone→ term for processes connecting nerve cells together to form network of nervous tissue Can be either receiving (dendrites) or transmitting (axon) nerve impulses

Question 83

Identify neurons as nerve cells that are the transmitters of signals by electro-chemical changes in their membranes

Answer 83

Nerves transmit signals along neuronal membranes and by chemicals from one neuron to next

Question 84

Neurones contain ions:

Answer 84

Body is electrically neutral (same number of positive and negative charges) Potential difference: Voltage measured between 2 points; exists across every cell plasma membrane Side of membrane exposed to cytoplasm (negative) Side exposed to extracellular fluid (positive) Differences on either side → cellular voltage (resting potential→ -70mV) indicates inside if membrane is negative (polarised) Occurs due to neurons containing ions (charged particles) Membranes selectively permeable to Na+ and Cl- (due to ion channels) When ion channel pores open→ ions move from one side of membrane to other Each channel→ allows only a specific type of ion to diffuse through it

Question 85

Depolarisation and action potential

Answer 85

Changes in neurone environment→ can affect permeability of plasma membrane to ions→ changes membrane potential Cell membrane potential can change in response to stimulation→ A positive shift in membrane potential from -70mV to -40mV→ called depolarisation If depolarization strong enough→ flow causes ions to generate nerve impulse (action potential) Action potentials→ transmitted from neurone to neurone across synapses (small gaps between end of axon and dendrites) → movement in 1 direction only At synapse→ neurotransmitters diffuse across gap from one neurone membrane of receiving neurone→ causes electrical response

Question 86

Perform a first hand investigation to examine an appropriate mammalian brain or model of a human brain to gather information to distinguish the cerebrum, cerebellum and medulla oblongata and locate the regions involved in speech, sight and sound perception

Answer 86

Sheep dissection; label pins onto the regions. Then dissect the brain in half and identify grey matter

Question 87

Cerebrum

Answer 87

Mass of wrinkled tissue(makes up 90% of brain) Responsible for complex thoughts, senses, muscle control, memory, thinking

Question 88

Medulla Oblongata

Answer 88

"Stem" of brain Controls activities not requiring conscious thought (Breathing, heartbeat)

Question 89

Cerebellum

Answer 89

"Base" of brain Controls complex muscle movements (cycling, running, walking)

Question 90

Define the term ‘threshold” and explain why not all stimuli generate an action potential

Answer 90

Threshold: Amount of positive charge in membrane potential required before action potential produced Depolarisation: Must reach a threshold at least 15 mV more positive than resting potential (-70mV) → No action potential produced if depolarisation below this level Each stimulus produces either full action potential, or none at all Each one is separate event→ a cell can’t produce another until previous is complete

Question 91

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound Cerebrum:

Answer 91

Split into 2 hemispheres (left and right) → divided into 5 lobes Each hemisphere receives impulses and exerts control over opposite body side Under tough protective covering, surface drawn into folds→ triples surface area Most of activities occur on outer surface (in layer of grey matter) Activities: 3 categories: Motor (movement) sensory (senses) and associative (reason and logic)

Question 92

Identify those areas of the cerebrum involved in the perception and interpretation of light and sound Light and sound and the cerebrum

Answer 92

Optic nerve→ sensory vision nerve, pass through skull via opening in eye socket Nerves from each eye→ partly cross over to form optic cross: provide each visual cortex with same image, (but each eye receives image at slightly different angles) Visual cortex in occipital lobe of each cerebral hemisphere Auditory nerves→ from cochlea and vestibule in inner ear→ merge to form one nerve (vestibulocochlear) From organ of Corti to auditory cortex in temporal lobe in each cerebral hemisphere

Question 93

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour OVERVIEW

Answer 93

Stimuli must be received and transmitted to brain before being interpreted and response Variety of reasons can cause ‘short circuit’ Lack of stimulus z(e.g. Cataracts, ear canal blockage) Trauma (E.g. Severing or damage to nerves, concussion) Lack of oxygen (asphyxiation, stroke) Legal/illegal drug reaction (alcohol, anaesthetic, sedatives) Age related or deterioration

Question 94

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour MULTIPLE SCLEROSIS (MS)

Answer 94

Autoimmune disease→ immune attack by body on own myelin protein Gradually myelin sheath destroyed Insulating layer non functional→ impulses short circuited, impulse stops Common symptoms: Problems controlling muscles

Question 95

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour Alcohol, anaesthetics and sedatives

Answer 95

All impair message transmission→ block nerve impulses (reduce plasma membranes permeability to sodium ions) If no sodium entry→ no action potential→ no nerve impulse Common symptoms: Poor coordination, tiredness, blurred vision and speech, retarded reflexes

Question 96

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour Cerebral Palsy

Answer 96

Caused by: Temporary lack of oxygen to a baby during difficult delivery Voluntary muscles lack coordination due to brain cell damage Brain cells can't transmit message to muscles→ muscles can't be controlled Common symptoms: Movement, speech, hearing,mission impairments

Question 97

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour Neurofibromatosis (Elephant man disease)

Answer 97

2 types: NF1 and NF2→ both genetic disorders: tumours grow along various nerves NF1 Common symptoms: Coffee coloured birthmarks and tumours in or under skin Tumours may develop on brain, spinal cord (learning difficulties) NF2 Much rarer, multiple tumours on nerves of spine and brain Common symptoms: Hearing loss in teens (tumours affecting auditory nerve)

Question 98

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour Rubella (German Measles)

Answer 98

Caused by rubella virus→ causes rash, fever, some respiratory tract infection (no more than common cold) Women contract in 1st 3 months of pregnancy→ virus may pass onto developing baby Damage to brain and spinal cord→ lack of transmission of nerve signals to organs Baby could be affected by rubella congenital syndrome (RCS) Common symptoms of RCS High rubella antibody level, cataracts, hearing loss, problems with development of spinal cord, spleen, liver, bones

Question 99

Explain using specific examples, the importance of correct interpretation of sensory signals by the brain for the coordination of animal behaviour Age related damage or deterioration

Answer 99

Human brain→ reaches max size in young adulthood→ after: neurons may die or be damaged→ contributed to gradual loss of weight and brain volume In total→ change is minimal Common symptoms Decline in reaction time and speed of decision making Some memory loss