4. Communication

Question 1

Identify the role of the receptor

Answer 1

To convert energy into nervous messages which can be transmitted throughout the body.

Question 2

Identify the purpose of communication

Answer 2

Increase efficiency when:

• collecting poles
• warning a nearby predator
• hunting and defending resources
• nest building, raising and protecting young

Question 3

Define: receptors

Answer 3

Sensory structures that fetch changes in the environment. Can be nerve endings, single receptor cells or receptor cells in groups.

Question 4

Identify and describe the five types of receptors

Answer 4

Mechanoreceptors: stimulated by forms or mechanical energy, such as pressure (touch), motion and sound. Hair cells are mechanoreceptors which can be found in the ear for hearing and they detect motion.
Nociceptors: detect excess heat, pressure and other stimuli which can create the sensation of pain.
Thermoreceptors: respond to heat energy, helping to regulate body temperature. These receptors send nervous impulses to the hypothalamus.
Chemoreceptors: detect changes in the osmolarity (solute concentration) of blood and can stimulate the reabsorption of water from the kidneys. Other receptors respond to specific molecules, or can produce taste and smell.
Electromagnetic receptors: detect electromagnetic energy much as light, electricity and magnetism. Photoreceptors detect visible light and are responsible for sight. Electroreceptors can detect electric fields in order to detect surroundings (such as in platypuses)

Question 5

Explain the stimulus response pathway

Answer 5

1. Stimulus: a change in the environment that stimulates one or more receptors
2. Receptor sends nerves impulses to messenger
3. Sensory nerve sends impulse to the CNS which coordinates a response
4. Messengers (motor neurones) send impulses to effectors to carry out response
5. Organisms responds to stimuli.

Question 6

Identify the two communication systems and where they intersect

Answer 6

Nervous system
Endocrine system
Hypothalamus

Question 7

Describe the different between a sensation and a stimulus.

Answer 7

A sensation is not a stimulus. A sensation is the feeling we experience when the nerve impulses fro the stimulus arrives in the brain

Question 8

Identify how different organisms use three different sense

Answer 8

Auditory: Bat; uses ultrasound and ears to eco-locate surroundings. Can locate prey and its environment at night.
Olfactory: silkworm moths; females emit pheromones that males detect by chemoreceptors in their antennae. When moths are together, pheromones also trigger courtship behaviours
Tactile: Chimps; greet each other with touch to establish social relationship.

Question 9

Define: Visual Acuity

Answer 9

The ability to see objects sharply and clearly

Question 10

Identify the structure and function of the conjunctiva

Answer 10

S: Layer of surface cells, forming mucous membrane of inner surface of eyelid and outer surface of sclera
F: keep eye moist

Question 11

Identify the structure and function or the cornea

Answer 11

S: At font, sclera becomes transparent cornea.
No blood vessels
Cells obtain oxygen from tears
Form nerve endings 
F: Fixed lens
Does 60% of light refraction

Question 12

Identify the structure and function of the sclera

Answer 12

S: tough, connective tissue, thickest as the back of the eye, surface contains small blood vessels and nerves
F: mechanical support and physical protection. Attachment site for 6 muscles, assist in focussing process

Question 13

Identify the striation and function of the choroid

Answer 13

S: thin layer of between sclera and retina. Extensive blood capillaries, cell secrete melanin
F: deliver blood and oxygen to retina, prevent internal refraction of light into the eye.

Question 14

Identify the structure and function of the retina

Answer 14

S: Photosensitive layer, outer layer of cells containing pigment, melanin
Thicker, inner layer containing photoreceptors (rods and cones), nerve cells and blood vessels
F:Melanin absorbs light to prevent reflection
Photoreceptor transforms lighting energy into electrical impulses that brain can read.
Liquid lens

Question 15

Identify the structure and function of the iris

Answer 15

S: Blood vessels, pigment cells and 2 layers of smooth muscle fibres
- Pupil-constricting muscles form a series of concentric circles around the pupil. In response to bright light, they contract and the diameter of the pupil decreases
- Pupil-dilating muscles extend radially away from the edge of the pupil. In response to dim light, they contract and the diameter of the pupil increases.
F: Muscles contract and relax to control amount of light that penetrates the eye

Question 16

Identify the structure and function of the lens

Answer 16

S: Lies behind the cornea and held in place by suspensory ligaments
Transparent colourless
No blood supply
F: Focus visual image into photoreceptors in retina by changing physical shape
Distance = flattened shape
Close object = spherical

Question 17

Identify the structure and function of the Aqueous Humour

Answer 17

S: In front of lens, behind cornea
Transparent colourless
Clear, watery fluid produced by ciliary body
F: Forms a fluid cushion and pressure to help maintain shape and stabilises position of retina
Provide nutrient supply and removal of wastes through tiny ducts

Question 18

Identify the structure and function of the Vitreous Humour

Answer 18

S: Behind lens
Transparent colourless
Does not circulate
Jelly-like 
F: No nutritional function
Maintains spherical shape
Supports retine 
Liquid lens

Question 19

Identify the structure and function of the ciliary body

Answer 19

S: Attached to outer edge of iris and junction of sclera and cornea
Ciliary muscle connected to suspensory ligaments that hold the lens in place
F: Contraction and relaxation to control amount of light that penetrates the eye

Question 20

Identify the structure and function of the optic nerve

Answer 20

S: Each nerve = 1 million nerve fibres
Meet at optic chiasm from both eyes
F: Carries visual information as electrical signals from photoreceptors to brain
Receives information from both eyes
Allows depth perception.
Right visual field goes to left occipital lobe.
Left visual field goes to right occipital lobe

Question 21

Describe the limited wavelength of light detected by humans and compare with other organisms

Answer 21

Light is a type of electromagnetic radiation. Visible light is a small band on the electromagnetic spectrum, also including gamma, UV rays.
Humans can only see wavelengths between 380-780 nanometers.
Bees can detect UV radiation (shorter than 380nm).
Rattlesnakes can detect infrared radiation (greater then 780)

Question 22

Identify the condition in which the refraction of light occurs

Answer 22

Light changes speed when it moves through different medium (300,000km/s in air). This causes it to change direction, referred to as refraction.
Light rays bend in different ways depending on the shape of the transparent media. In Concave lens, the light rays diverge, and in convex they converge.
The point in which all light rays meet is the focal point.

Question 23

Identify the refractive media in the eye

Answer 23

Visual acuity of the eye depends on the image being clear, which is achieved by the focal point landing on the retina. 
Cornea: 60% of refraction
Aqueous Humour
Lens: 40% of refraction 
Vitreous Humour

Question 24

Define: accomodation

Answer 24

The process in which ciliary muscles expand and contract to change the convexity of the lens, to adjust the focus of an object so the focal point of the refracting light is on the retina

Question 25

Describe how accomodation works when views close objects

Answer 25

ciliary muscles contract, causing sensory ligaments to relax, making the lens more spherical. The rounded shape increases the refracting power.

Question 26

Describe how accomodation works when view distant objects

Answer 26

ciliary muscles relax, causing sensory ligaments to pull at the edge of the lens, causing the lens to flatten and become narrow. Refracting power of the lens of low

Question 27

Define Myopia and technologies used to repair it

Answer 27

if the eyeball is too deep, or the restring curvature of the lens is too great, the focal point of an image of a distant object will form in front of the retina. As a result, an individual will see distant objects out of focus. To fix: Corrected by using concave (diverging) lenses. These lenses spread refracting light rays apart, as if the object were closer to the eye. Contact lenses: rest on cornea, using natural moisture to adhere to eye. The back surface of the contact lens is contoured to exactly fit the curvature of the cornea, in order to prevent scratching and damage. They provide a more normal image size as they are closer to the eye.

Question 28

Define Hyperopia and technologies used to fix it

Answer 28

if the eyeball is too shallow, or the resting curvature of the lens is to flat, the lens cannot provide enough refraction to focus near images onto the retina. As a result, the focal point occurs beyond the retina, causing blurry vision. To fix: Corrected by using convex (converging) lenses. These provide additional refraction.

Question 29

Identify technologies used to correct myopia and hyperopia

Answer 29

Radial keratotomy: surgically reshaping the cornea to alter its refractive power. A surgeon makes radial cuts with a diamond knife on the outer edge of the cornea. Corneal healing can take several years and there are concerns that the procedure creates weak points in the cornea. Photorefractive keratectomy: uses a computer-guided laser to shape cornea to exact specifications. However, issues with cloudiness of the cornea.

Question 30

Define: cataract

Answer 30

Abnormal lens that has lost its transparency. Lens takes on a 'yellowish' hue which causes objects to look hazy because of the irregular refraction of light and are dim because light of reflected off the lens rather than passing through the eye.

Question 31

Recount the cataract procedure

Answer 31

1. Eye is cleaned 2. Lens us removed thought a tiny incision, using ultra-sound to break it into pieces 3. New lens in inserted

Question 32

Describe the social impacts of cataract surgery,

Answer 32

Cataracts are the first cause of blindness in the world. Whilst the treatment is simple, 90% of all cataract patients are in developing countries, thus the financial and physical access to treatment is limited. Fred Hollows established eye lens factories in developing countries, enabling individuals to regain sight. In Nepal, Hollows was able to develop a cataract treatment for $7. The World Cataract Foundation is also involved in giving sight back to the impoverished.They supply countries with the intraocular lenses, equipment and medical supplies, yet train local doctors to perform the surgery.

Question 33

Identify and describe the two layers of the retina

Answer 33

1. Think inner layer of photoreceptors and neurones | 2. Thin outer layer of cells containing melanin that absorb light to prevent reflection

Question 34

Identify the role of the photoreceptor in the eye

Answer 34

To convert light energy into electrochemical impulses which ca be transmitted to the visual cortex of the occipital lobe in the brain.

Question 35

Describe the structure and function of rod photoreceptors

Answer 35

S: outer segment of seperate membraneous discs which contains rhodopsin. Must be transparent colourless F: Operate in dim light and the white/grey/black scale. It cannot discriminate between different colours. They contain rhodopsin which converts light energy to an electrochemical impulse. It is sensitive to blue/green light.

Question 36

Describe the structure and function of cone photoreceptors

Answer 36

S: Outer segment of infolding membrane that contain opsin. Must be transparent colourless and responds to red/green/blue light. F: operate in bright light and enable colour vision. three types: red/green/blue. The ratio of the three cones determines the shade of colour interpreted.

Question 37

Identify the process of converting light into an image

Answer 37

1. Light emitted from source 2. Light enters eye and moves through refractive media 3. Light is absorbed by rod and come photoreceptors 4. Receptors undergo chemical change to convert stimulus to electrochemical impulse 5. Impulse is transmitted from photoreceptor-bipolar cells-ganglion cell body to the ganglion axon, which forms the optic nerve.

Question 38

Compare the distribution of rods and cones in the eye

Answer 38

Rods: 125 million scattered around the retina, excepting the fovea. Cones: primarily in the retina (5 million)

Question 39

Describe the role of rhodopsin in rods and how it works

Answer 39

Rhodopsin in a pigment that absorbs light energy. It is made of opsin and a retinal molecule. It is sensitive to blue/green light. When light reaches the pigment, it undergoes a reversible chemical change where the bonds between the retinal molecule and opsin are broken, generating an electrical impulse.

Question 40

Define colourblindness and how it is caused

Answer 40

Colourblindness is the inability to distinguish between certain colours. It occurs when one or more types of cones do not function properly, they are unable to produce the necessary visual pigment or they are completely absent. Red/Green colour blindness is the most common and it is a recessive sex-linked trait.

Question 41

Describe the photoreceptor cells in an insect compound eye

Answer 41

Ommatidia are large photoreceptors, thus producing a less focussed image. It has individual corneas at the top of each cells which are crystalline and thus cannot change shape. There are 16 thousand.

Question 42

Describe the photoreceptor cells in a planarian simple eye

Answer 42

Pigment cup containing fluid to refract light. Few pigment cells and can only distinguish between the intensity and light and dark.

Question 43

Describe how different animals use colour to communicate

Answer 43

Communicating with colour occurs in animal groups whose eyes can detect colour. Birds - Male red-winged blackbird: bright red shoulder patch during mating season - Rainbow Lorikeet: intimidate rivals by spreading wings to expose colour Fish: male sticklebacks - develop red bellies to attract females Primates: male mandrill - bright colours to establish dominance and colours intensify when excited or angered.

Question 44

Explain why sound is useful

Answer 44

Sound is useful as it does not require contact or closeness and all organisms are surrounded my a medium that transports sound. Sound can be used when light can't.

Question 45

Describe the nature of sound waves

Answer 45

Sound waves move through a medium and are produced when an object vibrates. This is because the vibrating objects make the air pressure around them compress and rarefy. It is these compressions and rarefactions that produce sound.

Question 46

Define the term frequency in relation to sound waves and what it influences

Answer 46

Frequency refers to the rate of compressions or the rate of vibrations. Measured in Hertz. It influences the pitch of sound

Question 47

Define amplitude in relation to sound waves and what it influences

Answer 47

Amplitude is the maximum displacement of particles from the resting position and determines the volume of sound.

Question 48

Describe the structure of the larynx and the nature of sound production

Answer 48

Cylinder with cartilaginous walls that are stabilised by skeletal muscles. Upper opening is the glottis and is protected by the epiglottis. Arytenoid cartilage anchors the true vocal chords which lie under a mucus lining. Vestibular vocal chords (false) lie above the true vocal chords to assist in lubricating. Sound production (phonation) is caused when the vocal chords are tensed by muscles in the larynx, which then vibrate when strong air currents are passed between them.

Question 49

Identify the conditions that influence the pitch of sound

Answer 49

Dependant on the diameter, length and tension of vocal chords. Open larynx - short and tight chords - vibrate fast - high pitch Closed larynx - long and relaxed chords - vibrate slow - low pitch

Question 50

Identify and describe the three processes the aid in phonation

Answer 50

Phonation is the production of intelligible sounds. 1. Production of airflow: diaphragm and intercostal muscles expand and contract 2. Production of sound: rapid vibrations of the vocal chords 3. Articulation of voice.

Question 51

Identify the structures that aid in articulation, power, sound and resonance

Answer 51

A: tongue, mouth, lips and palette P: lungs, diaphragm and intercostal muscles S: larynx R: nasal cavity and sinuses

Question 52

Describe how three different animals communicate with sound

Answer 52

Grasshopper: brush stuff hairs on legs, scrape back legs against front legs Fish: moves bones/teeth against each other, vibrate gills, grunts by muscles in the bladder Dolphin: tissue complex of nasal region, movement of air in trachea/nasal sacs, release air from blowhole, slap water with tail.

Question 53

Describe how fish detect vibrations

Answer 53

Detect pressure waves. Vibrations in water are conducted through the skeleton of the head to the inner ear. Lateral line system has mechanoreceptors containing a cluster of hair cells in a cupula. The pressure of the water bends the cupula, generating an electrochemical impulse.

Question 54

Describe how insects detect vibrations

Answer 54

Detect low frequency vibrations Insects have a tympanic membrane stretched over an internal air chamber on their legs. Sound waves vibrate the membrane and receptor cells generate an impulse.

Question 55

Describe the structure and function of the pinna

Answer 55

S: soft cartilage, part of the outer ear F: collects sound waves to channel through the auditory canal

Question 56

Describe the structure and function of the tympanic membrane

Answer 56

S: thin delicate sheet separating outer and middle ear F: Vibrate due to the sound waves at the same frequency as the sound waves they hit it. Sound energy transformed to mechanical energy

Question 57

Describe the structure and function of the ear ossicles

Answer 57

S: 1. Malleus: smallest bone and connected to tympanic membrane. Articulates with the incus. 2. Incus: bone between malleus and stapes 3: Stapes: shaped like a stirrup, connects incus to the oval window F: work as a series of levers to conduct vibrations to the fluid-filled inner ear. Amplifies sound by 20x

Question 58

Describe the structure and function of the oval window

Answer 58

S: membrane that divides middle ear and inner ear F: transferring the mechanical energy from middle ear into the inner ear

Question 59

Describe the structure and function of the round window

Answer 59

S: membrane separating fluid-filled cochlea from air-filled middle ear. F: equalise the pressure on the cochlea

Question 60

Describe the structure and function of the cochlea

Answer 60

S: 1. Vestibular canal: houses organ of Corti and contains hair cells 2: Tympanic canal Converts mechanical energy into electrochemical energy F: House and protect organ of Corti

Question 61

Describe the structure and function of the organ of Corti

Answer 61

S: located on floor of basilar membrane. Fluid filled and location of hair cells for all frequencies between 20-20,--- Hz F: hair cells at the corresponding frequency of sound bend in response to the mechanical energy to generate and electrochemical impulse to the auditory nerve.

Question 62

Describe the structure and function of the auditory nerve

Answer 62

S: nerve connecting each hair cells in organ of Corti to the hearing centre of the temporal lobe of the brain F: transmit electrochemical signal from hair cells to hearing cortex.

Question 63

Describe the structure and function of the Eustachian Tube

Answer 63

S: connects pharynx to the middle ear F: equalises the pressure on their side of the ear drum

Question 64

Describe the 6 major steps in the process of hearing

Answer 64

1. Sound waves arrive at the tympanic membrane 2. Movement of tympanic membrane causes movement of ear ossicles 3. Movement of stapes at the oval window produces pressure waves in the fluid of the cochlea 4. The pressure waves distort the basilar membrane on their way to the round window 5. Vibrations of the basilar membrane cause vibrations of hair cells against the tectorial membrane 6. Information is carried to the brain along auditory nerves

Question 65

Summaries the energy transformations in the hearing process

Answer 65

1. Sound energy is transformed to mechanical energy at the tympanic membrane 2. Stimulates hair cells transformed energy into an electrochemical signal.

Question 66

Describe the sound shadow cast by the head

Answer 66

Nervous pathways from each ear to the brain are separate. This is because the ear are separated by the width of the head so there is a time difference from when sound reaches the brain from each ear. At low frequencies, the brain is able to determine the time difference. At high frequencies, there is much less bending of sound waves around the head, so that the head casts a sonic shadow. At high frequencies, it is the intensity of sound that enables the brain to determine direction.

Question 67

Describe the range of sounds a bat detects and how the frequency range is used

Answer 67

Greatest sensitivity 10,000-70,000 Hz. Bats use echolocation to perceive the position of prey and surroundings. They emit sounds of a similar frequency so that the wavelengths are shorter than the objects, enabling the objects to reflect the sound with greater detail. Bats thus must be able to also detect waves at the frequency. This is facilitated by large mobile pinnas.

Question 68

Describe the range of sounds a bat detects and how the frequency range is used,

Answer 68

50,000-200,000 Hz. Dolphins use echolocations. They produce sound in the larynx of a high frequency and thus they must also be able to detect these frequencies. The velocity of sound is greater in water than in air.

Question 69

Describe a hearing aid in relation to energy transfer occurring, conditions under which technology assists hearing and limitations

Answer 69

Energy transfer: sound - electrical - sound - mechanical - electrochemical Conditions: only works for people with conductive hearing loss (issues with sound in outer or middle ear). They increase loudness by using a microphone and amplifier. Limitations: can only be used to amplify sound; they do not aid in the stimulation of nerve fibres in the cochlea.

Question 70

Describe a cochlea implant in relation to energy transfer occurring, conditions under which technology assists hearing and limitations

Answer 70

Energy transfer: sound - electrical - electrochemical Conditions: used for profoundly deaf people, if their auditory nerves remain functional. It consists of electrodes embedded in the cochlea of the inner ear and bypasses dead hair cells and simulates the auditory nerve. A microphone detects sound signals and transmits them to a microprocessor which converts them to an electrical signal. These signals stimulate the auditory nerve endings. Limitations: only produces sound in the frequency range of normal speech. It is not able to replicate all the frequencies available by fully functioning hair cells. Individuals must thus learn to recognise the meaning and origin of sound.

Question 71

Identify the three main functions of the nervous system

Answer 71

1. Sensory input 2. Integration 3. Motor output

Question 72

Define: nerve

Answer 72

A bundle of axons, blood vessels and connective tissue.

Question 73

Identify the function of the axon

Answer 73

Long segments fibre which transmits information away from soma towards other neurones or effectors

Question 74

Identify the function of the Nodes of Ranvier

Answer 74

'Breaks' in the Myelin Sheath which generate impulses. Ions are transferred here.

Question 75

Identify the function of the Myelin Sheath

Answer 75

Layer of fatty tissue surrounding axon, prodives insulation to nerve impulses to allow fast transmission

Question 76

Identify the function of the Axon Terminal

Answer 76

Distal end of a nerve cell where neurotransmitters are stored in vesicles to be released into the synapse.

Question 77

Identify the function of the neurotransmitter

Answer 77

Chemical released into the synapse to allow transmission of a nerve impulse across the synapse

Question 78

Define nerve impulses

Answer 78

Electrical signals that depend on the flow of ions across the cell membrane, beginning as a change in the electrical gradient across the cell membrane. All cells have an electrical voltage difference across the membrane, referred to as the 'membrane potential' (-70mV)

Question 79

Describe the concentration of ions inside and outside a nerve cells

Answer 79

Inside: high concentration of potassium ions, small concentration of sodium ions and large negatively charged proteins and amino acids Outside: high concentration of sodium ions, small concentration of potassium ions.

Question 80

Describe the action potential process

Answer 80

Nerve cells respond to stimuli, which result in changes to the membrane potential. Initially, depolarisation occurs in which ion channels open and sodium ions move into the cell, making the inside more positive than the outside. If this reaches -55mV, the action potential will occur. The depolarising phase then occurs in which the membrane potential returns to its resting potential as a result on an increased flow of potassium ions outside of the cell. A refractory period occurs to return the cell to its resting potential using a sodium-potassium pump.

Question 81

Describe how chemical synapses occur

Answer 81

When the action potential arrives at the axon terminal, it stimulates the release of neurotransmitters from synaptic vesicles, which then diffuse to the receptors in the next neurone's dendrites. This triggers an action potential in the next nerve

Question 82

Identify the four lobes of the brain

Answer 82

Occipital, temporal, parietal, frontal

Question 83

Summarise the requirements for behaviour

Answer 83

Behaviour requires the detection of stimuli by sensory receptors, the transmission of information through the nervous system, and the correct interpretation of the signals by the brain to coordinate the behaviour.

Question 84

Distinguish between innate and learned behaviour

Answer 84

I: genetic inheritance of an animal. It occurs automatically in response to a specific stimulus. (e.g.: web construction by spiders) L: modified by experience. Stoke to the Broccas area can inhibit an individual's ability to form speech, a stroke to the Wernicke's area can inhibit the individual's ability to process and comprehend speech.