Coordination Nervous

8/3/2019 Coordination Nervous

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Coordination Year 06 Paper I 7(5)Q:

The table below contains some information related to the functions of the ear. Complete the

table with suitable words: (5 marks)

Function of ear Hearing Balance

Stimulus Sound (a)

Location of receptors (b) Semicircular canals

Nerve transmittingimpulses fromreceptors to the brain

(c)

Vestibular nerve

Part of brain to receivesensory input from theear

(d) (e)

A:

(a) movement of head (1) (5)

(b) cochlea (1) / Organ of Corti

(c) auditory nerve (1)

(d) cerebrum (1) / cerebral cortex(e) cerebellum (1)

Coordination Year 05 Paper I 4(6)Q:



(b) Name the event in phase B and state the direction of the net movement of Na* ions in this

phase. (2 marks)

(c) Describe how the change in membrane permeability to K* ions brings

about the drop in the membrane potential in phase C.

(2 marks)

A:

(b) *depolarization (1) (2)Na* moves into the axon (1)

(c) At phase C, the membrane permeability to K* increase (1) (2)

K* diffuses out of the axon (1), resulting in a lowering of the membrane

potential.

Coordination Year 04 Paper II 5a(10)Q:

(a) Reflexes are responses to various stimuli in both the internal and external environments.

Discuss with examples the importance of reflexes in the life of mammals.



(10 marks)

A:

(a)

Main concept:

‧ Importance in keeping homeostasis with examples to illustrate significance

‧ Protection of body from danger, with examples to illustrate significance

‧ Reactions to conduce body functions with examples to illustrate

significance

‧ Conditioned reflexes, with examples to illustrate significance

(Accept other correct alternatives)

e.g.

Homeostasis of several body parameters for optimal body function‧

homeostasis of breathing rate to ensure provision of oxygen for respiration /

clearance of carbon dioxide

homeostasis of heart rate to provide adequate nutrient supply to body cells / drainage

of metabolic product from tissues

homeostasis of temperature to maintain constant temperature for enzymatic

activities

‧ Reactions to protect body from damage

withdrawal from heat to protect the skin from getting burnt / scorched

blinking due to physical obstructions to protect the eyes from mechanical damage

(also accept tear production)

papillary reflex in control of pupil size to protect eyes from damage by strong light /

allow more light to reach the retina in dim light vision

coughing reflex to expel foreign particles from obstructing the trachea

‧ Reactions to conduct body function proprioceptors (muscles spindle ) for keeping muscle tone

‧ Conditioned reflex

learning to get new skills

salivation in anticipation of food to prepare for digestion in

Coordination Year 04 Paper I 6(3)

0416(3)Q:



(a) Identify and label two features in the above micrograph which are involved in the

transmission of nerve impulse and which are also found in the synaptic junction

(2 marks)

(b) Briefly describe the response of structure A upon the arrival of an impulse.

(1 marks)

A:

(a) correct identification and labeling of common features involved in impulse transmission

e.g.synaptic‧ *cleft

‧ *vesicles

(accept *pre-synaptic membrane)

(b) action slides towards myosin / myofilaments slide towards each other / sarcomere‧

shortens

Coordination Year 03 Paper I 1abd(12)



A:

(a) ‧ *fluid mosaic modal (1)

‧ fluidity: lateral movement of phospholipids molecules (1) (accept alternative

expression, e.g. membrane breaks and makes at points, exocytosis, endocytosis)

‧mosaic: protein molecules interspersed among phospholipid molecules (1)

(accept protein and phospholipid molecules fit into each other in a mosaic way)

(b) Structural-functional relationships:

Nature and arrangement Relationship with permeability

‧ phospholipid bilayer (1)

‧ hydrophobic tails of the

phospholipids molecules point

inwards (1) / hydrophobic core

‧ permeable to lipid- soluble / nonpolar substances (1)

‧ impermeable to polar substances (1)

transmembrane protein (1) /‧ embedded protein

permeable to polar substances (1)‧

(d) Y acts as a receptor or / and ion channel (1)‧

‧ neurotransmitter binds onto receptors on membrane (1)

‧ permeability to Na*increases (1) / ion channels for Na* will open

‧ Na* goes into the cell (1)

‧ Post-synaptic membrane depolarizes (1)

‧ Builds up an action potential which propagates as impulse (1) along the neurone

Coordination- nervous0225a(9)

Q: What are the roles played by the different parts of the nervous system in the

reception of various stimuli, signal integration and response initiation in the following

incident?

‘While riding a bicycle on the street, a boy saw a red traffic light in front and stopped

his bicycle.’ (9 marks)

A:

Terms with *, mark deduction for spelling error. Marks(a) Stimuli reception

(3)

(max. 4)

(max. 4)



cones on retina of eye stimulated by red light (1),*produce sensory impulse (1)

utriculus/ sacculus perceives position of head (1),

*generate sensory impulse (1)

semi-circular canals perceive rotational movement of the

head (1) at deceleration/ stopping

2

1

1

Signal integration association centre in the cerebral cortex (1) processes

impulses from the visual cortex (1) and medulla (1)/cerebellum, and relay them to the motor centre in thecerebral cortex (1)

4

Response initiation motor centre in cerebral cortex sends impulses (1)

to the muscles of the hands/ legs to stop bicycling (1)

sends impulses to other skeletal muscles to maintain

balance (1)

3

(N.B. *mark to be given once only, candidates must showthat they have attempted in all 3 areas to earn full mark of 9)

(max. 9)

0121(20)

Q: (a) In humans, sensory receptors convert stimuli into nervous signals. This process

is called transduction. State the exact location inside the ear where transduction occurs

when a man rotates his head. Use a flow chart to show the sequence of events starting

from the rotation of the head to the end of the transduction process. (6 marks)

(b) The structural features of a neurone can affect the rate of nervous impulse

conduction along the nerve fibre. State and explain one of these features. (2 marks)

(c) Compare and contrast the functions of the medulla oblongata and the spinal cord.

(5 marks)

(d) Describe how the automatic nervous system brings about responses of the

cardiovascular system when reacting to emergency situations. Explain the significance

of these responses. (7 marks)

A:

(a) Hair cells in ampulla(1) / ampulla of semi-circular canal

Transduction processmovement / inertia of endolymph in the semi-circular canals(1) deflection of cupula /



gelatinous mass(1) hair of sensory hair cell bent(1) depolarization of sensory hair

cell(1) (sensory hair cell stimulated 1/2 mark) action potential / nerve impulse initiated

in the nerve cell (1)

(b) Any one of the following: (1 mark for feature and effect, 1 mark for explanation) As the diameter of nerve fibre increases the rate of conduction increases(1), a

bigger diameter reduces the resistance to the conduction of nervous impulse(1)

Rate of conduction increases when nerve fibre is myelinated(1), as myelinated

sheath insulates the conduction of electrical current, impulse jumps from node to

node(1)

(c) Similarity:

- Both are reflex centers(1)

- Both act to relay ascending and descending impulses(1)

DifferencesSpinal cord Medulla

♦ No control/ regulatory center

♦ No chemoreceptors

♦ Reflex in trunk and limbs

♦ Contains other control/ regulatorycenters (1), that regulates heart rate(1)/ breathing rate

♦ Contains chemoreceptors (1) that

detect pH/ CO2 level in the body fluid

(1)

♦ Reflex in head also

N.B. No comparison, no mark #Unmatched comparison, 1/2 mark

(d) At emergency, sympathetic nervous system increases its output (1), resulted in more

noradrenaline released (1) to bring about the following:

Cardiovascular system Effect Significance♦ Heart

♦ Blood vessel

♦ rate↑(1)

♦ force of

contraction↑(1) / stoke

volume↑

♦ dilation of arterioles /

blood vessel to

skeletal muscle(1)

♦ constriction of

arterioles / blood

vessel to gut / smooth

muscle

More food / nutrient /glucose (any one) and O2

supply to the skeletalmuscles(1), to prepare for energy production / muscleactivity(1)



- stimulate adrenal medulla to secrete adrenaline which increases blood flow and

glucose supply to skeletal muscles (1)

- Parasympathetic nervous system decreases its output (1) / less acetylcholine at

emergency

0022(20)

Q:

(a) Explain how resting potential is maintained in a neurone. (6 marks)

(b) Contrast the transmission of a nervous signal within a neurone and its transmission

between neurones. (7 marks)

(c) It has been suggested that one of the initial functions of the auditory system in

vertebrates is to enable them to escape from dangers. Use a flow chart to show the

nervous pathway involved in the reception of auditory signals and the subsequent

voluntary escape movement. (7 marks)

A:

(a) - Na+ - K+ pump (1) at the membrane, pumps Na+ out of the cell (0.5) in exchange

for K+ (0.5) using energy (0.5)

- membrane of neurone is less permeable to Na+ and more permeable to K+ at

rest (1), tendency for more K+ to diffuse out (1), than Na+ diffusing in (0.5),

inside negative (0.5), outside positive (0.5)

(b)

transmission along the neurone transmission between neurones

- electrochemical in nature - chemical in nature 1- propagation of action potential (1)

as a result of depolarization of membrane (1)

- upon arrival of impulse,neurotransmitter released (1)from pre-synaptic knob

7- local current between the active

site and the neighbouring restingregion (1) depolarizes themembrane of the latter part (1)and elicit an action potential

- diffuses across the synapse andcombine with receptor (1) onpost-synaptic membrane (1),elicits an action potential in thesucceeding neurone

- fast - slow 1

(N.B.1. No contrast, no mark2. Accept diagrams showing equivalent and complete meaning.



3. Accept table form with notes showing complete concepts in comparison.)

(c) sensory cells in the organ of Corti/ cochlea/ sensory hair cells with hairs brushing

against tectorial membrane (1)

(1)auditory nerve

(Bonus = 1)

(bonus: mid-brain/ brain stem/ thalamus)

(1)

sensory cortex of cerebrum for audition

(1)

association centre in cerebrum

(1)

mortor cortex of cerebrum (1) cerebellum

(1)

spinal cord

(0.5)

motor neurone

(0.5)

muscle of the leg

(+ bonus = 1, max. 7)

(N.B. 1. If the concept of sound reception is wrong, mark the rest of the flow chart from

the symbol ↓downwards if sequence of voluntary escape is correct.2. No flow-chart given, deduct 2 marks: F = -2

3. More than one flow-charts give, deduct 1 mark: D = -1)

9917(6)

Q: The following photograph shows a section of the human brain and part of the spinal

cord:



(a) Contrast the nature of motor control of region 1with that of region 2. (1 mark)

(b) Region 3 contains areas that serve as chemoreceptors. State how these

chemoreceptors operate to bring about an increase in the rate and depth of

breathing. (4 marks)

(c) Name the hormone produced by region 4 that leads to lactation. (1 mark)

A:(a) 1 controls voluntary motor functions whereas 2 controls involuntary motor functions/

reflexes. (1)

(b) CO2 concentration in blood rises (1), H+ concentration in fluid in brain increases/ pH

decreases, detected by 3 (0.5), impulses will be sent from 3 (0.5) to the diaphragm

(0.5) and intercostal muscle (0.5) causing them to contract faster and more

powerfully (1).

(c) *oxytocin (1)

9821a(5)

Q: A man voluntarily bends his right arm.

(a) Describe the neural pathway involved. (5 marks)

A: Left () cerebral cortex (1/2) / motor area of cerebrum initiates (1/

2) impulse (1/2)

that travels along a neurone(1/2) / axon. Synapse (1/

2) with interneurone

() at the spinal cord (1/2). Synapse with a motor neurone (1/

2). Efferent

motor impulse (1/2) exits the spinal cord via the ventral root (1/

2),

reaches the muscle (1/2).

(max. 5)If afferent pathway is mentioned in addition to efferent pathway, total mark for (a)



is halved, denoted by WC =1/2, round up to the nearest integer.

Deduct for flow chart only, denote as F = -1/2

Deduct for point from answer, denoted as P -1/2

9813(7)

Q: In the mammalian ear, sensory receptors in the semicircular canals and the cochlea

are activated by fluid movement inside the ear. Describe how fluid movement is brought

about by natural stimulations and how this activates the two types of sensory receptors.

(7 marks)

A:

semicircular canals : when the head is rotated(0.5) / moved, the endolymph inside the

canals is moved(0.5) in the opposite direction of movement

due to inertia (0.5), displaces(0.5) the gelatinous mass

(cupulae) (0.5) in the ampullae (0.5) which deflects (0.5) the

hairs of the sensory receptors(0.5) max.3.5

cochlea : sound(0.5) sets the ear drum to vibrate(0.5), this vibration is conducted along

the ear ossicles(0.5)/ bones to the oval window(0.5), perilymph is disturbed /

vibrated(0.5) the endolymph in the cochlea is disturbed(0.5), endolymph

movement sets the basilar membrane into vibration(0.5), this deflects the hair

of the hair cells (0.5) 3.5(7)

9722c(5)

Q: Contrast tropic movements in flowering plants and reflex actions in mammals in

terms of the nature of stimuli, co-ordination and response. (5 marks)

A:

(c) Tropism in flowering plants Reflex actions in mammals

Stimulus : Unidirectional (1/2) － not unidirectional (1/2) 1

Co-

ordination :

Hormones (1/2) － nervous along neurone

(1/2)

1

Response : Directional (1/2) , uneven

growth (1/2) / growth (1/2)

curvature (1/2), long lasting

(1/2), slow (1/2)

－ muscle contraction /

glandular reaction (1/2)

quick (1/2) , not long

lasting (1/2), stereotyped

(1/2)

max

. 3

Deduct 1 mark if no comparison is made [Denote as N-1]Deduct 1/2 mark for answers in incomplete sentences in table form [Denote as T- 1/2]



9714 (5.5)

Q: The following figure illustrates the changes in the membrane potential of an axon

during the production of an action potential:

(a) Describe the events occurring along the membrane of the axon during periods

M and N. (41/2 marks)

(b) Account for the unidirectional conduction of nervous impulses along the axon.

(1 mark)

A: (a) M = After the arrival of a stimulus (1/2), there is a sudden increase

in membrane permeability to Na+ (1), Na+ rushes in (1/2) due

to the concentration gradient that exist between the outside

and the inside of the membrane (1/2). The membrane is

depolarised (1/2). / Membrane potential changes to (+) ve

value.

(3)

N = K+ moves out by diffusion (1/2), Na+ stops rushing in (1/2),

membrane is repolarized (1/2). / Membrane potential returns

to (-) ve value.

11/2

(41/2)

(b) Unidirectional transmission -a short refractory period (1/2) after the action



potential when axon will not respond to another stimulus (1/2).

(1)

Q4 = 51 /2 marks

9615(5)

Q: Draw a fully-labelled diagram of a synapse in the process of neurotransmission.

(5 marks)

A: Diagram of a synapse (1) in process of neurotransmission showing the following

features: synaptic knob, post-synaptic and presynaptic membrane, synaptic cleft,

vesicle discharging neurotransmitting substance.

(0.5 mark for each label, structure and name must correspond, 4)

9522(20)

Q: (a) A blindfolded man is walking on a narrow plank. Discuss in detail the roles of

the following organs in maintaining his balance while walking:(i) ear (5 marks)

(ii) brain (5 marks)

(iii) spinal cord (5 marks)

(b) When a man is walking, the motor signals that reach the leg muscles are transmitted

in the nervous system in a unidirectional way. Give a full explanation for this

unidirectional transmission. (5 marks)

A: (a) (i) Three semi-circular canals (0.5) in the inner ear contain receptors, the



canals are arranged at right angles to each other (0.5). When the head is

displaced (0.5) in any one plane, cupula/ gelatinous mass (0.5) in one or

more of canals will be deflected to the opposite direction (0.5) of the head

movement by the inertia of the endolymph (0.5). Sensory receptors/ hair cells

at the base of the cupula generate nerve impulses to the brain (0.5). Titling of the head (0.5) also activates the utricle (utriculus) (0.5) and saccule (0.5)

(sacculus). Their sensory hair cells generate nerve impulses to the brain

(brain stem). (1) (Max. 5)

(ii)

*Cerebrum (0.5) *Cerebellum (0.5)Receives Impulses from touch

receptors on foot(0.5)

1. impulses from the canals, utriculus,and sacculus about the position of thehead (0.5)

2. impulses from the limb receptors

(muscle/ joint) (0.5)

Process theinformation

Process the information (0.5)

Co-ordinates: (0.5)

1. muscular activities in the leg or leg

muscles (0.5)

2. reflexes in the body (0.5) to maintain

balance (0.5)

The medulla/ brain stem also assists to maintain the equilibrium state of the

body. (1) (Max. 5)

(iii) The spinal cord relays sensory impulses (0.5) along sensory neurones (0.5)

from the limb receptors (0.5) via the spinal nerves to the brain (0.5).

The interneurons and motor neurones (0.5) of the spinal cord relay motor

impulses (0.5) from the brain (0.5) to the leg muscles (0.5) via the spinal

nerves to effect co-ordinated movement (0.5) and to keep body in equilibrium

position (0.5).

The spinal cord serves as a pathway to allow the two-way conduction of

nervous impulses to and/ or from the brain and the leg muscles.(1+1 only)

(b) The unidirectional transmission is mainly determined at synapse (0.5)/ neural-

muscular junction.

Only the pre-synaptic element/ synaptic knob (0.5) possesses synaptic vesicles

(0.5) that contain neurotransmitter (0.5). Upon arrival of a nerve impulse, such

neurotransmitter is released (0.5) and it diffuses across a synaptic cleft (0.5) for relaying information to the opposite side. Only the post-synaptic membrane (0.5)



possesses receptors (0.5) to specifically combine with the neurotransmitter (0.5) ,

leading to post-synaptic depolarization (0.5) and propagation of nerve impulse.

(Bonus: mention of refractory period of nerve fibre also plays a role in unidirectional

transmission (1)) (Max. 5)

9423c(5)

Q: Outline how the sympathetic and parasympathetic nervous systems co-ordinate the

autonomic function of a named body part. (5 marks)

A: An example of a named body part (any appropriate body part): (0.5)

Correct description of the effects of sympathetic and parasympathetic control.

(Any one below or other suitable examples) (1)

iris (0.5) contraction (s) and retraction(p) (1)

heart rate (0.5) increase (s) and decrease(p) (1)

anal sphincter (0.5) dilation (p) and constriction(s) (1)

- co-ordination of autonomic function is by antagonistic activity (1) of the 2 systems

- have two different types of neurons by which antagonistic effects result due to

different chemical transmitters at the neuroeffector junctions (0.5) (excitatory /

inhibitory action):

- parasympathetic neurons : acetylcholine (1), i.e., cholinergic neurons

- sympathetic neurons secrete noradrenaline (1) / epinephrine, i.e., adrenergic

neurons

(Answers must relate to the action of the body part)

(Max. 5)

9324b(5)

Q: The initiation of muscular contraction depends on neural input. By means of a flow

chart, outline the processes that occur at the neuromuscular junction. (5 marks)

A: Arrival of nerve action potential at nerve terminals causes 1)

the entry of extracellular calcium ions into the nerve terminals; 1)

release of acetylcholine into the neuromuscular junction 1)

Acetylcholine combines with receptors on postjunctional membrane; 1) any 5

this causes depolarization of membrane to threshold for action potential; 1)

self-propagation of action potential on muscle membrane (sarcolemma) 1)

Depolarization (of T-tubules / T-system) leading to muscle contraction as a result of actin-myosin interaction 1)



9316c(2)

Q: Distinguish between instinctive and learned behaviour. (2 marks)

A: Instinctive behaviour refers to inborn responses made in full, irrespective of previousexperience, on the presentation of the appropriate stimulus. (1)

Learned behaviour is acquired as a result of previous experience. (1)

9226(20)

Q: Discuss how the structure of the ear is related to its functions in hearing and

balance in terrestrial mammals.

(20 marks)

A: Hearing (outer, middle and inner ear):

(a) Outer ear - pinna, external auditory canal and tympanic membrane

pinna strengthened by elastic cartilage - for protection,

its shape is suited for sound localisation and collection

external auditory canal - provides a passage for sound waves

tympanic membrane - thin and elastic, able to vibrate, thereby changing sound

waves to mechanical vibrations 2

(b) Middle ear -3 middle ear bones or ossicles (malleus, incus and stapes) - arranged to form

a lever system so that they oscillate in synchrony with the tympanic

membrane;2

to amplify the magnitude of vibration and allow effective transmission from air

medium (outer ear) to fluid medium (inner ear)

Eustachian tube - equalize air pressure difference between middle ear and

mouth to avoid damages of the tympanic membrane due to atmospheric

pressure changes. 1

(c) Inner ear - oval windows, cochlea (with 3 fluid-filled canals namely scala

vestibuli, scala media, scala tympani), round windows

sound pressure is transmitted from the stapes via the oval windows into the

cochlea fluid in inner ear is set into motion; since fluid is incompressible,

pressure is released via the round windows; (diagram) 4

receptors cells (hair cells) - located on the basilar membrane in scala media;

vibration of this membrane causes bending of the hairs against the tectorial

membrane; this shearing force activates the hair cells which in turn excites the

associated auditory nerve (the auditory part of the VIIIth cranial nerve)

(diagram)



4

auditory nerve - transmite sound to higher auditory centres (e.g. cortex) in the

form of action potential. 1

Balance (inner ear) :

(a) Semicircular canals - 4

3 fluid-filled canals (on each side of the head) are oriented at right angles

to one anotherl; (angular) acceleration of head movements in 3-

dimensional space causes fluid displacement, this introduces shearing

force which acts on hair cells

Description of the structure of macula, ampulla and the density of

endolymph and the gelatinous mass.

(b) Otolith organs (horizontal - oriented utricle, vertical-oriented asccule)－

2static head tilts (orientation of body with respect to gravity) and linear

accelerations introduce shearing force on the otolithic sensory epithelium

where the hair cells are located.

shearing force causes bending of the hairs on Vestibular receptors (hair

cells) in the inner ear;

hair cells in turn excites the associated vestibular nerve (the equilibrium or

Vestibular par of the VIIIth cranial nerve) transmits signal (in the form of

action potential) to the brain. 2max. (8)

max. (20)

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Coordination Nervous