Unit Unit 1111

Summary Summary checkcheck--

pointpoint

Unit Unit 1111

Summary Summary checkcheck--

pointpoint

p.130p.13011.111.1 11.111.1 Sensing the environmentSensing the environment

1 1 Humans have five sense organs — Humans have five sense organs —

the eye, ear, the eye, ear, ________ ________ (a) (a) , nose & sk, nose & sk

in to give us in to give us the five senses — the five senses — ______

____ ____ (b)(b) , _________ , _________ (C)(C) , , taste, smell taste, smell

and touch.and touch.

tonguetongue

sightsight hearinghearing

3 3 Our five senses help us to avoid Our five senses help us to avoid

_________ _________ (a) (a) and search for food and search for food

and shelter.and shelter.

dangersdangers

2 2 Different kinds of stimuli are detected Different kinds of stimuli are detected

by theby the ____________________________ (a) (a) in the sense in the sense

organs.organs.

sensory cellssensory cells

11.211.2 11.211.2 How do we see ?How do we see ? p.131p.131

44 lens > > helps focus light onto the retinahelps focus light onto the retina    

cornea > > helps focus light

pupil > > allows light to enter the eye

> > changes the size of the pupil to control the amount of light entering the eye

______ (a) (a) irisiris

focusing muscles > change the thickness of the lens

44 protective coat > > protects the eyeball

retinaretina________ (b) (b)

> > contains light- sensitive cells; sends messages to the brain when light falls on it

optic nerve > > carries messages from

the retina to the brain

blind spot> at where optic nerve

leaves the eye

5 5 When we look at distant objects, tWhen we look at distant objects, the focusing muscles relax andhe focusing muscles relax and

the lens becomesthe lens becomes _________ _________ (a)(a)..  thinnerthinner

6 6 When we look at near objects, the When we look at near objects, the focusing muscles contract andfocusing muscles contract and

the lens becomesthe lens becomes ________ ________ (a)(a)..  thickerthicker

7 7 ____________ (a) (a) are sensitive to bright light are sensitive to bright light

butbut _______ _______ (b) (b) work well in dim light.work well in dim light.

Cones give colour images whereas rCones give colour images whereas r

ods give black and white images.ods give black and white images.

rodsrods

conescones

8 8 Using suitable ___________ Using suitable ___________ (a) (a) can hecan he

lp us see objects that are too small alp us see objects that are too small and too far away nd too far away to be seen by naked to be seen by naked eyes. Microscopes andeyes. Microscopes and _____ _____

___________ ___________ (b) (b) are examples.are examples.

11.311.3 11.311.3 Limitations of our eyesLimitations of our eyes

instrumentsinstruments

telescopestelescopes

9 9 The ___________The ___________ (a) (a) of the retina conof the retina con

tains no light-sensitive cells.tains no light-sensitive cells.

We cannot see image if light falls We cannot see image if light falls

on it.on it.

blind spotblind spot

11.411.4 11.411.4 Eye defectsEye defects

10 10 People with People with ______________ (a) (a) sight cannot sight cannot

see distant objects clearly. It can besee distant objects clearly. It can be

corrected by corrected by wearingwearing _________ _________ (b) (b)

lenses.lenses.

shortshort

concaveconcave

11 11 People withPeople with ______ ______ (a) (a) sight cannot sight cannot

see near objects clearly. It can be see near objects clearly. It can be

corrected by wearing _____corrected by wearing _____________ (b) (b)

lenses.lenses.

longlong

convexconvex

p.132p.13212 12 __________________________ (a) (a) is an eye is an eye

defect caused by the uneven defect caused by the uneven curvature of the cornea or lens.curvature of the cornea or lens.

AstigmatismAstigmatism

13 13 People withPeople with __________________ (a) (a) have have

cloudy lenses which can be cloudy lenses which can be

replaced by man-made ones.replaced by man-made ones.

cataractcataract

14 14 People withPeople with ________________ ________________ (a) (a)

have difficulty in distinguishing have difficulty in distinguishing between between colours. This inherited colours. This inherited eye defect cannot be cured.eye defect cannot be cured.

colour blindnesscolour blindness

15 15 Sound is produced bySound is produced by __________ __________ (a) (a) ..vibrationsvibrations

11.511.5 11.511.5 How do we hear ?How do we hear ?

1616 Sound can travel through aSound can travel through a

_________ _________ (a) (a) but not in abut not in a

_________ _________ (b) (b) ..

mediummedium

vacuumvacuum

1717

eardrumeardrum

outer earouter earouter earouter ear

ear flapear flap > > helps collect sound vibrationshelps collect sound vibrations

ear canalear canal > > along which sound along which sound vibrations arevibrations are passed from the passed from the outside outside to the to the eardrumeardrum

_________ (a) (a)

> > vibrates when sound vibrates when sound vibrations hit itvibrations hit it

middle middle earear

middle middle earear

inner earinner earinner earinner ear

cochlea > > sensory cells sensory cells inside detectinside detect the vibrationsthe vibrations & change& change them into them into messagesmessages

__________ (b) (b)

> > magnify the vibrations &magnify the vibrations & pass them to the inner earpass them to the inner ear

ear bonesear bones

> > carries messages carries messages from from the cochleathe cochlea to the brainto the brain

______________ (c)(c)auditory nerveauditory nerve

18 18 The frequency is the number of The frequency is the number of vibrations per second. It is vibrations per second. It is

measured inmeasured in ________ ________ (a)(a) (Hz) (Hz) ..

One Hz is equal to one vibration One Hz is equal to one vibration per second.per second.

11.611.6 11.611.6 Limitations of our earsLimitations of our ears

hertzhertz

19 19 Human ears can only hear a limited Human ears can only hear a limited

range of range of ____________ ____________ (a) (a) . Different . Different

animals have animals have different hearing different hearing ranges.ranges.

frequenciesfrequencies

11.711.7 11.711.7 Noise pollutionNoise pollution

20 20 ________ ________ (a)(a) are the annoying & are the annoying &

unwanted sounds. They affect our unwanted sounds. They affect our work and health.work and health.

NoisesNoises

21 21 Sound level is measured inSound level is measured in

____________________ (a)(a) (dB) (dB). It can be. It can be

measured by a measured by a decibel meter.decibel meter.

decibelsdecibels

22 22 People becomePeople become ______ ______ (a)(a) when when

they lose their hearing.they lose their hearing.

deafdeaf

11.811.8 11.811.8 Smell, taste & touchSmell, taste & touch

23 23 _______________ _______________ (a) (a) in the nose &in the nose &

__________ __________ (b) (b) on the tongue work on the tongue work

together to give us the flavour of together to give us the flavour of

the food.the food.

Smell receptorsSmell receptors

taste budstaste buds

p.133p.133

24 24 There are four kinds of tastes. There are four kinds of tastes. Different areas of the tongue are Different areas of the tongue are good at detecting different good at detecting different tastes.tastes.

_______ _______ (a)(a)

_______ _______ (d) (d)

_______ _______ (b)(b)

_______ _______ (c) (c)

sweetsweet

bitterbitter

saltysalty

soursour

26 26 Different parts of our skin are not Different parts of our skin are not

equallyequally __________ __________ (a) (a) to touch.to touch. sensitivesensitive

25 25 Our sense of smell affects our Our sense of smell affects our sense of taste.sense of taste.

27 27 Our skin is not always reliable in Our skin is not always reliable in

detectingdetecting _____________ _____________ (a)(a) . .temperaturetemperature

11.911.9 11.911.9 The brain & our sensesThe brain & our senses

28 28 TheThe _________ _________ (a) (a) function of the function of the

brain is to receive and interpret the brain is to receive and interpret the sensory messages. This gives us sensory messages. This gives us

the the ___________ ___________ (b) (b) . . It then decides It then decides

what to do and sends messages to what to do and sends messages to muscles to muscles to respond. This is therespond. This is the

________ ________ (c) (c) function.function. motormotor

sensationssensations

sensorysensory

29 29 The functions of different parts of The functions of different parts of the brainthe brain : :

Part of the brain Function

______________________ (a)(a)

___________ ___________ (b)(b)

____________________ (c)(c)

control balance ; control balance ; muscle coordinationmuscle coordination

intelligence, memory intelligence, memory and thinking; control and thinking; control voluntary actionsvoluntary actions

control involuntary control involuntary actions such as actions such as breathing and heartbeatbreathing and heartbeat

MedullaMedulla

CerebellumCerebellum

CerebrumCerebrum

30 30 __________________ (a) (a) occur if the messages occur if the messages

are not interpreted by the brain are not interpreted by the brain

correctly.correctly.

IllusionsIllusions

11.1011.10 11.1011.10 Drugs, solvents & our sensesDrugs, solvents & our senses

31 31 AA __________________________ (a) (a) is used to is used to

measure the concentration of measure the concentration of

alcohol in a person’s breath.alcohol in a person’s breath.

breathalyzerbreathalyzer

32 32 ______ ______ (a) (a) and _________ and _________ (b)(b) affectaffect

our judgement and responses.our judgement and responses.

___________ ___________ (c)(c) and sniffing and sniffing

__________________ (d) (d) can damage the braincan damage the brain

and can even kill.and can even kill.

Drug abuseDrug abuse

DrugsDrugs solventssolvents

solventssolvents