Transcript 11_es

Unit 11
Summary check-point
11.1 Sensing the environment
p.130
1 Humans have five sense organs —
tongue (a) , nose &
the eye, ear, ________
skin to give us the five senses —
sight (b) , _________
hearing (C) , taste,
_______
smell and touch.
2 Different kinds of stimuli are detected
sensory cells (a) in the sense
by the ______________
organs.
3 Our five senses help us to avoid
dangers (a) and search for food
_________
and shelter.
11.2 How do we see ?
p.131
4
lens
> helps focus light onto the retina
cornea
> helps focus light
pupil
> allows light to
enter the eye
iris (a)
______
> changes the size of the pupil to control
focusing muscles
the amount of light entering the eye
> change the thickness of the lens
4
protective coat
> protects the eyeball
retina (b)
________
> contains lightsensitive
blind
spot cells;
> atsends
wheremessages
optic nerve
to the brain
when
leaves
the eye
light falls on it
optic nerve
> carries messages from
the retina to the brain
5 When we look at distant objects,
the focusing muscles relax and
thinner (a).
the lens becomes _________
6 When we look at near objects, the
focusing muscles contract and
thicker (a).
the lens becomes ________
cones (a) are sensitive to bright light
7 ______
rods (b) work well in dim light.
but _______
Cones give colour images whereas
rods give black and white images.
11.3 Limitations of our eyes
instruments (a) can
8 Using suitable ___________
help us see objects that are too
small and too far away to be seen by
naked eyes. Microscopes and _____
telescopes (b) are examples.
___________
blind spot (a) of the retina
9 The ___________
contains no light-sensitive cells.
We cannot see image if light falls
on it.
11.4 Eye defects
short (a) sight cannot
10 People with _______
see distant objects clearly. It can be
concave (b)
corrected by wearing _________
lenses.
long (a) sight cannot
11 People with ______
see near objects clearly. It can be
convex (b)
corrected by wearing _________
lenses.
Astigmatism (a) is an eye p.132
12 _____________
defect caused by the uneven
curvature of the cornea or lens.
cataract (a) have
13 People with _________
cloudy lenses which can be
replaced by man-made ones.
colour blindness (a)
14 People with ________________
have difficulty in distinguishing
between colours. This inherited
eye defect cannot be cured.
11.5
How do we hear ?
vibrations (a) .
15 Sound is produced by __________
16 Sound can travel through a
medium (a) but not in a
_________
vacuum (b) .
_________
17
ear flap
> helps collect sound vibrations
ear canal
> along which sound
vibrations are
passed from the
outside to the
eardrum
eardrum (a)
_________
> vibrates when sound
vibrations hit it
outer ear
auditory nerve
ear bones (b)
__________
______________
(c)
> carries
messages
> magnify the vibrations
&
from
pass them to the inner
earthe cochlea
to the brain
middle
ear
inner ear
cochlea
> sensory cells
inside detect
the vibrations
& change
them into
messages
11.6
Limitations of our ears
18 The frequency is the number of
vibrations per second. It is
hertz
measured in ________
(a) (Hz) .
One Hz is equal to one vibration
per second.
19 Human ears can only hear a limited
frequencies (a) . Different
range of ____________
animals have different hearing
ranges.
11.7
Noise pollution
Noises (a) are the annoying &
20 ________
unwanted sounds. They affect our
work and health.
21 Sound level is measured in
decibels (a) (dB). It can be
__________
measured by a
decibel meter.
deaf (a) when
22 People become ______
they lose their hearing.
11.8 Smell, taste & touch
p.133
Smell receptors (a) in the nose &
23 _______________
taste buds (b) on the tongue work
__________
together to give us the flavour of
the food.
24 There are four kinds of tastes.
Different areas of the tongue are
good at detecting different tastes.
bitter (a)
_______
sour (b)
_______
salty (c)
_______
sweet (d)
_______
25 Our sense of smell affects our
sense of taste.
26 Different parts of our skin are not
sensitive (a) to touch.
equally __________
27 Our skin is not always reliable in
temperature (a) .
detecting _____________
11.9
The brain & our senses
sensory (a) function of the
28 The _________
brain is to receive and interpret the
sensory messages. This gives us
sensations (b) . It then decides
the ___________
what to do and sends messages to
muscles to respond. This is the
motor (c) function.
________
29 The functions of different parts of
the brain :
Part of the brain
Cerebrum
___________
(a)
Function
intelligence, memory
and thinking; control
voluntary actions
Cerebellum (b) control balance ;
___________
muscle coordination
Medulla (c) control involuntary
__________
actions such as
breathing and heartbeat
Illusions (a) occur if the messages
30 _________
are not interpreted by the brain
correctly.
11.10 Drugs, solvents & our senses
breathalyzer (a) is used to
31 A _____________
measure the concentration of
alcohol in a person’s breath.
solvents
Drugs (a) and _________
32 ______
(b) affect
our judgement and responses.
Drug abuse
___________
and sniffing
(c)
solvents
_________
(d) can damage the brain
and can even kill.