Unit 11 Unit 11 Summary check-point Unit 11 Unit 11 Summary check-point

p Sensing the environment 1 Humans have five sense organs — the eye, ear, ________ (a), nose & skin to give us the five senses — _______ (b), _________ (C), taste, smell and touch. tongue sighthearing

3 Our five senses help us to avoid _________ (a) and search for food _________ (a) and search for food and shelter. and shelter. dangers 2 Different kinds of stimuli are detected by the ______________ (a) in the sense organs. sensory cells How do we see ? p.131

4 lens > helps focus light onto the retina > helps 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) iris focusing muscles > change the thickness of the lens

4 protective coat > > protects the eyeballretina (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 When we look at distant objects, the focusing muscles relax and the lens becomes _________ (a). the lens becomes _________ (a). thinner 6 When we look at near objects, the focusing muscles contract and the lens becomes ________ (a). the lens becomes ________ (a). thicker

7 ______ (a) are sensitive to bright light but _______ (b) work well in dim light. Cones give colour images whereas rods give black and white images. Cones give colour images whereas rods give black and white images. rods cones

8 Using suitable ___________ (a) can help us see objects that are too small and too far away to be seen by naked eyes. Microscopes and _____ ___________ (b) are examples. ___________ (b) are examples Limitations of our eyes instruments telescopes

9 The ___________ (a) of the retina contains no light-sensitive cells. We cannot see image if light falls We cannot see image if light falls on it. on it. blind spot

Eye defects 10 People with _______ (a) sight cannot see distant objects clearly. It can be see distant objects clearly. It can be corrected by wearing _________ (b) corrected by wearing _________ (b) lenses. lenses. short concave

11 People with ______ (a) sight cannot see near objects clearly. It can be see near objects clearly. It can be corrected by wearing _________ (b) corrected by wearing _________ (b) lenses. lenses. long convex

p _____________ (a) 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. Astigmatism 13 People with _________ (a) have cloudy lenses which can be cloudy lenses which can be replaced by man-made ones. replaced by man-made ones. cataract 14 People with ________________ (a) have difficulty in distinguishing have difficulty in distinguishing between colours. This inherited between colours. This inherited eye defect cannot be cured. eye defect cannot be cured. colour blindness

15 Sound is produced by __________ (a). vibrations How do we hear ? 16 Sound can travel through a _________ (a) but not in a _________ (a) but not in a _________ (b). _________ (b). medium vacuum

17 eardrum outer ear ear flap > helps collect sound vibrations ear canal > along which sound vibrations are vibrations are passed from the passed from the outside to the outside to the eardrum eardrum (a) _________ (a) > vibrates when sound vibrations hit it vibrations hit it

middle ear inner ear cochlea > sensory cells inside detect inside detect the vibrations the vibrations & change & change them into them into messages messages (b) __________ (b) > magnify the vibrations & pass them to the inner ear pass them to the inner ear ear bones > carries messages from the cochlea from the cochlea to the brain to the brain (c) ______________ (c) auditory nerve

18 The frequency is the number of vibrations per second. It is vibrations per second. It is measured in ________ (a) (Hz). measured in ________ (a) (Hz). One Hz is equal to one vibration One Hz is equal to one vibration per second. per second Limitations of our ears hertz 19 Human ears can only hear a limited range of ____________ (a). Different range of ____________ (a). Different animals have different hearing animals have different hearing ranges. ranges. frequencies

Noise pollution 20 ________ (a) are the annoying & unwanted sounds. They affect our unwanted sounds. They affect our work and health. work and health. Noises 21 Sound level is measured in __________ (a) (dB). It can be __________ (a) (dB). It can be measured by a measured by a decibel meter. decibel meter. decibels 22 People become ______ (a) when they lose their hearing. they lose their hearing.deaf

Smell, taste & touch 23 _______________ (a) in the nose & __________ (b) on the tongue work __________ (b) on the tongue work together to give us the flavour of together to give us the flavour of the food. the food. Smell receptors taste buds p.133

24 There are four kinds of tastes. Different areas of the tongue are Different areas of the tongue are good at detecting different tastes. good at detecting different tastes. _______ (a) _______ (d) _______ (b) _______ (c) sweet bitter salty sour

26 Different parts of our skin are not equally __________ (a) to touch. equally __________ (a) to touch. sensitive 25 Our sense of smell affects our sense of taste. sense of taste. 27 Our skin is not always reliable in detecting _____________ (a). detecting _____________ (a). temperature

The brain & our senses 28 The _________ (a) 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 ___________ (b). It then decides the ___________ (b). It then decides what to do and sends messages to what to do and sends messages to muscles to respond. This is the muscles to respond. This is the ________ (c) function. ________ (c) function. motor sensations sensory

29 The functions of different parts of the brain : the brain : Part of the brain Function ___________ (a) ___________ (b) __________ (c) control balance ; muscle coordination intelligence, memory and thinking; control voluntary actions control involuntary actions such as breathing and heartbeat Medulla Cerebellum Cerebrum

30 _________ (a) occur if the messages are not interpreted by the brain are not interpreted by the brain correctly. correctly. Illusions

Drugs, solvents & our senses 31 A _____________ (a) is used to measure the concentration of measure the concentration of alcohol in a person’s breath. alcohol in a person’s breath. breathalyzer 32 ______ (a) and _________ (b) affect our judgement and responses. our judgement and responses. ___________ (c) and sniffing ___________ (c) and sniffing _________ (d) can damage the brain _________ (d) can damage the brain and can even kill. and can even kill. Drug abuse Drugs solvents solvents