INTERACTIVE SCIENCE 2B Workbook Solutions (Enrichment Edition) Chapter 11 SENSING THE ENVIRONMENT Part A Sectional Exercise 11.1 Concept checking p.63 1. False 2. True 3. True 4. False 5. True Questions p.63 1. Stimulus Sense organ Sense produced (a) Light from a torch Eyes Sight (b) Sound from a landing aeroplane Ears Hearing (c) Heat from a fire Skin Heat (d) Coal gas from a leaking pipe Nose Smell (e) Salt on potato chips Tongue Taste (f) Wind from a fan Skin Touch 2. Substances to be distinguished (a) Grape juice and orange juice (b) Durian and orange inside sealed bags made of black cloth (c) Table salt and powdered sugar (d) A piece of colourless glass and a piece of colourless plastic (e) A sealed wooden box of nails and a sealed wooden box of coins (f) Potato chips with a strong flavour and potato chips with a plain flavour Sense organ(s) used Eyes, tongue and nose Nose and skin Tongue Skin and eyes Ears Nose and tongue 11.1
11.2 Concept checking p.64 1. True 2. False 3. False 4. True 5. False Multiple choice p.65 1. C 2. B 3. C 4. A 5. D Matching p.66 (a) --- (i), (iv) (b) --- (i), (iv) (c) --- (ii), (iii) (d) --- (ii), (iv) (e) --- (i), (iii) Questions p.66 (a) A: Cornea D: Pupil E: Lens I: Blind spot J: Optic nerve (b) (i) A, C, E and F (ii) G (iii) A and E (C and F are also correct.) (c) (i) No (ii) No 11.3 Concept checking p.67 1. True 2. True 3. False 4. False 5. False Matching p.68 (a) --- (iv) --- (viii) (b) --- (iii) --- (v) (c) --- (i) --- (vi) (d) --- (ii) --- (vii) 11.2
11.4 Multiple choice p.69 1. A 2. A 3. C 4. B 5. D 6. C Matching p.71 (a) --- (iv) (b) --- (iii) (c) --- (i) (d) --- (ii) (e) --- (i) (f) --- (ii) Questions p.72 (a) Keep himself 3 m or more away from the television screen. Let the eyes relax after watching television for an hour, such as looking at distant objects or something green for a few minutes. (or other reasonable answers) (b) Keep the reading distance at 35 cm or more. Let the eyes relax after reading for an hour, such as looking at distant objects r something green for a few minutes. (or other reasonable answers) 11.5 11.6 Fill in the blanks p.72 (a) vibration (b) sound level (c) decibels (d) frequency (e) vibrations (f) second (g) hertz Multiple choice p.73 1. C 2. D 3. B 4. B 5. A Questions p.74 1. (a) A: Ear canal D: Cochlea B: Eardrum E: Auditory nerve C: Ear bones (b) (i) It vibrates and transmits sound waves to the middle ear. (ii) They magnify the vibrations of the eardrum and pass them to the inner ear. 11.3
(iii) It transmits signals produced in the cochlea to the brain. (c) D (d) (i) No (ii) No (iii) No 2. (a) (i) Grasshopper (ii) Bat (b) The lowest frequency of sound that we can hear is about 20 Hz. (c) (i) No. This is because the frequencies of ultrasounds are beyond the human audible frequency range. (ii) Robin, dog, cat and bat can hear ultrasounds. (iii) Cleaning and hole-drilling (any other reasonable answers) 11.7 Multiple choice p.76 1. B 2. B 3. B Questions p.77 1. Avoid using earphones/headphones to listen to loud music or any loud sounds for a long time. Avoid using earphones/headphones to listen to music or any sounds in a noisy environment (because one will turn the volume to a higher level). (or other reasonable answers) 2. C < D < E <B < A 11.8 Concept checking p.78 1. F 2. F 3. T 4. T 5. F Multiple choice p.78 1. B 2. C 3. C 4. A 5. B 6. D 11.9 Multiple choice p.79 1. A 2. A 11.4
3. B 4. B 5. D Questions p.81 1. (a) (i) cerebellum (ii) medulla (iii) cerebrum (b) B is the front of the brain. (c) Cerebrum and cerebellum have folds. 2. (a) stimuli (b) receptors (c) brain (d) responses 11.10 Multiple choice p.82 1. C 2. D 3. D Fill in the blanks p.82 1. (a) Drug abuse (b) heroin (c) morphine (d) MDMA [or other reasonable answers for (b) to (d)] 2. (a) breathalyser (b) breathed air (c) orange (d) green Questions p.83 1. (a) A, B and H (b) C, D, E, F and G 2. Understand the harmful effects of drugs on our health. Be firm and do not take drugs in order to please your friends. (or other reasonable answers) Part B Integrated Exercise Multiple choice p.83 1. C 2. B 3. B 4. C 5. D 6. A 7. D 8. D 11.5
9. C 10. A 11. C 12. B 13. C 14. A 15. D 16. B 17. D Fill in the blanks p.87 1. nose 2. (a) touch (b) temperature 3. (a) taste buds (b) receptors 4. cerebrum 5. vibrations in one second 6. inner 7. (a) medium (b) vacuum 8. loudness/level 9. optic nerve 10. auditory nerve Questions p.88 1. (a) Light Eyes Sight (b) Stimulus caused by the sharpness of the nail Skin Pain (c) Temperature of water Skin Heat and cold (d) Chemicals/citric acid in the drink Tongue Taste (e) Chemicals/LPG/town gas in air Nose Smell (f) Light and sound/thundering and lightning Eyes and ears Sight and hearing 2. (a) Sound travels the fastest in solids, then in liquids and the slowest in gases. (b) Steel has a higher density than iron. The particles are packed closer together and thus sound vibration is transmitted faster in steel than in iron. (c) Water particles have more energy at a higher temperature. They move faster and thus sound vibration is transmitted faster. 11.6
(d) Sound travels faster in air at 30 than at 20. The reason is that air particles have more energy and move faster at a higher temperature, so sound vibration is transmitted faster. 3. (a) The string and the paper cups are vibrating. (b) Solid is used for sound transmission through the string telephone. (c) No. This is because the string cannot vibrate. (d) If the string is loose, it does not vibrate and therefore does not transmit sound. 4. (a) Eyes are tested in this experiment. (b) Optic nerve carries signals from the sense organ to the brain. (c) The muscles of the arm/fingers are responsible for carrying out the response. (d) The longer the distance fallen by the ruler when it was caught, the longer the reaction time. (e) Peter has the fastest response. (f) Different people may take different time for signals to travel from the sense organs to the brain. (or other reasonable answers) 5. (a) (i) two (ii) two (b) (i) One can of beer (ii) Three glasses of wine (iii) Three serves of whisky (c) Loss of balance and blurred vision (or other two reasonable answers) (d) Heart disease/liver disease (or other reasonable answers) Part C Concept Diagram p.94 1. sight 2. eye 3. retina 4. optic nerve 5. cataract 6. light sensitive cells 7. hearing 8. sounds 9. eardrum 10. cochlea 11. auditory nerve 12. smell 13. smell receptors 14. taste 15. tongue 16. taste buds 17. touch 18. skin 19. skin receptors 20. cerebellum Part D Reading Comprehension p.96 (a) Putting on sunglasses are necessary when going outdoors on a bright, sunny day. This is because sunglasses protect the eyes from the harmful ultraviolet rays in sunlight. They also provide protection against strong light and glare. 11.7
(b) UV rays can cause painful sensation on our eyes. Long exposure can lead to cataract and even blindness. (c) On a bright, sunny day, drivers may come across certain light reflecting surfaces, such as water and glass walls, that can reflect a great amount of light. The glare can hide objects and distract drivers, which may cause accidents. (d) Brand III is the best for eye protection. It can block 100% of UV rays as it belongs to UV-400 type. It is grey in colour and does not affect colour perception. In addition, it is a wrap-around type of sunglasses having side shields that can reduce damaging rays from entering the eyes. Part E Little Einstein s Corner p.98 (a) The density of air at high altitude is lower than that at sea level. Air particles are thus further apart. This affects the transmission of sound. (b) Janet is likely to have an infection of the middle ear. This is because the germs causing sore throat may have gone from the throat to the middle ear along the tube joining these two parts. (c) In fact, lightning and thunder occur at the same time. However, the transmission of light is faster than the transmission of sound in air. (d) The time lag is the reaction time. This is the time needed for the driver to respond (i.e. applying the brake) to the stimulus (i.e. the presence of the obstacle on the road). / The time lag is the time needed for signals to travel from the eyes of the driver to the brain and then from the brain to the legs so that he/she can apply on the brake. 11.8