INTERACTIVE SCIENCE 2A

Transcription

1 INTERACTIVE SCIENCE 2A Workbook Solutions (Enrichment Edition) Chapter 7 LIVING THINGS AND AIR Part A Sectional Exercise 7.1 Concept checking p.1 1. False 2. True 3. True 4. False 5. False Multiple choice p.1 1. B 2. C 3. A 4. D 5. B Fill in the blanks p.2 (a) mixture (b) nitrogen (d) carbon dioxide (e) water vapour (g) nitrogen (h) carbon dioxide (c) oxygen (f) noble gases (i) 21 % Matching p.3 (a) --- (iii) (d) --- (iv) (b) --- (v) (e) --- (vi) (c) --- (i) (f) --- (ii) Questions p.3 1. (a) A nitrogen; B oxygen; C carbon dioxide (b) Sample Y is breathed air. This is because it contains more carbon dioxide (gas C) and less oxygen (gas B). (c) Put a glowing splint into a test tube containing gas B. The glowing splint relights in gas B shows that the gas is oxygen. (Or other reasonable answers) 7.1

2 2. (a) Tube A (b) Tube B. This is because breathed air, which contains more carbon dioxide than unbreathed air does, passes through tube B. (c) The burning splint in tube A will burn for a longer time. This is because unbreathed air, which contains more oxygen than breathed air does, passes through tube A. 7.2 Multiple choice p.4 1. D 2. C 3. A 4. D 5. B Fill in the blanks p.6 (a) oxygen (e) water (b) fuel (f) heat (c) heat (g) light (d) carbon dioxide Questions p.6 1. B, C, F, G and H 2. (a) fuel, heat, oxygen (b) It shows the necessary conditions to maintain a fire. (c) (i) A wet towel should be used to put out the fire. The wet towel covering the oil removes the oxygen required for burning. (ii) Burning oil floats on water and spreads the fire together with water. 7.3 Fill in the blanks p.7 1. (a) chemical (b) light (c) heat 2. Respiration 7.2

3 Questions p.8 (a) 60 C (b) The highest water temperature reached = Water temperature at the beginning + (change in water temperature for 4 g of food Z used / 2) = 20 C + 60 C /2 = 50 C (c) Food Y. This is because it shows the greatest temperature rise per gram. (d) Food Z 7.4 & 7.5 Concept checking p.9 1. True 2. False 3. False 4. False 5. True Multiple choice p.9 1. A 2. C 3. C 4. A 5. B 6. C 7. D 8. D Fill in the blanks p (a) carbon dioxide (b) water (c) sugar (d) oxygen (e) starch 7.3

4 2. (a) feeding (b) photosynthesis (c) producers (d) green plants (e) consumers Questions p (a) A---(ii) B---(iv) C---(i) D---(iii) (b) C D B A (c) Dark blue 2. (a) A variegated leaf has both green and non-green parts. (b) Chlorophyll (c) (d) Chlorophyll is necessary for photosynthesis. 3. (a) Grass and trees (b) Rabbits, zebra and grasshoppers (Or other reasonable answers) (c) Lion and snake (Or other reasonable answers) (d) grass rabbit snake grass rabbit lion grass zebra lion fruits/seeds bird snake 7.6 Multiple choice p B 2. B 3. C Fill in the blanks p.16 (a) contract 7.4

5 (b) ribs (c) downwards (d) increases (e) decreases Questions p.17 (a) Does Does How does the level of carbon respiration photosynthesis Colour of Tube dioxide change? take place? take place? indicator (unchanged/increase/decrease) ( /X) ( /X) A red unchanged B purple decrease C X X red unchanged D X yellow increase E X yellow increase F X yellow increase G X X red unchanged H X yellow increase (b) As tube E is placed in the dark, the plant inside will not undergo photosynthesis. However, both plant and snail carry out respiration which gives out carbon dioxide. Therefore, the level of carbon dioxide increases and the indicator changes from red to yellow. (c) Tubes C and G 7.7 Multiple choice p D 2 B 3. D 4. A 5. C Fill in the blanks p (a) air pollutants (b) motor vehicles (c) power stations (d) fuels 7.5

6 (e) poisonous gases (f) small solid particles 2. passive smoking Questions p.19 (a) (b) (i) Nasal problem, excessive phlegm and asthma (ii) Frequent coughing (c) Children who smoke or suffer from passive smoking are more likely to have respiratory diseases than non-smoking children. (Or other reasonable answers) Part B Integrated Exercise Multiple choice p D 2. C 3. D 4. D 5. A 6. A 7.6

7 7. B 8. C Matching p (a)---(ii), (iii), (v), (vii) (b)---(i), (iv), (vi), (viii) 2. (a)---(iii), (iv) (b)---(ii), (v) (c)---(i), (vi) Questions p (a) The gas is oxygen. Put a glowing splint into the test tube with the gas. If the splint relights, it shows that the gas is oxygen. (b) A lower rate is expected. The light becomes weaker as the lamp is moved further away. The rate of photosynthesis becomes lower and thus the rate of bubbling decreases. (c) Among white, red and green light, white light is the most suitable for the green water plant to carry out photosynthesis. Green light is the least suitable. 2. (a) (i) It remains colourless. This is because carbon dioxide in the incoming air is absorbed by sodium hydroxide solution in flask A. (ii) It changes to yellow. This is because the mouse carries out respiration and releases carbon dioxide. (b) It absorbs carbon dioxide from the incoming air. This ensures that the colour change of the indicator in flask C is due to carbon dioxide released from the mouse inside the bell jar. (c) (i) Cover the bell jar (with the plant inside) with a black cloth. (Or other reasonable answers) (ii) Without light, the plant cannot undergo photosynthesis and will only undergo respiration. This ensures that the experimental result is not affected by photosynthesis but due to respiration of the plant only. (Or other reasonable answers) 3. (a) (i) Respiration (ii) Photosynthesis (b) This means the plant has a net release of oxygen. (c) (i) 0600 and 1800 (ii) around 0300 to 1200 (d) The rate of photosynthesis equals the rate of respiration. Therefore, the amount of oxygen released in photosynthesis equals the amount of oxygen taken up in 7.7

8 respiration. (e) As the light intensity increases, the rate of photosynthesis increases. Therefore, the rate of oxygen production is increasing and the rate of net oxygen absorption is decreasing. 4. (a) Carbon monoxide lowers the oxygen content in blood. If our brain does not get enough oxygen, we may experience headaches and dizziness. (Or other reasonable answers) Sulphur dioxide may cause irritation to our respiratory system, and may result in difficulties in breathing. (Or other reasonable answers) (c) Mongkok is a busy commercial centre. There are a lot of motor vehicles emitting exhaust fumes that pollute the air. Shatin is a residential district with less vehicles moving on the roads. Therefore, the pollution problem in Mongkok is more severe. According to the table, the pollution problem in district A is more severe than in district B, so district A is Mongkok. (Or other reasonable answers) (d) In December, air pollutants from mainland China are carried to Hong Kong by wind (via the winter monsoon). In June, the wind direction is different (summer monsoon mainly comes from the Pacific Ocean). Therefore, the average amount of air pollutants recorded in December is higher than that recorded in June. (Or other reasonable answers) Part C Concept Diagram p chlorophyll 2. light 3. water 4. photosynthesis 5. respiration 6. glowing splint 7. hydrogencarbonate indicator 8. lime water 9. fire triangle 10. greenhouse effect 11. global warming 12. gaseous exchange 13. respiratory system 14. intercostals muscles 15. ribs 16. diaphragm 17. Air Pollution Index 7.8

9 18. tar 19. nicotine 20. carbon monoxide Part D Reading Comprehension p.30 (a) It could lead to the spread of diseases. It will make polar ice caps melt and make glaciers thinner. These lead to rises in sea levels that could flood coastal communities. The changing rainfall patterns will lead to widespread flooding in some regions of the world and cause drought in others. (b) The burning of fossil fuels like coal, oil, and gas produces a large amount of carbon dioxide and other gases. They build up in the atmosphere, cover the Earth and trap heat energy, causing excessive greenhouse effect which in turn causes global warming. (c) The cutting down of large number of trees for making paper and making furniture (Or other reasonable answers) (d) The power sector produces the largest amount of carbon dioxide. (e) This may be achieved by increasing energy efficiency, decreasing dependence on coal and gas and increasing the use of renewable energy. (f) Hydro-electric power, wind power, solar power, tidal power, geothermal power (Any three of them) Part E Little Einstein s Corner p (a) Tubes 1 and 3 (b) Tube 3. The fish carry out respiration and give out carbon dioxide. A higher level of carbon dioxide leads to a faster rate of photosynthesis. (c) (i) The fish will die. (ii) The green plant does not carry out photosynthesis and no oxygen is released for the fish to carry out respiration. The fish dies due to suffocation. 2. (a) (i) Yes (ii) Comparing air samples A and B that have the same oxygen content, the breathing rate is higher when there is a higher carbon dioxide content. The same situation occurs when comparing air samples C and D. (b) (i) No (ii) Comparing air samples A and C that have the same carbon dioxide content, the breathing rate remains the same even though the oxygen content is different. The same situation occurs when comparing air samples B and D. (c) Ask more people to perform the experiment to reduce errors. (Or other reasonable answers) 7.9

10 (d) (i) Air sample A (ii) Air sample D (e) (i) According to the experimental results, a higher carbon dioxide content in air can increase the breathing rate of a person. Since breathed air has a higher carbon dioxide content than unbreathed air, blowing breathed air into the victim s body could stimulate their breathing rhythm or help him/her breathe faster. (ii) Observe whether the victim s chest rises when air is blown through the mouth of the victim. 7.10