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SA1 Revision 2 2012 Answer Notes


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SA1 Revision 2 2012 Answer Notes

  1. 1. SA1 REVISION 2 2012P6 Science
  2. 2. Booklet A What to do  Understand the concept for each question.  Underline the key words (question).  Understand the explanations for each question.  Write down the correct answer as correction.
  3. 3. Question 1 – Answer (1) Concept:  Classification of plants Key words (Question)  classify Explanation  Tomato and love grass are dispersed by animals.  Coconut and pong pong are dispersed by water.  Pong pong and love grass are inedible plants.  Tomato and coconut are edible plants.
  4. 4. Question 2 – Answer (3) Concept:  Classification of materials Explanation
  5. 5. Question 3 – Answer (1) Concept:  Life cycle of butterfly Key words (Question)  Stage X, Stage Y Explanation Caterpillar moults a number of times Pupa is the stage where it does not eat at all
  6. 6. Question 4 – Answer (3) Concept:  Seed dispersal Key words (Question)  most likely Explanation  Plant S – found near the sea, so most likely dispersed by water.  Plant T – found near each other, so most likely dispersed by splitting.  Plant U – found scattered all over the island, so most likely dispersed by animals.
  7. 7. Question 5 – Answer (1) Concept:  Hereditary (passing down of characteristic traits) Key words (Question)  adopted, most likely Explanation  Since both Mr and Mrs Tng have double eyelids, it is not likely for their children to have single eyelid. Thus, Arnold is most likely the adopted child.
  8. 8. Question 6 – Answer (3) Concept: bryophyllum  Reproduction of plants Key words (Question)  most likely heliconia Explanation  W – ferns reproduce from spores Water chestnut  X – Bryophyllum is able to reproduce from leaves  Y – Water chestnut is an underground stem  Z – Heliconia reproduce from suckers
  9. 9. Question 7 – Answer (4) Concept:  Water cycle Key words (Question)  Water cycle Explanation
  10. 10. Question 8 – Answer (4) Concept:  Environment Key words (Question)  same amount, same amount, different, find out Explanation  The water level drops because water is able to flow and occupy the air spaces.
  11. 11. Question 9 – Answer (1) Concept:  Water boiling Key words (Question)  Most likely, true Explanation  A is false – different amount of water means the water will boil at different times since the amount of heat supplied is the same.  B is false – both have 2 burners, thus heat energy is the same.  C is true – boiling temperature is always 100oC no matter the amount of water.
  12. 12. Question 10 – Answer (1) Concept:  Function of the stomata in plants Key words (Question)  Layer of cooking oil on both surfaces, died Explanation  Since the stomata is blocked by the oil, it cannot take in carbon dioxide (for photosynthesis) and oxygen (for respiration).  Since oil is transparent, light can still pass through.  Since oil is not an insulator of heat, warmth can
  13. 13. Question 11 – Answer (4) Concept:  Carbon dioxide is taken in during photosynthesis and given out during respiration. Key words (Question)  Amount of carbon dioxide, 12 midnight to 12 noon Explanation  At night, photosynthesis does not occur (due to the lack of light), therefore carbon dioxide level will be high.  In the daytime, photosynthesis occurs, thus carbon dioxide level will drop.
  14. 14. Question 12 – Answer (2) Concept:  Blood in humans Key words (Question)  Blood, helps Explanation  One of the function of blood is to transport nutrients from the small intestine to all parts of the body as well as to carry waste to the rectum.  Blood also carries oxygen (from lungs) and carbon dioxide (to lungs).
  15. 15. Question 13 – Answer (4) Concept:  Heart rate Key words (Question)  heartbeat Explanation  Playing soccer will cause his heart rate to increase the most.  Resting will lower his heart rate  Walking will increase his heart rate again but not as high as playing soccer.
  16. 16. Question 14 – Answer (2) Concept:  Plant cells and its parts Key words (Question)  Structures, all Explanation  Allplant cells have cell wall, cytoplasm and cell membrane.  Not all plant cells have chloroplasts (e.g. root cells) since only the leaves make food.
  17. 17. Question 15 – Answer (4) Concept:  Cell division (every cell divides itself into 2) Key words (Question)  Every 15 seconds, 128 Explanation Cell Count Time (seconds) 8 45 16 60 32 75 64 90 128 105
  18. 18. Question 16 – Answer (3) Concept:  Cell parts and function Key words (Question)  true Explanation  A is true – cell Z cannot make food as it does not have chloroplast.  B is false – all cells can reproduce (all living things can reproduce)  C is true – Cell Z does not have cell wall  D is true – Since cell Z does not have cell wall it must be an animal cell.
  19. 19. Question 17 – Answer (4) Concept:  Electricity Key words (Question)  X, blow Explanation  when a bulb blows, it forms an open circuit
  20. 20. Question 18 – Answer (4) Concept:  Electricity conductors Key words (Question)  Conductors of electricity Explanation  Pencil lead is a conductor of electricity but not a good one (thus the light produced is dim)  Plastic ruler and glass fibre is not a conductor of electricity (thus no light produced)  Steel nail is a good conductor of electricity (thus very bright light produced by bulb)
  21. 21. Question 19 – Answer (4) Concept:  Electrical circuit Key words (Question)  false Explanation  A is false – Set up Y is a series circuit  B is false – When batteries are arranged in series, it will have more electrical energy as compared to a parallel circuit, thus Y will be brighter.  C is true – When a bulb in series blows, the whole circuit will fail to work.  D is false – When a bulb in parallel blows, the other bulbs will continue to light up.
  22. 22. Question 20 – Answer (4) Concept:  Interaction of organisms (how one affect the other) Key words (Question)  rapidly Explanation  A will happen – Water hyacinth is a floating plant, if there are too many, they will cover the surface of the river and block sunlight from reaching the submerged plants (thus these submerged plants cannot photosynthesize and produce oxygen.)  B will happen – The water hyacinth will create obstacles for the boats to travel.  C will happen – Sunlight blocked preventing submerged plants from making food (same reason as A)
  23. 23. Question 21 – Answer (1) Concept:  Photosynthesis of plants Key words (Question)  Most adapted, hot and dry Explanation  P is more adapted to survive in hot and dry space as it is able to retain the most amount of water.
  24. 24. Question 22 – Answer (3) Concept:  Food web (how change in one organism affects the others) more predators Key words (Question)  Changes, D increases Explanation less organisms eating more food more predators
  25. 25. Question 23 – Answer (4) Concept:  Environment – overcrowding, fair test Key words (Question)  overcrowding Explanation  Variable to change – size of pot  Variable to keep the same – Number of seeds and type of soil
  26. 26. Question 24 – Answer (3) Concept:  Forces Key words (Question)  true Explanation  A is true – Gravitational force acts from a distance  B is true – Magnets only exert magnetic force on magnetic objects  C is true – Weight is due to gravitational force acting on it  D is false – (common misconception) An object remains stationary because frictional force is acting on it, otherwise it will start moving.
  27. 27. Question 25 – Answer (3) Concept:  Magnets with stronger magnetic force is able to attract pins from a longer distance Key words (Question)  Strings of different length, true Explanation 1. False – Although B attracted the most pins, it is also the nearest to the pins 2. False – Although C attracted the least number of pins, it is the furthest away from the pins, thus its magnetic force is not the weakest 3. True – D and A attracted the same number of pins, but since D is nearer to the pins, D’s magnetic force is weaker than A’s 4. False – same reason as (3)
  28. 28. Question 26 – Answer (2) Concept:  Extension of the spring is proportional to the mass of the load Key words (Question)  Original length, 8 cm, extension, 90g Explanation  Every 10 g causes the length of spring to increase by 2 cm  Therefore, 90 g  26 cm (length of spring)  Thus extention  26 – 8 = 18
  29. 29. Question 27 – Answer (3) Concept:  Hardness of metals Key words (Question)  Descending order of hardness Explanation A material is hard if it is able to scratch another material  Y is hardest  can scratch W, X and Z  W is 2nd hardest  can scratch X and Z  Z is 3rd hardest  can scratch X  X is softest  cannot scratch any of the 3
  30. 30. Question 28 – Answer (2) Concept:  Light and shadow Key words (Question)  Smaller shadow Explanation  The nearer an object to the screen the smaller the shadow  When you move the light source away from the object, the shadow becomes smaller as well
  31. 31. Question 29 – Answer (3) Concept:  Heat gain, heat loss – Heat travels from hot to cold Key words (Question)  Cold milk, hot water, correct Explanation A is incorrect – cold milk gains heat from the hot water  B is correct – the hot water loses heat to the cold milk, thus the temperature will drop  C is correct – the mug is cooler than the hot water, thus it gains heat
  32. 32. Question 30 – Answer (1) Concept:  Heat travels Key words (Question)  Irrelevant Explanation 1. A is relevant – this experiment shows that heat travels through matter 2. B is irrelevant – whether matter expends when heated does not affect the outcome of this experiment 3. C is irrelevant – this experiment is to investigate whether air, water or metal is a better conductor of heat 4. D is relevant - this experiment is to investigate whether air, water or metal is a better conductor of heat
  33. 33. Booklet B What to do  Understand the concept for each question.  Underline the key words (question).  Write down the key words (answer) for each question (that you did not get full marks) as correction.
  34. 34. Question 31 Key Concept:  Classification of materials Key Words or Phrases Question Answera) Suggest, Natural Materials headingb) Wrongly Silk, silkworm classfied, explain Silk comes from an animal (0m) (not specific enough)
  35. 35. Question 32 Key Concept:  (a) Seed germination, (b) life cycle of animal Key Words or Phrases Question Answera) Tick T, NPTT, F, Fb) How many 4 stages stagesc) How many days, 11 days adult
  36. 36. Question 33 Key Concept:  Water does not have definite shape Key Words or Phrases Question Answera) Reason, overflow Gaps in sand, water can occupy the spaceb) Property Does not have definite shape
  37. 37. Question 34a Key Concept:  Testing for presence of starch Key Words or Phrases Question Answeri) Which, dark Cell B blueii) Reason Chloroplast, make food
  38. 38. Question 34b Key Concept:  Celldivision (we grow because our cells are dividing) Key Words or Phrases Question Answeri) Size, explain, Cell division cause increase in wrong heightii) State, wrong Replacement of damaged cells
  39. 39. Question 35 Key Concept:  Factors that affect the survival of an organism Key Words or Phrases Question Answera) Complete, graph See next slideb) State 2 factors, 1. Sudden change in increase, deaths, temperature September 2. Predators introduced 3. Adult guppy ate smaller guppy
  40. 40. Question 36 Key Concept:  Environment – soil erosion (Plants hold the soil together to prevent soil erosion) Key Words or Phrases Question Answera) Observed More soil in drain Y than Xb) Reason No grass (prevent soil erosion)c) Hill resort, apply Grow grass
  41. 41. Question 37 Key Concept:  Forces – Gravitational force Key Words or Phrases Question Answera) What, force Gravitational forceb) Who, easier Benc) Explain Moving load downwards, same direction as gravity
  42. 42. Question 38 Key Concept:  Extension of spring Key Words or Phrases Question Answera) Line graph See next slideb) Relationship The greater the mass of the weights hung on the spring balance, the greater the extension of the spring
  43. 43. Question 39 Key Concept:  Electromagnet Key Words or Phrases Question Answera) value of x, reason 0o,, no battery to turn rod into electromagnet.b) Explain, moved Steel rod is now electromagnet, away iron thumbtack attracted to steel rod
  44. 44. Question 40 Key Concept:  Light and shadow Key Words or Phrases Question Answera) Light can pass Soya Sause – Q (translucent) through Cooking oil – R Identify, suggest Mineral water – S (transparent) Black coffee / dark ink – T (opaque)b) bases, aligned, draw, shadow
  45. 45. Question 41 Key Concept:  Water - boiling Key Words or Phrases Question Answera) How, boiling Temperature reach 100oC pointb) Right, white No. Steam is gaseous state, cloud, steam, cannot be seen explain
  46. 46. Question 42 Key Concept:  Heat transfer | Cold contracts  Important – Coldness cannot travel. Heat travels from hot to cold. Heat from rod travels to ice. Key Words or Phrases Question Answera) Explain, cool end S Rod is good conductor of heat, coldness transferredb) Another change Contractsc) Increased gradually Gain heat from surroundings to 20oC, explain
  47. 47. Question 43 Key Concept:  Heat expands Key Words or Phrases Question Answera) Why, open Lid expandedb) Explain Gain heat from warm water
  48. 48. Question 44 Key Concept:  Heat expands Key Words or Phrases Question Answera) What, after Stopper pop out some timeb) Explain Air in flask expanded when heated, force stopper out