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# Sa1 revision 1 2012 answer notes

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### Sa1 revision 1 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 (2) Concept:  Food web Key words (Question)  removed, most negative impact Explanation  Plants provide food for all living thing, thus they will have the most negative impact when removed.
4. 4. Question 2 – Answer (4) Concept:  Food chain Key words (Question)  NOT true Explanation 1. True – grass gets energy from Sun to make food 2. True – Mynah gets energy from grasshopper when the mynah eats the grasshopper 3. True – Energy is passed from one organism to another in the food chain 4. NOT true – grasshopper does not make food
5. 5. Question 3 – Answer (1) Concept:  Energy forms and Uses Key words (Question)  incorrect Explanation 1. Incorrect – energy is not created 2. Correct – solar means light 3. Correct – fossil fuels are organisms that was once alive 4. Correct – Every organism gets its energy directly or indrectly from the Sun.
6. 6. Question 4 – Answer (1) Concept:  Friction Key words (Question)  surface, distance travelled, true Explanation  The greater the friction, the lesser the distance travelled by the box.
7. 7. Question 5 – Answer (3) Concept:  Force Key words (Question)  NOT Explanation  Mass is the amount of matter in an object. Weight is the force acting on an object due to gravity.
8. 8. Question 6 – Answer (2) Concept:  Photosynthesis Key words (Question)  Successful production of oxygen Explanation  Photosynthesis occurs only in the presence of light.
9. 9. Question 7 – Answer (1) Concept:  Energy conversion Key words (Question)  Temperature rises considerably at point Z Explanation  Thekinetic energy (when the wire is bending back and forth) is converted to heat energy.
10. 10. Question 8 – Answer (4) Concept:  Elastic potential energy Key words (Question) 5 turns, 10 turns, 15 turns, 20 turns Explanation  The only variable that is changed is the number of turns.
11. 11. Question 9 – Answer (3) Concept:  Elastic spring force Key words (Question)  Forces acting on the spring Explanation  When you stretch a spring, the spring will exert a force to try and pull it back to its original length.  When you compress a spring, the spring will exert a force to try and push it back to its original length.
12. 12. Question 10 – Answer (1) Concept:  Volume and weight (matter) Key words (Question)  Equal volume, different weights Explanation  Volume is the amount of space an object takes up.  Mass is the amount of matter in an object.  Therefore, although all 4 cubes have the same volume, it does not mean they have the same mass.
13. 13. Question 11 – Answer (2) Concept:  Environment Key words (Question)  Fungi Explanation  Fungi grow in damp and warm places.
14. 14. Question 12 – Answer (1) Concept:  Food web Key words (Question)  Increase,  mynah population Explanation  When mynah’s population increase, they will eat more ladybird and spider. Therefore if ladybird and spider’s population decreases, their prey (which are aphid and whitefly) will have less predator and thus increase in number.
15. 15. Question 13 – Answer (1) Concept:  Adaptation Key words (Question)  Function, drip tip Explanation  The drip tip allows raindrops to run off quickly so that it doesn’t collect on the leaves which will block the stomata.
16. 16. Question 14 – Answer (4) Concept:  Forces Key words (Question)  Correct forces Explanation  A – gravity acts from a distance and is always a pull  B – magnetic force acts from a distance and can be a pull (attraction) or a push (replusion)  C – friction acts only on contact and opposes the motion  D – push only acts when you are touching the object and it follows the motion
17. 17. Question 15 – Answer (2) Concept:  Elastic potential energy Key words (Question)  Number of turns, distance moved Explanation 1 – true, based on graph  2 – false, 120 turns is needed to move 8 cm  3 – true, more number of turns, more energy stored, thus greater distance moved  4 – true, based on graph
18. 18. Question 16 – Answer (2) Concept:  friction Key words (Question)  Coated with liquid D, lubricating Explanation  The aim of lubricating the moving parts of a machine is to reduce friction to prevent wear and tear. Thus, the liquid used must be able to reduce friction the best.  The greater the distance moved by the wooden block, the lesser the friction (or reduce the friction
19. 19. Question 17 – Answer (4) Concept:  Environment – conditions for survival Key words (Question)  Kill, more quickly Explanation  Fair test – only the variable tested must change. In this case, the variable that is changed is the type of pesticide. All other variables must be kept the same.
20. 20. Question 18 – Answer (2) Concept:  Environment – interaction of organisms Key words (Question)  Effectively remove the caterpillars Explanation  BirdQ eats the most caterpillars (as number of caterpillars left is the least) thus the most effective to remove the caterpillars.
21. 21. Question 19 – Answer (4) Concept:  Decomposers Key words (Question)  decomposers Explanation  Decomposers (e.g. bacteria) act on dead organisms and animal waste to break them down into simpler substances (e.g. nutrients) which is absorbed by the plants.
22. 22. Question 20 – Answer (3) Concept:  Environment – factors affecting survival Key words (Question)  disease Explanation A disease will cause the drop in the number of rabbits.
23. 23. Question 21 – Answer (2) Concept:  Environment – factors affecting survival Key words (Question)  Supported by the above data Explanation 1. Wrong – The presence of some earthworms indicate earthworms can still survive in clayey soil. 2. Correct – The number of earthworms in garden soil is the greatest. 3. Wrong – there is not much moisture in sand and clayey soil. 4. Wrong – Since the numbers are all different, the earthworms do not thrive equally well.
24. 24. Question 22 – Answer (2) Concept:  Matter – good conductor of heat and electricity Key words (Question)  Good conductor, heat, electricity Explanation 1. Book is a poor conductor of heat and electricity 2. Iron nail and key are made of metal which are good conductors of heat and electricity 3. Plastic comb is a poor conductor of heat and electricity 4. Rubber phone cover is a poor conductor of heat and electricity
25. 25. Question 23 – Answer (1) Concept:  Water - Condensation Key words (Question)  Cold room, tiny droplets Explanation  Warm water vapour from the surrounding air touches the cooler surface of the window, loses heat and changes to water droplets.
26. 26. Question 24 – Answer (4) Concept:  Cells Key words (Question)  Does not belong Explanation  Option 1 – 3 are animal cells, option 4 is a plant cell since only plant cells have cell wall.
27. 27. Question 25 – Answer (3) Concept:  Materials Key words (Question)  Different materials Explanation  Foam is the worst conductor of heat thus heat from the cup will take the longest to escape to the surrounding air, thus will contain the highest water temperature after 1 hour.
28. 28. Question 26 – Answer (2) Concept:  Human digestive system Key words (Question)  Produce digestive juices Explanation  Mouth, stomach and small intestines contains digestive juices. Large intestines only absorbs water, so no digestion takes place there.
29. 29. Question 27 – Answer (1) Concept:  Plant parts Key words (Question)  Plant parts Explanation  They are all stems that store food.
30. 30. Question 28 – Answer (4) Concept:  Electricity Key words (Question)  Diagram 1, only bulb B lit up  Diagram 2, bulb A lit up but bulb B did not Explanation  Sinceonly the right bulb lights up, Y is the conductor of electricity but X is not.
31. 31. Question 29 – Answer (3) Concept:  Seed dispersal Key words (Question)  hooks Explanation  Seeds / fruits with hooks will be dispersed by clinging onto the fur of animals.
32. 32. Question 30 – Answer (2) Concept:  Reproduction Key words (Question)  Reproduction, plants, animals Explanation 1. Not true for animals 2. True for both 3. Not true for both 4. Animals does not have pollen grains
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:  Living things need air, food and water to survive. Key Words or Phrases Question Answera) Name, gas Oxygenb) Explain, Plants give out oxygen dependent during photosynthesisc) Explain, dark room Lizard die because no oxygen
35. 35. Question 32 Key Concept:  Living things need air, food and water to survive. Key Words or Phrases Question Answera) Explain, survive Snails give carbon dioxide for plants to make foodb) Explain, survive Plants give out oxygen during photosynthesis needed by snailsc) Explain, amount Less oxygen as more snails
36. 36. Question 33  Key Concept:  Photosynthesis requires sunlight, water and carbon dioxide.  Key Words or Phrases Question Answera) True, False, NPTT F, F, NPTT, NPTTb) Suggest why, Plants cannot receive unfavourable enough sunlight to make foodNo sunlight  Wrong concept as sheltered areas will stillget sunlight. It’s just not enough.
37. 37. Question 34 Key Concept:  Different factors affect the local environment Key Words or Phrases Question Answera) Explain, Most loss Q. Strong wind, evaporate in mass faster (Q does not have most exposed surface area so large exposed surface area is correct but not larger/largest exposed surface area)b) What, P dry faster Bigger (comparison) surfaced areac) Suggest, dry Sunny place / less humid faster without
38. 38. Question 35 Key Concept:  Adaptations serve to enhance survival Key Words or Phrases Question Answera) Explain, change Hide / blend with colour, survive surroundings to escape predatorsb) Which feature, Large ears. Large surface explain area to allow animal to cool down
39. 39. Question 36 Key Concept: A force can move a stationary object Key Words or Phrases Question Answera) State, change in GPE  KE energyb) State, which balls 3, 4, 5c) Ball 1 heavier, Ball 5 – move further / what change higher http://www.walter-fendt.de/ph14e/ncradle.htm
40. 40. Question 37 Key Concept:  Friction is an opposing force relative to the motion of objects.  Test is on the size of wheel Key Words or Phrases Question Answera) Describe, Same plank correct (fair test)b) List, 2 mistakes Did not change size of wheel Did not use same number of wooden
41. 41. Question 38 Key Concept:  Forces causes the extension of springs  Compare mass of … Key Words or Phrases Question Answera) List, 2 Same spring / Same scale pan variablesb) What, Length of spring / Extension of measure, the spring greatest mass
42. 42. Question 39 Key Concept:  Environmental conditions affects the habitat of decomposers Key Words or Phrases Question Answera) What, min temp 25oCb) State, conclusion The lower the temperature, the slower the rate of decompositionc) Suggest, one way, Cold place / refrigerator Explain slow down the rate of decomposition.
43. 43. Question 40 Key Concept:  Plants, animals, fungi and microorganism forms the 4 major groups in classification of living things . Key Question Phrases Words or Answera) Explain, cake P not enough water / little water / moistureb) How, mould get break down the cake into simpler food substances and absorb nutrientsc) Another similarity, respond to changes OR fungi, plants grow and reproduce OR cannot move freely from place to
44. 44. Question 41 Key Concept:  Use of magnets to separate magnetic objects Key Words or Phrases Question Answera) Suggest, Use magnet to attract steel ball separate bearingsb) Suggest, Pour contents slowly into the another, bucket of water. Cork pieces separate will float
45. 45. Question 42 Key Concept:  Temperature is a measurement of how hot or cold an object is; heat is a form of energy.  Key Words or Phrases Question Answera) Arrange S,Q,R,Pb) Explain, longer Greater volume of water at 100oC
46. 46. Question 43 Key Concept:  Anelectrical system comprises of various components. Key Words or Phrases Question Answera) Group Parallel – B, D, E Series – A, C, F
47. 47. Question 44 Key Concept:  Plants reproduce to ensure the suvival of their own kind. Key Words or Phrases Question Answera) How many 5 months monthsb) Draw, Red Clover