Answer Scheme for Science Form 3 Mid Year Exam 2015 1. (a) (i) (ii) First class (iii) Fulcrum is located between the load and effort (b) Pliers 2. (a) (i) Stamen / Anther (ii) Pistil / Ovary (b) (i) Ovary (ii) Ovule (c) 2, 4, 1, 5, 3 3. (a) Q, R, T (b) Second and fifth (c) Protein is digested into polypeptides/peptones before further broken down into amino acid by protease enzyme. 4. (a) Blue, Red, Red, Blue (b) Alkaline – Pure coffee and bitter gourd juice Acidic – Orange juice and pineapple juice 5. (a) J : Competition, K : Mutualism (b) L : Parasitism, Rafflesia lives on its host body and obtain nutrients from it which causes harm to the host as it lost all nutrients to the parasite M : Commensalism, Remora fish attaches itself to a shark and feeds on food scattered by the shark where the shark neither benefits nor is harmed by it 6. (a) P : Medulla, Q : Cortex (b) Urea, excess mineral salts, water, uric acid, ammonium compound (c) - Blood is drawn out from the patient’s artery - The blood passes through a series of semi-permeable tubing where small waste products (water, urea, salts) diffuse through it - The clean blood is then returned back to the patient’s vein 7. (a) Food/glucose accumulated on the upper part of the stem (b) Phloem (c) (i) Vegetative reproduction (ii) No variation / Low resistance towards diseases (d) Food cannot be transported from the leaves to other parts of the tree because phloem is being cut through by the tightly tied wire. 8. (a) It returns back to the original shape

(b) The higher the temperature, the higher the air pressure. (c) - Light the strips of paper with a lighter and put into the glass bottle - Immediately put the peeled hard boiled egg onto the mouth of the bottle - Once the fire extinguished, the egg will fall into the glass bottle. - Oxygen which is used up during the combustion decreases the air pressure in the bottle. Higher atmospheric pressure exerts force on the egg forces the egg into the bottle 9. (a) (i) Air sacs (ii) Air sacs decreases the density of the plant that makes it stay afloat on the water surface. (b) (i) Cell turgidity / Turgid cells (ii) When water is absorbed by the plants, it fills up the vacoule and creates pressure against the cell wall that makes the plant stand upright. (c) Endoskeleton – Snake and Frog Hydrostatic skeleton – Caterpillar Exoskeleton – Crab 10. (a) Air pressure (b) When air is blown into the balloon, air pressure increases causing the balloon to inflate. When air is released/sucked out, air pressure decreases in the balloon causing it to deflate. (c) Straw – Trachea, Balloon – Lungs (d) P, Q 11. (a) Produces unwanted heat and noise, wastes energy (b) Friction can be reduced by using (i)ball bearings to move heavy objects (ii) rollers to move heavy objects like those used in factories/airport/grocery stores (iii) wheels to move sewing machines or refrigerators easily (c) Increase frictions between two surfaces for eg using a rough gloves so that strong grip can be obtained while climbing the rocks, use a strong rope that can give a strong grip to increase friction, use shoe that is covered with a vulcanized rubber layer to increase the grip of the foot on the rock. 12. (a) Trachea, Bronchiole, Alveolus (b) - Amount of tar is 72 times more in shisha smoke than in cigarette smoke - Amount of nicotine is 4 times more in shisha smoke than in cigarette smoke - Amount of carbon monoxide is 11 times more in shisha smoke than in cigarette smoke (c) - Shisha contains tar that blackens the lungs, - Shisha containes carcinogens that cause cancer 13. (a) (i) Positive hydrotropism/Positive geotropism (ii) Positive hydrotropism (b) To enable the plants in search for source of water, support and sunlight for photosynthesis. (c) (i) Nastic movement, Positive thigmotropism (ii) Venus flytrap – Nastic movement, non-directional response, in search for food (insects)

Cucumber plant – Thigmotropism, directional growth response towards the stimulus (touch), in response to get support and sunlight. 14. (a) Plants à Sambar deer à Malayan tiger (b) Commercial poaching / Loss of habitat / Declining prey base (c) Sambar deer is the main food for Malayan tigers, The decline in the number of Sambar deers will eventually cause the extinction of Malayan tigers. (d) - National Tiger Conservation Plan : To keep and protect the tigers under full care - Forest reserves : To protect these tigers from illegal hunting - Breeding centres : To reproduce tigers in increasing their population - Law enforcement : To severely punish those illegal hunters