Sec 2 G3 Revision Paper 2024 Mark Scheme (1)

Sec 2 G3 Revision Paper 1 2024 Science EOY Mark Scheme Section A 1 2 3 4 5 6 7 8 9 10 C C B A A B A D A D 11 12 13 14 15 16 17 18 19 20 B C A D B C D B A D 21 22 23 24 25 26 27 28 29 30 B B B A B B D B B C Section B B1a It is renewable/does not produce pollution/clean energy Reject sustainable without explanation. 1 B1b gravitational potential energy à kinetic energy à electrical energy One energy conversion – 1m each Accept also gravitational potential energy à kinetic energy of water à kinetic energy of turbine à electrical energy -1m if students wrote additional incorrect energy conversions to demonstrate how electrical energy is used without context. 2 B1c The water pressure increases with depth/water pressure is highest/water pressure is higher at the base and hence the base need to be thicker to resist the pressure to avoid breaking. Reject atmospheric pressure 1 B2a Q and R 1 B2b P 1 B2c Particles will be closely packed in a disorderly arrangement and the particles will slide past each other in a random manner. Note all keywords to be present. 1 1 B2di X and Z 1 B2dii Accept if students wrote 1- or -1 for this time only. Reject if no square brackets given. Reject if the gained electron is not of a different symbol. 1 X

B3a Smooth and white surface is a poor absorber of infrared radiation/ This slows down heat gain by the rate of radiation. 1 B3b Polystyrene foam contains many air pockets; and air is a poor conductor of heat. Polystyrene foam is a poor conductor of heat/This reduces heat gained by the refrigerator through conduction/ This reduces heat gained by the refrigerator through convection 1 1 1 B3c The air near the cooling coil/at the top cools and contracts, causing its density to increase and sinks to the bottom. The warmer air at the bottom, which is less dense, rises to the top and get cooled This cycle of sinking and rising repeats and set up the convection currents in the air which cools the refrigerator. Reject float. 1 1 1 B3d To be placed at the top shelf of the refrigerator. 1 B4a A: Oesophagus/Gullet/Esophagus B: Rectum 1 1 B4b physical digestion: Chewing of food breaks the food pieces down in smaller sizes and mixes the food with saliva to increase action by enzymes. chemical digestion: Carbohydrase/Amylase in saliva breaks down carbohydrates in the food to simpler carbohydrates/simpler sugars. 1 1 B4c The stomach is partially removed surgically; as only the amount of amino acids had significantly decreased from 8.7 units to 4.1 units before and after removal of organ. With parts of the stomach removed, rate of protein digestion to form partially digested protein is slower / lesser protease produced by stomach to digest proteins in a same amount of time. 1 1 1 polystyrene foam air pockets cooling coil smooth white surface for both inner wall and outer wall

B4d Side effect: The patient will lose the good bacteria in his gut/small intestine/ The p