CGS 2024 P2 MS ANS

1 CGS 2024 Biology Prelim Paper 2 Answers Qn Answer Key Section A 1a • high temperature denatures the enzymes • (Few hours before) allows sufficient time for enzymes to work on the proteins in the meat / more proteins to be broken down 1 1 1b • Pepsin, digest / break down proteins into polypeptides 1 2ai 750 / 5800 X 100% = 12.931 = 13% (nearest whole number) 1 1 2aii Coronary artery 1 2aiii 600 2b • Cardiac / skeletal muscle • More oxygen and glucose supplied for higher rate of respiration to release more energy OR • To remove lactic acid / carbon dioxide at a faster rate • skin • allow more heat to be lost to the surrounding 1 1 1 1 2c • less blood + QV , is transported to the digestive organs • less / slower digestion / absorption of digested food products 1 1 3b • ventricular diastole is occurring / left ventricles are relaxing • when pressure of left ventricle is less than the pressure of left atrium • bicuspid valves are opened 1 1 1 4a Both have muscle/elastic tissues / valves 1 4b C F Has RBC/WBC/platelets/plasma No RBC/WBC/platelets/plasma Has proteins/antibodies/amino acids/glucose/fats No proteins/antibodies/amino acids/fats/glucose Lower urea concentration Higher urea concentration 1 1 1 4c C Dialysis fluid Has RBC/WBC/platelets/plasma/ antibodies / urea No RBC/WBC/platelets/plasma / antibodies / urea 1 5a Respiration : glucose Growth : amino acids / proteins 1 1 5b • add pH buffer for optimum pH OR • place / incubate at optimum temperature • to speed up the rate of enzyme reaction 1 1 5ci H 1

2 Qn Answer Key 5cii • bacteria • antibiotics are effective against / kills bacteria 1 1 5d • bacteria is of different variety • some bacteria are more resistant to bacteria • patients did not complete course, resulting in more resistant bacteria surviving and reproducing 1 1 1 6ai • root hair cell 1 6aii • solvent for transport • maintains turgidity of cells / keep leaf upright • medium for enzyme action any 2 1 1 1 6c • photosynthesis • transpiration / replace thin film of moisture on mesophyll cells 1 1 6d • rate of water loss is greater than rate of water uptake / rate of transpiration is greater than rate of water absorption • cell loses turgidity / wilting occurs 1 1 7b • 90% of the energy is lost as heat via respiration / uneaten body parts / egested waste / excreted waste 1 7c • Washed into the lake by rain and absorbed by the water plants • Organochlorides are non-biodegradable and cannot be excreted, will accumulate / become concentrated in the fatty tissues of organisms • As it passes along the food chain, it increases in concentration along the trophic level and become most concentrated at the highest trophic level 1 1 1 7d • Nitrates / phosphates washed into the lake promotes the growth of algae, leading to eutrophication • Algae will block sunlight from reaching the underwater plants, which will die as they cannot undergo photosynthesis • Decomposers/bacteria will mul