KCPSS_2024_4E_Sci Bio_Prelim_P4_MS

1 KUO CHUAN PRESBYTERIAN SECONDARY SCHOOL Sec 4 Express / Sec 4 Normal Academic (SBB) Biology (5088) Prelim Examination / 2024 Marking Scheme Important Note: 1. Mark only answers clearly written in black or blue ink. Section A – Multiple Choice Questions [20 marks] – Using OTAS Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 B D B D A C A B C B Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 Q19 Q20 D C D B A C A B D C SECTION A [55 marks] 1 (a) A: starch B: (salivary) amylase 2 correct for 1 mark. 1 (b) 1. 1 mark for correct drawing of enzyme-substrate complex and maltose 2. 1 mark for correct labelling of enzyme-substrate complex, amylase and maltose. 2 (c) solution with substrate A: remains blue solution with final products: brick-red / orange / yellow / green ppt 2 correct for 1 mark. 1 Total: 4

2 2 (a)(i) A: oesophagus B: small intestine C: large intestine D: rectum Any 2 – 1m 2 (a)(ii) B / C. 1 (b) (i) Any 1 point: 1. stimulates the conversion of excess glucose to glycogen in the liver / muscles 2. increased uptake of glucose by cells 3. increase permeability of cell membranes to glucose 1 (b) (ii) Blood glucose concentration will remain high for a longer period of time. 1 Comments: Total: 5 3 (a) coronary artery [R: coronary heart artery] 1 (b) Any one: high level of stress / smoking / lack of exercise / old age / obesity / genetics Reject: diet high in cholesterol/saturated fats 1 (c)(i) 1 point for 1m 1. less oxygenated blood and glucose (nutrients) is pumped to heart muscles/tissues [R: heart] 2. less/no aerobic respiration/more anaerobic respiration 1 1 1

3 3. less/no energy released [R: produced] 4. less/no contraction/pump of heart muscle to pump blood (out of aorta)/reduced pressure generated by heart muscle. 1 Total: 6 4 (a)(i) To absorb carbon dioxide gas. 1 (a)(ii) Maggots respire, taking in oxygen , thus volume of gas within capillary tube decreases, causing the droplet to move towards the left. 1 Comments: (b)(i) 1. During vigorous exercise, glycogen is converted to glucose as 2. glucose is needed to be oxidised via respiration to release energy for the muscle cells. 1 1 Comments: (b)(ii) 1. As muscles did not get enough oxygen to release energy the body needs, anaerobic respiration has occurred. 2. As anaerobic respiration happen, lactic acid, a by-product is produced and accumulated . Hence, the increase in concentration is observed. 1 1 Total: 6 5 (a)(i) Percentage change = (final – initial)/initial x 100% = (240-1400)/1400 x 100% = – 82.9% (3s.f.) Working – 1 mark, Final answer – 1 m (if didn’t put (–), no 1m for final answer) 1 1

4 (a)(ii) Any 1 point 1m 1. Vaccine contains an agent that resembles the pathogen. 2. Vaccines stimulates WBC to produce antibodies. 3. The white blood cells remain in the blood and can