CHIJ St Nicholas 2016 Bio Prelim P2 MS

7 Paper 2 Section A (80 marks) Qn Answer Marks Markers’ Report 1(a) Long and narrow protrusion/extension; To increase surface area to volume ratio for absorption/diffusion; [1] 0.5m each Function is not for exchange of substances 1(b) 51/1.6= x31.9 [1] Many candidates do not know that 1cm = 10mm 1(c) Structure 1 Structure 2 glucose Diffusion and active transport NA Amino acids Diffusion and active transport NA Fatty acids NA diffusion [2] Any mistakes minus 0.5m 2(ai) 0.6:1 [1] 2(aii) As SA:VOL ratio decreases rate of diffusion decreases (or vice versa); Use figures with correct units (mms-1 for rate) to illustrate trend; The larger the plant, the lower the SA:V ratio; Plants cannot rely on diffusion to absorb nutrients (will require to carry out active transport) [2] 0.5m each 2(b) First student’s answer; The student considered the SA:V ratio than the length of the cube only. [2] 1m each Also accepted: The first student divided the answer by 2 as distance has to be to centre of cube rather than whole length of side/ Student assumed diffusion occurs (across whole cube) from whole length of one side; 171 trendylinedered the SA:V ratio than the length of t achT istance has to be whole length of side/ Studeassumeddiffu whole cube) fromwhotrendyyyyline

8 Qn Answer Marks Markers’ Report 3(a) Blurred vision/delayed speed of reaction/increased reaction time/impaired judgement/slower reflex actions [1] Any one 3(b) 184mg per 100cm3 [1] 3(c) Alcohol dehydrogenase produced by the liver; Will catalyse; the breakdown of alcohol into acetaldehyde; then further into compounds used for respiration [2] 0.5m each 3(d) Extend line using ruler until it reaches the dotted line; Read off time on dotted line [1] 0.5m each Ideal answer: 9.12am Each small box is 24 minutes 4(a) Double circulation means blood passes through the heart twice in one circulation; Pulmonary circulation and systemic circulation; blood flows out through pulmonary artery to capillaries in lungs; blood flows out through aorta to arteries to body and returns to heart through veins; [2] 0.5m each In description, reference must be made to Figure 4.1 – at least 1 part of circulatory system from the figure must be explicitly named Need to mention that blood from capillaries flows back to the heart 4(b) Oxygen molecules combine with haemoglobin in red blood cells; To form oxyhaemoglobin; When muscles in wall of left ventricle; contract / undergo ventricular systole; The pressure in the left ventricle increases; and becomes higher than aorta; aortic valve opens; (semilunar valve – 0m) blood flows through hepatic artery to liver; oxygen in blood diffuses; from red blood cell into plasma into tissue fluid and into liver cells; [Max 4] 0.5m each Description should only start from point at which oxygen is forced out of left ventricle of the heart, and not from left atrium / lungs. 172 trendylineer t;(semiluna