CCHY 2015 Bio Yearly TYS ANS

6093 Biology Yearly TYS 2015 No Paper 1 Explanation 1 B Cytoplasm present in RBC 2 C Oxygen is used up in mitochondria during aerobic respiration 3 B Against concentration gradient across a membrane 4 B Starch is storage form of glucose in plants 5 B 6 B 7 D 8 B Enzymes are secreted into the small intestine from the pancreas or intestinal glands. Liver only produce bile that is stored in the gall bladder. 9 D 10 A 11 B 12 C Rate of p/s exceeds rate of aerobic r/p 13 C 14 B 15 B 16 B 17 D 18 C 19 C 20 C High hydrostatic pressure 21 B 22 D 23 B 24 A 25 D 26 A Sensory neurone is damaged 27 C 28 B 29 A Male gamete has x and y chromosome 30 D 31 C Gene loci are at the same position 32 B 33 B 34 A 35 A 36 D 37 A 38 A 39 A 40 B Total 40

Paper 2 Section A No Answers Marks Remarks 1a A: starch B: maltose C: salivary amylase 3 1bi Temperature in the alimentary canal 1 1bii pH in the alimentary canal 1 1c Bile cannot be released from the gall bladder into the small intestines; Fats will not be emulsified into smaller fat droplets + surface area to volume ratio is not increased; Slower rate of digestion of fats by lipase; 1 1 1 Total 8 2a Sexual reproduction involves a process of fusion of nuclei of male and female haploid gametes to form a diploid zygote; Produces genetically dissimilar offspring; Gametes are produced by meiosis; 1 1 1 2b Rough surfaces + cling onto hairy body of insects; Insect follows nectar guide into flower to collect nectar + transfer pollen grains from anther of another flower to sticky stigma; 1 1 Structure + function Explain 2ci A is the pollen tube 1 2cii Pollen tube grows down the style into the ovary + pollen tube secretes enzymes to d igest surrounding tissues of the stigma and style; Pollen tube enters the ovule through micropyle + within the ovule, the tip of the pollen tube absorbs sap and bursts + releasing two male gametes; Nucleus of one male gamete fuses with the nucleus of the ovum to form a zygote + nucleus of the other male gamete fuses with the definitive nucleus to form the endosperm nucleus; 1 1 1 Describe + explain Total 9

No Answers Marks Remarks 3a 40 – 16 = 24 1 3b The higher the air temperature, the higher the body temperature of insect; No thermoregulation mechanism in the body 1 1 Relationship 3c Horizontal line from 20°C to 36°C of air temperature – constant human body temperature is 37°C 1 3d Temperature is higher than normal body t emperature detected by thermo-receptors in the skin stimulates sweat glands to become more active; Increased production of sweat by sweat glands + more water in sweat evaporates into water vapour from surface of the skin; More latent heat of vaporisation lost from body + body temperature decreases/restored to normal level 1 1 1 stimulus + gland sweat production homeostasis Total 7 4a A: aorta/ aortic arch B: pulmonary vein 1 1 4b Prevent backflow of blood from pulmonary artery/lungs into the heart when P(RV) < P(pulmonary artery) 1 4c D: Deoxygenated blood from the rest of the body flows into RA + through vena cava; E: muscles of RA contracts + P(RA) is higher than P(RV) + tricuspid valves open + D: allow blood flow from RA to RV; E: muscles of RV contracts + P(RV) is higher than P(PA) + semilunar valves open + D: blood forced out of RV into PA + at high pressure + transported to lungs D: P(RV) is higher in P(RA) + triscuspid valves closes E: to prevent backflow of blood into RA/ P(PA) is higher in P(RV) + semilunar valves closes to prevent backflow of blood into RV 1 1 1 1 Entry of blood into heart Atrial contraction Ventricular systole Closure of valves R: atrium contract A: muscles of the atrium contracts Total 7

No Answers Marks Remarks 5a Concentration of insulin decreased by 90 a.u. 1 5b Low concentration of blood glucose due to no intake of food; No excess glucose to convert to glycogen + pancreas is not stimulated to secrete insulin into the bloodstream; 1 1 5c increased contraction of muscles + increased rate of aerobic respiration + demand for glucose and oxygen increases in the muscles + BGC decreases; Stimulate the hypothalamus in the brain + nerve impulses transmitted to adrenal gland via spinal cord + adrenal gland secretes more adrenaline into bloodstream; Adrenaline  Stimulates liver to convert glycogen to glucose + more glucose available in the blood for muscle contraction  Stimulates increase metabolic rate  Stimulates increase rate of heartbeat + rise in BP so that oxygen and glucose are carried faster to the muscles  Stimulates constriction of arterioles to the gut + decrease digestive activities  Stimulates constricts of arterioles in skin + channel more blood to the muscles in the limbs 1 1 1 Stimulus Response Explain: 2 Effects Total 6 6ai Male Parent: IAIO 4 6aii Genotype Child 3: IBIO 1 6aiii Phenotype Child 2: AB Phenotype Child 4: O 1 1 6b IA and IB 1 Total 8 7ai organisms that are not able to make their own food + obtain energy and nutrients by feeding other organisms; 1 7aii feeding position of an organism in a food chain; 1 7bi plankton  small fish  large fish  fishermen/humans 1 7bii mercury is insoluble in water + plankton takes in mercury compound; mercury cannot be broken down by organisms and are not excreted + mercury is stored in the fatty tissues of the plankton; concentration increases in the body of small fishes as more plankton containing mercury are consumed + accumulation of chemicals in the bodies of organism is bioaccumulation; 1 1 1 R: no relation to context

No Section B Marks Remarks 8a Axes labelled + all ticks labelled at equal intervals; Best fit curve + no shading + smooth curve; All points plotted accurately; Maximise the size of grid provided; 4 8bi 0.320 – 0.014 = 0.306 1 8bii Between 0400 to 0600, % of CO2 increases rapidly from 0.04 to 0.32 + no light for photosynthesis + only respiration is taking place + CO2 accumulates; Between 0600 to 0800, % of CO2 decreases rapidly from 0.32 to 0.014; light intensity increases + increasing rate of photosynthesis + CO2 is used up; Between 0800 to 1400,% of CO2 maintains at a fairly constant value of between 0.014 to 0.02 + maximum rate of photosynthesis is reached; 1 1 1 1 8biii Rate of photosynthesis exceeds rate of respiration + more oxygen is given out than taken in 1 Total 10 0.04 0.32 0.026 0.02 0.016 0.014 0.016 0.024 0.036 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 Carbon Dioxide Concentration/ percentage by volume Time of the day Graph of Carbon Dioxide Concentration against Time of Day

No Answers Marks Remarks 9a Nicotine; makes blood clot easily, increase risk of blood clots blocking/narrowing the arteries + increase risk of coronary heart disease; addictive drug that causes the release of hormone adrenaline, increase heartbeat rate and blood pressure; Carbon monoxide; combines with haemoglobin to form carboxyhaemoglobin + reduces ability of blood to carry oxygen + oxygen supply to cells reduces + lowering rate of aerobic respiration; increases fatty deposits on the inner arterial wall leading to narrowing/blocking of the lumen of arteries caused increase in BP + increased risk of coronary heart disease,; Tar; Causes uncontrolled cell division, increases risk of cancer in lungs; paralyses cilia lining the air passages, increase risk of bronchitis and emphysema, breathing difficulty leads to lack of oxygen supplied to cells; irritants;