CCHY 2014 Bio Yearly TYS ANS

6093 Biology Yearly TYS 2014 No Paper 1 Marks Remarks 1 A 1 2 B 1 3 C 1 4 C 1 5 D 1 6 B 1 7 B 1 8 B (supposed to be breakdown of haemoglobin; not RBC) 1 9 B 1 10 C 1 11 D 1 12 C 1 13 D 1 14 C 1 15 D 1 16 C 1 17 A 1 18 C 1 19 A 1 20 C 1 21 C 1 22 C 1 23 C 1 24 D 1 25 C 1 26 D 1 27 B 1 28 A 1 29 C 1 30 A 1 31 C 1 32 D 1 33 C 1 34 C 1 35 B 1 36 A 1 37 A 1 38 C 1 39 A 1 40 B 1 Total 40

Paper 2 Section A No Answer Marks Remarks 1a Process by which metabolic waste products and toxic substances are removed from the body of an organism; Metabolism produces waste products + accumulation of waste/excretory products of metabolism can be toxic + harmful to the organism + must be removed immediately; 1 1 1bi 200 – 17 = 183 1 1bii Uric acid/ creatinine/ excess water 1 1c Increase water potential above normal level in blood plasma stimulates hypothalamus in the brain to trigger pituitary gland to release less ADH into bloodstream; ADH stimulates cells in the walls of the collecting ducts to become less permeable to water + less water reabsorbed from the collecting duct into the blood capillaries; Larger volume of urine + urine produced is more diluted / lower concentration; 1 1 1 Total 7 2a Liver 1 2bi Volume of pure alcohol consumed = 3 × 175 × 12 100 = 63 𝑐𝑚2 No of units of alcohol consumed = 63 ÷ 10 = 6.3 units 1 1 2bii Amount of time = 6.3 units ÷ 1h = 6.3h 1 2c Short-term: Reduced self-control + effect; increased reaction time/ slow reaction + effect; blurred vision + effect; poor muscular co-ordination + effect; unable to walk steadily + effect; slurred speech + effect; judgement deteriorates + effect; long-term: liver cirrhosis + elaboration; stomach/gastric ulcers + elaboration; addiction/ alcoholic + elaboration; 2 2 TB pg. 107-108 Total 8

3ai Vein/ branch vein 1 3aii Xylem tissue; Forms a continuous lumen/hollow tube without any partition walls/ protoplasm + Transports water and dissolved mineral salts to mesophyll cells from the roots; / Phloem tissue; Sieve tube cells are joined end to end to form sieve plates + Conducts manufactured food (sucrose and amino acids) away from the leaf to the other parts of the plant; 1 1 Identify Structure + Function 3bi Transpiration 1 3bii 17 – 8 = 9 h 1 3biii 6th hour + 20th hour 1 3biv Humidity of air/ Wind or air movement/ Light intensity 1 Total 7 4a A carbon sink is an area that stores carbon compounds for an indefinite period + stores more carbon than it releases; removes carbon dioxide from atmosphere, reducing the rate of global warming; 1 1 4bi Aerobic respiration 1 4bii Changing land use and agriculture takes in more carbon dioxide than releases carbon dioxide by 1 gigaton of carbon a year 1 4biii Sum (Release – absorbed) = (119 – 120) + (18 – 19) + (88 – 90) + 6 = -1 + (-1) + (-2_) + 6 = 2 gigatons 1 1

4biv Oceans are largest carbon sinks on Earth + one-third of the carbon dioxide releases by human activities is absorbed by oceans; carbon dioxide that dissolves in the ocean’s water is absorbed an d used by phytoplankton and algae in p/s; A portion of carbon compounds found in oceans is buried in the seabed + in the form of fossil fuels such as natural gas and oil; Presence of iron compounds in the ocean stimulates the growth of phytoplankton; increasing rate of photosynthetic activi ty + increasing rate of absorption of carbon dioxide by phytoplankton; 1 1 1 1 1 Total 11 5a Carbon monoxide in tobacco smoke combines with haemoglobin to form carboxyhaemoglobin; reducing the ability of haemoglobin to bind with oxygen + concentration of oxygen carried in RBC reduces + rate of aerobic respiration decreases + less energy released for cellular activities; / Increases rate of fatty deposits on the inner arterial wall; causes narrowing of the lumen of arteries and leads to increase in BP + may increased risk of coronary heart disease; 1 1 5bi 324 : 36 9 : 1 1 1 5bii Tobacco smoke contains tar that causes uncontrolled cell division + increasing risk of cancer in lungs; 1 Total 5 6a Asexual reproduction is the process resulting in the production of genetically identical offspring (clones) from one parent; Does not involve the fusion of gametes but involves mitosis; 1 1 6b A: prophase B: telophase C: anaphase D: metaphase 4 Total 6

7a IA, IB, IO 1 7b 5 Total 6 O B A IAIO IBIO father mother Parental genotype Gametes F1 offspring genotype F1 offspring phenotype IA IO IB IO IAIB IBIO IOIO IAIO AB

Section B 8a Arteries have thick muscular walls with much elastic tissue but veins have thin muscular walls with little elastic tissue; Arteries have small lumen relative to diameter but veins have large lumen relative to diameter; valves are absent in arteries but present in veins; Any 2 Wall Lumen Valves 8bi Speed of blood gradually decreases at a steady rate from 48cm/s in the aorta (highest speed) to 40cm/s in the arteries; Speed of blood rapidly decreases at a steady rate from 48 cm/s from the arteries through the small arteries until the capillaries at 4cm/s (lowest speed); Speed of blood gradually increases from capillaries at 4cm/s to small veins at 9cm/s + rapidly increases at veins to 26cm/s + slightly increase at vena cava to 28cm/s (lower speed than that in the artery); 1 1 1 R: no quotation of data R: did not specify lowest and highest speed 8bii Axes labelled correctly + equal intervals + correct orientation; All points plotted correctly; Best fit line; Graph occupies at least 2/3 of grid; 4 8biii Ventricular systole + contraction of the muscles of the ventricles; 1 8biv Pressure is force per unit area + with the same amount of force, pressure decreases as area increases/ As the blood flows through the arteries, arterioles, capillaries, venules, veins towards the vena cava, the surface area in which blood flows increases + reducing the pressure; 1 Definition of pressure Effect of area on pressure Total 11 0 20 40 60 80 100 120Mean Blood Pressure (mmHg) Types of blood vessel Graph of Mean Blood Pressure against Type of Blood Vessel

9a In light -dependent stage, chlorophyll absorbs/traps light energy + convert into chemical energy; Light energy is used to split water molecules into oxygen and hydrogen atoms + photolysis of water; In light-independent stage, hydrogen reduce carbon dioxide to glucose / carbon dioxide gains hydrogen to form glucose + using the chemical energy from the light dependent stage; Glucose is used immediately by plant cells + excess glucose are converted to sucrose and transported to storage organs + excess glucose stored as starch in starch granules; 1 1 1 1 chlorophyll photolysis reduction storage 9b Conditions can be controlled to the optimum to ensure rate of p/s is the maximum; Factors: light intensity, temperature, concentration of carbon dioxide, amount of water, concentration of mineral salts in soil, soil pH; Use a computerised system/ technology to monitor the conditions so that rate of p/s is kept at an optimum; Lamps/ light bulbs + to ensure high light intensity to ensure high rate of p/s takes place throughout the day / temperature sensor/ thermostat + ensure optimum temperature to prevent enzymes from being inactive or from being denatured, hence maintaining highest rate of p/s / more carbon dioxide can be supplied by intro ducing animals/ other organisms to release carbon dioxide + to maintain high rate of p/s; 1 1 1 2 function of green