CCHY 2019 Bio Yearly TYS ANS

6093 Biology Yearly TYS 2019 No Paper 1 Marks Remarks 1 B 1 2 D 1 3 C 1 4 B 1 5 D 1 6 D 1 7 B 1 8 C 1 9 B 1 10 A 1 11 D 1 12 B 1 13 B 1 14 C 1 15 D 1 16 A 1 17 C 1 18 C 1 19 C 1 20 D 1 21 C 1 22 D 1 23 B 1 24 D 1 25 C 1 26 A 1 27 D 1 28 D 1 29 A 1 30 A 1 31 C 1 32 C 1 33 A 1 34 D 1 35 D 1 36 D 1 37 D 1 38 A 1 39 B 1 40 C 1 Total 40

Paper 2 Section A 1ai Cell surface membrane/ cell membrane; Partially permeable + controls substances entering or leaving the cell by allowing only some substances to pass through; 1 1 1aii Ribosome; Attached to the ER + synthesise proteins that are usually transported out of the cell; 1 1 1b Large number of mitochondria releases large amount of energy by aerobic respiration + many functions carried out by liver; Many vital functions e.g. regulation of BGC/ production of bile to emulsify fats into smaller fat droplets in small intestines/ breakdown of haemoglobin and storage of iron/ synthesis of proteins such as prothrombin and fibrinogen/ deamination of amino acids into ammonia and then urea/ detoxification of alcohol into acetyledehyde by alcohol dehydrogenase 1 1 1c Cellulose cell wall Chloroplast Large central vacuole 2 1d Increase surface area to volume ratio + increasing the rate of absorption of digested food substances through the epithelium of villi; epithelium is made up of epithelial cells with microvilli + epithelium is one-cell thick to shorten diffusion distance for faster absorption of digested food; 1 1 Total 10

2a A: right atrium + B: left atrium + C: right ventricle + D: left ventricle; A and B have the same lowest thickness of 3mm + thinner muscular walls compared to the C and D + they only force blood into the ventricles + does not need to withstand high pressure; D has a thicker muscular wall of 12 mm compared to C (5 mm) + to withstand higher pressure than that in C + to pump blood round the whole body; C has a thinner muscular wall of 5mm compared to D (12 mm) + need to withstand lower pressure than that in D + to pump blood to lungs located close to the heart; 1 1 1 1 R: no quotation of data 2b Oxygenated blood in the left atrium will mix with the deoxygenated blood in the right atrium + amount of oxygenated blood flowing into left ventricle , aorta and the rest of the body is reduced/ lowered; Blood transports less oxygen (hypoxemia) + insufficient oxygen supply for aerobic respiration in cells (hypoxia) + body cannot function as per normal/ feels tired easily/ lacks energy to function; 1 1 2c Atherosclerosis 1 Total 7

3a Water molecules move from 1 (xylem) to 2 ( mesophyll cell) by osmosis down water potential gradient; Water molecules moves out of the mesophyll cells by osmosis to form a thin film of moisture over surfaces of the