CCHY 2016 Bio Yearly TYS ANS

6093 Biology Yearly TYS 2016 No Paper 1 Explanation 1 D 2 A 3 D Active transport requires a cell membrane 4 D 5 A Reducing sugar, proteins, fats; sucrose is not a reducing sugar; 6 B 7 B HPV carries blood from SI to liver 8 B 9 C Light intensity is no longer the limiting factor 10 D Cells in the epidermis has no chloroplasts. 11 A Transpiration cannot take place if stomata is closed 12 B 13 C 14 C 15 C 16 B 17 B 18 B Decrease in pressure is caused by increased in volume in lungs 19 B 20 C 21 D 22 D 23 C 24 D Perception of pain is always by brain 25 C 26 B 27 B 28 D 29 C 30 B 31 C 32 C 33 D 34 A 35 A 36 C 37 A 38 C 39 C 40 B Total 40

Paper 2 Section A No Answers Marks Remarks 1a A: fibrin thread B: red blood cell 1 1 1b Damaged tissues and platelets + produce/release enzyme thrombokinase; Thrombokinase, in the presence of calcium ions , catalyses the conversion of inactive prothrombin into active thrombin; Thrombin catalyses conversion of short, soluble fibrinogen into long, insoluble fibrin threads + RBCs and platelets entangle/traps in fibrin threads forming blood clot to prevent entry of foreign particles into the bloodstream; 1 1 1 1c capillaries are blocked + stopped/ restrict blood flow; less/ no oxygen and glucose supply to brain cells resulting in a stroke + lose ability to control body organs; brain cells may eventually die if there is continuously no supply of oxygen and glucose; 1 1 1 Total 8 2a Salivary amylase Polypeptides Intestinal glands/pancreas 1 1 1 2b Mouth: B; Optimum pH is pH 7 + salivary amylase works best in neutral pH at which rate of enzyme reaction is the highest; Stomach: A; Optimum pH is pH 2 + pepsin works best in acidic pH at which rate of enzyme reaction is the highest; 1 1 1 1 Total 7

No Answers Marks Remarks 3a Mutation is a sudden random change in the structure or in the chromosome number of a gene during replication + error is not repaired + gene is modified/ chromosome is altered; 1 3bi D d d Dd dd d Dd dd 1: dd (homozygous recessive) D d d Dd dd d Dd dd 2: Dd (heterozygous) 2 3bii P p P PP Pp p Pp pp 3: Pp (heterozygous) P p p Pp pp p Pp pp 4: pp (homozygous recessive) 2 3biii P p p Pp pp p Pp pp 50% 1 Total 6

No Answers Marks Remarks 4ai Root hair cells 1 4aii Absorption of water by osmosis and dissolved mineral salts by diffusion; Uptake of ions by active transport; 1 1 4aiii Long and narrow + increase surface area to volume ratio so as to increases the rate of absorption of water and dissolved mineral salts; Cell surface membrane prevents cell sap from leaking out + cell saps contain sugars, amino acids and salts creating a lower water potential than the solution in the soil + steep water potential gradient for high rate of water absorption by