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 osmosis; Contains mitochondria where aerobic respiration takes place to release energy for active transport of ions into the cells; any 2 structure + function 4b Xylem tissue; Transports water and dissolved mineral salts to mesophyll cells of the leaves from the roots by transpiration pull; 1 1 Total 7 5ai A: mitochondrion B: smooth endoplasmic reticulum 1 1 R: plural 5aii site where aerobic respiration takes place + Glucose oxidised to release energy for the cell 1 R: produce energy 5b Plant cell has cellulose cell wall that provides support for the cell, while animal cell does not have a cell wall; Plant cell has chloroplast that enable it to carry out photosynthesis, while an animal cell does not have chloroplasts; Plant cell has a large central vacuole that contains cell sap, while animal cell have many smaller vacuoles. 1 1 1 Contrasting statements R: no comparative word such as while, but Total 6

No Answers Marks Remarks 6a 1: fruit bats; 2: banana plants one arrow from banana plant to monkeys; one arrow from macaws to pythons; 1 1 1 1 6b trophic level is a feeding position of an organism in a food chain; TL1 is always made up of producers which are plants i.e. orchids, seeds, banana plants and bamboo plants / TL2 is made up of primary consumers which are herbivores i.e. macaws, fruit bats and monkeys / TL3 is made up of secondary consumers which are carnivores i.e. pythons and jaguars 1 1 definition Any one reference 6c energy is lost as heat to the environment through respiration; energy is lost in uneaten part or dead bodies, faeces and excretory products, trapped in the form of chemical energy; 1 1 6d 1 1 Total 10 7ai Concentration of urine increases as concentration of ADH in blood plasma increases; more ADH into blood plasma stimulates cells in the walls of the collecting ducts to become more permeable to water; more water reabsorbed from the collecting duct into the blood capillaries + smaller volume of urine + urine produced is more concentrated; 1 1 1 Relationship Effect of ADH Effect of increase permeability 7aii Rate of flow of urine through the ureter decreases as the concentration of urine increases / Rate of flow of urine through the ureter decreases as the concentration of ADH in blood plasma increases 1 7b Vigorous exercise + increase perspiration/ sweating to regulate body tem perature + increase water excreted in sweat + decrease water potential below normal level in blood plasma; stimulates hypothalamus in the brain to trigger pituitary gland to release/secrete more ADH into bloodstream; 1 1 Total 6 Pyramid of Biomass banana plants monkey jaguar

Section B No Answers Marks Remarks 8a 12.8 ÷ 16 = 0.8 1.0 × 16 = 16.0 1 1 8b All bars of equal width; Axis labelled + equal intervals; All bars plotted correctly; Occupy the whole grid; 4 8c Measure the height of the trees 1 Light is needed for p/s + light energy absorbed by chlorophyll needed to convert carbon dioxide and water into glucose and oxygen; Glucose serves as a source of food and energy for trees to grow + higher light intensity leads to more glucose being formed by p/s; 1 1 8e temperature/ concentration of carbon dioxide/ volume of water/ water potential in soil solution/ concentration of mineral salts in soil/ soil pH Any 2 AW Total 11 1.2 1.2 0.8 0.4 7.4 0.6 1 1.2 0 1 2 3 4 5 6 7 8 Growth Rate per Year

No Answers Marks Remarks 9a Excess amino acids are transported to the liver for deamination + amino groups are removed from amino acids; Remains of amino acids are converted to carbon residue + which in turn is converted to glucose; Glucose dissolves in blood plasma carried to other body cells for aerobic respiration + excess glucose will be converted into glycogen + stored in the liver or muscle cells; Amino group is converted to ammonia + which in turn is converted to urea; Urea dissolves in blood plasma + carried to the kidneys in the bloodstream + excreted in urine; 1 1 1 1 1 Deamination Conversion to glucose Transport of glucose Formation of urea Excretion of urea 9b Large amount of carbon dioxide produced from aerobic respiration + carbon dioxide diffuses from cells into the blood and enters RBCs; Carbon dioxide reacts with water in RBCs to form carbonic acid + catalysed by enzyme carbonic anhydrase present in RBCs; Carbonic acid is converted into hydrogencarbonate ions which diffuse out of the RBCs into the blood plasma + a small amount of carbon dioxide is also dissolved in the RBCs; In the lungs, hydrogencarbonate ions diffuse back into RBCs + converted back into carbonic acid + converted into water and carbon dioxide + carbon dioxide diffuses o