MFSS 2024 P2 MS ANS

1 2024 Prelim 6093 Suggested Answers Qns Answer 1a Organisms that spread diseases from one organisms to another 1b Cell wall – inhibit synthesis of the cell wall; Cell membrane – breaks up cell membrane ; Cytoplasm – prevent synthesis of folic acid; Ribosome – prevent protein synthesis; Reject nucleus, RER, SER 1c Complete dose of antibiotics ; Use antibiotics only when necessary ; 2a all four organisms in a diagram ; producer/s and consumer/s linked by lines to reindeer ; correct arrow/s from (grasses ferns and mosses) to ground squirrels ; 2b Only 10% of energy is pass to next trophic level : As 90% of the energy is loss in the form of heat via respiration/uneaten body parts/undigested food/faeces; If too many trophic levels, the energy transfer will not be effective; 2ci carbon / C + hydrogen / H + oxygen / O 2cii Onlu organisms that has the enzyme to digest lichenan ; Lichenan can fit into active site of the enzyme to form E-S complex ; 3ai Breathing rate at rest = 1 breath every 5 seconds = 12 breathes per minute; Breathing rate while exercising = 1 breath every 2.5 seconds = 24 breathes per minute; Differences = 24 – 12 = 12 breathes per minute 3aii During exercise, higher rate of aerobic respiration to release more energy needed for vigorous muscular contractions; Higher volume of carbon dioxide produced that needs to be removed More oxygen needed to be taken; 3b body incurred an oxygen debt and accumulation of lactic acid, produced by anaerobic respiration; oxygen is needed to convert the lactic acid back to sugar/glucose in the liver; 4a U: Capillaries; reject glomerulus V: Urea; 4b fall in glucose concentration then concentration rises; glucose forced out of the glomerulus during ultrafiltration glucose is selectively reabsorbed into blood at proximal convoluted tubule;

5 3: bicuspid valve ; P: right ventricle ; 5b 1: Closed 2: Open 3: Closed 4: Open for every 2 correct answers 5c Graph higher than original ; Crests and troughs at similar time points as original ; 6abi The level of iodine solution in tubing A decreased ; Accept also the solution remains brown, 6aii The concentrated starch solution in tubing B turned blue-black ; 6b There is a higher concentration of iodine molecules in tubing B as compared to the surrounding concentrated starch solution ; Net movement of iodine molecules into the starch solution by diffusion; Iodine molecules are small enough to diffuse through the pores of tubing B into the starch solution. react with starch, turning the starch solution blue-black ; 6c Ileum; Starch is too huge to pass through the walls of the ileum; Must be digested into small diffusible/soluble glucose before it can be absorbed ; 7a Insect/ Bee/ Butterfly ; Nectar guides/ non-feathery stigma/ large petals/ non-pendulous stamens (R: colourful/ sweet smelling/ nectar present as these are not observable)

7b Disadvantage: Energy consuming as need to attract insects ; depends on the availability of the insects