PLMGSS 2024 4E ScBio P4 Ans

1 Ans: 2024 Secondary 4 Science Bio 5088_Prelim Paper 4 Qn Ans Marks Remarks LO 1a for absorption + (become soluble) + small enough, for diffusion / active transport ; 1 4 (a) describe the functions of the various parts of the digestive system: mouth, salivary glands, oesophagus, stomach, duodenum, pancreas, gall bladder, liver, ileum, colon, rectum, anus, in relation to ingestion, digestion, absorption, assimilation and egestion of food, as appropriate 1bi Enzyme – protease / pepsin Substrate – protein Product – polypeptides 1 R product as amino acids R substrate as polypeptide 4 (b) describe the functions of enzymes (e.g. amylase, maltase, protease, lipase) in digestion, listing the substrates and end-products 1bii 1 Biological catalyst +speed up rate of reaction; 2 without being chemically unchanged; 3 can be reused; 4 Provide alternative pathway with lower activation energy; 2 1 must be in answer 3 (d) explain the mode of action of enzymes in terms of an active site, enzyme-substrate complex and enzyme specificity using the ‘lock and key’ hypothesis

2 1ci Lipase 1 4 (b) describe the functions of enzymes (e.g. amylase, maltase, protease, lipase) in digestion, listing the substrates and end-products 1cii any two from: enzymes are specific OR idea of, one type removes protein and one removes fats / AW ; protein (stains/substrate) will not fit into the active site of lipase / AW ora ; enzyme and substrate have complementary shapes ; 2 3 (d) explain the mode of action of enzymes in terms of an active site, enzyme-substrate complex and enzyme specificity using the ‘lock and key’ hypothesis 1ciii compare with tubes A, B and C to assess effect of lipase and / or bile + quote time taken to turn colourless bile, does not (chemically) digest fats / does not make solution acidic ; lipase / enzyme, is required (for breakdown of fats in milk) ; bile help speed up digestion of fats + emulsify fats; 3 4(b) describe the functions of enzymes (e.g. amylase, maltase, protease, lipase) in digestion, listing the substrates and end-products 4 (d) state the role of the liver in: • fat digestion Total 10m

3 2a 1.25 – 1.32 / 1.32 *100% = -5.3 1 R if not in one DP Ig if no working shown but warn students 3. manipulate numerical and other data; Calculate is used when a numerical answer is required. In general, working should be shown, especially where two or more steps are involved. 2bi 1m scale 1m plot 1m best fit 3 See last page (in words or by using symbolic, graphical and numerical forms of presentation) to translate information from one form to another. 2bii 0.44 / mol dm-3; where graph intersects X-axis 1 2c potato (cube) in 0.8 (mol dm –3 solution) loses (percentage) mass / ora + potato in 0.4 mol dm –3 solution gain mass/ora + quote data; water molecules moves from an area of high water potential to an