Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ Carbohydrates and Lipids Question Paper 1 Level International A Level Subject Biology Exam Board CIE Topic Biological Molecules Sub Topic Booklet Carbohydrates and Lipids Theory Paper Type Question Paper 1 Time Allowed : 42 minutes Score : / 35 Percentage : /100 Grade Boundaries: A* >85% A 777.5% B 70% C 62.5% D 57.5% E U 45% <45% Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ 1 Fig. 5.1 shows a diagram of the molecular structures of tristearin (a triglyceride) and phosphatidylcholine (a phospholipid). H CH3 H C N+ CH3 H C H CH3 O O P H H H H C C C O O O H H C OC OC O H H O C C C O O H O– H C OC O tristearin phosphatidylcholine Fig. 5.1 (a) Table 5.1 shows a structural difference between the two molecules shown in Fig. 5.1. Complete Table 5.1 with two further structural differences other than in numbers of different types of atoms. Table 5.1 structural feature length of fatty acid chains tristearin all the same length phosphatidylcholine different lengths [2] Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ (b) Cells in the pancreas secrete enzymes, such as amylase and trypsin, into a duct. The enzymes are packaged in vesicles so that they can be exported from these cells as shown in Fig. 5.2. enzymes plasma membrane cytoplasm Fig. 5.2 With reference to Fig. 5.2, explain how enzymes that are secreted by cells in the pancreas are packaged into vesicles and exported. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[4] Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ (c) Water has many significant roles to play in cells and living organisms. Complete Table 5.2 below by stating the property of water that allows each of the following to take place. Table 5.2 role of water property of water solvent for glucose and ions movement in xylem helps to decrease body temperature in mammals [3] [Total: 9] Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ 2 Starch is composed of two polysaccharides, amylose and amylopectin. Fig. 3.1 shows a molecule of α-glucose before being added to the end of a molecule of amylose. H ..... O CH2OH O H OH H H H OH H O CH2OH O H OH H H H H O OH CH2OH O H OH H H H OH H HO OH CH2OH O H OH H H H OH OH Fig. 3.1 (a) (i) Complete Fig. 3.1 to show how a molecule of α-glucose is added to the amylose. [3] (ii) Name the bond that forms between glucose molecules in polysaccharides, such as amylose. .............................................................................................................................. [1] (b) Glycogen and cellulose are two other polysaccharides. Complete Table 3.1 to compare glycogen and cellulose with amylose. Table 3.1 feature monomer branched or unbranched molecule role in organisms amylose glycogen cellulose α-glucose unbranched energy storage [3] Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ (c) Type 2 diabetes (insulin-independent diabetes) is a non-infectious disease. If not treated, this disease is characterised by large fluctuations in the concentration of glucose in the blood. Maltase is an enzyme that completes the digestion of starch in humans. Molecules of maltase are bound to the microvilli of epithelial cells in the small intestine. Ascorbase is a drug used in the treatment of type 2 diabetes. Molecules of ascorbase have a very similar shape to that of the substrate for maltase. (i) Explain how ascorbase acts to inhibit these membrane-bound enzymes. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [3] (ii) Suggest why ascorbase can be used to treat people who have type 2 diabetes. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ...................................................................................................................................... [2] [Total: 12] Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ 3 Polysaccharides are synthesised by condensation reactions between monosaccharide or disaccharide subunits (monomers). (a) Name the type of bond formed when polysaccharides are synthesised. ..................................................................................................................................... [1] (b) Disaccharides are formed following synthesis from monosaccharides or as a result of polysaccharide hydrolysis. Cellobiose, maltose, sucrose and trehalose are four different disaccharides found in nature. Fig. 4.1 shows the molecular structure of these disaccharides. Identify the disaccharides, labelled A to D, using the information below. • The disaccharide cellobiose is formed from the hydrolysis of the polysaccharide cellulose. • When cellobiose is hydrolysed, two β-glucose molecules are produced. • One of the disaccharides is sucrose. • Trehalose is a disaccharide that is synthesised from two α-glucose molecules. • The disaccharide maltose is formed from the hydrolysis of amylose, a component of starch. Write the name of the disaccharides in the spaces provided on Fig. 4.1. Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ CH2OH H OH O H OH H H H H OH OH H HOH2C O O H H OH H OH A ......................................................... CH2OH H OH CH2OH O H OH H H OH H H O O H OH H H OH H OH B ......................................................... CH2OH H OH CH2OH O H H OH H H OH O H O H OH H H OH OH H C ......................................................... CH2OH H OH O H OH H H OH CH2OH H O H OH O H HO CH2OH H D ......................................................... [3] Fig. 4.1 Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ In some organisms, trehalose is used as an energy store and gives protection against the harmful effects of very low temperatures. Trehalose is sometimes referred to as a cryoprotectant, allowing organisms to survive in freezing conditions. Freezing temperatures can damage the cell surface membrane and membranes within the cell. (c) Explain the importance of the cell surface membrane to cells. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ..................................................................................................................................... [3] (d) Freezing temperatures can also completely stop enzyme activity by causing the molecules to undergo ‘cold denaturation’. Enzyme activity is not recovered when temperatures are increased to a normal working temperature range. (i) Explain the mode of action of enzymes. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. ............................................................................................................................. [3] (ii) Suggest how the molecular structure of the enzyme changes during ‘cold denaturation’. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. ............................................................................................................................. [2] Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ (e) Cryoprotectants, such as trehalose, are of particular interest in their application to preserving cells, tissues or organisms for future use. An investigation was carried out to find the protective effect given by different concentrations of two cryoprotectants, trehalose and glycerol, on a respiratory enzyme. The enzyme was subjected to a freezing temperature and then returned to its optimum temperature. The activity of the enzyme was measured at its optimum temperature. Fig. 4.2 is a graph showing the results of the investigation. 100 80 percentage of maximum activity 60 40 20 0 0 20 40 60 80 cryoprotectant concentration / mmol 100 trehalose glycerol Fig. 4.2 With reference to Fig. 4.2, describe the results of the investigation. .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... ..................................................................................................................................... [4] [Total: 16] Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ 4 Fig. 5.1 shows five different biological molecules. O– O C H CH3 O H H H C H H C H C H C OH H O C N C C H N H C H H C C H N H C C H H O OH C O– O J CH2OH H O K H H O O H H OH H OH OH OH H H H O H H O H H OH H H O O H OH H H O H OH CH2 O H H OH OH CH2OH C H OH O H H OH H H O H OH H H O O H CH2OH O H OH H OH H O H H OH H H O H OH OH H CH2OH O H H H O OH Fig. 5.1 H OH O H H O H OH CH CH CH2 O H CH2 CH C O HC H CH2OH O H OH H OH HN M CH2OH H OH OH CH2OH O CH2OH O HO O O CH2OH O H OH L H H H O O H H OH CH2OH CH2OH CH2OH O H H OH O H H CH2OH H O H OH H OH CH2 Save My Exams! – The Home of Revision For more awesome GCSE and A level resources, visit us at www.savemyexams.co.uk/ Complete Table 5.1 by indicating which molecule matches each statement. You may use each letter (H to M) once, more than once or not at all. You should write only one letter in each box. Table 5.1 statement letter contains peptide bonds part of the molecule forms the hydrophobic part of cell membranes contains 1-4 and 1-6 glycosidic bonds forms the primary structure of a protein used for energy storage in plants forms a helical structure the sub-unit molecule is β-glucose [Total: 7]
