IB SL Biology Paper 2: Test Review Questions with Complete and Verified Answers for Exam Preparation

2010 TZ1 2. (a) Glucose and galactose are examples of monosaccharides. State one other example of a monosaccharide. (b) The equation below shows the production of glucose and galactose from lactose. (i) There are several different types of carbohydrates. State which type of carbohydrate lactose is. (ii) State the type of chemical reaction that occurs when lactose is digested into glucose and galactose. (c) Lactase is widely used in food processing. Explain three reasons for converting lactose to glucose and galactose during food processing. (d) Simple laboratory experiments show that when the enzyme lactase is mixed with lactose,the initial rate of reaction is highest at 48°C. In food processing, lactase is used at a much lower temperature, often at 5 °C. Suggest reasons for using lactase at relatively low temperatures. - Ans .(a) fructose/ribose/deoxyribose/ribulose/other monosaccharides apart from glucose and galactose (b) (i) disaccharide (ii) hydrolysis (c) it allows people who are lactose intolerant/have difficulty digesting lactose to consume milk (products); galactose and glucose taste sweeter than lactose reducing need for additional sweetener (in flavoured milk products); galactose and glucose are more soluble than lactose / gives smoother texture /reduces crystalization in ice cream; (bacteria) ferment glucose and galactose more rapidly (than lactose) shortening production time (of yogurt/cottage cheese); (d) less denaturation / enzymes last longer at lower temperatures; lower energy costs / less energy to achieve 5° C compared to 48° C; reduces bacterial growth / reduces (milk) spoilage; to form products more slowly / to control rate of reaction; 2010 TZ2 2. (c) Describe the movement of water across membranes. (d) State the role of water in photosynthesis. - Ans .(c) osmosis / moves passively; from regions of low solute/high water potential/concentration to high solute concentration / low water potential/concentration; passes through protein channels/aquaporins/selectively-permeable membrane; (d) water molecules undergo photolysis/are split by light energy; forms oxygen as a by-product; hydrogen helps power the fixation of carbon (into organic molecules); 2010 TZ2 4. (a) State a word equation for anaerobic cell respiration in humans. - Ans .(a) pyruvate/pyruvic acid lactate/lactic acid; glucose (pyruvate/pyruvic acid) lactate/lactic acid 2010 Nov 2. (d) Explain, using one example, how non-disjunction in meiosis can lead to changes in chromosome number. - Ans .(d) pair of homologous chromosomes moves in same direction/does not separate during anaphase I / chromatids move in same direction/do not separate during anaphase II; leaving a cell with an (some) extra chromosome(s)/missing chromosome(s); an example; (e.g. Down syndrome / trisomy 21); 2010 Nov 3. (a) List two functions of membrane