Biomolecules Tutorial answers (H1)

St Andrew’s Junior College The Cell and Biomolecules of Life / Carbohydrates 2021 H1 Biology 1 Full Name: Civics group: 21S Index no.: Date: Core Idea 1: The Cell and Biomolecules of Life Tutorial 2 Biomolecules - Carbohydrates MCQ 1 2 3 4 5 6 B B C A D A 9700 / 2010 / Nov - adapted 1 The equation shows a reversible reaction. In this reaction, what enzyme catalyses reaction 1 and what types of reaction occur at 1 and 2? enzyme reaction at 1 reaction at 2 A sucrase condensation hydrolysis B sucrase hydrolysis condensation C sucrose condensation hydrolysis D sucrose hydrolysis condensation 9700 / s2016 / QP12 / Q7 2 The diagrams show four monosaccharides with the formula C6H12O6. Which diagram shows α-glucose? ANS: B Thinking question: What is the term that describe these 4 monosaccharides having the same formula C6H12O6 but different structural arrangements? disaccharide monosaccharides = simple sugars β-glucose -OH group at the plane different from the α-glucose and β-glucose And β-glucose For general info only: (D) α-mannose For general info only: (C) α-allopyranose α-glucose Note: Remember for α-glucose =  

St Andrew’s Junior College The Cell and Biomolecules of Life / Carbohydrates 2021 H1 Biology 2 ANS: ISOMERISM Class Activity: Three monosaccharides condensed together to form a trisaccharide. How many glycosidic bonds does a trisaccharide have? Ans: Draw the condensation reaction of 2 α -glucose to self-check if you are able to understand and apply the concept of LO1(h)(i) ie the formation of glycosidic bonds. Note: Draw a disaccharide consisting of 2 β–glucose for a challenge. Ans: 9700 / 2005 / Nov 3 Which molecule in the key is sucrose? ANS: C 4 Which statements about amylopectin and cellulose are correct? 1 Both contain 1-4 glycosidic bonds. 2 Amylopectin contains β-glucose while cellulose contains α–glucose. 3 Both have cross-linkages. 4 Both are branched molecules. A 1 only B 1 and 2 only C 2 and 3 only D 3 and 4 only 5 carbon sugar 6 carbon sugar Note: Sucrose is a non-reducing sugar, that you must know. It is also comprised of 2 hexose sugars (Glucose & Fructose).

St Andrew’s Junior College The Cell and Biomolecules of Life / Carbohydrates 2021 H1 Biology 3 5 Which statement describes how the molecular structure of starch is suited to its function? A Amylose has a branched structure and amylopectin is coiled to give a compact molecule for transport.  amylose is coiled while amylopectin is coiled and branch. Further, amylose & amylopectin for storage, not for transport purpose B In the breakdown of amylose and amylopectin, many condensation reactions release stored energy.  breakdown is hydrolysis reaction C The helical s tructure of amylose and amylopectin gives starch high tensile strength. D The amylose-amylopectin complex is insoluble and does not affect the