8328-55c0-4202-ad2b-09437dbd386f","questionNumber":null,"questionType":"LA","specification":"","difficulty":4,"difficultyBand":"medium","totalMarks":7,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"58d4e9b2-4a2d-4ea5-971c-a7d3e8b1c710","label":null,"content":"Compare and contrast the structure of cellulose and the structure of glycogen.","markscheme":"- Both are polysaccharides composed of glucose monomers. B1\n- Both contain glycosidic bonds / 1,4-glycosidic bonds. B1\n- Both contain only carbon, hydrogen, and oxygen (C, H, and O). B1\n- Cellulose is made of $\\beta$-glucose, whereas glycogen is made of $\\alpha$-glucose. B1\n- In cellulose, alternate glucose monomers are rotated $180^\\circ$ relative to each other, whereas in glycogen they are in the same orientation. B1\n- Cellulose consists of long, straight, unbranched chains, whereas glycogen is highly branched / contains 1,6-glycosidic bonds. B1\n- Cellulose chains form hydrogen bonds between parallel chains to form microfibrils, whereas glycogen does not form microfibrils / hydrogen bonds between parallel chains. B1","marks":7,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"paired_comparison","label":"Paired structural comparison","steps":[{"type":"text","order":0,"title":"Identify the polymers","content":"Both cellulose and glycogen are **polysaccharides composed of glucose monomers**. A polysaccharide is a polymer made by joining many monosaccharides (simple sugars).\n\n**Examiner annotation: B1** for stating this shared structural feature.","highlights":[{"text":"Compare and contrast the structure of cellulose and the structure of glycogen.","location":"specification"}]},{"type":"text","order":1,"title":"Name the shared bonds","content":"Both contain $1,4$-glycosidic bonds joining neighbouring glucose monomers. A glycosidic bond is the covalent bond that links sugar monomers.\n\n**Examiner annotation: B1** for this bond similarity."},{"type":"text","order":2,"title":"State their elements","content":"Both contain only carbon, hydrogen and oxygen: $\\mathrm{C}$, $\\mathrm{H}$ and $\\mathrm{O}$.\n\n**Examiner annotation: B1** for identifying the same elemental composition."},{"type":"text","order":3,"title":"Contrast glucose forms","content":"Cellulose is made from $\\beta$-glucose, whereas glycogen is made from $\\alpha$-glucose. These are different forms of glucose because the groups around the first carbon atom have different arrangements.\n\n**Examiner annotation: B1** for the correct paired contrast."},{"type":"text","order":4,"title":"Compare monomer orientation","content":"In cellulose, alternate glucose monomers are rotated through $180^\\circ$ relative to each other. In glycogen, the glucose monomers have the same orientation.\n\n**Examiner annotation: B1** for comparing the relative orientation of the monomers."},{"type":"text","order":5,"title":"Compare chain branching","content":"Cellulose has long, straight, unbranched chains, whereas glycogen is highly branched. The branches in glycogen are formed by $1,6$-glycosidic bonds.\n\n**Examiner annotation: B1** for contrasting the chain structures; either describing glycogen as highly branched or naming its $1,6$-glycosidic bonds completes this point."},{"type":"text","order":6,"title":"Compare hydrogen bonding","content":"Cellulose chains form hydrogen bonds between parallel chains, producing microfibrils. Glycogen does not form microfibrils through hydrogen bonding between parallel chains.\n\n**Examiner annotation: B1** for this final paired comparison."}]}],"generatedAt":"2026-07-20T16:39:49.802Z","modelVersion":"gpt-5.6-sol","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":{"percent":24}},{"id":"a639d88e-f5b5-4ab7-9355-480ab63b32be","revisionId":"ca263bb8-643d-40ca-bc81-8d6ac9d710ec","questionNumber":null,"questionType":"LA","specification":"Cartilage tissue contains various structural glycoproteins that assist in collagen fib

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