Zadanie 8, Paper 2, maj 2024, TZ1, Biologia IB HL
Wzorowane na: Biology HL Paper 2, May 2024, TZ1, pytanie 8. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
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Zadanie
Polecenie
(a) Describe the assembly of cellulose from monosaccharides.
(b) Outline how rising greenhouse-gas concentrations threaten coral reefs.
(c) Explain the incorporation of carbon dioxide into organic compounds in the light-independent reactions.
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Odpowiedź z klucza
(a)
The monomer is beta-glucose. ✔
Monomers are joined by glycosidic bonds. ✔
Condensation reactions remove the elements of water. ✔
Only 1–4 glycosidic links are formed OR the polymer is unbranched. ✔
Alternate glucose units are reversed OR neighbouring chains are cross-linked OR microfibrils form. ✔
(b)
Additional greenhouse gases increase the greenhouse effect. ✔
Ocean temperature can rise. ✔
Heat stress can cause loss of symbiotic photosynthetic algae, producing bleaching. ✔
Loss of algal photosynthesis reduces nutrient supply to the coral. ✔
Bleaching can reduce growth or lead to coral death. ✔
More atmospheric CO₂ dissolves into seawater. ✔
Dissolved CO₂ acidifies seawater. ✔
Coral skeletons may dissolve OR skeleton formation is impaired OR carbonate uptake/availability for calcification is reduced. ✔
(c)
The reactions take place in the chloroplast stroma. ✔
They use energy OR ATP supplied by the light-dependent reactions. ✔
They form the Calvin cycle. ✔
The cycle begins with a five-carbon compound OR RuBP. ✔
Carbon dioxide is fixed OR attached to RuBP. ✔
Rubisco catalyses carbon fixation. ✔
The initial product splits into two three-carbon glycerate-3-phosphate molecules. ✔
Glycerate-3-phosphate is reduced OR converted to triose phosphate. ✔
Reduced NADP supplies hydrogen/electrons OR becomes oxidized. ✔
Two triose-phosphate molecules can be used to form one hexose sugar. ✔
Some triose phosphate is used to regenerate RuBP. ✔
Quality of communication: clear on first reading, concise and without unnecessary repetition or irrelevant material. ✔
Schemat punktowania
Part (a): any 3 points, maximum 3. Part (b): any 5 points, maximum 5. Part (c): any 7 points, maximum 7. Award 1 independent communication mark across the complete answer. Maximum 16. Accept scientifically equivalent wording and relevant annotated diagrams.