School / IB / BIOLOGY HL / Theme C: Interaction and interdependence (HL) Exam-style + marking analysis
Theme C: Interaction and interdependence (HL) HL-only depth on chemiosmosis, cell respiration, photosynthesis, chemical signalling and immune defence.
30 activities ≈ 68 minutes
Biology HL Theme C: Interaction and interdependence (HL)
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1 Explain the difference between competitive and non-competitive enzyme inhibition, referring to the active site. ✓ Reviewed Medium 4 marks No calculator + 2 Marking analysis: A learner attempts the following task: “Explain the difference between competitive and non-competitive enzyme inhibition, referring to the active site.” Their response addresses only this point: “States that a competitive inhibitor has a similar shape to the substrate and binds directly to the active site, blocking the substrate from binding.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Medium 4 marks No calculator + 3 Outline how the rate of an enzyme-catalysed reaction changes with increasing substrate concentration, at a fixed enzyme concentration, and explain why it eventually plateaus. ✓ Reviewed Easy 3 marks No calculator + 4 Marking analysis: A learner attempts the following task: “Outline how the rate of an enzyme-catalysed reaction changes with increasing substrate concentration, at a fixed enzyme concentration, and explain why it eventually plateaus.” Their response addresses only this point: “States that at low substrate concentration, the rate of reaction increases roughly proportionally with substrate concentration.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 5 Outline the role of the electron transport chain and chemiosmosis in producing ATP during oxidative phosphorylation. ✓ Reviewed Medium 4 marks No calculator + 6 Marking analysis: A learner attempts the following task: “Outline the role of the electron transport chain and chemiosmosis in producing ATP during oxidative phosphorylation.” Their response addresses only this point: “States that electrons from NADH and FADH₂ are passed along a series of protein carriers (the electron transport chain) in the inner mitochondrial membrane.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Medium 4 marks No calculator + 7 Explain why oxygen is essential for aerobic cell respiration to continue, in terms of its role at the end of the electron transport chain. ✓ Reviewed Easy 3 marks No calculator + 8 Marking analysis: A learner attempts the following task: “Explain why oxygen is essential for aerobic cell respiration to continue, in terms of its role at the end of the electron transport chain.” Their response addresses only this point: “States that oxygen acts as the final electron acceptor at the end of the electron transport chain, combining with electrons and H⁺ ions to form water.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 9 Outline the light-dependent reactions of photosynthesis, including the roles of water and the products formed. ✓ Reviewed Medium 4 marks No calculator + 10 Marking analysis: A learner attempts the following task: “Outline the light-dependent reactions of photosynthesis, including the roles of water and the products formed.” Their response addresses only this point: “States that light energy is absorbed by chlorophyll and other pigments in the thylakoid membrane, exciting electrons.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Medium 4 marks No calculator + 11 Outline the light-independent reactions (Calvin cycle) of photosynthesis, including the roles of ATP, NADPH and carbon dioxide. ✓ Reviewed Easy 3 marks No calculator + 12 Marking analysis: A learner attempts the following task: “Outline the light-independent reactions (Calvin cycle) of photosynthesis, including the roles of ATP, NADPH and carbon dioxide.” Their response addresses only this point: “States that carbon dioxide is fixed by combining with a five-carbon acceptor molecule (ribulose bisphosphate, RuBP), catalysed by the enzyme rubisco.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 13 Explain the effect of increasing light intensity on the rate of photosynthesis, and why the rate eventually plateaus even as light intensity continues to increase. ✓ Reviewed Easy 3 marks No calculator + 14 Marking analysis: A learner attempts the following task: “Explain the effect of increasing light intensity on the rate of photosynthesis, and why the rate eventually plateaus even as light intensity continues to increase.” Their response addresses only this point: “States that at low light intensity, the rate of photosynthesis increases as light intensity increases, since light is the limiting factor.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 15 Outline why anaerobic respiration produces far less ATP per glucose molecule than aerobic respiration, in terms of the electron transport chain. ✓ Reviewed Easy 3 marks No calculator + 16 Marking analysis: A learner attempts the following task: “Outline why anaerobic respiration produces far less ATP per glucose molecule than aerobic respiration, in terms of the electron transport chain.” Their response addresses only this point: “States that anaerobic respiration (fermentation) stops after glycolysis, since there is no oxygen available to act as the final electron acceptor for the electron transport chain.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 17 Explain why an increase in temperature, up to the optimum, increases both enzyme reaction rate and the rate of respiration. ✓ Reviewed Easy 3 marks No calculator + 18 Marking analysis: A learner attempts the following task: “Explain why an increase in temperature, up to the optimum, increases both enzyme reaction rate and the rate of respiration.” Their response addresses only this point: “States that increasing temperature increases the kinetic energy of both enzyme and substrate molecules, causing them to move faster.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 19 Compare the location within the chloroplast of the light-dependent reactions and the light-independent reactions of photosynthesis. ✓ Reviewed Easy 2 marks No calculator + 20 Marking analysis: A learner attempts the following task: “Compare the location within the chloroplast of the light-dependent reactions and the light-independent reactions of photosynthesis.” Their response addresses only this point: “States that the light-dependent reactions occur on/in the thylakoid membranes.” Evaluate the response against the complete 2-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 2 marks No calculator + 21 Explain how auxin controls the phototropic response of a shoot growing towards a unidirectional light source. ✓ Reviewed Medium 4 marks No calculator + 22 Marking analysis: A learner attempts the following task: “Explain how auxin controls the phototropic response of a shoot growing towards a unidirectional light source.” Their response addresses only this point: “States that auxin is produced in the shoot tip and is transported laterally away from the light towards the shaded side.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Medium 4 marks No calculator + 23 Outline the role of gibberellin in breaking seed dormancy and initiating germination in cereal seeds. ✓ Reviewed Easy 3 marks No calculator + 24 Marking analysis: A learner attempts the following task: “Outline the role of gibberellin in breaking seed dormancy and initiating germination in cereal seeds.” Their response addresses only this point: “States that water uptake by the seed triggers the embryo to release gibberellin.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 25 Outline how the primary and secondary immune responses differ in speed and magnitude, and explain the biological reason for this difference. ✓ Reviewed Medium 4 marks No calculator + 26 Marking analysis: A learner attempts the following task: “Outline how the primary and secondary immune responses differ in speed and magnitude, and explain the biological reason for this difference.” Their response addresses only this point: “States that the primary response is slow to develop (taking days) and produces a relatively low concentration of antibody.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Medium 4 marks No calculator + 27 Explain how a vaccine can provide immunity against a pathogen without causing the disease itself. ✓ Reviewed Easy 3 marks No calculator + 28 Marking analysis: A learner attempts the following task: “Explain how a vaccine can provide immunity against a pathogen without causing the disease itself.” Their response addresses only this point: “States that a vaccine contains antigens from the pathogen (e.g. a weakened, inactivated, or partial form) that are not able to cause the full disease.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Easy 3 marks No calculator + 29 An enzyme is tested at substrate concentrations of 1, 2, 4 and 8 mmol dm⁻³. Rates without inhibitor are 12, 20, 31 and 40 units; with inhibitor they are 6, 12, 24 and 38 units. (a) Compare the effect of the inhibitor at low and high substrate concentration. (b) Deduce the most likely type of inhibition. (c) Explain the molecular basis for this deduction. (d) Suggest additional data that would strengthen the conclusion. ✓ Reviewed Medium 5 marks No calculator + 30 Marking analysis: A learner attempts the following task: “An enzyme is tested at substrate concentrations of 1, 2, 4 and 8 mmol dm⁻³. Rates without inhibitor are 12, 20, 31 and 40 units; with inhibitor they are 6, 12, 24 and 38 units. (a) Compare the effect of the inhibitor at low and high substrate concentration. (b) Deduce the most likely type of inhibition. (c) Explain the molecular basis for this deduction. (d) Suggest additional data that would strengthen the conclusion.” Their response addresses only this point: “States that the inhibitor substantially reduces rate at low substrate concentration.” Evaluate the response against the complete 5-mark task. Identify what earns credit and state every additional requirement needed for full marks. ✓ Reviewed Marking analysis Medium 5 marks No calculator + Self-assessed 0 / 0
Set total 102
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