School / IB / BIOLOGY SL / Theme C: Interaction and interdependence Exam-style + marking analysis
Theme C: Interaction and interdependence Enzymes, cell respiration and photosynthesis, neural signalling, immunity, and energy and matter transfer within ecosystems.
32 activities ≈ 72 minutes
Biology SL Theme C: Interaction and interdependence
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1 Explain how enzymes lower the activation energy of a reaction, using the concept of the enzyme-substrate complex. ✓ Reviewed Easy 3 marks No calculator + 2 Marking analysis: A learner attempts the following task: “Explain how enzymes lower the activation energy of a reaction, using the concept of the enzyme-substrate complex.” Their response addresses only this point: “States that the substrate binds to the enzyme's active site, forming an enzyme-substrate complex.” 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 + 3 Explain the effect of increasing temperature above the optimum on the rate of an enzyme-catalysed reaction. ✓ Reviewed Easy 3 marks No calculator + 4 Marking analysis: A learner attempts the following task: “Explain the effect of increasing temperature above the optimum on the rate of an enzyme-catalysed reaction.” Their response addresses only this point: “States that above the optimum temperature, the rate of reaction decreases sharply.” 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 difference between anaerobic cell respiration in yeast (alcoholic fermentation) and in human muscle cells (lactic acid fermentation). ✓ Reviewed Easy 3 marks No calculator + 6 Marking analysis: A learner attempts the following task: “Outline the difference between anaerobic cell respiration in yeast (alcoholic fermentation) and in human muscle cells (lactic acid fermentation).” Their response addresses only this point: “States that both processes begin with glycolysis, producing pyruvate and a small yield of ATP, without requiring oxygen.” 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 + 7 Compare the net ATP yield of anaerobic fermentation with that of aerobic cell respiration for the complete breakdown of one glucose molecule, and explain the reason for the difference. ✓ Reviewed Easy 3 marks No calculator + 8 Marking analysis: A learner attempts the following task: “Compare the net ATP yield of anaerobic fermentation with that of aerobic cell respiration for the complete breakdown of one glucose molecule, and explain the reason for the difference.” Their response addresses only this point: “States that anaerobic fermentation yields a small net amount of ATP (glycolysis only, approximately 2 ATP per glucose).” 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 Producers in an ecosystem store 48 000 kJ m⁻² yr⁻¹ and primary consumers store 7200 kJ m⁻² yr⁻¹. Calculate the percentage transfer and explain two causes of energy loss. ✓ Reviewed Medium 5 marks Calculator + 10 Marking analysis: A learner attempts the following task: “Producers in an ecosystem store 48 000 kJ m⁻² yr⁻¹ and primary consumers store 7200 kJ m⁻² yr⁻¹. Calculate the percentage transfer and explain two causes of energy loss.” Their response addresses only this point: “Uses percentage transfer = 7200/48 000 × 100.” 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 Calculator + 11 Distinguish between a population, a community and an ecosystem. ✓ Reviewed Easy 3 marks No calculator + 12 Marking analysis: A learner attempts the following task: “Distinguish between a population, a community and an ecosystem.” Their response addresses only this point: “Defines a population as a group of organisms of the same species living in the same area at the same time, capable of interbreeding.” 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 role of decomposers in recycling nutrients within an ecosystem. ✓ Reviewed Easy 3 marks No calculator + 14 Marking analysis: A learner attempts the following task: “Explain the role of decomposers in recycling nutrients within an ecosystem.” Their response addresses only this point: “States that decomposers (e.g. bacteria and fungi) break down dead organic matter and waste products.” 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 the processes by which carbon enters and leaves the atmosphere as part of the carbon cycle. ✓ Reviewed Medium 4 marks No calculator + 16 Marking analysis: A learner attempts the following task: “Outline the processes by which carbon enters and leaves the atmosphere as part of the carbon cycle.” Their response addresses only this point: “States that photosynthesis removes carbon dioxide from the atmosphere, fixing carbon into organic compounds in producers.” 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 + 17 A food chain is: grass → grasshopper → frog → snake. Identify the trophic level of the frog and explain why food chains rarely extend beyond four or five trophic levels. ✓ Reviewed Easy 3 marks No calculator + 18 Marking analysis: A learner attempts the following task: “A food chain is: grass → grasshopper → frog → snake. Identify the trophic level of the frog and explain why food chains rarely extend beyond four or five trophic levels.” Their response addresses only this point: “Identifies the frog as a secondary consumer (third trophic level).” 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 Outline how a pyramid of energy differs from a pyramid of numbers, and state one advantage of using a pyramid of energy. ✓ Reviewed Easy 2 marks No calculator + 20 Marking analysis: A learner attempts the following task: “Outline how a pyramid of energy differs from a pyramid of numbers, and state one advantage of using a pyramid of energy.” Their response addresses only this point: “States that a pyramid of numbers represents the number of individual organisms at each trophic level, while a pyramid of energy represents the rate of energy flow (e.g. kJ m⁻² yr⁻¹) through each trophic level.” 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 competition for a limited resource can affect the carrying capacity of a population in an ecosystem. ✓ Reviewed Easy 3 marks No calculator + 22 Marking analysis: A learner attempts the following task: “Explain how competition for a limited resource can affect the carrying capacity of a population in an ecosystem.” Their response addresses only this point: “Defines carrying capacity as the maximum population size that an environment can sustainably support given its available resources.” 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 + 23 Outline the process of primary succession, from bare rock to a more established community. ✓ Reviewed Easy 3 marks No calculator + 24 Marking analysis: A learner attempts the following task: “Outline the process of primary succession, from bare rock to a more established community.” Their response addresses only this point: “States that primary succession begins on newly exposed, lifeless substrate (e.g. bare rock) with no existing soil.” 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 one direct method and one indirect method used to estimate the population size of an animal species in the field. ✓ Reviewed Easy 2 marks No calculator + 26 Marking analysis: A learner attempts the following task: “Outline one direct method and one indirect method used to estimate the population size of an animal species in the field.” Their response addresses only this point: “Outlines a direct method, e.g. the capture-mark-release-recapture technique, where a sample is captured, marked, released, and a second sample is later captured to estimate total population from the proportion of marked individuals recaptured.” 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 + 27 Outline the process by which nerve impulses are transmitted across a chemical synapse. ✓ Reviewed Medium 4 marks No calculator + 28 Marking analysis: A learner attempts the following task: “Outline the process by which nerve impulses are transmitted across a chemical synapse.” Their response addresses only this point: “States that an arriving nerve impulse causes calcium ion channels to open, allowing Ca²⁺ to enter the presynaptic neuron.” 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 + 29 Outline how the antibody-mediated (humoral) immune response leads to the production of antibodies against a specific pathogen. ✓ Reviewed Medium 4 marks No calculator + 30 Marking analysis: A learner attempts the following task: “Outline how the antibody-mediated (humoral) immune response leads to the production of antibodies against a specific pathogen.” Their response addresses only this point: “States that a B-lymphocyte with a receptor complementary to a specific antigen on the pathogen binds to that antigen.” 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 + 31 A student counts a moss species in five equal quadrats beneath trees and five equal quadrats in an open area. Counts beneath trees are 12, 9, 15, 10 and 14; open-area counts are 3, 5, 4, 2 and 6. (a) Calculate the mean count for each habitat. (b) State the pattern shown. (c) Identify one limitation of the investigation. (d) Suggest one improvement that directly addresses that limitation. ✓ Reviewed Medium 4 marks No calculator + 32 Marking analysis: A learner attempts the following task: “A student counts a moss species in five equal quadrats beneath trees and five equal quadrats in an open area. Counts beneath trees are 12, 9, 15, 10 and 14; open-area counts are 3, 5, 4, 2 and 6. (a) Calculate the mean count for each habitat. (b) State the pattern shown. (c) Identify one limitation of the investigation. (d) Suggest one improvement that directly addresses that limitation.” Their response addresses only this point: “Calculates a mean of 12 moss plants per quadrat beneath trees.” 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 + Self-assessed 0 / 0
Set total 104
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