School / IB / BIOLOGY HL / Theme B: Form and function (HL) Exam-style + marking analysis
Theme B: Form and function (HL) HL-only depth on plant transport, environmental adaptation, and muscle and kidney structure and function.
20 activities ≈ 48 minutes
Biology HL Theme B: Form and function (HL)
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1 Explain how the cohesion-tension theory accounts for the rise of water through the xylem of a tall tree. ✓ Reviewed Medium 4 marks No calculator + 2 Marking analysis: A learner attempts the following task: “Explain how the cohesion-tension theory accounts for the rise of water through the xylem of a tall tree.” Their response addresses only this point: “States that water evaporates from the mesophyll cells and leaves the stomata during transpiration, lowering water potential in the leaf.” 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 the pressure flow (mass flow) hypothesis for translocation of sugars in phloem sieve tubes. ✓ Reviewed Medium 4 marks No calculator + 4 Marking analysis: A learner attempts the following task: “Outline the pressure flow (mass flow) hypothesis for translocation of sugars in phloem sieve tubes.” Their response addresses only this point: “States that sucrose is actively loaded into the sieve tubes at the source (e.g. a photosynthesising leaf), lowering the water potential there.” 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 + 5 A student measures the transpiration rate of a leafy shoot using a potometer at three different humidity levels. Predict and explain the effect of increasing humidity on the rate of water uptake. ✓ Reviewed Easy 3 marks No calculator + 6 Marking analysis: A learner attempts the following task: “A student measures the transpiration rate of a leafy shoot using a potometer at three different humidity levels. Predict and explain the effect of increasing humidity on the rate of water uptake.” Their response addresses only this point: “Predicts that the rate of water uptake will decrease as humidity increases.” 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 Explain why xylem tissue is composed of dead, hollow cells while phloem tissue is composed of living cells. ✓ Reviewed Medium 4 marks No calculator + 8 Marking analysis: A learner attempts the following task: “Explain why xylem tissue is composed of dead, hollow cells while phloem tissue is composed of living cells.” Their response addresses only this point: “States that xylem transports water and dissolved minerals passively, driven by transpiration pull, which does not require living cell processes.” 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 + 9 A ring of bark and phloem is removed from around the trunk of a tree (girdling), leaving the xylem intact. Predict what will happen to the roots and explain your reasoning. ✓ Reviewed Easy 3 marks No calculator + 10 Marking analysis: A learner attempts the following task: “A ring of bark and phloem is removed from around the trunk of a tree (girdling), leaving the xylem intact. Predict what will happen to the roots and explain your reasoning.” Their response addresses only this point: “Predicts that the roots will eventually die (or stop growing and be starved).” 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 + 11 Explain how the structure of guard cells enables stomata to open in response to light. ✓ Reviewed Medium 4 marks No calculator + 12 Marking analysis: A learner attempts the following task: “Explain how the structure of guard cells enables stomata to open in response to light.” Their response addresses only this point: “States that light stimulates guard cells to actively pump H+ ions out, and K+ ions are then taken up into the guard cells.” 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 + 13 Outline one adaptation of xerophytic plants that reduces water loss, and explain how it achieves this. ✓ Reviewed Easy 3 marks No calculator + 14 Marking analysis: A learner attempts the following task: “Outline one adaptation of xerophytic plants that reduces water loss, and explain how it achieves this.” Their response addresses only this point: “Names a valid xerophytic adaptation, for example sunken stomata (in pits), a thick waxy cuticle, or reduced leaf surface area (e.g. spines instead of leaves).” 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 Using the sliding filament model, outline the role of calcium ions in initiating muscle contraction. ✓ Reviewed Medium 4 marks No calculator + 16 Marking analysis: A learner attempts the following task: “Using the sliding filament model, outline the role of calcium ions in initiating muscle contraction.” Their response addresses only this point: “States that a nerve impulse arriving at the neuromuscular junction triggers the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm.” 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 Explain why skeletal muscles function in antagonistic pairs, using the biceps and triceps at the elbow joint as an example. ✓ Reviewed Easy 3 marks No calculator + 18 Marking analysis: A learner attempts the following task: “Explain why skeletal muscles function in antagonistic pairs, using the biceps and triceps at the elbow joint as an example.” Their response addresses only this point: “States that muscles can only actively contract and pull; they cannot actively push or extend themselves.” 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 the process of ultrafiltration in the nephron, including the role of the pressure difference between the glomerulus and the Bowman's capsule. ✓ Reviewed Medium 4 marks No calculator + 20 Marking analysis: A learner attempts the following task: “Outline the process of ultrafiltration in the nephron, including the role of the pressure difference between the glomerulus and the Bowman's capsule.” Their response addresses only this point: “States that the afferent arteriole entering the glomerulus is wider than the efferent arteriole leaving it, creating high hydrostatic pressure within the glomerular capillaries.” 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 72
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