School / IB / BIOLOGY SL / Theme B: Form and function Exam-style + marking analysis
Theme B: Form and function Membrane structure and transport, organelle function, and structural adaptations for gas exchange, absorption and circulation.
26 activities ≈ 62 minutes
Biology SL Theme B: Form and function
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1 A cubic cell has sides of length 2.0 cm. Calculate its surface-area-to-volume ratio. Compare it with a cubic cell of side 1.0 cm and explain one consequence for exchange with the environment. ✓ Reviewed Medium 5 marks No calculator + 2 Marking analysis: A learner attempts the following task: “A cubic cell has sides of length 2.0 cm. Calculate its surface-area-to-volume ratio. Compare it with a cubic cell of side 1.0 cm and explain one consequence for exchange with the environment.” Their response addresses only this point: “For the 2.0 cm cube, calculates surface area = 24 cm².” 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 + 3 Explain what happens to a plant cell placed in a hypotonic solution. Refer to water potential, osmosis and the cell wall. ✓ Reviewed Medium 4 marks No calculator + 4 Marking analysis: A learner attempts the following task: “Explain what happens to a plant cell placed in a hypotonic solution. Refer to water potential, osmosis and the cell wall.” Their response addresses only this point: “The external solution has a higher water potential than the cell contents.” 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 Outline the roles of the rough endoplasmic reticulum and the Golgi apparatus in the production and secretion of a protein. ✓ Reviewed Medium 4 marks No calculator + 6 Marking analysis: A learner attempts the following task: “Outline the roles of the rough endoplasmic reticulum and the Golgi apparatus in the production and secretion of a protein.” Their response addresses only this point: “States that ribosomes on the rough endoplasmic reticulum synthesize the protein, which enters the RER lumen.” 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 how the fluid mosaic model describes the structure of the plasma membrane. ✓ Reviewed Easy 3 marks No calculator + 8 Marking analysis: A learner attempts the following task: “Explain how the fluid mosaic model describes the structure of the plasma membrane.” Their response addresses only this point: “States that the membrane consists of a phospholipid bilayer, with hydrophilic heads facing outward and hydrophobic tails facing inward.” 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 Explain why the surface area to volume ratio limits the maximum size of a single cell. ✓ Reviewed Easy 3 marks No calculator + 10 Marking analysis: A learner attempts the following task: “Explain why the surface area to volume ratio limits the maximum size of a single cell.” Their response addresses only this point: “States that as a cell increases in size, its volume (and hence its metabolic demand for nutrients and oxygen, and waste production) increases faster than its surface area.” 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 Outline the process of active transport across a plasma membrane, and explain why it requires ATP. ✓ Reviewed Easy 3 marks No calculator + 12 Marking analysis: A learner attempts the following task: “Outline the process of active transport across a plasma membrane, and explain why it requires ATP.” Their response addresses only this point: “States that active transport moves substances across the membrane via specific carrier proteins, against their concentration gradient.” 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 Distinguish between a monosaccharide, a disaccharide and a polysaccharide, giving one example of each. ✓ Reviewed Easy 3 marks No calculator + 14 Marking analysis: A learner attempts the following task: “Distinguish between a monosaccharide, a disaccharide and a polysaccharide, giving one example of each.” Their response addresses only this point: “States that a monosaccharide is a single sugar unit, e.g. 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 + 15 Outline the level of protein structure at which hydrogen bonding creates an alpha helix or beta pleated sheet. ✓ Reviewed Easy 2 marks No calculator + 16 Marking analysis: A learner attempts the following task: “Outline the level of protein structure at which hydrogen bonding creates an alpha helix or beta pleated sheet.” Their response addresses only this point: “States that this is the secondary structure of a protein.” 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 + 17 Explain how the alveoli of the human lung are structurally adapted for efficient gas exchange. Refer to surface area, diffusion distance and blood supply. ✓ Reviewed Medium 4 marks No calculator + 18 Marking analysis: A learner attempts the following task: “Explain how the alveoli of the human lung are structurally adapted for efficient gas exchange. Refer to surface area, diffusion distance and blood supply.” Their response addresses only this point: “States that alveoli provide a very large total surface area for diffusion.” 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 + 19 Outline the roles of villi and microvilli in increasing the efficiency of absorption in the small intestine. ✓ Reviewed Easy 3 marks No calculator + 20 Marking analysis: A learner attempts the following task: “Outline the roles of villi and microvilli in increasing the efficiency of absorption in the small intestine.” Their response addresses only this point: “States that villi are finger-like projections of the intestinal wall, and microvilli are even smaller projections on the surface of the epithelial cells covering each villus.” 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 + 21 Explain the process of gas exchange between alveolar air and blood in the lungs, referring to diffusion gradients. ✓ Reviewed Medium 4 marks No calculator + 22 Marking analysis: A learner attempts the following task: “Explain the process of gas exchange between alveolar air and blood in the lungs, referring to diffusion gradients.” Their response addresses only this point: “States that the concentration of oxygen is higher in alveolar air than in the deoxygenated blood arriving at the alveoli, so oxygen diffuses from the air into the blood.” 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 roles of the SA node and AV node in coordinating the cardiac cycle. ✓ Reviewed Easy 3 marks No calculator + 24 Marking analysis: A learner attempts the following task: “Outline the roles of the SA node and AV node in coordinating the cardiac cycle.” Their response addresses only this point: “States that the sinoatrial (SA) node, located in the right atrium, acts as the heart's natural pacemaker, generating an electrical impulse that triggers atrial contraction.” 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 Explain how the structure of the nephron enables both filtration and selective reabsorption during urine formation. ✓ Reviewed Easy 3 marks No calculator + 26 Marking analysis: A learner attempts the following task: “Explain how the structure of the nephron enables both filtration and selective reabsorption during urine formation.” Their response addresses only this point: “States that in the glomerulus, high blood pressure forces water and small solutes (e.g. glucose, salts, urea) out of the capillaries and into the Bowman's capsule, while blood cells and large proteins are retained (ultrafiltration).” 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 + Self-assessed 0 / 0
Set total 88
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Questions learners ask about this practice Are these official IB questions? No. These are original SubjectScout practice questions for Theme B: Form and function. They are not official past-paper questions or endorsed material.
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