B11: Plant Physiology, Transport, Photosynthesis and Potometers
Official Cambridge & Imperial ESAT specification requirements for Plant Physiology, Transport, Photosynthesis and Potometers on the Biology paper. Understand the syllabus boundaries, spot distractor traps engineered by examiners, and master the 2-step Sub-90 shortcuts that compress solve time well below the 88.8-second cutoff.
Official Syllabus Subtopics
Requirements specified in the UAT-UK framework
- 1Leaf anatomy: waxy cuticle, upper epidermis, palisade mesophyll (high chloroplast density), spongy mesophyll, stomata with guard cells
- 2Photosynthesis: 6CO₂ + 6H₂O ⟶ C₆H₁₂O₆ + 6O₂ and limiting factors (light intensity, CO₂ concentration, temperature)
- 3Inverse-square law for light intensity: I ∝ 1 / d²
- 4Xylem vessel structure: dead hollow lignified tubes for unidirectional cohesion-tension water and mineral transport
- 5Phloem sieve tube elements and companion cells for bidirectional translocation of sucrose and amino acids
- 6Transpiration pull, stomatal opening/closing mechanisms, and environmental factors (temperature, humidity, air movement, light)
- 7Potometer calculations: water uptake rate = (π r² Δx) / Δt
Sub-90 Exam Speed Tips
How top candidates solve this spec under the 88.8s clock
A potometer measures the rate of water UPTAKE, not transpiration directly, because a small fraction (<1–2%) of water is used in photosynthesis and maintaining cell turgor.
When using capillary tube diameter in potometer questions, remember radius r = diameter / 2 before computing volume π r² h.
Examiners engineer distractor options using common algebraic expansions and sign slips. Always test structural ratios or invariants before calculating arithmetic values.
Tested Topics in Specification B11
Master the individual question patterns and Sub-90 shortcuts for this specification.
Photosynthesis Inverse-Square Law (I ∝ 1/d²), Limiting Factors & Capillary Potometers (πr²ʰ/t)
Potometer 2-step check: (1) Halve capillary diameter to radius r = d/2 before computing V = pi*r²*h; (2) Divide by time in minutes/hours. For lamp distance d1 -> d2, multiply light intensity by (d1 / d2)².
Ready to Master Specification B11 Under Exam Conditions?
Practice timed questions under the authentic Pearson VUE interface with live split stopwatch pacing, dry-wipe scratchpad, and distractor forensics.