Energy, Environment, Microbiology and Immunity

Worked examples (6)

• 1Chloroplast structure and function (3 marks)
• 2Absorption vs action spectrum (2 marks)
• 3Products of the light-dependent reactions (4 marks)
• 4Cyclic vs non-cyclic photophosphorylation (4 marks)
• 5Calculating an Rf value (3 marks)
• 6Calvin cycle when light is removed (4 marks)

Model answers (10)

• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer 2
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style (levels-based)
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer 6
• ✓Model answer — Edexcel IAL Biology Unit 4 style (data interpretation)
• ✓Model answer 8
• ✓Model answer — Core Practical 10 style
• ✓Model answer — Core Practical 10 style

Worked examples (6)

• 1Ecological terms: population, community and ecosystem (3 marks)
• 2Reading a food web (2 marks)
• 3Calculate net primary productivity (4 marks)
• 4Percentage energy transfer efficiency (4 marks)
• 5Mean abundance and density from quadrats (6 marks)
• 6Explain how an abiotic factor limits distribution (6 marks)

Model answers (10)

• ✓Model answer 1
• ✓Model answer 2
• ✓Model answer 3
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style

Worked examples (6)

• 1Order the stages of primary succession (2 marks)
• 2State how greenhouse gases warm the Earth (2 marks)
• 3Explain the effect of temperature on metabolic rate (4 marks)
• 4Evaluate biofuels as a way to reduce CO₂ (5 marks)
• 5Evaluate evidence for climate change (6 marks)
• 6Explain effects of warming on distribution and food chains (6 marks)

Model answers (10)

• ✓Model answer — Practice question — spec 5.1
• ✓Model answer — Practice question — spec 5.4
• ✓Model answer — Practice question — spec 5.2
• ✓Model answer — Practice question — spec 5.1
• ✓Model answer — Practice question — spec 5.4
• ✓Model answer — Adapted from Edexcel IAL Biology Unit 4 data-response — spec 5.5
• ✓Model answer — Practice question — spec 5.3/5.6
• ✓Model answer — Practice question — spec 5.5
• ✓Model answer — Practice question — spec 5.7
• ✓Model answer — Practice question — spec 5.5

Worked examples (6)

• 1Putting natural selection in order (3 marks)
• 2Directional or stabilising? (3 marks)
• 3Explaining antibiotic resistance (5 marks)
• 4Hardy–Weinberg: finding the carrier frequency (4 marks)
• 5Explaining allopatric speciation (6 marks)
• 6Hardy–Weinberg from a dominant phenotype (6 marks)

Model answers (10)

• ✓Model answer 1
• ✓Model answer 2
• ✓Model answer 3
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer 5
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style

Worked examples (6)

• 1One difference between a virus and a bacterium (2 marks)
• 2Gram positive vs Gram negative walls (2 marks)
• 3Viable count from a serial dilution (4 marks)
• 4Flaming and cooling the inoculating loop (5 marks)
• 5Exponential growth using N = N₀ × 2ⁿ (6 marks)
• 6Explain the stationary phase (6 marks)

Model answers (10)

• ✓Model answer — Practice question — spec 6.1
• ✓Model answer — Practice question — spec 6.2
• ✓Model answer — Practice question — spec 6.3 (CP13)
• ✓Model answer — Practice question — spec 6.4
• ✓Model answer — Practice question — spec 6.5
• ✓Model answer — Adapted from Edexcel IAL Biology Unit 4 (CP13) — spec 6.5
• ✓Model answer — Practice question — spec 6.2
• ✓Model answer — Adapted from Edexcel IAL Biology Unit 4 — spec 6.4/6.6
• ✓Model answer — Practice question — spec 6.1/6.2
• ✓Model answer — Practice question — spec 6.3/6.5 (CP13)

Worked examples (6)

• 1Order the stages of phagocytosis (2 marks)
• 2Classify the type of immunity (2 marks)
• 3Relate antibody structure to function (4 marks)
• 4Distinguish humoral and cell-mediated responses (5 marks)
• 5Interpret a primary vs secondary response graph (6 marks)
• 6Evaluate a mass vaccination programme (6 marks)

Model answers (10)

• ✓Model answer — Practice question — spec 6.3
• ✓Model answer — Practice question — spec 6.2
• ✓Model answer — Practice question — spec 6.7
• ✓Model answer — Practice question — spec 6.4
• ✓Model answer — Practice question — spec 6.6
• ✓Model answer — Practice question — spec 6.7
• ✓Model answer — Practice question — spec 6.8
• ✓Model answer — Adapted from Edexcel IAL Biology Unit 4 data-response — spec 6.8
• ✓Model answer — Adapted from Edexcel IAL Biology Unit 4 data-response — spec 6.7
• ✓Model answer — Practice question — spec 6.8

Worked examples (6)

• 1Decomposers vs detritivores (3 marks)
• 2Processes of the carbon cycle (2 marks)
• 3Naming the nitrogen-cycle bacteria (4 marks)
• 4Extracellular digestion by decomposers (4 marks)
• 5Explain the eutrophication sequence (6 marks)
• 6Apply: improving soil nitrogen (6 marks)

Model answers (10)

• ✓Model answer 1
• ✓Model answer 2
• ✓Model answer 3
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style

Worked examples (6)

• 1The three stages of PCR and their temperatures (3 marks)
• 2Direction of DNA movement in electrophoresis (2 marks)
• 3PCR doubling calculation: N = N₀ × 2ⁿ (3 marks)
• 4Reading a paternity DNA profile (4 marks)
• 5Rigor mortis and ATP (4 marks)
• 6Why smaller fragments travel further (4 marks)

Model answers (10)

• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer 2
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer 4
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer 6
• ✓Model answer 7
• ✓Model answer 8
• ✓Model answer — Edexcel IAL Biology Unit 4 style
• ✓Model answer — Edexcel IAL Biology Unit 4 style