IB Geography HL — Food systems and the spread of disease

Key Idea: Topic 12.2 is about how we produce food, why some people still go hungry, and how disease spreads through places. It pulls together three ideas: 12.2.1 — food systems & production: the chain from field to plate (production → processing → distribution → consumption), the energy inputs and outputs of farming, energy efficiency (output ÷ input), and how new methods diffuse (the Green Revolution, vertical farming). 12.2.2 — food security & famine: food security = reliable access for all to enough safe food; famine is its extreme failure. Causes are physical, economic, political and social — and they combine. 12.2.3 — the spread of disease: how disease diffuses through space — expansion (ripples from a source) or relocation (carried by people) — and the physical/human factors and barriers that speed it up or stop it. This is Option F content, examined on Paper 1 (SL answers 2 options, HL 3 — same questions). Each option = a short data-response + structured question, then a [10] extended-answer essay (Examine / Evaluate / Discuss).

🌾 12.2.1 — Food systems & food production

A food system runs from production → processing → distribution → consumption, with inputs (energy, water, labour, seeds, fertiliser) and outputs (food, waste, emissions) at every stage. The headline skill is energy efficiency — the output ÷ input ratio — and how production changes over time as farms mechanize and new methods diffuse.

Tip: An intensive system uses many inputs per hectare but is often not energy-efficient — intensive beef returns only 0.2 units per unit in, while low-input cassava returns 12. To find the most efficient product, read the output ÷ input column, not the raw output. To find the lowest output, read the output column — beef (8 GJ), not the smallest input.

🍚 12.2.2 — Food security & famine

Food security exists when all people, at all times, have reliable access to enough safe, nutritious food. It rests on three pillars — availability (enough food), access (people can afford and reach it) and stability (a reliable supply). Famine is the extreme failure of all three at once. Causes are rarely single: physical, economic, political and social factors combine — a drought becomes a famine only when poverty and conflict block the response.

Enough food can exist in a country yet people still starve. A drought is only the trigger — whether it becomes a famine depends on poverty (can people afford food?), conflict (can it be grown and delivered?) and governance (is there a reserve and a response?). Stable, well-governed states avoid famine despite the same droughts.

🦟 12.2.3 — The geography & spread of disease

The geography of disease asks how a disease spreads from place to place — its diffusion — and what speeds it up or stops it. Expansion diffusion ripples outward from a source (cholera through a crowded settlement); relocation diffusion is carried by people who move (a traveller flying with dengue). Speed and reach depend on physical, human, economic and political factors, fought by barriers (clean water, nets, vaccination, quarantine).

A vector-borne disease (malaria, dengue) is spread by an organism; a water-borne disease (cholera, typhoid) by contaminated water. In a [10] disease essay, choosing the wrong type for the question (e.g. cholera when it asks for vector-borne) caps you at about 4/10 — name a real disease and place of the right type in your first line.

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