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Introductory Concepts Model Answers

Section 1.3.1 — Annotated model answers for scarcity, opportunity cost, and the basic economic problem.

These model answers demonstrate how to structure responses for Edexcel International A-Level (IAL) Economics and Business exams. Each answer includes a mark scheme breakdown, PEEL structure (where applicable), annotated paragraphs, and examiner commentary explaining what earns marks at each band.
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4 marks
Unit 1 · 1.3.1 Introductory Concepts · Knowledge & Application
Explain: what is meant by scarcity and opportunity cost.
Mark Scheme Breakdown
1–2 marksDefinition of scarcity (unlimited wants, limited/finite resources)
3–4 marksDefinition and application of opportunity cost (next best alternative forgone with example)
KKnowledge/Definition
AApplication
Model Answer
Scarcity is the fundamental economic problem — it arises because human wants are unlimited, yet the resources available to satisfy those wants are finite. K Because resources (land, labour, capital, enterprise) are scarce relative to wants, societies must make choices about how to allocate them. K

Opportunity cost is the next best alternative forgone when a choice is made. K For example, if the UK government chooses to spend £50bn on the HS2 rail project, the opportunity cost is the hospitals, schools, or tax cuts that money could have funded instead. A Opportunity cost exists because of scarcity — if resources were unlimited, choosing one option would not require giving up another. A
Examiner Commentary

Both terms must be defined precisely. Scarcity must reference the tension between unlimited wants and limited resources — not simply "things are rare." Opportunity cost must include "next best alternative forgone," not just "what you give up." The HS2 example grounds the answer in a real-world context, earning the application marks that push into the top band.

Likely Score4 / 4
8 marks
Unit 1 · 1.3.1 Introductory Concepts · Analysis
Analyse: how a production possibility frontier (PPF) diagram can be used to illustrate economic growth.
Mark Scheme Breakdown
1–2 marksKnowledge: definition of PPF and/or economic growth
3–4 marksApplication: outward shift represents increased productive capacity
5–8 marksAnalysis: causes of shift (investment, technology, education), distinction between actual and potential growth, movement to vs shift of PPF
PEEL Structure
P
Point

Economic growth can be shown as a movement toward the PPF or an outward shift of the entire curve.

E
Evidence

E.g. China's massive infrastructure investment in the 2000s expanded productive capacity.

E
Explain

A movement from inside the PPF represents actual growth (using spare capacity). An outward shift represents potential growth — the economy can now produce more of both goods.

L
Link

This distinction helps explain why some growth is inflationary (near the PPF) and some is sustainable (shifting the PPF).

KKnowledge
AApplication
AnAnalysis chain
Model Answer
Para 1
A production possibility frontier (PPF) shows the maximum output combinations of two goods an economy can produce when all resources are used efficiently. K Economic growth is a sustained increase in real GDP — the total output of goods and services in an economy. K
Para 2
On a PPF diagram, actual economic growth can be illustrated as a movement from a point inside the PPF toward the frontier. This occurs when an economy uses previously unemployed or underused resources — for example, when a recession ends and workers return to employment. An This type of growth does not require an increase in productive capacity; it simply means existing resources are being used more efficiently. An
Para 3
Potential economic growth is shown as an outward shift of the entire PPF. An This occurs when the economy's productive capacity increases — through investment in capital, technological innovation, improved education, or discovery of new resources. For example, China's sustained investment in infrastructure and manufacturing capacity throughout the 2000s shifted its PPF outward dramatically. A An outward shift means the economy can now produce more of both goods than before — representing a genuine increase in the economy's potential output. An
Para 4
The PPF also illustrates why growth involves trade-offs and opportunity cost. If an economy chooses to produce more capital goods today (sacrificing consumer goods), the PPF shifts outward more in the future — illustrating the trade-off between current consumption and future growth. An This helps explain why economies that invest heavily (high savings ratio) tend to grow faster in the long run. An
Examiner Commentary

Strong answer that clearly distinguishes between actual growth (movement toward PPF) and potential growth (outward shift). The China example provides concrete application. The final paragraph on the trade-off between capital and consumer goods shows sophisticated understanding. A labelled diagram showing both types of growth would secure full marks.

Likely Score7–8 / 8

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