SQA Year 12 Economics Unit Test Mock Paper Analysis | SQA 12年级经济单元测试模拟卷解析

📚 SQA Year 12 Economics Unit Test Mock Paper Analysis | SQA 12年级经济单元测试模拟卷解析

This article provides a detailed walkthrough of a mock unit test designed to match the SQA Higher Economics specification for Year 12. Each question is dissected step by step, with clear reasoning and model answers, helping students bridge the gap between theory and exam technique. The topics covered include opportunity cost, elasticity, externalities, taxation, price controls, and comparative advantage – all core building blocks of the course.

本文详细解析一份针对SQA 高级经济学（Year 12）课程设计的单元测试模拟卷。每道题目都逐步拆解，给出清晰的推理和标准答案，帮助学生在理论知识与考试技巧之间搭建桥梁。所涵盖的主题包括机会成本、弹性、外部性、税收、价格管制和比较优势——这些都是课程的核心模块。

1. Question 1: Opportunity Cost Calculation | 第一题：机会成本计算

Question: A farmer can use a plot of land to grow either potatoes or carrots. If the opportunity cost of producing 1 tonne of potatoes is 0.5 tonnes of carrots, what is the opportunity cost of producing 1 tonne of carrots?

题目： 一位农民可以用一块地种植土豆或胡萝卜。如果生产1吨土豆的机会成本是0.5吨胡萝卜，那么生产1吨胡萝卜的机会成本是多少？

The key to solving this is understanding that opportunity cost is the value of the next best alternative forgone. Here, 1 tonne of potatoes costs 0.5 tonnes of carrots. This means the trade‑off ratio is 1 potato : 0.5 carrots.

解题关键在于理解机会成本是所放弃的次优选择的价值。此题中，1吨土豆的成本是0.5吨胡萝卜，这意味着交换比率为1土豆 : 0.5胡萝卜。

arrots, then 1 carrot must be worth 2 potatoes. Therefore, the opportunity cost of producing 1 tonne of carrots is 2 tonnes of potatoes.

要求出1吨胡萝卜的成本，需要将比率倒置。如果1土豆 = 0.5胡萝卜，那么1胡萝卜必然值2土豆。因此，生产1吨胡萝卜的机会成本为2吨土豆。

Students often get this wrong by simply halving the figure. Remember: opportunity cost reflects the alternative output sacrificed, not the input. Always state the quantity of the other good given up.

学生常误认为只需将数字减半。请记住：机会成本反映的是牺牲掉的另一种产出，而非投入。务必写明所放弃的另一种商品的数量。

---

2. Question 2: Price Elasticity of Demand (PED) | 第二题：需求价格弹性（PED）

Question: A shop raises the price of a designer bag from £200 to £220. Weekly sales fall from 100 units to 80 units. Calculate the price elasticity of demand using the midpoint method, and interpret the result.

题目： 某商店将一款设计师包的价格从200英镑提高到220英镑，周销量从100个下降到80个。使用中点法计算需求价格弹性，并解释结果。

Use the midpoint formula to avoid asymmetry: PED = (ΔQ / Q_avg) ÷ (ΔP / P_avg). First compute the changes: ΔQ = 80 − 100 = −20; Q_avg = (100 + 80) / 2 = 90. ΔP = 220 − 200 = 20; P_avg = (200 + 220) / 2 = 210.

采用中点法避免不对称性：PED = (ΔQ / Q_avg) ÷ (ΔP / P_avg)。先计算变化量：ΔQ = 80−100 = −20；Q_avg = (100+80)/2 = 90。ΔP = 220−200 = 20；P_avg = (200+220)/2 = 210。

Now plug into the formula: % change in Qd = (−20 / 90) × 100 = −22.22%; % change in price = (20 / 210) × 100 = 9.52% 22.22 / 9.52 = −2.33 (using exact values gives −2.33). In absolute terms, the PED is 2.33.

代入公式：需求量变动百分比 = (−20/90)×100 = −22.22%；价格变动百分比 = (20/210)×100 = 9.52%。PED = −22.22/9.52 = −2.33（精确计算得−2.33）。取其绝对值，PED为2.33。

Since PED > 1, demand is price elastic. The firm raised its price but saw a more than proportionate drop in quantity demanded, so total revenue will fall. The correct interpretation: a 1% price rise leads to a 2.33% fall in quantity demanded.

由于PED > 1，需求富有弹性。该店提价后，需求量下降的比例更大，因此总收入将减少。正确的解释是：价格每上升1%，需求量便下降2.33%。

---

3. Question 3: Negative Production Externality | 第三题：生产的负外部性

Question: A chemical factory discharges waste into a river, damaging fish stocks used by a local fishery. With the help of a diagram, explain why the free‑market equilibrium leads to a misallocation of resources.

题目： 一家化工厂向河流排放废水，破坏了当地渔场的鱼群。借助图示解释为何自由市场均衡会导致资源错配。

Draw a standard negative externality diagram. The y‑axis is price, the x‑ above MPC by the amount of external cost. The demand curve (D = MSB) is downward sloping.

画出标准的负外部性图示。纵轴为价格，横轴为数量。边际私人成本（MPC）曲线向上倾斜，边际社会成本（MSC）曲线位于MPC上方，高出部分即外部成本。需求曲线（D = MSB）向下倾斜。

The free market produces where MPC = D at quantity Q_market. But the socially efficient output is where MSC = D at Q_social. Because MSC > MPC, Q_market is greater than Q_social – the factory overproduces.

自由市场在MPC = D处生产，产量为Q_market。而社会有效产出位于MSC = D处，产量为Q_social。由于MSC > MPC，Q_market大于Q_social——工厂过度生产。

At Q_market, the marginal social cost exceeds the marginal social benefit, creating a deadweight welfare loss (the triangle between MSC and D from Q_social to Q_market). The externality means the factory ignores the costs imposed on the fishery, so market prices do not reflect the full social cost.

在Q_market处，边际社会成本超过边际社会效益，产生无谓损失（即从Q_social到Q_market之间MSC与D围成的三角形）。外部性意味着工厂忽略了加诸渔场的成本，因此市场价格未能反映全部社会成本。

This misallocation arises because the supply curve only captures private costs. The missing spillover cost leads to an over‑allocation of resources to chemical production and an under‑allocation to the fishery, a classic case of market failure.

这种错配的产生是因为供给曲线仅反映了私人成本。缺失的溢出成本导致过多资源配置到化工生产，而配置到渔场的资源不足，这是市场失灵的典型例子。

---

4. Question 4: Incidence of a Specific Tax | 第四题：从量税的归宿

Question: The government imposes a per‑unit tax of £5 on a product whose demand is relatively inelastic and supply is relatively elastic. Using a diagram, analyse the tax burden shared between consumers and producers.

题目： 政府对一种需求相对缺乏弹性、供给相对富有弹性的产品征收每单位5英镑的从量税。借助图示分析消费者与生产者之间的税负分担。

Draw supply and demand axes. The original equilibrium is at P1, Q1. A per‑unit tax shifts the supply curve vertically upward by the amount of the tax. The new supply curve S + tax intersects demand at a higher price P2 (consumers pay) and a lower quantity Q2. Producers receive P2 − tax, which is below P1.

画出供求坐标轴。原均衡点为P1、Q1。从量税使供给曲线垂直向上移动税额的幅度。新的供给曲线S + tax与需求曲线交于更高的价格P2（消费者支付）和更低的产量Q2。生产者实际得到P2减去税额，低于P1。

Because demand is inelastic, consumers bear most of the tax. The vertical gap between P2 and P1 represents the consumer burden; the gap between P1 and (P2 − tax) represents the producer burden. With relatively elastic supply, producers are more responsive and can avoid some of the tax by reducing quantity supplied more sharply.

由于需求缺乏弹性，消费者承担大部分税收。P2与P1之间的垂直距离即为消费者负担；P1与（P2−税）之间的距离则为生产者负担。供给相对富有弹性，生产者反应更灵敏，可通过更大幅度减少供给量来规避部分税收。

The diagram should show a larger upper segment (consumer incidence) and a smaller lower segment (producer incidence). This demonstrates the general rule: taxes fall more heavily on the side of the market that is less price elastic.

图示应显示出较大的上方分段（消费者归宿）和较小的下方分段（生产者归宿）。这印证了一般规律：税收更多地落在市场中价格弹性较小的一方。

---

广告 / Sponsored

5. Question 5: Minimum Price and Surplus | 第五题：最低限价与过剩

Question: A government sets a minimum price above the equilibrium level for wheat to protect farmers' incomes. Explain the market outcome and illustrate the resulting surplus.

题目： 政府为了保护农民收入，将小麦的最低限价设定在均衡价格之上。解释市场结果并说明引发的过剩。

A minimum price (price floor) above equilibrium creates a persistent surplus. At the higher price, quantity supplied expands along the supply curve, while quantity demanded contracts along the demand curve. The difference between Qs and Qd is the surplus.

高于均衡水平的最低限价（价格下限）会造成持续性的过剩。在较高价格下，供给量沿供给曲线扩大，而需求量沿需求曲线收缩。供给量Qs与需求量Qd之差即为过剩数量。

The market cannot return to equilibrium because the price is not allowed to fall. The surplus must be addressed by government intervention, such as purchasing the excess supply, or by imposing production quotas. If not, unsold wheat will accumulate, wasting resources.

由于不允许价格下降，市场无法回到均衡点。过剩问题必须通过政府干预来解决，例如政府收购多余供给，或实施生产配额。否则，未售出的小麦将不断积压，造成资源浪费。

This policy creates a deadweight loss, as trades that would have occurred between Qd and the original equilibrium are prevented. Consumers pay a higher price and buy less, while taxpayers may bear the cost of storing the surplus.

该政策会产生无谓损失，因为本应在Qd与原均衡量之间发生的交易被阻止。消费者支付更高价格并减少购买，而纳税人可能要承担储存过剩小麦的成本。

---

6. Question 6: Price Elasticity of Supply Calculation | 第六题：供给价格弹性计算

Question: A bakery supplies 2,000 loaves of bread per day when the price is £1.20. When the price rises to £1.50, supply increases to 2,500 loaves. Calculate the price elasticity of supply (PES) and state whether supply is elastic or inelastic.

题目： 某面包店在价格为1.20英镑时每天供给2000条面包。当价格升至1.50英镑，供给量增至2500条。计算供给价格弹性（PES），并判断供给是富有弹性还是缺乏弹性。

Use the standard formula: PES = (% ΔQ_supplied) / (% 500, average Q = (2000+2500)/2 = 2,250. ΔP = 0.30, average P = (1.20+1.50)/2 = 1.35. Thus %ΔQ = (500/2250)×100 = 22.22%; %ΔP = (0.30/1.35)×100 = 22.22%.

采用标准公式：PES =（供给量变动%）/（价格变动%）。计算变化：ΔQ=500，平均Q=2250；ΔP=0.30，平均P=1.35。因此供给量变动% = (500/2250)×100 = 22.22%；价格变动% = (0.30/1.35)×100 = 22.22%。

PES = 22.22 / 22.22 = 1.0. The supply is unit elastic in this range. A 1% increase in price leads to exactly a 1% increase in quantity supplied. This is a proportional response.

PES = 22.22 / 22.22 = 1.0。在该范围内供给具有单位弹性。价格每上升1%，供给量恰好增加1%。这是一种同比例的反应。

In exam answers, always include the formula, show working, and interpret the coefficient. Unit elastic supply is uncommon but can occur over specific ranges when firms can easily adjust production without significant cost increases.

在考试回答中，务必写出公式、展示计算过程并解释系数含义。单位弹性供给并不常见，但当企业能够在不显著增加成本的情况下轻松调整产量时，在特定区间可能出现。

---

7. Question 7: Comparative Advantage and Trade | 第七题：比较优势与贸易

Question: Country A can produce 50 units of cars or 200 units of textiles with its resources. Country B can produce 30 units of cars or 150 units of textiles. Determine who has the comparative advantage in each good, and explain the pattern of trade.

题目： A国利用其资源可生产50单位汽车或200单位纺织品。B国可生产30单位汽车或150单位纺织品。确定各国分别在哪一种商品上具有比较优势，并解释贸易模式。

5 cars. For Country B: 1 car costs 150/30 = 5 textiles. 1 textile costs 30/150 = 0.2 cars.

比较优势取决于机会成本。A国：1辆汽车的成本为200/50=4单位纺织品；1单位纺织品的成本为50/200=0.25辆汽车。B国：1辆汽车的成本为150/30=5单位纺织品；1单位纺织品的成本为30/150=0.2辆汽车。

Compare the costs: Country A has a lower opportunity cost in cars (4 < 5), so it has a comparative advantage in cars. Country B has a lower opportunity cost in textiles (0.2 < 0.25), so its comparative advantage lies in textiles.

比较成本：A国在汽车上的机会成本较低（4<5），因此在汽车上具有比较优势。B国在纺织品上的机会成本较低（0.2<0.25），因此它在纺织品上具有比较优势。

According to the theory, Country A should specialise in cars and export them, while importing textiles. Country B should specialise in textiles and export them, importing cars. Both countries can then consume beyond their production possibility frontiers if terms of trade lie between their domestic opportunity costs.

根据理论，A国应专门生产汽车并出口，同时进口纺织品。B国应专门生产纺织品并出口，进口汽车。只要贸易条件位于两国国内机会成本之间，双方都能在各自的生产可能性边界之外进行消费。

This classic example shows that even if one country is absolutely less productive in both goods, gains from trade still exist as long as opportunity costs differ. It is the foundation of mutually beneficial international trade.

这个经典例子表明，即使一国在两种商品上均具有绝对劣势，只要机会成本不同，依然存在贸易得益。这正是互利的国际贸易得以建立的基础。

---

8. Question 8: Government Intervention – Taxation vs Regulation for Negative Externalities | 第八题：政府干预——针对负外部性的税收与规制比较

Question: Evaluate the effectiveness of indirect taxation and direct regulation as two methods governments can use to correct the market failure arising from negative externalities of production.

题目： 评价间接税与直接规制作为政府用以纠正生产负外部性所引致市场失灵的两种方法之有效性。

Governments can impose a Pigouvian tax equal to the marginal external cost at the socially efficient output. This internalises the externality, shifting the supply curve from MPC to MSC. The price rises, quantity falls to Q_social, and the deadweight loss is eliminated in theory.

政府可征收等于社会有效产量处边际外部成本的庇古税。此举将外部性内部化，使供给曲线从MPC移至MSC。价格上升，产量降至Q_social，理论上无谓损失被消除。

Taxation is economically elegant but faces practical difficulties. Estimating the exact external cost is extremely challenging. If the tax is set too low, the externality persists; if set too high, it creates a new distortion. Moreover, taxes raise the price, which may be regressive for low‑income households.

税收在经济理论上很精妙，但存在实际困难。精确估算外部成本极富挑战。税若定得过低，外部性依然存在；若定得过高，则会产生新的扭曲。此外，税收抬高价格，可能对低收入家庭造成累退影响。

Direct regulation, such as emission limits or outright bans on certain pollutants, imposes legal standards. This guarantees a reduction in pollution to a specific level, providing certainty. However, regulation lacks flexibility and does not incentivise firms to innovate beyond the minimum requirement.

直接规制，如排放限值或对某些污染物的完全禁止，会施加法定标准。这能确保污染被削减至特定水平，提供确定性。然而，规制缺乏灵活性，且无法激励企业超越最低要求进行创新。

A hybrid approach often works best. For example, emission permits (cap‑and‑trade) combine the certainty of quantity limits with the cost‑effectiveness of market mechanisms. In an SQA essay, you would need to evaluate the pros and cons of each method, using relevant real‑world examples, and conclude which policy is most suitable under specific circumstances.

混合手段往往效果最佳。例如，排放许可证（总量控制与交易）将数量限制的确定性与市场机制的成本效益相结合。在SQA论文中，你需要评价每种方法的利弊，引用相关的现实世界案例，并判断在特定情境下哪种政策最为适宜。

Always remember that both methods can generate government revenue (tax) or compliance costs (regulation), and unexpected behavioural responses, such as illegal dumping, can undermine the intervention. A successful essay balances theoretical rigour with practical assessment.

请始终记得，这两种方法都可能产生政府收入（税收）或合规成本（规制），而意想不到的行为反应（如非法倾倒）则可能削弱干预效果。一篇成功的论文应兼顾理论严谨性与现实评估。

---

Published by TutorHao | Economics Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）