WAEC SSCE - Geography - 1999

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The earth lies between Venus and Mars.

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The separation of ancient Gondwana land into different land masses was mainly caused by continental drift. Millions of years ago, there was a single landmass called Pangaea, which later split into two: Laurasia and Gondwana. Gondwana eventually split into South America, Africa, Australia, India, and Antarctica. This splitting was caused by the movement of tectonic plates, which gradually separated the land masses over millions of years.

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The North Atlantic sea route, which stretches from Europe to North America, is a major shipping route that has some potential hazards. One of the likely hazards at the North American end of the route is fog. The region is notorious for its thick fog that reduces visibility and makes navigation difficult for ships. Another likely hazard is iceberg. The area is known to have icebergs that break away from the Arctic ice cap and float southward. These icebergs can damage or sink ships, especially those that are not ice-reinforced. It is important for ships to be aware of these hazards and take necessary precautions while navigating the route to ensure safe travel.

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Minerals are non-renewable natural resources. This is because minerals are naturally occurring substances found in the earth's crust and once they are extracted, they cannot be replaced. The process of mineral formation takes millions of years, and human activities such as mining and extraction have accelerated the depletion of these resources. Some examples of non-renewable minerals include oil, coal, and gold. On the other hand, soil, vegetation, and wildlife are renewable resources that can be replenished over time through natural processes.

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The correct answer is erosion. Erosion is the process by which soil or rock particles are removed and transported by natural agents like wind or water. Wind erosion occurs in arid and semi-arid areas where there is little vegetation to protect the soil. Running water erosion occurs in areas with high rainfall or where the land is sloping, and the force of the water removes soil and rock particles.

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Among the given options, the least hazardous form of pollution to man is "A sound of 50 decibels in the air." Sound pollution is the presence of unwanted sound that can harm human health and the environment. A sound of 50 decibels is considered to be in the range of normal conversation or background noise, which is relatively harmless to humans. On the other hand, toxic waste disposed in rivers can pollute the water and harm aquatic life, and chemicals used for fishing can accumulate in the food chain and harm both animals and humans. Flaring of gas from refineries can release harmful gases into the air, causing air pollution and posing health risks to people living nearby.

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A megalopolis is a continuous amalgamation of a series of cities. It refers to a large urbanized region that comprises several cities or metropolitan areas, which are closely situated and physically linked together. The individual cities in a megalopolis tend to grow and merge with each other over time, resulting in a vast, interconnected urban area with a very high population density. The term is often used to describe areas such as the Northeast megalopolis in the United States, which includes cities like New York, Boston, and Philadelphia, among others.

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The ocean current that lowers the temperature of the adjacent coastland is the Benguela current. The Benguela current is a cold ocean current flowing from south to north along the western coast of southern Africa. It is caused by upwelling of cold water from the depths of the Atlantic Ocean. As the current moves northward, it cools the warm air coming from the interior of the continent, resulting in a cold, dry climate along the coast. The Benguela current is known for its rich marine life and supports one of the most productive fishing grounds in the world.

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Block mountains are created by faulting. Faulting is the process of breaking and displacement of rock layers due to tensional or compressional forces. When one block of rock is pushed upwards and another block is pushed downwards, a block mountain is formed. The uplifted block is called a horst and the lowered block is called a graben. As the blocks continue to move, they can create a series of parallel mountains and valleys known as horsts and grabens. This process is common in regions of tectonic activity such as the East African Rift Valley and the Rocky Mountains in the United States.

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The correct answer is Yardang. Yardang is a landform created by wind erosion. It consists of a steep-sided and elongated ridge with a sharp crest, formed by the erosion of alternating layers of hard and soft rock, aligned with the prevailing wind direction. The softer rocks are eroded more quickly, leaving behind the harder rocks standing high and forming the crest of the ridge. Therefore, a steep-side feature with vertical bands of alternate hard and soft rocks, aligned in the direction of the prevailing winds is a Yardang.

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The most common environmental problem in the Niger Delta is coastal flooding. This is due to several factors such as rising sea levels, heavy rainfall, and poor drainage systems. The Niger Delta is a low-lying region with many coastal communities, making it vulnerable to flooding. Flooding can cause damage to homes, crops, and infrastructure, leading to displacement, food insecurity, and economic losses. Additionally, flooding can lead to environmental degradation, including oil spills, which further exacerbate the problems faced by the people of the Niger Delta.

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Marble and Schist are examples of metamorphic rocks. Metamorphic rocks are formed by the transformation of existing rock types through heat, pressure, and chemical processes, typically deep within the Earth's crust. Marble is formed from limestone that has been subjected to high temperatures and pressures, while Schist is formed from shale that has been metamorphosed due to heat and pressure. These rocks exhibit unique patterns and textures due to the conditions under which they were formed, and are used in various industries, including construction and sculpture.

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The features commonly found along the lower course of a river are meanders. Meanders are bends or curves in a river that are caused by the lateral erosion of the riverbanks. They are usually found in the lower course of a river where the gradient is lower, and the river has more energy to erode sideways rather than downwards. Meanders can form oxbow lakes when the river erodes through the narrow neck of a meander and takes a shorter, straighter course.

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Equatorial lowlands are regions near the equator with low altitude. These regions typically experience heavy thunderstorms and rainfall in the afternoon due to the intense solar heating of the land and oceans, which causes rising air and the subsequent condensation of water vapor into rain. This phenomenon is known as convectional rainfall. Therefore, the correct answer is "heavy thunder rains in the afternoons."

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A delta is a landform that is created at the mouth of a river when it flows into a standing body of water, such as a sea or an ocean. The formation of a delta requires specific conditions to be present. Therefore, the question is asking which of the following conditions is not favorable for the formation of a delta. The correct answer is "presence of large lakes in the river course." This condition is not favorable for the formation of a delta because a lake has still water, and it will not provide enough force to carry the sediments downstream to form a delta. In contrast, a river flowing into a standing body of water with enough force to transport and deposit sediments creates a delta. Therefore, options "availability of adequate sediments," "absence of strong current at the river mouth," and "presence of sheltered coast" are favorable conditions for the formation of a delta.

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Industries are classified into different types based on their function and output. The most common classification of industries is into primary, manufacturing (also known as secondary), and tertiary industries. Primary industries are involved in the extraction and production of raw materials such as mining, farming, and fishing. These industries are the basis of all other industries because they provide the raw materials needed for production. Manufacturing or secondary industries involve the transformation of raw materials into finished products such as cars, textiles, and electronics. These industries add value to the raw materials obtained from the primary industries. Tertiary industries are also known as service industries and include businesses such as banking, transportation, and healthcare. These industries provide services to people and other industries. Other classifications of industries can include cocoa processing, furniture making, and food processing, but these are usually considered as subcategories of manufacturing or primary industries.

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Exfoliation is a type of weathering process in which curved plates of rock are stripped from rock surfaces due to release of pressure on the underlying rocks. This commonly occurs in regions with large diurnal range of temperature such as semi-arid regions. This is because, during the day, rocks expand due to heat and contract during the night due to cooling. The repeated expansion and contraction of rocks over time causes them to weaken, crack and eventually shed the outer layers of rocks. Hence, the answer is: Semi-arid regions with large diurnal range of temperature.

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The instrument used for measuring wind velocity is called an anemometer. An anemometer is a device that measures the speed and direction of the wind. It has several cups mounted on arms that rotate when the wind blows, and the rotation is translated into wind speed. Anemometers come in various forms, including mechanical, electric, and sonic anemometers. The measurement of wind speed is essential for weather forecasting, aviation, sailing, and many other fields.

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The bulk of Nigeria's timber is exploited from the rainforest. The rainforest is a dense forest characterized by high rainfall and a variety of broad-leaved evergreen trees. Nigeria's rainforest is located in the southern part of the country, and covers a significant portion of the Niger Delta region, as well as parts of Cross River, Akwa Ibom, and Ondo states. The rainforest provides a habitat for a variety of flora and fauna, and is a major source of timber, which is used for furniture, construction, and other purposes. Due to illegal logging and deforestation, the rainforest is under threat, and there are efforts to protect and conserve this valuable ecosystem.

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The answer is Lubumbashi. Lubumbashi is a city in the southeastern part of the Democratic Republic of Congo (DRC), which is known for its rich copper deposits. It is the center of copper mining in the Katanga Province and the surrounding region, producing a large percentage of the copper exported by the country. Therefore, most of the copper exported from the DRC is produced in and around Lubumbashi.

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Nigeria's major trading partners are the countries that engage in the highest volume of trade activities with Nigeria. These countries are involved in importing and exporting goods and services to and from Nigeria. Based on the options provided, the correct answer is (a) Britain, USA, Germany, and Japan. These countries are among the top exporters of goods and services to Nigeria, and Nigeria also exports to them. The United Kingdom, United States, Germany and Japan are among the largest economies in the world and have a significant influence on the global trade system. As such, Nigeria's trade relationship with these countries has a significant impact on its economy.

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(a) Marking features on the map

• (i) Knoll (K): print over a small isolated low hill shown by a few small closed contour rings. Sand deposit (SD): print over the stippled/dotted symbol along a river channel. Disappearing stream (DS): print where a blue stream line ends abruptly and the water sinks underground.
• (ii) Shading: shade clearly the area enclosed by the 925 ft contour in the north-east.

(b) In the answer book

(i) Length of the secondary road. Measured map length \(=28.0\text{ cm}\); scale 1:50,000, so

The secondary road is 14 km long.

(ii) Type of rock: limestone, because disappearing streams occur where water sinks through porous, jointed limestone.

(iii) Possible industry: a cement factory, if the limestone occurs in commercial quantity.

(c) Effects of relief and drainage

• (i) Communication pattern: roads avoid areas liable to flood and the many stream valleys, so roads are limited and footpaths are numerous; the secondary road in the north-east keeps to higher ground and avoids the river valleys.
• (ii) Settlement pattern: settlements are fewer in the west owing to the lack of surface water and are dispersed as people search for water; there are more settlements near the river valleys in the east, and settlements avoid areas liable to flood.

(d) Three possible occupations (with reasons)

• Fishing - the rivers and streams provide a ready supply of fish.
• Cattle rearing - the scrubland provides grazing for livestock.
• Farming - the scattered cultivation shown on the map indicates crop growing.

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(a) Winds

• Winds blowing from the sea onto the land (onshore winds) are moisture-laden; they bring cloud, high humidity and rainfall to coastlands, for example the south-west monsoon giving heavy rain to the Guinea coast.
• Winds blowing from the land carry little moisture and produce dry conditions, for example the dusty, dry Harmattan reaching the coast in the dry season.
• Warm winds raise coastal temperatures while cold winds lower them, so wind direction and source strongly control the temperature and rainfall of adjacent coastlands.

(b) Ocean currents

• Warm currents flowing along a coast raise the temperature of the air above them and of the adjacent land, and add moisture, encouraging rainfall; the warm Guinea Current keeps the West African coast warm and wet.
• Cold currents lower coastal temperatures, and because the cool air resists rising they suppress rainfall, producing aridity and coastal fogs; the cold Benguela Current gives the dry Namib coast, and the Canary Current cools north-west Africa's coast.

(c) Distance from the sea

• Coastlands lie close to the sea, which heats and cools slowly, so they enjoy a maritime (equable) climate: mild winters, cool summers and a small annual range of temperature (for example Lagos).
• The sea is a source of moisture, so coasts generally receive higher and more reliable rainfall and higher humidity.
• As one moves inland the moderating influence weakens; places far from the sea have a continental climate with hot summers, cold winters, a large temperature range and lower rainfall (for example Kano compared with Lagos).

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(a) Features of plantation agriculture in Africa

• Large estates covering very wide areas of land.
• Specialisation in a single cash crop (monoculture) such as cocoa, oil palm, rubber, coffee, tea or sugar cane.
• Crops are grown mainly for export to earn foreign exchange rather than for local food.
• Heavy use of capital, machinery and scientific methods (improved seeds, fertilisers, pest control).
• Employment of a large, mostly unskilled labour force, often supervised by trained management.
• Usually foreign or company ownership and located near ports or good transport, with on-site processing.

(b) Four ways plantation agriculture has contributed to economic development

• Earns foreign exchange through exports, boosting national income.
• Provides employment for many people, reducing poverty.
• Supplies raw materials for local processing and industries.
• Stimulates the development of infrastructure - roads, railways, ports, schools and health facilities - in the plantation areas.

(c) Four problems of plantation agriculture

• Dependence on one crop: a fall in world price or a disease outbreak devastates income.
• Exhaustion of the soil through continuous monoculture.
• Pests and diseases spread easily in a single-crop estate.
• Fluctuating world market prices and demand, shortage of labour, and high cost of capital and maintenance.

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(a) Appearance and formation of any two landforms

(i) Delta

• Appearance: a low, flat, roughly triangular or fan-shaped mass of alluvium at a river mouth, split by many branching distributaries and dotted with swamps, sandbars and lagoons.
• Formation: as a heavily laden river enters a sea or lake, its velocity is suddenly checked. It can no longer carry its load, so it deposits sand, silt and mud at the mouth. Where deposition is faster than the sea can remove it, the sediment builds up, splits the channel into distributaries and extends seaward as a delta (for example the Niger Delta).

(ii) Waterfall

• Appearance: a vertical or steep drop where a river plunges over a rock step, with a plunge pool at its foot and often a gorge downstream.
• Formation: where a band of hard rock lies across the course above softer rock, the river erodes the soft rock downstream faster. This leaves the hard rock as a step over which the water falls. The falling water erodes the soft rock at the base, forming a plunge pool and undercutting the hard band, which collapses. Repeated collapse makes the fall retreat upstream, leaving a gorge.

Inselberg (alternative): an isolated, steep-sided residual hill of bare, resistant rock (often granite) rising abruptly above a plain, formed when surrounding weaker rock is worn away by long-continued weathering and erosion, leaving the resistant mass standing.

River capture (alternative): the diversion of the headwaters of one river into the valley of a neighbouring, more powerful river. The stronger stream, eroding headward, breaks into the weaker stream's valley at an elbow of capture, beheading it and leaving a dry wind gap and a misfit stream.

(b) Importance to man (one for each chosen feature)

• Delta: the fertile alluvial soils and abundant water support intensive farming and fishing; deltas such as the Niger Delta also yield petroleum.
• Waterfall: provides a site for generating hydro-electric power and attracts tourists.
• Inselberg: serves as a defensive/settlement site and a source of building stone and tourism.
• River capture: the enlarged captor river gives a bigger water supply and power potential.

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Irrigation farming is the artificial supply of water to farmland to grow crops. In Nigeria it is practised mainly in the drier northern states, where rain-fed farming alone cannot support cultivation throughout the year.

(a) Factors that favour the type of agriculture

• Very high temperatures throughout the year, giving long growing seasons and strong sunshine for crop ripening.
• Dry conditions with low annual rainfall (often less than 75 cm, e.g. the Sokoto and Chad basins), which makes rain-fed farming unreliable and creates the need to irrigate.
• Short wet season (only about four months), so water must be stored and applied artificially during the long dry season.
• Low relative humidity in the north, which reduces crop disease and suits irrigated cereals and vegetables.
• Development of large-scale irrigation schemes and dams (Tiga, Kainji, Bakolori, Goronyo, Challawa) that store water and feed canals for dry-season farming.
• Presence of perennial rivers and fertile alluvial (fadama) soils along the Niger, Benue, Sokoto-Rima, Hadejia and Yobe valleys, providing both water and rich land.
• Extensive flat land suited to gravity canal irrigation, and government support through the River Basin Development Authorities.

(b) Major farming areas and associated crops

(c) Problems

• Flooding of farmland when rivers overflow or when dams release excess water.
• Fluctuation in the level of water as rivers fall sharply in the dry season and reservoirs silt up, reducing the supply available for irrigation.
• Displacement of settlements and farmland when large dams and reservoirs are built.
• Disruption of the normal flow of rivers by dams, which affects downstream users and fisheries.
• Accumulation of mineral salts (salinisation) and waterlogging from poor drainage under intense evaporation, which lowers soil fertility.
• High cost of building and maintaining dams, canals and pumps, together with a shortage of technical manpower and the spread of water-borne diseases and pests.

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(a) Two countries: commodities exported and imported (outside West Africa)

Nigeria

• Exported: crude petroleum and cocoa (also rubber, tin).
• Imported: machinery/vehicles and refined chemicals or manufactured goods.

Ghana

• Exported: cocoa and gold (also timber, bauxite).
• Imported: machinery/motor vehicles and petroleum products or manufactured goods.

(Sierra Leone exports diamonds and iron ore; The Gambia exports groundnuts; both import machinery and manufactured goods.)

(b) Three active foreign customers of one country

Taking Nigeria, three of its most active foreign trading partners (customers) are the United States of America, the United Kingdom and India (China, the Netherlands and Germany are also acceptable).

(c) Four measures to remedy an unfavourable balance of trade

An unfavourable (adverse) balance of trade occurs when the value of a country's imports exceeds that of its exports. To correct it a country can:

• Reduce imports by raising tariffs, using quotas or banning non-essential goods.
• Promote local production and import substitution so that goods once bought abroad are made at home.
• Increase and diversify exports, adding processed and manufactured goods rather than raw materials only.
• Discourage extravagant spending abroad, devalue the currency to make exports cheaper, and encourage exports through incentives.

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(a) Distinction between weather and climate

• Weather is the day-to-day, short-term condition of the atmosphere of a place at a particular time, described by its elements such as temperature, rainfall and wind. It changes from hour to hour and day to day.
• Climate is the average condition of the atmosphere of a place taken over a long period (usually 30 years or more). It is stable and describes the general pattern rather than a single day.

(b) Four elements of weather

• Temperature: the degree of hotness or coldness of the air, measured with a thermometer in degrees Celsius.
• Rainfall (precipitation): moisture falling from clouds to the ground, measured with a rain gauge in millimetres.
• Wind: air moving from areas of high to low pressure; its direction is found with a wind vane and speed with an anemometer.
• Humidity: the amount of water vapour in the air, measured with a hygrometer. (Others acceptable: air pressure, cloud cover, sunshine.)

(c) Three uses of rainfall data to man

• It guides farmers in choosing crops and in timing planting and harvesting.
• It aids water-resource planning, such as siting dams, reservoirs and irrigation schemes and forecasting floods or drought.
• It assists engineers and town planners in designing drainage, bridges and buildings, and helps prepare against flooding.

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(a) Sketch map of Nigeria showing three vegetation zones (at least one from each broad belt)

Nigeria's natural vegetation is grouped into two broad belts: the forest belt in the rain-soaked south and the savanna belt in the drier north. The belts run roughly east–west, becoming drier as one moves from the coast towards the far north. Choosing across both belts, the three zones located and named on the map below are:

• Mangrove & fresh-water swamp forest — forest belt, along the southern coast and the Niger Delta.
• Guinea savanna — savanna belt, the wide Middle Belt across the centre.
• Sudan savanna — savanna belt, the far north.

(b) Relating the vegetation to the climate of one zone (Sudan savanna)

The Sudan savanna experiences a single short rainy season of only about 500–750 mm (50–75 cm) of rain, followed by a long, hot dry season dominated by the dry, dust-laden Harmattan wind. Temperatures are high all year. Because rainfall is low and the dry season is long, the vegetation shows the following features, each a direct response to the climate:

• Short grasses that dry up and turn brown in the long dry season, because the rains are too brief to support tall growth.
• Scattered, drought-resistant trees such as the baobab, acacia and silk cotton, widely spaced so that each can draw enough moisture from a large area.
• Small, thorny or reduced leaves and thick, fire-resistant bark, which cut down water loss through transpiration during the hot, dry months.
• Long tap roots that reach deep for underground water.

Thus the sparse, thorny, drought-adapted vegetation of the Sudan savanna is a direct reflection of its low, strongly seasonal rainfall and high temperatures.

(c) Two major agricultural produce from any two of the zones

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(a) The three types of rainfall

1. Convectional rainfall
2. Orographic (relief) rainfall
3. Cyclonic (frontal) rainfall

(b) Formation and characteristics of any two

Convectional rainfall

• Formation: intense heating of the ground makes the air in contact with it warm, expand and rise as strong convection currents. As the air rises it cools, condenses around the dew point and forms towering cumulonimbus clouds, releasing heavy rain.
• Characteristics: occurs in the hot afternoons, is heavy and of short duration, and is usually accompanied by thunder and lightning. It is typical of equatorial regions and of the wet season in the tropics.

Orographic (relief) rainfall

• Formation: moist winds from the sea are forced to rise over a mountain or highland barrier. The rising air cools, condenses and drops its moisture as rain on the windward slope. On the far (leeward) side the descending air is dry and warm, giving a rain shadow.
• Characteristics: heavy and prolonged rain on the windward slope, marked contrast with the dry leeward side, and it occurs wherever moist winds meet highlands.

Cyclonic (frontal) rainfall (alternative)

• Formation: where a mass of warm, light air meets a mass of cold, dense air, the warm air is forced to rise gently over the cold air along a front. It cools, condenses and produces rain.
• Characteristics: steady, moderate rainfall over a wide area lasting several hours or days, common in temperate latitudes.

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(a) Sketch map of Nigeria locating two game reserves and an important town in each area

The two game reserves chosen are Yankari Game Reserve (Bauchi State) and Borgu Game Reserve / Kainji Lake National Park (Niger State). The important town near each is Bauchi and New Bussa respectively. On the sketch map below, each reserve is marked with a shaded patch and labelled, and each associated town is shown as a dot.

(b) Three ways tourism has affected the lives of the people in the Yankari (Bauchi) area

1. Employment: Many local people earn a living as tour guides, drivers, rangers and hotel and park staff, which has raised household incomes.
2. Provision of amenities and infrastructure: To serve tourists, facilities such as good roads, electricity, pipe-borne water and communication networks have been developed in the area, benefiting the residents too.
3. Income from trade in crafts and souvenirs: Tourism has opened brisk markets for local crafts, artefacts, food and other goods, while contact with visitors has led to acculturation (exchange of ideas and cultures). (A negative effect is the loss of some farmlands taken up by the reserve and tourist facilities.)

(c) Three ways tourism may be boosted in Nigeria

1. Adequate security: Ensuring good security arrangements for the lives and property of tourists so that people feel safe visiting the sites.
2. Improved infrastructure and hotel facilities: Providing good roads, airports, adequate transport and comfortable hotels close to the tourist centres.
3. Adequate publicity and development of sites: Advertising Nigeria's attractions widely at home and abroad, backed by deliberate government policy to develop and preserve the natural endowments of each region and to train tourism personnel.

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None

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(a) What is a conurbation?

A conurbation is a very large, continuous built-up area formed when several separate towns and cities grow outward and merge into one another, so that their boundaries can no longer be distinguished. It results from the horizontal spread and coalescence of neighbouring urban centres.

(b) One conurbation in each of three different countries

• United Kingdom - Greater London (or the West Midlands around Birmingham).
• United States of America - New York (or the Boston-New York-Washington belt).
• Japan - the Tokyo-Yokohama conurbation. (Nigeria: Greater Lagos is also acceptable.)

(c) Four problems of a conurbation

• Traffic congestion on overloaded roads, with long delays.
• Housing shortage and slums, with overcrowding and high rents.
• Pressure on services such as water, electricity, schools, hospitals and waste disposal, leading to shortages and poor sanitation.
• Pollution of air, water and land, and high rates of crime and unemployment.

(d) Three solutions to the problems

• Build new satellite towns and encourage decentralisation to draw people and industry away from the congested core.
• Provide an efficient mass-transit system (rail, underground, bus lanes) and construct ring roads and flyovers to ease traffic.
• Undertake urban renewal and low-cost housing schemes, expand and upgrade public utilities, and improve waste management to reduce pollution.

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(a) Four factors influencing the location of manufacturing industries in developing countries

• Raw materials: industries that use bulky or perishable raw materials locate near their source, for example cement factories near limestone at Ewekoro and Sokoto.
• Power/energy supply: industries settle where electricity, gas or fuel is available, for example plants sited near the Kainji hydro-power supply.
• Market: firms making bulky or fragile finished goods, or serving many people, locate near large towns, for example breweries and bottling plants in Lagos and Kano.
• Labour supply: labour-intensive industries such as textiles locate in densely populated areas that supply cheap workers, for example textile mills at Kaduna and Kano.
• (Also: transport links, water supply, capital and government policy.)

(b) Four problems of establishing heavy industries in West Africa

• Shortage of capital: heavy industries need huge investment which poor countries cannot easily raise.
• Inadequate power supply: unreliable electricity handicaps large plants.
• Shortage of skilled labour and technical know-how, forcing reliance on costly expatriates.
• Poor infrastructure: inadequate roads, railways, ports and machinery raise costs and delay production. (Also: small/low-purchasing-power market and dependence on imported machinery and spare parts.)

(c) Solutions to the problems

• Raise capital through government funding, foreign investment and loans, and encourage joint ventures.
• Expand and stabilise power supply by building more power stations and improving the grid.
• Train indigenous manpower through technical colleges and industrial training schemes.
• Develop infrastructure (roads, rail, ports) and promote regional economic co-operation (ECOWAS) to enlarge the market.

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(a) Characteristics of the cool temperate grasslands

The cool temperate grasslands (Steppes, Prairies, Pampas, Downs, Veld) lie in the continental interiors of the mid-latitudes.

• Vegetation is dominated by grass with very few trees; the grass is short and nutritious in drier parts and tall in the wetter margins.
• Grasses grow in tufts and turn green in the warm rainy season and brown/dormant in the cold dry season.
• Trees are largely absent because rainfall is too low and the winters too cold; where present they cluster along river banks.
• The grasses have deep, matted root systems that resist drought and cold.
• Moderate rainfall (about 250-750 mm) falls mainly in summer, with a marked dry season.
• A large annual temperature range with hot summers and cold winters.

(b) Five factors affecting the distribution of this vegetation type

• Rainfall: the moderate, summer-concentrated and unreliable rainfall is enough for grass but too little for forest.
• Temperature: cold winters and hot summers with frost check the growth of trees and favour hardy grasses.
• Continentality (distance from the sea): the deep interior location produces the dry, extreme climate that grasses tolerate.
• Relief: the vast level plains allow the grasslands to spread widely.
• Soil: deep, fertile black and chestnut soils rich in humus support the grasses.
• Human activity/fire: grazing, burning and cultivation help maintain grass at the expense of trees.

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(a) Three ways human activities affect the composition of the atmosphere

• Burning of fossil fuels in industries, power stations and vehicles releases carbon dioxide, carbon monoxide and sulphur oxides, raising the level of these gases.
• Deforestation and bush burning reduce the trees that absorb carbon dioxide and add smoke and carbon dioxide, so the proportion of carbon dioxide rises while oxygen falls.
• Release of chlorofluorocarbons (CFCs) from aerosols, refrigerators and air-conditioners adds ozone-destroying gases to the atmosphere; industrial gases and dust also add particles and pollutants.

(b) Physical changes associated with the increasing reduction of the ozone layer

The ozone layer in the stratosphere shields the earth by absorbing harmful ultra-violet (UV) radiation from the sun. Its thinning lets more UV reach the surface, so the likely physical changes are:

• A general rise in surface temperature and reinforcement of global warming.
• Melting of ice caps and glaciers, leading to a rise in sea level and flooding of low-lying coasts.
• Increased UV radiation reaching the ground, which harms plants, reduces crop yields and damages marine life such as plankton.
• Changes in weather and rainfall patterns, with more droughts in some areas and heavier rain or storms in others.
• Increased human and animal health hazards such as skin cancer, cataracts and weakened immunity (a consequence of the increased UV).

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(a) Factors favouring the development of hydro-electric power (HEP)

• Large, steady supply of water: a big river with a high, reliable volume throughout the year, fed by heavy or well-distributed rainfall.
• A waterfall, rapids or steep gradient (or a narrow gorge for a dam) to provide the head and force of falling water.
• A suitable dam site - a narrow valley with a wide basin behind it to store water and hard, impermeable rock for a firm foundation.
• Availability of capital to finance the costly dam, turbines and transmission lines.
• Nearby market/demand for electricity from towns and industries, and the technical manpower to build and run it.

(b) Benefits of HEP supply to the people of Nigeria

• Provides cheaper, cleaner and renewable electricity for homes, offices and industries.
• Powers industrialisation, creating jobs and boosting the economy.
• Dams also aid irrigation, flood control, fishing, water supply and inland navigation, and create tourist/recreation sites.
• Improves the standard of living through lighting, refrigeration and modern services.

(c) Three major problems facing HEP development in Nigeria

• Seasonal fall in river levels: reduced water in the dry season lowers generation.
• Silting of reservoirs reduces storage capacity and dam efficiency.
• Shortage of capital and technical manpower, and high cost of maintenance, spare parts and long transmission lines (also displacement of people from flooded areas).

Akọwa Nkọwa

(a) Rainfall

• The amount and duration of rainfall largely determine the type and density of vegetation.
• Areas of heavy, all-year rainfall (over 1,500 mm) near the equator support dense tropical rain forest, for example the Congo basin.
• Areas of moderate, seasonal rainfall support savanna grassland with scattered trees, for example the Sudan zone.
• Areas of very low rainfall support only sparse, drought-resistant scrub or desert vegetation, for example the Sahara. Thus vegetation becomes poorer as rainfall decreases.

(b) Altitude

• As altitude increases, temperature falls, so vegetation changes with height on high mountains (vertical zonation).
• On the East African mountains such as Kilimanjaro, the lower slopes carry rain forest, giving way upward to bamboo and montane forest, then montane grassland/moorland, and finally bare rock and snow at the summit.
• Highlands also receive more relief rainfall and are cooler, favouring temperate-type plants.

(c) Soil type

• The depth, texture and fertility of the soil control the plants that can grow.
• Deep, fertile, well-drained soils support luxuriant forest, for example the alluvial soils of river valleys.
• Thin, sandy or leached soils support only grasses and scrub, for example the sandy soils of the Sahel.
• Waterlogged, saline coastal soils support special vegetation such as mangroves in the Niger Delta, while swampy soils carry swamp forest.