WAEC SSCE - Geography - 1991

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The most critical element in an ecosystem is energy flow within the system. An ecosystem is a community of living organisms and their physical environment, which interact with each other to form a functional unit. The ecosystem is sustained by the flow of energy, which is captured by producers (plants) through photosynthesis and then transferred to consumers (animals) through feeding. Energy flow is critical to the functioning of an ecosystem because all living organisms require energy to carry out their metabolic processes. Without energy flow, the ecosystem would collapse, and all the organisms in it would die. While growth per day, the number of species, the extent of area covered, and the location of the ecosystem are all important factors, they are ultimately dependent on the flow of energy. For example, the growth of plants and the survival of animals depend on the availability of energy in the form of food. Similarly, the number and diversity of species in an ecosystem depend on the availability of energy and nutrients. Therefore, energy flow is the most critical element in an ecosystem because it is essential for the survival and functioning of all living organisms within the ecosystem.

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The product of chemical weathering is a change in the chemical composition of rocks and minerals, resulting in the formation of new substances. Therefore, the answer to the question would be one of the options that is a result of chemical weathering. Among the options listed, the product of chemical weathering is "Grike." Grike is a solution hollow formed by the chemical weathering of limestone bedrock. As water flows through the cracks and fissures in the rock, it dissolves the rock's calcium carbonate and creates openings and cavities called grikes. Therefore, the correct answer to the question is "Grike."

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Transportation helps economic development through all the options given except the distribution of population. Transportation facilitates the movement of people and goods from one place to another, which in turn leads to increased economic activity and development. With transportation, people can travel to new places to find work or start businesses, and goods can be transported to different markets, promoting national and international trade. Transportation also plays a crucial role in the diffusion of ideas and technology, as it allows for the transfer of knowledge and innovation across regions and countries. Additionally, transportation helps promote national integration by connecting different regions of a country and allowing people to move freely between them. However, transportation may not necessarily contribute to the distribution of population, as people tend to migrate to areas with better economic opportunities, regardless of whether there is adequate transportation infrastructure or not. Therefore, transportation may not directly impact the distribution of population in a significant way.

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Man (human activities) is the factor that least affects the distribution of vegetation. While humans can certainly have an impact on the environment and ecosystems through activities like deforestation, land-use changes, and pollution, their impact is generally localized and can be limited in scale. In contrast, the other factors listed - rainfall, wind, soil, and temperature - are all natural factors that have a significant influence on the distribution of vegetation. For example, different types of vegetation are adapted to specific temperature ranges, rainfall levels, and soil conditions. Wind can also affect vegetation distribution by drying out plants or damaging them physically. Therefore, while humans can have an impact on vegetation distribution, their impact is generally less significant than natural factors such as rainfall, wind, soil, and temperature.

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When a plateau is enclosed by fold mountains it is called an intermontane plateau. This type of plateau is usually formed due to tectonic activities where the plateau is lifted up by folding and faulting of the earth's crust. The fold mountains that enclose the plateau act as natural boundaries, and the plateau may have a flat or undulating surface. Intermontane plateaus are often rich in minerals due to their geological formation and can be found in various parts of the world, including the Rocky Mountains in North America and the Tibetan Plateau in Asia.

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Johannesburg is the most important town for the mining of gold in Africa. Johannesburg is located in South Africa and is known as the City of Gold because of its rich history and connection to gold mining. It was founded in the late 1800s after gold was discovered in the area, and it quickly became a center for gold mining and related industries. Today, Johannesburg is still an important center for gold mining in Africa, with several large gold mines located in the area.

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Water pollution is not caused by sand filling. Sand filling, which involves the placement of sand in a specific area to fill in gaps or create land, does not necessarily involve the discharge of pollutants into the water. However, the other options listed - increased silt load, sewage disposal, industrial effluent, and mineral workings - can all contribute to water pollution. Increased silt load can lead to sedimentation, blocking sunlight, and reducing oxygen levels, which can harm aquatic life. Sewage disposal can introduce harmful bacteria and viruses into the water, which can cause diseases in humans and aquatic life. Industrial effluent can contain toxic chemicals and heavy metals that can damage aquatic ecosystems and affect the health of people who consume the contaminated water. Mineral workings can produce acidic runoff that can pollute nearby streams and rivers, killing fish and other aquatic organisms.

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A conurbation refers to a region that comprises several towns or cities that have grown and expanded to the point where their suburbs have merged, creating a single large urban settlement. Essentially, it's a densely populated area made up of multiple cities and towns that are physically and economically interconnected. So, option B, "several towns whose suburbs have expanded and merged to form an urban sprawl," best describes a conurbation.

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Alumina is the product of the aluminum industry and not the chemical industry. Therefore, the correct answer is Alumina. The chemical industry is responsible for producing a wide range of products, including synthetic rubber, dye, fertilizers, and plastics. These products are made through a variety of chemical processes and are used in a wide range of applications across different industries. Alumina, on the other hand, is produced through the refining of bauxite ore and is primarily used in the production of aluminum.

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The monthly range of temperature is the difference between the highest and lowest daily temperatures for the month. This means that for each day of the month, the highest temperature and the lowest temperature are recorded. The range of temperature for the month is then calculated by subtracting the lowest temperature from the highest temperature for the month. For example, if the highest temperature recorded during the month was 30°C and the lowest temperature recorded was 10°C, the range of temperature for the month would be: 30°C - 10°C = 20°C Therefore, the correct answer is "differences between the highest and lowest daily temperature for the month."

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To calculate the population density, we divide the population by the land area: Population density = Population / Land area Substituting the given values, we have: Population density = 6,175,000 / 17,700 Population density = 348.87 people per km² (rounded to the nearest whole number) Therefore, the approximate population density per km² is 349 people. Answer option (iv) is the correct answer.

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The environmental hazard that has been paired with the wrong factor is "Floods and human factor only." Floods are not caused by human factors alone. Floods can also be caused by natural factors like heavy rainfall, snowmelt, storm surges, and tsunamis. Human factors can contribute to floods by altering the natural landscape through activities like deforestation, construction, and urbanization. However, natural factors still play a significant role in the occurrence of floods. To summarize, floods are not solely caused by human factors, but rather by a combination of both natural and human factors.

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The most important cash crop in the irrigated Nile Basin is cotton. Cotton is a major cash crop in the Nile Basin due to its importance in the textile industry and the high demand for cotton products globally. The Nile Basin region has suitable climatic conditions for cotton cultivation, with sufficient water resources from the river Nile and its tributaries, making it an ideal crop for irrigation. Cotton cultivation in the Nile Basin is an important economic activity, providing employment opportunities for millions of people in the region, and contributing significantly to the economies of countries such as Egypt and Sudan. The region also produces other crops such as wheat, sugarcane, and groundnuts, but cotton remains the most important cash crop due to its economic value and high demand in the global market.

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The greatest hydro-electric power potential in Nigeria is found in the Niger-Benue trough. This is because the Niger-Benue trough is a geological feature that runs through the center of Nigeria, and it is characterized by several large rivers and reservoirs that can be used for hydro-electric power generation. The major rivers in this trough include the Niger, Benue, and Kaduna rivers, which have the potential to generate a significant amount of electricity. Additionally, there are several dams and hydro-electric power plants located in this region, such as the Kainji, Jebba, and Shiroro dams, which are some of the largest in Nigeria. Therefore, the Niger-Benue trough has the greatest potential for hydro-electric power generation in Nigeria.

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Pluto has the longest orbit around the Sun compared to the other four options given. It takes Pluto approximately 248 Earth years to complete one orbit around the Sun. In contrast, Earth takes about 365 days to complete one orbit around the Sun. This means that Pluto takes almost 248 times longer than Earth to complete one orbit around the Sun. So, Pluto has the longest orbit around the Sun among the five options provided.

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The liquid portion of the earth is referred to as the "hydrosphere". The hydrosphere is the part of the Earth's surface where water exists, including oceans, seas, rivers, lakes, and groundwater. It is composed of all the water on the planet, which makes up about 71% of the Earth's surface. The other major spheres of the Earth are the atmosphere, which is the layer of gases that surrounds the planet; the lithosphere, which is the solid outer layer of the Earth's surface; and the biosphere, which is the part of the Earth where life exists. Therefore, the hydrosphere refers specifically to the liquid portion of the Earth, while the other spheres refer to different aspects of the planet.

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Harmattan is the option that does not intervene in the natural environment. Harmattan is a dry and dusty trade wind that blows from the Sahara desert over West Africa towards the Gulf of Guinea during the winter months. It is a natural occurrence caused by atmospheric pressure differences between the Sahara and the Gulf of Guinea. Unlike the other options listed, harmattan does not involve human activities that have an impact on the natural environment. Construction works, land reclamation, farming, and pollution are all human activities that can have a negative impact on the environment.

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The Isoberlina tree is characteristic of the Guinea savanna region in Nigeria. Guinea savanna is a transitional zone between the tropical rainforest and the arid Sahel region, and it is characterized by a mixture of grassland and woodland with scattered trees. The Isoberlina tree is a deciduous tree that is well adapted to the Guinea savanna region. It grows in association with other savanna trees such as the shea tree, locust bean tree, and acacia trees. The Isoberlina tree is an important source of firewood, charcoal, and timber, and its leaves are used for medicinal purposes. It is also an important food source for wildlife, especially during the dry season when other vegetation is scarce.

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The aim of ECOWAS (Economic Community of West African States) is to promote economic integration among its member states in West Africa. The organization seeks to achieve this through the establishment of a common market, harmonization of economic policies, and the removal of trade barriers among member states. Additionally, ECOWAS aims to improve political stability and security in the region, promote cultural and educational cooperation, and provide a common fund to help the needy. Therefore, the option that is not one of the aims and objectives of ECOWAS is "encourage emigration of people in all member states."

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A conurbation is a term used to describe a region or area where several towns and their suburbs have expanded and merged together, forming a continuous urban sprawl. It is characterized by a high population density and economic integration, with people living and working across different towns and cities within the area. A conurbation may consist of two or more towns joined together, but still retaining their distinct identities, or it may be a continuous belt of urban settlements. Essentially, a conurbation is a large metropolitan area formed by the merging of several smaller towns and suburbs.

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The major relative advantage of road transportation over rail is that it provides door-to-door service. Unlike rail transportation, which is limited to specific stations and depots, road transportation can deliver goods and passengers directly to their desired destination, making it a more convenient and flexible mode of transportation. This also allows for quicker delivery times and more personalized service.

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(a) Outline map of West Africa: ECOWAS members and capitals

On the outline, locate and name (examples):

• (i) Two coastal ECOWAS members: Nigeria (capital Abuja) and Ghana (capital Accra). Other coastal members: Senegal (Dakar), Cote d'Ivoire (Yamoussoukro), Liberia (Monrovia), Togo (Lome), Benin (Porto-Novo).
• (ii) Two interior (landlocked) ECOWAS members: Niger (capital Niamey) and Mali (capital Bamako). The other landlocked member is Burkina Faso (Ouagadougou).
• (iii) Mark each capital with a dot beside the country name as above.

(b) Six benefits a member derives from ECOWAS (e.g. Nigeria)

• Free movement of persons: citizens can travel, live and work within member states without visas.
• Free trade / larger market: removal of tariffs and trade barriers widens the market for its goods and promotes intra-regional trade.
• Economic cooperation and joint projects: shared development of roads, power, communications and a common currency proposal.
• Collective security and peace-keeping: the ECOMOG/standby force helps keep peace and stability in the region.
• Bigger bargaining power: the group negotiates as a bloc with the outside world, obtaining better trade and aid terms.
• Employment and investment opportunities: a wider market and free movement attract investment, create jobs and promote cultural and technical exchange among members.

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(a) Characteristics and (b) formation of each rock type

(i) Granite

Characteristics:

• It has large, visible interlocking crystals.
• It is hard, coarse-grained and usually light-coloured.
• It does not occur in layers or strata and does not contain fossils.

Formation: Granite is formed by the slow cooling and solidification of molten magma deep below the earth’s surface. It is therefore a plutonic or intrusive igneous rock.

(ii) Limestone

Characteristics:

• It occurs in layers or strata.
• It often contains fossils of plants and animals, such as shells and corals.
• It is mainly composed of calcium carbonate and reacts with dilute acid.

Formation: Limestone is formed from the remains of marine organisms such as corals, shellfish and other animals. Their shells and skeletons accumulate on the sea bed, then become compacted and cemented together to form a sedimentary rock.

(iii) Graphite

Characteristics:

• It is dark grey to black in colour and is soft and slippery to the touch.
• It is a crystalline form of carbon and can leave marks on paper.
• It conducts heat and electricity; it does not contain fossils.

Formation: Graphite is formed when carbon-rich materials, such as coal or organic sediments, are changed by intense heat and pressure deep within the earth’s crust. It is a metamorphic rock.

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(a) Outline map of Africa: features to locate and name

• (i) Lines: draw the Prime Meridian (0°) and longitude 20°E as vertical lines, and latitude 4°N and latitude 35°S as horizontal lines across the continent.
• (ii) Rivers: mark the Zambezi in south-central/south-east Africa and the Volta in West Africa (Ghana).
• (iii) Mountains: mark Mount Ruwenzori on the Uganda-DR Congo border (equatorial East Africa) and the Atlas Mountains in north-west Africa (Morocco/Algeria).
• (iv) Towns: mark Yaounde (Cameroon, West-Central) and Entebbe (Uganda, on Lake Victoria).
• (v) Man-made lake on the Nile: mark Lake Nasser (behind the Aswan High Dam in southern Egypt).
• (vi) Desert: mark the Namib Desert along the south-west (Atlantic) coast of Namibia.

(b) Four ways the rivers of Africa are important

• Hydro-electric power: rivers are dammed (Volta, Zambezi, Nile) to generate electricity for homes and industry.
• Irrigation and agriculture: river water and flood plains support farming, e.g. the Nile and Niger valleys.
• Transport and trade: navigable stretches provide inland waterways for moving people and goods.
• Water supply and fishing: rivers supply domestic and industrial water, support fishing, and provide tourism/recreation; they also aid national/international communication.

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(a) Three types of rural settlement and their characteristics

• Nucleated (clustered) settlement: houses are grouped closely together in a compact village, often around a central feature such as a market, well, church or road junction; farmland lies around the built-up cluster. It develops where water is localised or for defence and social convenience.
• Dispersed (scattered) settlement: individual houses/farmsteads are spread widely apart, each standing on its own farmland, with no central cluster. It is common where water is widely available and land is farmed individually.
• Linear (ribbon) settlement: houses are strung out in a line along a road, river bank, coast or valley, one or two buildings deep, following the line of the routeway or water body.

(Other acceptable type: compact/roadside or planned settlement.)

(b) Four ways rural and urban settlements are interdependent

• Food supply: rural areas produce food and raw materials for the urban population and for urban industries.
• Market and manufactured goods: urban centres provide a market for rural produce and supply the countryside with manufactured goods and equipment.
• Labour and services: rural areas supply labour and migrants to the towns, while towns provide higher-order services (hospitals, higher schools, banks, administration) used by rural dwellers.
• Employment and remittances: town-dwellers send money (remittances) back to rural relatives, and both are linked by transport, trade and communication networks.

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(a) Land and sea breezes

These are local winds caused by the unequal heating and cooling of land and sea. By day the land heats faster than the sea; the warm air over the land rises and the cooler, denser air from the sea blows in to replace it, giving a sea breeze (from sea to land). By night the land cools faster than the sea; the air over the sea is now warmer and rises, so cooler air from the land blows out to sea, giving a land breeze (from land to sea). They are common along coasts and moderate coastal temperatures.

(b) Temperature inversion

Normally temperature falls with height in the lower atmosphere. A temperature inversion is a reversal of this, where a layer of warm air lies above cooler air near the ground, so temperature rises with height. It occurs typically on clear, calm nights when the ground loses heat rapidly by radiation and chills the air just above it, and in valleys where cold, dense air drains down and collects at the bottom. Inversions trap smoke, fog and pollutants near the surface and prevent convection.

(c) Convectional rainfall

Convectional rainfall results from the intense heating of the ground (as in the tropics and in equatorial regions on summer afternoons). The hot surface heats the air above it, which becomes light and rises rapidly by convection. As it rises it cools, water vapour condenses to form tall cumulonimbus clouds, and heavy rain falls, usually in the afternoon and often with thunder and lightning. It is the chief rainfall type near the Equator.

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(a) Outline map of West Africa (features to show)

• (i) Area with less than four months of rain: shade the far north (Sahel/Sahara margin), e.g. northern Mali/Niger/northern Nigeria, where the short rainy season lasts under four months.
• (ii) Area with rainfall all year round: shade the southern coastal belt near the Equator, e.g. the Guinea coast/Niger Delta and the mountains of Cameroon, which have rain in every month.
• (iii) Position of the high-pressure belt in January: draw the continental high pressure (with the ITD/ITCZ pushed south, near the coast) lying over the Sahara in the north, from which the dry north-east trades (Harmattan) blow.

(b) Three reasons for the length of the rainy season in the dry north (a)(i)

• The area lies far inland/far north, away from the sea, so it is reached by the moist maritime south-west monsoon for only a short part of the year.
• The rain-bearing ITD (Inter-Tropical Discontinuity) reaches it only briefly around July-August before retreating southward, giving a short single rainy season.
• For most of the year the dry, dust-laden north-east trade winds (Harmattan) dominate, keeping the area dry and shortening the rains.

(c) Three problems rainfall poses to agriculture in the wet coastal south (a)(ii)

• Heavy, continuous rain causes serious soil erosion and leaching, washing away nutrients and lowering soil fertility.
• Excessive moisture encourages pests, weeds and crop diseases (fungal rots) and hinders the drying and storage of harvested crops.
• Waterlogging and flooding damage crops, and the lack of a dry season makes it hard to grow crops that need a dry spell to ripen and makes farm operations difficult.

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This question is on the vegetation belts of Nigeria. Part (a) requires an actual sketch map, so it is drawn and labelled below; parts (b) and (c) follow as points.

(a) Sketch map of Nigeria showing four vegetation belts

Nigeria’s natural vegetation runs in broad east–west belts that change from the wet coast in the south to the dry interior in the north. Four of these belts, located and named, are shown on the sketch map below.

The four vegetation belts located and named on the map are:

1. Mangrove and Fresh-water Swamp Forest – along the southern coast and the Niger Delta.
2. Tropical (Lowland) Rainforest – the forest zone just north of the coastal swamps.
3. Guinea Savanna – the wooded “middle belt” of the country.
4. Sudan Savanna – the drier grassland of the far north.

(b) Four ways in which the forest vegetation contributes to the economy

1. Supply of timber: the forest yields hardwood timber (e.g. mahogany, iroko, obeche) used for building houses and making furniture, supporting the construction and wood industries.
2. Foreign-exchange earnings: the export of timber and other forest products brings in foreign exchange, boosting national revenue.
3. Provision of employment: forest activities create jobs for many people, such as lumbermen, saw-millers, forest guards and furniture makers.
4. Source of raw materials and herbs: the forest provides medicinal herbs for the pharmaceutical industry and raw materials (latex, wood pulp, chewing sticks) for other industries.

(c) Four problems associated with the exploitation of the forest vegetation

1. Heterogeneous (mixed) nature of the trees: economic trees are scattered among many worthless species, making selective felling difficult and uneconomic.
2. Poor accessibility: the lack of motorable roads and the swampy ground make it hard to reach and evacuate felled logs.
3. High cost of survey and extraction: locating the few economic trees requires costly surveys, and the huge sizes of the logs make felling and haulage expensive.
4. Risk to life and dense undergrowth: felling of the tall timber is dangerous and lives are often lost, while the thick undergrowth and pests (e.g. tsetse fly) hinder work in the forest.

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Contrast between the Sokoto Plains and the Eastern Highlands of Nigeria

(a) Relief and drainage

(b) Resources and human activities

(c) Problems of development

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None

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(a) Meaning of hinterland

A hinterland is the inland area served by, and trading through, a sea port. It is the region from which the port draws its exports (raw materials, produce) and to which it distributes its imports. For example, most of northern and central Nigeria forms part of the hinterland of the port of Lagos (Apapa).

(b) Importance of sea ports in the economy of Nigeria (with examples)

• Handling of foreign trade: ports such as Lagos (Apapa/Tin Can Island), Port Harcourt, Warri, Calabar and Onne handle the bulk of Nigeria's imports and exports (petroleum, cocoa, manufactured goods).
• Export of oil and revenue: the oil terminals (e.g. Bonny, Escravos) export crude oil, earning the greater part of national foreign exchange and revenue.
• Employment and urban growth: ports create jobs (dockworkers, shipping, clearing) and have stimulated the growth of large port cities.
• Industrial growth: port locations attract industries (refineries, cement, manufacturing) that use imported materials, and they link Nigeria to landlocked neighbours.

(c) Four problems of port development in Nigeria

• Silting and shallow water at some harbours, requiring costly dredging to admit large ships.
• Congestion of ships, cargo and traffic, causing long delays.
• Inadequate/obsolete equipment and infrastructure and poor access roads and railways to the hinterland.
• High cost of construction and maintenance, bureaucracy/corruption, and over-concentration of traffic on Lagos ports.

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(a) Two main types of environmental pollution and causes of one

Two main types are air (atmospheric) pollution and water pollution (others include land/soil pollution and noise pollution).

Three causes of air pollution:

• Burning of fossil fuels in vehicles, power stations and homes, releasing carbon monoxide, sulphur dioxide and smoke.
• Industrial emissions from factories and refineries discharging smoke, soot, dust and toxic gases into the atmosphere.
• Bush burning and gas flaring (and burning of refuse), which release smoke, carbon dioxide and other gases.

(If water pollution is chosen: discharge of industrial effluents/oil spillage into rivers; dumping of untreated sewage and refuse; and run-off of agricultural fertilizers and pesticides.)

(b) Three effects of pollution on man

• Ill-health and disease: polluted air causes respiratory diseases (bronchitis, asthma) and polluted water causes cholera, typhoid and other water-borne diseases.
• Death and shortened life: exposure to toxic gases and contaminated water can cause poisoning and death.
• Loss of livelihood and damage to property: pollution destroys crops, kills fish and livestock, contaminates drinking water and food, and corrodes buildings, reducing income and quality of life.

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(a) Factors favouring rapid growth of population

Two physical factors:

• Favourable climate: a moderate, healthy climate (neither too hot, cold nor too wet) encourages settlement and reduces death from harsh conditions.
• Fertile soils and adequate water: productive land and reliable water supply provide abundant food, supporting a large and growing population (e.g. river valleys and lowlands).

Two human factors:

• Improved medical services: better health care, immunisation and control of disease lower the death rate, especially infant mortality, so population grows.
• High birth rate and immigration: early marriage, large-family customs and religious/social attitudes keep the birth rate high, while good economic opportunities (jobs, industry) attract in-migrants.

(b) Five problems arising from rapid population growth

• Pressure on food supply, leading to food shortage, high prices and possible famine.
• Unemployment and underemployment, as jobs cannot grow as fast as the labour force.
• Shortage of housing, giving rise to overcrowding and slums.
• Strain on social services and infrastructure (schools, hospitals, water, electricity, roads, transport), which become inadequate.
• Environmental problems and pressure on land, including deforestation, over-farming, pollution, waste disposal problems and rural-urban migration/congestion.

Also acceptable: increased crime rate and social vices; low per-capita income and poverty.

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Five factors that determine the volume of trade between Nigeria and Ghana

• Range and differences in products: trade is larger when each country produces goods the other needs (complementarity). If both produce similar goods (cocoa, oil palm) there is little to exchange, reducing trade.
• Nature and cost of transport: the availability, efficiency and cost of road, sea and air transport linking the two countries affects how easily and cheaply goods can be moved, and so the volume traded.
• Government policy and trade barriers: tariffs, import/export duties, quotas, border restrictions and ECOWAS agreements encourage or discourage the flow of goods; free-trade arrangements raise the volume.
• Currency and purchasing power: the exchange rate and convertibility of the naira and cedi, and the level of income/demand in each country, determine how much each can afford to buy.
• Political relations and stability: good, peaceful relations and stable governments promote trade, while political disputes, border closures or insecurity reduce it.

Other acceptable factors: distance between the trading centres, and the size of population/market in each country.

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(a) Sketch map of Nigeria showing the major zones of modern manufacturing industries

The three major zones of modern manufacturing industries in Nigeria are the Lagos (South-Western) Zone, the Kano-Kaduna (Northern) Zone and the Port Harcourt (Southern/Niger Delta) Zone. Each zone, together with two of its important industrial towns, is located and named on the sketch map below.

(b) Three problems resulting from the concentration of manufacturing industries in these zones

1. Industrial and air pollution: the crowding of factories in a few centres releases large volumes of smoke, fumes, effluent and waste, polluting the air, land and rivers of these zones.
2. Excessive pressure on social amenities and infrastructure: the industries and the workers they attract place a heavy strain on the limited electricity, water supply, roads and housing, leading to shortages, traffic congestion and overcrowding.
3. Rural-urban migration and uneven regional development: the concentration draws workers away from other parts of the country, causing over-population and slums in the industrial zones while the neglected areas remain under-developed with few jobs.

(c) Three steps that can be taken to encourage the growth of industries outside these zones

1. Provision of basic infrastructure outside the zones: government should extend electricity, pipe-borne water, good roads and healthcare to other areas so that industries can operate there conveniently.
2. Granting of loans and financial assistance: soft loans and credit facilities should be given to entrepreneurs who are willing to establish industries outside the existing zones.
3. Granting of incentives such as free land and tax holidays: offering free or cheap land and long tax-holiday periods to industries sited outside the zones will attract investors and spread industrial activity across the country.

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(a) Outline map of West Africa: minerals, towns and routes

• Diamond: mark the Sierra Leone field (town: Kono/Koidu), with a route to the port of Freetown for export.
• Petroleum: mark the Niger Delta, Nigeria (town: Port Harcourt/Warri), with a pipeline/route to the oil terminals at Bonny/Forcados for export.
• Gold: mark Ghana (town: Obuasi/Tarkwa), with a rail route to the port of Takoradi for export.

(b) One method of mining a named mineral

Petroleum (drilling): after geological and seismic survey locates an oil-bearing structure, a derrick and rotary drill bore a well down through the rock to the oil reservoir. The oil rises up the well under natural pressure (or is pumped) to the surface, is separated from gas and water, and is piped to storage tanks and refineries or export terminals.

(For gold by deep/shaft mining: vertical shafts and horizontal tunnels are sunk to reach the gold-bearing reef, the ore is blasted, brought to the surface, crushed and the gold extracted chemically. For diamond by alluvial mining: gravel is dug from river beds and washed/sieved to recover the stones.)

(c) Four problems associated with mining in West Africa

• Shortage of capital and modern machinery, so mining is often small-scale and inefficient.
• Shortage of skilled/technical manpower, forcing reliance on foreign experts.
• Poor transport and infrastructure from mine to port, and irregular power supply.
• Environmental damage and hazards (land degradation, pollution, mine collapse), plus dependence on unstable world prices and smuggling.

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Ways transportation contributes to the economic development of a country (e.g. Nigeria):

• Movement of raw materials and goods: transport carries raw materials to factories and finished products to markets and ports, keeping industry supplied and reducing costs.
• Opening up of areas / access to resources: roads, railways and waterways make remote regions accessible, allowing mineral, agricultural and forest resources to be exploited and new land to be settled and farmed.
• Promotion of trade: good transport widens the market, links producing and consuming regions, and promotes both internal and international trade, encouraging specialisation.
• Employment and income: the transport sector itself provides jobs (drivers, mechanics, construction workers, port and airline staff) and generates income and government revenue.
• Encourages agriculture and industry: reliable transport allows perishable farm produce to reach markets quickly and lets industries locate efficiently, boosting output.
• Aids other services and national integration: it supports tourism, distribution of social services and the movement of people, and links different parts of the country, promoting national unity and administration.
• Earns foreign exchange: ports, shipping and airlines handle exports and imports and can earn foreign exchange for the economy.

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(a) Characteristics of tropical grassland (savanna) vegetation

• It is dominated by tall grasses (up to 3-4 metres near the forest margin, shorter toward the desert) that turn green in the rains and brown in the dry season.
• Trees are scattered/isolated and short, drought-resistant (xerophytic) and deciduous, with features such as thick bark, small leaves, deep roots and flat crowns (e.g. acacia, baobab, shea).
• Vegetation shows a marked seasonal rhythm, growing luxuriantly in the wet season and drying up, often with bush fires, in the long dry season.
• Grass cover becomes thinner and shorter, and trees fewer, as one moves from the wetter forest edge toward the drier semi-desert margin.
• Trees often occur in gallery (fringing) forest along river banks where water is available all year.

(b) Economic values of savanna vegetation to the inhabitants

• Grazing land: the extensive grasses support cattle, sheep and goat rearing and pastoralism.
• Farmland: cleared and burnt land is used for growing crops such as grains (millet, guinea corn, maize), groundnuts and cotton.
• Timber, fuel and building materials: trees provide firewood, charcoal, poles and thatching grass.
• Economic tree products: shea butter, gum arabic, locust bean and fruits are collected and sold.
• Wildlife and tourism: the open grassland supports abundant game animals, encouraging game reserves, hunting and a tourist industry. It also supports beekeeping/honey collection.

Detalles de la respuesta

(a) Importance of the Aswan High Dam to the Nile Basin

• Hydro-electric power: the dam generates large amounts of electricity for Egypt's homes and industries, promoting industrial development.
• All-year irrigation: stored water in Lake Nasser provides perennial irrigation, allowing two or three crops a year and the reclamation of desert land for farming.
• Flood control: it controls the annual Nile floods, preventing destructive floods in wet years.
• Water storage against drought: the reservoir stores water for use in dry years, giving a reliable water supply.
• Other benefits: improved navigation on the river, a fishing industry on Lake Nasser, and tourism at the dam and lake.

(b) Four problems resulting from the construction of the dam

• Loss of fertile silt: the dam traps silt behind it, so farmland downstream no longer receives the natural fertilising mud and farmers must buy artificial fertilizers.
• Displacement of people and loss of sites: the reservoir flooded land, displacing the Nubian people and threatening ancient monuments (Abu Simbel had to be moved).
• Increased evaporation and salinity/waterlogging: high evaporation from Lake Nasser wastes water, and continuous irrigation causes salinity and waterlogging of soils.
• Spread of disease and coastal erosion: the still water encourages bilharzia (schistosomiasis) and malaria, and the loss of silt has caused erosion of the Nile delta coast and a decline in Mediterranean sardine fishing.

Detalles de la respuesta

(a) Distinction between rotation and revolution of the earth

Rotation	Revolution
It is the spinning of the earth on its own axis.	It is the movement of the earth in its orbit around the sun.
The earth turns from west to east.	The earth travels along an elliptical path round the sun.
One complete rotation takes about 24 hours (one day).	One complete revolution takes about 365¼ days (one year).
It is a movement about the earth’s axis.	It is a movement along the earth’s orbit round the sun.
It causes day and night.	It causes the seasons and the varying length of day and night.

(b) Two effects of the rotation of the earth

1. Alternation of day and night: as the earth spins on its axis, the half facing the sun experiences day while the half turned away experiences night, and the two alternate every 24 hours.
2. Deflection of winds and ocean currents (Coriolis effect): the earth’s rotation deflects moving winds and ocean currents (to the right in the Northern Hemisphere and to the left in the Southern Hemisphere) and also produces the difference in local time between places on different meridians.

(c) An eclipse of the sun (solar eclipse)

An eclipse of the sun occurs when the Moon comes exactly between the Sun and the Earth, so that the three bodies lie in a straight line and the Moon’s shadow falls on the Earth, cutting off the sun’s light from part of the earth’s surface. It can happen only at new moon.

Because the Moon is much smaller than the Sun, its shadow has two parts. The dark, cone-shaped inner shadow is the umbra; where its tip touches the earth the sun is completely hidden and observers there see a total eclipse. Surrounding it is the lighter shadow, the penumbra; places within it see only part of the sun covered, giving a partial eclipse. As the Earth rotates and the Moon moves in its orbit, the shadow sweeps across the earth, so the eclipse lasts only a short time at any one place.

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Explanatory notes on any three of the following:

(a) Government's influence on the location of industries in Tropical Africa

Governments strongly influence where industries are sited. Through industrial policy they establish industrial estates and free-trade zones, grant incentives (tax holidays, cheap land, loans) to firms that locate in chosen areas, and provide infrastructure (roads, power, water). To reduce regional inequality they may deliberately disperse industries to less-developed regions, or site strategic industries (steel, refineries) for political and defence reasons, so factories often locate where the government directs rather than purely on economic grounds.

(b) Nearness to market as a factor of industrial location in Tropical Africa

Industries locate near their markets to cut transport costs and reach consumers quickly. This is important for weight-gaining and perishable/fragile products (soft drinks, bread, furniture) and for industries serving large urban populations. Large towns provide a big, concentrated market and purchasing power, so consumer-goods factories cluster in and around cities such as Lagos, Accra and Kano.

(c) The concentration of manufacturing industries in urban centres of developing countries

Manufacturing concentrates in a few big towns because they offer large labour supply, a big local market, better infrastructure (electricity, water, ports, roads), banking and commercial services, and government offices. Existing industries also attract others (agglomeration/linkage). This leads to over-concentration in a few cities while other regions remain industrially backward.

(d) The predominance of consumer-oriented industries in developing countries

Developing countries are dominated by light, consumer-goods industries (textiles, food and drink, soap, plastics) rather than heavy capital-goods industries. This is because they have limited capital and technology, a shortage of skilled labour, small and low-income markets that demand cheap everyday goods, and a desire to process local raw materials and reduce imports. Such industries need less capital and yield quicker returns.

Detalles de la respuesta

Explanatory notes on any four of the following:

(a) Cocoa growing in Western Nigeria

Cocoa is the leading cash crop of the south-west (Ondo, Osun, Oyo, Ogun, Ekiti). It thrives on the region's hot, wet climate (over 1200 mm rain), deep well-drained forest soils and shade. It is grown mainly on small peasant farms, takes several years to mature, and the dried beans are a major export earning foreign exchange. Problems include ageing trees, pests/diseases (black pod, capsid) and price fluctuations.

(b) Oil palm production in the eastern states

The oil palm flourishes in the high rainfall and forest soils of the south-east and Niger Delta. It is largely gathered from semi-wild and small-holder groves, yielding palm oil and palm kernel used locally and for export. It provides food, cooking oil, soap-making material and income, but output is limited by reliance on wild palms, low-yielding varieties and simple processing methods.

(c) Rice cultivation in the middle belt

Rice is widely grown in the middle belt (Benue, Niger, Kwara) in river valleys and fadama (flood-plain) land where seasonal flooding provides water. Both swamp (wet) and upland rice are grown, mostly by small farmers. It is a staple food and cash crop, but faces problems of poor water control, pests, and inadequate milling and storage.

(d) Intensive farming in the Kano close-settled zone

Around Kano is one of Africa's most densely populated rural areas, where land is farmed very intensively and continuously. Farmers use manure (from livestock and household refuse), crop rotation, intercropping and permanent cultivation to keep the land productive. Crops include guinea corn, millet, groundnuts, cowpeas and vegetables, often combined with livestock keeping. Pressure on land is high, so holdings are small and every piece of land is used.