WAEC SSCE - Geography - 1997

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The major effect of flooding in Nigeria is the destruction of farms and houses. Flooding occurs when water overflows from its natural channels and covers the surrounding land. This can result in the destruction of homes, farmlands, and other properties, which can lead to displacement of people and loss of livelihoods. Flooding can also cause injuries and loss of lives, as well as the spread of water-borne diseases. The dumping of refuse along river channels can exacerbate the impact of flooding by blocking drainage channels and increasing the risk of flooding.

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Deltas are not a feature of river erosion. River erosion occurs when the flowing water of a river wears away at the surrounding rock and soil over time. This erosion can lead to the formation of various landforms such as waterfalls, gorges, V-shaped valleys, and interlocking spurs. However, deltas are not formed by the process of erosion. Deltas are formed when sediment, such as sand and silt, is carried by a river and then deposited at the mouth of the river where it meets a larger body of water, such as a lake or an ocean. Over time, the deposited sediment builds up, creating a delta landform. This process is known as deposition, not erosion.

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The statement that is not correct about sedimentary rocks is: "are formed in upland areas." Sedimentary rocks are actually formed in low-lying areas, such as riverbeds, lakes, and oceans, where sediment accumulates over time and is eventually compacted and cemented together. This is why they often contain fossils, as the remains of organisms can become trapped in the sediment and preserved over millions of years. Sedimentary rocks are usually in layers, non-crystalline, and could be formed by water.

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The atmospheric condition of a place over a long period of time refers to its climate. Climate is the average weather pattern of a place over a period of at least 30 years. It includes factors such as temperature, rainfall, humidity, wind, and other weather conditions. Climate is an important factor in determining the type of vegetation, animals, and human activities that can thrive in a particular region. It helps us understand how different regions of the world are affected by natural phenomena such as hurricanes, droughts, and floods.

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The Kabora Bassa dam is located on the Zambesi River.

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A radiation fog is likely to develop when there is a rapid loss of heat by radiation on clear, calm nights. During the day, the sun heats the earth and air above it, and as the air warms, it rises and cool air from surrounding areas takes its place. At night, the opposite occurs: the earth and air cool, and the cool air sinks, replacing the warm air. If the sky is clear and winds are calm, the earth and air can continue to cool rapidly by radiation, causing the temperature to drop and the air to become saturated with moisture. This can result in the formation of a radiation fog, which can reduce visibility and affect transportation and other activities.

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The correct option is Hausa. The Hausa people are found in most parts of West Africa, particularly in Nigeria, Niger, Ghana, and Cameroon. They are one of the largest ethnic groups in Africa, and their language, Hausa, is widely spoken across the region as a lingua franca. The Hausa people have a long history of trade and commerce and have played a significant role in the economic and cultural development of West Africa.

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The climate being described is a savanna. A savanna is a type of tropical climate characterized by distinct rainy and dry seasons. In the rainy season, there is a lot of rainfall, and in the dry season, there is little or no rainfall. The vegetation of savannas typically consists of tall grasses and some trees that are mostly deciduous, meaning they shed their leaves during the dry season to conserve water.

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The major irrigation scheme on the Nile Valley is the Managil extension. This scheme is located in Sudan and is one of the largest irrigation systems in the country. It is designed to irrigate the Managil and Rahad plains in eastern Sudan, covering an area of about 8,700 square kilometers. The scheme has several canals, pumping stations, and reservoirs, which are used to distribute water to the farms in the area. The water for the scheme is drawn from the Blue Nile River and is used to grow a variety of crops, including cotton, sorghum, and vegetables.

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Exfoliation is a weathering process associated with hot, arid regions. It is a mechanical weathering process that involves the peeling off of the outer layer of rocks in sheets or layers due to extreme temperature changes. In hot and arid regions, rocks experience intense heating during the day and rapid cooling at night, leading to the expansion and contraction of the outer layer of the rocks. Over time, this process causes the outer layer to weaken and eventually crack and peel off, resulting in the exfoliation of the rock surface. This process is also known as onion skin weathering due to its resemblance to the peeling of onion layers. Examples of areas with exfoliation include deserts such as the Sahara and the Mojave Desert.

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The correct option that affects the flow of ocean currents is Earth's rotation. Earth's rotation causes the Coriolis effect, which deflects ocean currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The rotation of the Earth also creates differences in pressure, which drive the flow of ocean currents. The other options listed do not directly affect the flow of ocean currents. Latitude affects temperature and precipitation patterns, humidity is a measure of atmospheric moisture, longitude is a measure of east-west distance, and ocean depth affects the speed and direction of ocean currents.

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The correct answer is "soil profile". A soil profile is a vertical cross-section of the soil layers, showing the different layers of soil and their characteristics such as color, texture, and composition. These layers are called soil horizons, and each horizon has distinct characteristics that are determined by factors such as climate, vegetation, and topography. By studying the soil profile, scientists can gain insight into the soil's history and properties, which can be useful for agriculture, land use planning, and environmental management.

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The crop that requires sandy, porous, and well-aerated soils for growth is groundnut, also known as peanuts. This is because groundnuts are a type of legume that have a taproot system, which means they need deep, well-draining soils to develop their roots and access water and nutrients. Sandy soils are good for groundnuts because they allow for good drainage and aeration, which prevents waterlogging and root rot. The porosity of sandy soils also allows for easy root penetration, which helps the plant to establish quickly and grow vigorously. Overall, groundnuts thrive in soils that are rich in organic matter, well-draining, and well-aerated.

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The question asks which of the given options is NOT a metamorphic rock. Metamorphic rocks are formed by the transformation of pre-existing rocks due to heat, pressure, and chemical reactions. Therefore, the answer is the option that is NOT a metamorphic rock. - Gabbro: This is an igneous rock that is formed from the solidification of molten magma. It is not a metamorphic rock. - Therefore, the answer is gabbro. In summary, the rock that is not metamorphic is gabbro.

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The correct answer is "Birth control". Birth control is not a problem associated with urban population growth, as it refers to the use of methods to prevent pregnancy and is a personal decision made by individuals. The other options listed are all common problems associated with urban population growth. Unemployment, poor housing, insufficient food supply, and inadequate health facilities are often the result of rapid urbanization, as large numbers of people move from rural areas to cities in search of better opportunities. These issues can lead to overcrowding, poor living conditions, and health problems.

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The process by which the Earth's surface is generally reshaped and lowered is known as denudation. Denudation involves the wearing away of the Earth's surface by various agents of erosion such as water, wind, ice, and gravity. Over time, these agents of erosion gradually remove or strip away the top layers of rock, soil, and other materials, causing the Earth's surface to become smoother and lower. Denudation can occur on a small scale, such as the gradual wearing away of rocks by a river, or on a larger scale, such as the formation of canyons or valleys by glaciers or tectonic activity.

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Stars tend to form cluster known as galaxies. A galaxy is a massive system of stars, dust, and gas that is held together by gravitational forces. There are billions of galaxies in the universe, and they come in different shapes and sizes. Our own solar system is located within the Milky Way galaxy, which is a barred spiral galaxy. Galaxies can contain anywhere from a few million to a trillion stars, as well as various types of interstellar matter such as gas, dust, and dark matter.

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The planet with the shortest orbit around the sun is Mercury. It takes Mercury only about 88 Earth days to complete one orbit around the sun, making it the closest planet to the sun. Mercury's proximity to the sun also means it has a very hot surface temperature, with temperatures reaching up to 800 degrees Fahrenheit (430 degrees Celsius) during the day and dropping to -290 degrees Fahrenheit (-180 degrees Celsius) at night.

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The energy received from the sun at a particular place is called insolation. Insolation is short for "incoming solar radiation" and refers to the amount of solar energy that reaches the Earth's surface. This energy is received in the form of electromagnetic waves, which include visible light, ultraviolet (UV) radiation, and infrared (IR) radiation. The amount of insolation received at a given location is affected by a variety of factors, including latitude, time of year, cloud cover, and atmospheric conditions. Insolation is an important factor in many natural processes, including photosynthesis, evaporation, and atmospheric circulation.

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Carnivores are important in the food chain because they feed on other animals. They are at a higher trophic level and therefore are responsible for regulating the populations of herbivores that they prey on. This helps to maintain balance in the ecosystem, preventing overgrazing and allowing plant populations to recover. Additionally, as they consume a variety of prey, carnivores also help to prevent any one prey species from becoming too dominant, which can also upset the balance of the ecosystem. By doing so, carnivores play a crucial role in maintaining the biodiversity and stability of an ecosystem.

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The mean annual range of temperature of a place is the difference between the highest and lowest mean monthly temperatures for the year. This is which involves finding the mean temperature for each month of the year, and then subtracting the lowest mean monthly temperature from the highest mean monthly temperature. This value gives an indication of the variability of temperature over the course of the year at that location.

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The zone in Nigeria that has the least concentration of manufacturing industries is the North-Western zone. This is because the North-Western zone is predominantly agrarian, with a focus on livestock farming and crop cultivation. As a result, the zone has limited industrial development and lacks the necessary infrastructure and resources to support a thriving manufacturing sector. In contrast, other zones such as the Western zone and South-Eastern zone have a long history of industrialization and are home to some of Nigeria's largest and most developed cities, such as Lagos and Onitsha. Overall, while the North-Western zone has enormous potential for economic growth, its focus on agriculture means that it is currently the least developed in terms of manufacturing industries.

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Exfoliation is not typically associated with mining, while the other options are. Mining activities often involve digging deep into the earth's surface, which can cause erosion and deforestation as trees and other vegetation are removed. Pollution is also a major concern associated with mining, as toxic chemicals and waste materials can be released into the environment. Dumping of waste materials, including tailings and overburden, is also a common practice in mining, which can lead to further pollution and environmental degradation. Exfoliation, on the other hand, refers to the shedding or peeling of a material in thin layers, usually due to weathering or other natural processes. While it is possible that mining activities could indirectly contribute to exfoliation by altering the natural environment, exfoliation itself is not a direct result of mining activities.

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Overgrazing will lead to deterioration of the environment. Overgrazing happens when there are too many animals grazing on a particular piece of land. As a result, the vegetation is unable to regenerate and soil erosion occurs, which can lead to desertification. This leads to the destruction of the natural habitat, loss of biodiversity and decreased soil fertility, which in turn affects agriculture and food production. On the other hand, activities such as planting of trees, contour ploughing, afforestation and creation of shelter belts help in conserving the environment by preventing soil erosion and improving soil fertility.

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Man least explains the variations in the natural vegetation cover in Nigeria. While man's activities such as deforestation and agriculture can have a significant impact on the natural vegetation cover, the other factors listed (temperature, rain, relief, and soil) are natural factors that directly influence the growth and distribution of vegetation. Human activities are only secondary causes of changes in vegetation cover.

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A continuous urban or industrial stretch resulting from the merging of cities is called a conurbation. A conurbation is a region comprising several cities, towns, and suburban areas that have grown and merged together to form a continuous built-up area. This process is often driven by urbanization, population growth, and economic development. Conurbations can be found in many parts of the world and are often associated with high levels of economic activity, transportation infrastructure, and social interaction. Examples of conurbations around the world include the Greater London area in the UK, the Randstad in the Netherlands, and the BosWash corridor in the eastern United States. Conurbations can also have significant environmental and social impacts, including traffic congestion, air pollution, and urban sprawl, as well as opportunities for economic growth and cultural exchange.

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The savanna lands of East Africa are best known for their wildlife. These areas are home to a variety of wild animals such as lions, elephants, giraffes, zebras, and many others. The grassy plains and open woodlands provide a natural habitat for these animals, making it a popular destination for tourists who want to go on safari and see them in their natural environment. The Maasai Mara National Reserve in Kenya and the Serengeti National Park in Tanzania are among the most popular wildlife reserves in the world, attracting thousands of visitors every year.

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The substance that cements soil particles together is colloids. Colloids are particles that are smaller than sand particles and are found in soil. They have a large surface area and can attract and hold water, nutrients, and other particles, which help to bind soil particles together. This binding effect creates a stable soil structure and prevents erosion. So, colloids are an essential component of soil and are responsible for its fertility and productivity.

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A mountain that has been denuded is called a residual mountain. Denudation is the process by which the surface of the earth is lowered through the removal of rocks and soil by agents such as wind, water, and ice. Residual mountains are formed when resistant rocks or hard rocks are left behind after the denudation process has taken place. These mountains often have a flat top and steep sides, and are also referred to as inselbergs. They can be found in various parts of the world, including Africa, Australia, and South America.

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The Mediterranean vegetation can be found in the areas around Cape Town, which is located in the southwestern region of South Africa. This region has a Mediterranean climate characterized by mild, wet winters and hot, dry summers. The Mediterranean vegetation is adapted to these conditions and includes plants such as fynbos, which are endemic to this region. The fynbos vegetation is known for its biodiversity and is considered a global biodiversity hotspot. It is also an important habitat for many species of animals, including birds, mammals, and reptiles.

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The major useful component of the atmosphere is oxygen. Oxygen makes up about 21% of the air we breathe, and it is essential for the survival of most living organisms, including humans. Oxygen is used by our bodies to break down food and release energy, a process known as cellular respiration. It is also important for combustion, which is the process of burning fuel to produce heat and energy. In addition, oxygen is involved in the formation of ozone, which is a protective layer in the upper atmosphere that helps to absorb harmful ultraviolet radiation from the sun. Without oxygen, life as we know it would not be possible on Earth.

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The statement "Rocks that are changed by great heat and pressure are called sedimentary rocks" is not correct. Sedimentary rocks are actually formed through the accumulation and solidification of sediment, while rocks that are changed by great heat and pressure are called metamorphic rocks. Metamorphic rocks are formed from other rocks that undergo extreme heat and pressure, resulting in the recrystallization of minerals and the development of new textures and structures. Examples of metamorphic rocks include marble and gneiss. Igneous rocks are formed through the solidification of molten magma, and examples include basalt and granite. Volcanic rocks are a type of igneous rock that are formed through the extrusion of magma onto the earth's surface. Igneous rocks generally do not contain fossils, as the intense heat and pressure involved in their formation destroys any organic matter.

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The soils of the rainforest are rich in humus because of the large quantity of decayed leaves. In the rainforest, there is a dense vegetation cover with a variety of plant species. The canopy of the trees forms a dense layer that blocks out much of the sunlight at the surface. This leads to a lack of photosynthesis in the lower layers, and dead organic matter accumulates on the forest floor. This organic matter gradually decomposes to form humus, which is a nutrient-rich layer of soil. The heavy rainfall in the rainforest helps to accelerate the decomposition process, as it provides the moisture necessary for the breakdown of organic matter. This humus layer provides essential nutrients for the growth of the rainforest vegetation, and it also helps to retain moisture in the soil.

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The climate being described is the tundra type. This type of climate is characterized by long, very cold winters, low annual rainfall, and short, cool summers. It occurs in regions close to the poles, where the sun is low on the horizon or absent for long periods of time during the winter months, resulting in 24 hours of darkness in the middle of winter. The tundra type is associated with low-growing vegetation, permafrost, and a lack of trees due to the harsh environmental conditions.

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(a) Solstice and Equinox

(A sketch shows the sun's rays vertical over the Tropic of Cancer at the June solstice and over the Equator at the equinox.)

(b) Rotation and Revolution of the Earth

(A sketch shows the earth spinning about its tilted axis and, separately, circling the sun.)

(c) Parallels of latitude and Meridians of longitude

(A sketch of the globe shows horizontal parallels and vertical converging meridians.)

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(a) Four irrigation schemes within the Nile Basin:

• In Egypt: (i) the Aswan High Dam scheme (Lake Nasser); (ii) the Delta Barrage / Nile Delta irrigation scheme.
• In Sudan: (iii) the Gezira scheme (between the Blue and White Nile); (iv) the Managil (Gezira extension) scheme, and the Khashm el-Girba scheme on the Atbara.

(b) Factors that favoured the development of the Gezira scheme:

• Suitable relief: the Gezira is a flat, gently sloping clay plain between the Blue and White Nile, so water can be led by gravity through canals without pumping.
• Availability of water: the Sennar Dam on the Blue Nile stores water and provides a reliable, controlled supply for irrigation.
• Fertile soils: the heavy dark clay ("black cotton") soils are fertile and hold water well, ideal for cotton growing.
• Favourable climate and labour: the hot, sunny climate suits cotton, and a large local population supplies the labour needed.
• Government support and capital: planned investment provided the dam, canals and organisation to manage the scheme.

(c) Contributions of the Gezira scheme to economic development:

• It made Sudan a leading producer and exporter of high-quality long-staple cotton, earning foreign exchange.
• It provides employment for thousands of tenant farmers and workers.
• It supports food production (wheat, groundnuts, sorghum) grown in rotation, improving food supply.
• It has stimulated industry and infrastructure (ginneries, roads, railways, towns) and raised farmers' incomes.

(d) Three problems associated with irrigation schemes in the Nile Valley:

• Silting: canals and reservoirs become choked with silt, reducing storage and requiring costly dredging.
• Salinity and waterlogging: over-watering and poor drainage raise the water table and leave salt on the surface, damaging the soil.
• Spread of water-borne diseases: stagnant canal water encourages bilharzia (schistosomiasis) and malaria among the farming population.

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(a) Sketch map of Africa showing the vegetation belts

Key: Dark green represents tropical rain-forest; yellow represents tropical grassland (savanna); orange represents temperate grassland (veld).

(b) Characteristics of the tropical rain-forest of Africa

1. It is a dense, luxuriant and evergreen forest because rainfall and temperatures are high throughout the year.
2. The trees are very tall, commonly about 45 to 60 metres, and form a continuous closed canopy.
3. Vegetation occurs in distinct layers or storeys: emergent trees, canopy, under-storey and shrub or ground layer.
4. There is a great variety of mixed tree species. Lianas and epiphytes are common, while many tall trees have buttress roots for support.

(c) Economic importance of the tropical rain-forest

1. It supplies valuable hardwood timber, such as mahogany, iroko and ebony, for construction, furniture-making and export.
2. It provides fuelwood and charcoal for domestic and small-scale industrial use.
3. It supplies food and other forest products, including fruits, nuts, mushrooms, honey, rubber, medicinal plants, raffia and oil-palm products.
4. It provides raw materials for local craft and processing industries, such as carving, basket-making, paper-making and furniture production, and creates employment in logging and sawmilling.

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(a)(i) One European trading partner of Nigeria: the United Kingdom (Britain).

(a)(ii) Two commodities exported by each partner

• Nigeria exports to the UK: crude petroleum (oil) and cocoa (also rubber, tin, hides and skins).
• The UK exports to Nigeria: machinery/vehicles and manufactured goods such as chemicals and electrical equipment.

(b) Four benefits both countries derive from the trade

1. Foreign exchange earnings: each country earns money from the goods it sells to the other.
2. Supply of needed goods: Nigeria obtains machinery and manufactured products it does not make, while Britain obtains raw materials (oil, cocoa) for its industries.
3. Employment and industrial growth: the trade creates jobs in production, shipping and ports and keeps industries supplied in both countries.
4. Promotion of good relations and development: the exchange strengthens diplomatic and economic ties and brings in technology and investment.

(c) Four problems facing the trade between the two countries

1. Unfavourable terms of trade: Nigeria sells cheap primary products but buys costly manufactured goods, so the balance often favours Britain.
2. Price fluctuation of primary commodities: the world prices of oil and cocoa rise and fall, making Nigeria's earnings unstable.
3. Trade restrictions and tariffs / quality standards imposed on Nigerian goods entering the European market.
4. Distance and high transport/insurance costs, plus foreign-exchange and currency-difference problems and competition from other suppliers.

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Rail transportation in African countries (examples: the Lagos-Kano line in Nigeria, the Kenya-Uganda railway, TAZARA between Tanzania and Zambia).

(a) Reasons for construction

1. To move bulky mineral and agricultural exports cheaply from the interior to the ports (e.g. tin and groundnuts to Lagos, copper on TAZARA to Dar es Salaam).
2. To open up and develop the interior and link inland producing areas to the coast and markets.
3. To ease the movement of people and goods over long distances at low cost per tonne-kilometre.
4. Administrative and strategic reasons: colonial powers built lines to control territory and, later, to promote national integration and trade. (Also to reduce dependence on a neighbour's ports, as with TAZARA.)

(b) Problems

1. High cost of construction and maintenance across difficult relief (highlands, rivers, forests, deserts).
2. Disconnected networks and different gauges between countries, so lines do not link up and through-traffic is difficult.
3. Old, worn-out equipment and poor management, giving frequent breakdowns, derailments and slow, unreliable services.
4. Shortage of capital and competition from road transport, plus concentration of lines only on export routes leaving many areas unserved.

(c) Solutions

1. Provide more capital investment (government and foreign partners) to rehabilitate and extend the lines.
2. Standardise the gauge and link national networks so trains can run across borders (regional rail integration).
3. Modernise the system: replace old track, locomotives and coaches, and improve management, maintenance and staff training.
4. Extend lines into unserved productive areas and improve coordination with road and water transport. (Also privatisation/concession to improve efficiency.)

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(a) Three causes of air pollution (with examples)

1. Burning of fossil fuels: factories, power stations and motor vehicles burning coal, petrol and diesel release smoke, carbon monoxide, sulphur dioxide and lead into the air (e.g. traffic fumes in Lagos).
2. Industrial and mining processes: refineries, cement works and smelters give off dust, fumes and toxic gases (e.g. gas flaring in the Niger Delta oilfields).
3. Bush burning and burning of refuse: clearing farmland by fire and open burning of waste release smoke and soot into the atmosphere. (Others: volcanic eruptions and use of aerosols/CFCs.)

(b) Three major effects of air pollution

1. Health problems in man: respiratory diseases, bronchitis, lung cancer and eye irritation.
2. Acid rain: sulphur and nitrogen gases dissolve in rain to form acids that damage crops, forests, buildings and aquatic life.
3. Global warming and ozone-layer depletion: greenhouse gases raise world temperatures, while CFCs thin the ozone layer; smog also reduces visibility and harms plants.

(c) Three ways of controlling air pollution

1. Fit filters/scrubbers and catalytic converters to factory chimneys and vehicle exhausts to trap or reduce harmful gases and smoke.
2. Use cleaner energy and fuels (gas, solar, hydro-electric power, unleaded/low-sulphur fuel) instead of dirty coal and heavy oil.
3. Legislation and public education: enact and enforce anti-pollution laws, ban indiscriminate bush and refuse burning, and encourage tree planting to absorb carbon dioxide. (Also site industries away from residential areas.)

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(a) Four factors that determine the pattern of movement of ocean currents (North Pacific Ocean)

1. Prevailing winds: the planetary winds drag surface water along, giving currents their main direction. The North-East Trades drive the North Equatorial Current westward, while the Westerlies drive the North Pacific (West Wind) Drift eastward.
2. Rotation of the earth (Coriolis force): the earth's spin deflects moving water to the right in the Northern Hemisphere, so the North Pacific currents circulate in a clockwise gyre.
3. Shape and position of the land masses (coastal configuration): continents block and deflect the currents; Asia turns the equatorial water northward as the Kuroshio (Japan) Current, and North America turns the drift southward as the California Current.
4. Differences in water temperature, salinity and density: warm, less-dense equatorial water flows towards the poles while cold, dense polar water (the Oyashio/Kamchatka Current) moves towards the Equator, helping drive the circulation.

(b) One cold current: the California Current and its effects on the adjacent coast

The California Current is a cold current flowing southward along the western coast of North America.

• It lowers the temperature of the coastland, giving cool summers on the Californian coast.
• Being cold, it chills the air above it and reduces rainfall, so the adjoining coast is dry (helping to keep the California/Baja desert arid).
• It causes advection fog and mist where the cold current meets warmer air over the land.
• Where it drives cold, nutrient-rich water upward (upwelling) it encourages plankton and rich fishing grounds off the coast.

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(a) Outline map of Africa showing the required features

Key: rivers are shown by blue lines; mountain/highland locations by black triangles; the East African Rift Valley by a broken red line.

(b) Effects of mountains on the climate of Africa

1. They lower temperature. Temperature decreases with altitude; consequently, highlands are cooler than the surrounding lowlands. For example, the East African Highlands have relatively cool conditions despite their low latitude near the Equator.
2. They cause heavy relief rainfall on windward slopes. Moist winds are forced to rise over mountain barriers, cool as they rise and condense to give rain. For example, the eastern, windward side of the Drakensberg receives heavy rainfall.
3. They produce rain-shadow conditions on leeward slopes. Air descending the leeward side becomes warmer and drier after losing much of its moisture on the windward slope. Thus, the leeward side receives scanty rainfall.

(c) Economic importance of the highlands of Africa

1. Agriculture: highlands often have fertile volcanic or well-developed soils and cooler conditions suitable for crops such as coffee, tea, pyrethrum and temperate vegetables. Examples include the Kenya and Ethiopian Highlands.
2. Minerals: many highland areas are sources of valuable minerals, thereby supporting mining and related employment.
3. Hydro-electric power: steep gradients and rapidly flowing rivers originating in highlands provide suitable sites for dams and HEP generation; they also supply water for irrigation and domestic use.
4. Tourism: mountain scenery, cool climate, wildlife and features such as volcanic peaks and escarpments attract tourists and earn foreign exchange.

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(a) Four factors that can influence the climate of a place

1. Latitude (distance from the Equator): places near the Equator receive the sun's rays nearly vertically and are hot all year, while temperature falls towards the poles where the rays are slanting.
2. Altitude (height above sea level): temperature falls with height (about 6.5°C per 1000 m), so highland places are cooler than lowlands on the same latitude.
3. Distance from the sea (continentality): coastal places have a small temperature range and moist air, while inland places have hot summers, cold winters and a large range.
4. Ocean currents and prevailing winds: warm currents/onshore winds bring warmth and rain to a coast, while cold currents/offshore winds bring cool, dry conditions. (Also relief and vegetation cover.)

(b) Three ways climate affects man

1. Agriculture: climate decides which crops can be grown and the type of farming; rainfall and temperature determine planting and harvesting, so it governs food supply.
2. Type of settlement, dress and housing: people build and dress to suit the climate (light clothing and open houses in the hot tropics, heavy clothing and heated homes in cold lands), and dense settlement avoids very harsh climates (deserts, ice).
3. Health and occupation/economic activity: climate influences the spread of diseases (malaria in the hot wet tropics) and the kind of work and industries (tourism, fishing, timber) that people undertake. (It also affects transport.)

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(a) Sketch map of Nigeria

The required locations are shown and labelled on the sketch map below. HEP means hydro-electric power station.

Key locations: Rivers Imo and Kaduna; HEP stations at Kainji and Jebba; thermal stations at Egbin and Afam; oil refineries at Port Harcourt and Warri.

(b) Contributions of the oil industry to the economic development of Nigeria

1. It provides a major source of foreign exchange through the export of crude oil and petroleum products.
2. It provides fuel and gas for domestic consumption, transportation and industrial use.
3. It creates employment opportunities directly in oil exploration, production and refining, and indirectly in transport, construction and other services.

(c) Problems arising from the exploitation of crude oil in Nigeria

1. Oil spills and gas flaring cause serious pollution of land, rivers and the atmosphere.
2. Oil operations can lead to rural depopulation and displacement of farming and fishing communities.
3. The industry depends greatly on foreign capital, technology and skilled manpower.
4. Oil spills, pipelines and drilling activities waste or damage farmlands and fishing waters, reducing agricultural and fish production.

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Desert encroachment (desertification) is the spread of desert-like conditions into once-productive land at the desert margins.

(a) Causes

1. Prolonged drought / declining rainfall at the desert margin (e.g. the Sahel).
2. Overgrazing by too many cattle, sheep and goats, which strips the grass cover.
3. Deforestation and over-cultivation, including bush burning and the cutting of trees for fuelwood, which expose the soil.
4. Population pressure forcing continuous farming without fallow, exhausting and loosening the soil so that wind and water erode it.

(b) Areas liable

• The Sahel belt of Africa south of the Sahara (northern Nigeria, Niger, Chad, Mali, Sudan, Sudan-savanna zone).
• Margins of other great deserts: the fringes of the Kalahari, the Arabian, Thar, Gobi and Australian deserts.
• Generally, semi-arid savanna/steppe lands with low, unreliable rainfall next to hot deserts.

(c) Effects

1. Loss of farmland and fall in crop and animal yields, leading to famine and food shortage.
2. Death of livestock and destruction of vegetation as pasture and water dry up.
3. Migration of people (environmental refugees) away from the affected land, and drying up of wells, rivers and lakes (e.g. shrinking of Lake Chad).
4. Increased soil erosion and dust storms and general impoverishment.

(d) Methods of prevention

1. Afforestation / planting of shelter belts (tree planting) to bind the soil and check the wind (e.g. the Great Green Wall).
2. Controlled grazing by limiting herd sizes and rotating pastures to allow grass to recover.
3. Good farming methods: crop rotation, fallowing, mulching and irrigation to keep the soil covered and productive.
4. Public education and enforcement against bush burning and indiscriminate tree felling, plus provision of alternative fuel to reduce fuelwood cutting.

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(a) Sketch map of Africa

Key: E is the Congo Basin equatorial-climate area and K is Kisangani, a major town in that area. D is the Sahara Desert climatic area and T is Tamanrasset, a major town in that area.

(b) Characteristics of the equatorial climate

1. High temperatures throughout the year: Mean monthly temperatures are generally about 27°C, with a very small annual temperature range.
2. Heavy convectional rainfall: Strong surface heating causes warm, moist air to rise, cool and condense, producing frequent heavy thunderstorms, often in the afternoon.
3. Rainfall occurs throughout the year: Annual rainfall is commonly above 2,000 mm. There is no marked dry season and many places experience two rainfall maxima as the overhead sun passes twice yearly.

(c) Adaptations of tropical rainforest vegetation to the equatorial climate

1. Trees are tall and grow in layers, with a dense upper canopy, in order to obtain sunlight in the intensely competitive forest.
2. Many large trees develop broad buttress roots or aerial roots for support in the shallow, heavily leached and wet soils.
3. Leaves are broad and evergreen to trap available light; they often have waxy surfaces and drip tips that allow heavy rainwater to run off quickly.

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(a) Four ways a town differs from a village

(A town also covers a larger built-up area and has higher-order services than a village.)

(b) Three functions a town performs for a village (with examples)

1. Market/commercial function: the town acts as a market centre where villagers sell their farm produce and buy manufactured goods they cannot get in the village (e.g. Onitsha or Kano markets serving surrounding villages).
2. Service function (health, education, administration): the town provides higher-order services such as hospitals, secondary schools, banks and government offices that serve the villagers (e.g. villagers travel to a nearby town for a general hospital or a bank).
3. Employment and industrial function: the town offers jobs in industries, offices and services, and processes the raw materials produced in the villages (e.g. a cotton-ginnery or cocoa-processing town buying and processing produce from nearby farming villages).

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(a) Examples of industries in Tropical Africa

• Local crafts (two): hand-weaving of cloth (aso-oke, kente) and leatherwork; also pottery, wood-carving, blacksmithing and cane/basket weaving.
• Manufacturing industries (two): textile mills and cement manufacture; also food and beverage processing, brewing and vehicle assembly.

(b) Five factors that affect the location of manufacturing industries in Tropical Africa

1. Raw materials: industries that use bulky or perishable materials (cement, food processing) are sited near their source.
2. Power/energy supply: industries locate where electricity (e.g. from hydro dams) or fuel is available and reliable.
3. Transport: good roads, railways and ports attract industry by easing the movement of materials and finished goods.
4. Market: firms settle in or near large towns where there is a big population to buy the products.
5. Labour and capital: availability of cheap or skilled workers and of investment funds influences where factories are built. (Also water supply and government policy.)

(c) Three problems facing manufacturing industry in the sub-region

1. Shortage of capital and skilled labour, which limits the setting up and running of modern factories.
2. Inadequate and unreliable power and infrastructure, raising costs and interrupting production.
3. Small local market and low purchasing power, plus competition from imported goods, which restrict the growth of local manufacturing. (Also dependence on imported machinery and raw materials.)

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(a) Four factors that determine population distribution

1. Relief: flat and gently sloping lowlands are densely settled because they are easy to build on and farm, while rugged mountains are sparsely peopled.
2. Climate: areas with moderate temperature and reliable rainfall attract people, whereas very hot deserts, cold polar lands and very wet equatorial forests repel settlement.
3. Soil fertility: fertile soils (river valleys, deltas, volcanic soils) support farming and dense population; poor, thin soils carry few people.
4. Economic/mineral and industrial opportunities: mining areas, ports, industrial towns and good transport concentrate people, while remote areas lacking jobs are thinly settled. (Also water supply and political/historical factors.)

(b) Two types of population movement

1. Rural-urban migration: the movement of people from villages and rural areas to towns and cities in search of jobs, education and better amenities.
2. International migration: the movement of people across national boundaries from one country to another (emigration and immigration), which may be permanent or temporary. (Others: seasonal migration and rural-rural migration.)

(c) Four problems associated with rural-urban migration

1. Overcrowding and pressure on housing in the towns, producing slums and shanty settlements.
2. Unemployment and under-employment as job-seekers exceed available jobs, leading to poverty and crime.
3. Strain on urban services and facilities: water, electricity, transport, schools and hospitals become overstretched, and pollution and traffic congestion increase.
4. Depopulation of the rural areas: loss of the able-bodied young leaves a shortage of farm labour, falling food production and neglect of the villages.

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(a) Sketch map of Nigeria

Key: The shaded Y-shaped belt represents the Niger-Benue trough. Lokoja is the confluence town where River Benue joins River Niger. Bacita lies in the Niger valley, while Numan lies on the River Benue.

(b) Commercial production of sugarcane in the Niger-Benue Trough

(i) Method of cultivation

• Sugarcane is cultivated commercially on large estates, especially on the fertile, level alluvial floodplains of the Niger and Benue valleys.
• The land is cleared, ploughed, harrowed and made into ridges or furrows, often with tractors and other machinery.
• Short pieces of mature cane stem, called setts, each with buds, are planted in furrows. Planting is commonly carried out from about November to April.
• Water from Rivers Niger and Benue is used to irrigate the farms during the dry season.
• The crop is weeded, supplied with fertiliser where necessary, protected from pests and allowed to mature before harvesting.

(ii) Method of harvesting

• Mature cane stalks are cut a few centimetres above ground level, either manually with cutlasses or mechanically with harvesters.
• The leafy tops and dry leaves are stripped off and the stalks are tied or loaded.
• The cut cane is transported quickly by lorry or rail to the sugar factory for crushing, since delay reduces its sugar content.

(iii) Economic importance

• It supplies raw material to sugar-processing industries, including the sugar estates and factories at Bacita and Numan.
• It provides employment and income for farm workers, factory workers, transporters and farmers.
• It produces sugar for consumption and thereby helps to reduce the importation of sugar and conserve foreign exchange.
• Its by-products are useful: molasses may be used in alcohol production and animal feed, while bagasse may be used as fuel, for paper-making or as livestock feed.
• The cane itself may be chewed as food, and its residues can serve as fodder for cattle.

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(a) Five features of rotational bush fallowing in West Africa

1. Land is cultivated for a few years then rested (fallowed): A piece of land is farmed for about two to three years and then abandoned for several years to allow it to recover its fertility naturally.
2. Shifting of cultivation between plots, not settlements: The farmer moves from one plot to another within the same area while remaining in a permanent home settlement.
3. Use of simple tools and low technology: Farming is done mainly with hand tools such as the hoe and cutlass, with little or no machinery.
4. Clearing by cutting and burning the bush: The natural vegetation is cut and burnt, and the ash adds nutrients to the soil before planting.
5. Mixed cropping on small holdings: Several crops (for example yam, cassava, maize and vegetables) are grown together on small, scattered plots, largely for subsistence.

(Reliance on natural restoration of fertility and use of family labour are also acceptable features.)

(b) Four advantages of the system

1. Restores soil fertility naturally: The fallow period allows the soil to regain nutrients and structure without artificial fertiliser.
2. Cheap and low input: It requires little capital, no expensive machinery or chemicals, and uses available family labour.
3. Controls pests, weeds and diseases: Resting and burning the land breaks the life cycle of pests, weeds and crop diseases.
4. Reduces soil erosion and exhaustion: Regrowth of vegetation during fallow protects the soil surface and prevents rapid exhaustion of the land.

(c) Four disadvantages of the system

1. Requires a large area of land: Because much land is left fallow at any time, the system is wasteful of land and unsuitable where population is dense.
2. Low output and small farm size: Yields per farmer are low and production is mainly at subsistence level, giving little surplus for sale.
3. Not suited to mechanisation: The small, scattered plots with tree stumps make it difficult to use machinery, keeping productivity low.
4. Shorter fallows cause soil degradation: As population grows, fallow periods are shortened, so the soil cannot recover fully, leading to declining fertility and erosion.

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