WAEC SSCE - Geography - 1994

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Temperate grasslands are commonly known as steppes. Steppes are large areas of flat grassland found in temperate climates, which are characterized by cold winters and hot summers. They are mostly found in the interior of continents and are also known as prairies, pampas, or savannas depending on the region of the world where they occur.

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Cameroon is not a member of the Economic Community of West African States (ECOWAS). ECOWAS is a regional economic union made up of fifteen West African countries. Cameroon, while it shares some borders with ECOWAS member countries and has strong economic ties with the region, is not considered part of West Africa and therefore is not a member of the organization.

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Desert encroachment refers to the gradual expansion of arid or desert areas into previously habitable lands due to human activities or climate change. The best way to control desert encroachment is to plant trees, which is known as afforestation. Trees help to stabilize soil, retain moisture, and prevent wind erosion, thus helping to maintain the fertility of the land. This can be achieved by planting trees in strategic locations or through reforestation programs. Erecting barriers, deforestation, overgrazing, and slopewise cultivation can have negative impacts on the environment and may exacerbate desert encroachment in the long run.

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Sand is the most permeable soil type. Permeability refers to the soil's ability to allow water to pass through it. Sand has larger particles with wider spaces between them, which allows water to flow more easily through the soil. This makes it easier for plant roots to access water and nutrients in the soil. In contrast, clay soils have smaller particles with less space between them, which makes it more difficult for water to pass through. Loam is a combination of sand, silt, and clay, and its permeability depends on the proportions of these components. Laterite soils are typically rich in iron and aluminum, which makes them hard and impermeable. Peat soils are composed of partially decayed organic matter and tend to be waterlogged, which reduces their permeability.

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An aquifer is a type of rock layer that is permeable and can hold water. Water is able to flow through the small spaces and cracks within the rock, and this makes the aquifer an important source of groundwater. The permeability of the rock allows water to be stored within the aquifer, and this water can be accessed through wells for human use.

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Koppen's classification of climate is based on two primary factors: precipitation and temperature. These factors are used to classify the world's climates into five major groups, which are further subdivided into smaller groups based on other factors such as seasonality, humidity, and wind patterns. The classification system takes into account the amount and distribution of rainfall throughout the year and the average temperature of the warmest and coolest months. By combining these two factors, Koppen's classification provides a comprehensive system for understanding the major climatic regions of the world.

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When the sun is directly overhead at the tropic of Capricorn on 22nd December, the Northern Hemisphere experiences its winter solstice. The winter solstice is the day with the shortest period of daylight and the longest night of the year. This occurs because the North Pole is tilted furthest away from the sun on this day. As a result, the sunlight falls at a very oblique angle on the Northern Hemisphere causing less energy to be received in the region, leading to a decrease in temperature.

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Tropical Asia has the highest population concentration. This is because the region has a very high population density due to the presence of large countries with large populations such as China and India, as well as high urbanization rates. Additionally, the region has a relatively small land area compared to its population, which makes it one of the most densely populated regions in the world.

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When on-shore winds blow over cold ocean currents, the temperatures of adjacent coastlands are reduced because the temperature of the prevailing winds is influenced by the cold currents. The cold currents cool the overlying air, which in turn cools the onshore winds blowing over them. This results in a decrease in temperature along the coastlands. So, the correct option is "current influences the temperature of the prevailing winds."

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All the options listed in the question are causes of mechanical weathering except rain action. Mechanical weathering involves the physical breakdown of rocks into smaller fragments without altering their chemical composition. Rain action or dissolution is a chemical weathering process that involves the breakdown of rocks through the chemical alteration of minerals. Temperature changes, alternate wetting and drying, frost action, and action of plants and animals are examples of mechanical weathering processes that occur due to physical forces such as expansion, contraction, and pressure.

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The best option that explains the drift of population from rural to the cities in Nigeria is that there are more job opportunities in the cities. This means that people migrate from rural areas to urban areas in search of jobs or better economic opportunities. The cities provide more employment opportunities in the manufacturing, service, and trade sectors. Many young people also move to cities in search of better education and training facilities. Other factors, such as access to better healthcare, social amenities, and improved standards of living, also attract people to the cities.

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Wind action is more predominant in arid regions than in humid regions because of the loose surface materials and the absence of vegetation cover in arid regions. In arid regions, there is little or no vegetation to hold the soil in place, and the loose surface materials make it easier for wind to move the soil particles around. In contrast, in humid regions, the soil is held in place by vegetation cover, and the soil is generally denser, making it harder for wind to move the soil particles. Additionally, the other options are not correct explanations for why wind action is more predominant in arid regions than in humid regions.

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The bush fallowing system is an agricultural practice used in West Africa where farmers clear a plot of land, cultivate it for a few years, and then allow it to lay fallow for a period of time to regain its fertility before clearing and cultivating another plot. This system has several advantages, including allowing the land to regain its fertility during fallow, being very economical in the use of land, and reducing the need for the use of artificial fertilizers. However, one disadvantage of the bush fallowing system is that it could lead to soil erosion. Therefore, the correct answer to the question is option D: "could lead to soil erosion."

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Greenheart, mahogany, and ebony are commonly found in the natural vegetation belt known as the Selvas. The Selvas is a tropical rainforest vegetation belt that is characterized by dense forests with tall trees, high rainfall, and high humidity. The region is also known for its high biodiversity with a wide variety of flora and fauna. The Selvas is found in parts of South America, Central America, and West Africa.

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The best account for the decline in the importance of rail transport in Africa is high competition from road transport. Road transport has become a more popular mode of transportation in Africa due to the increasing number of vehicles on the roads and the flexibility it offers in terms of destination and speed. Unlike rail transport, road transport offers door-to-door delivery, which makes it more convenient for businesses and individuals. This has led to a decline in the use of railways for transporting goods and people, resulting in a decrease in the importance of rail transport in Africa.

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A state of inter-dependence within the ecosystem is best achieved when the components are undisturbed. This is because every living and non-living component of an ecosystem plays a vital role in sustaining life. The components of an ecosystem depend on each other for survival and function as a unit. Any disturbance to one component can lead to a ripple effect on the others, leading to imbalances and possible collapse of the ecosystem. Thus, maintaining the natural balance and inter-dependence within an ecosystem is crucial for its stability and sustainability.

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The size of the individual grains of soil is referred to as the texture. Texture is one of the most important physical properties of soil, and it refers to the size distribution of the mineral particles that make up the soil. Soil texture can be classified as either sand, silt, or clay, depending on the size of the mineral particles. Sand particles are the largest, followed by silt and then clay, with clay particles being the smallest. The texture of the soil affects the ability of the soil to retain water and nutrients, as well as its workability for agricultural purposes.

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The Aswan Dam in Egypt provides both irrigation water and hydro-electricity. The dam is located on the Nile River and was completed in 1970. It is one of the largest dams in the world, and its reservoir, Lake Nasser, provides water for irrigation to over 3 million acres of land, as well as hydroelectric power for much of Egypt's population. The other dams listed also provide hydro-electricity, but their main purpose is either irrigation (Gezira) or flood control (Kainji, Cabora Bassa, Akosombo).

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Coal is associated with organically-formed sedimentary rocks. Coal forms from the accumulation and transformation of plant material over millions of years under heat and pressure. These organic materials include leaves, wood, bark, and other plant remains that are buried in sedimentary basins. As they are subjected to heat and pressure, they undergo chemical and physical changes that eventually transform them into coal. Therefore, coal is typically found in rocks such as shale, sandstone, and limestone that were formed from sediments deposited in swamps, lakes, and other wetland environments where plant material could accumulate.

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The effect of rural-urban migration on the source region is rural depopulation. When people migrate from rural areas to urban centers in search of better job opportunities, healthcare facilities, education, and improved living standards, the rural areas experience a decline in population. This can have a negative impact on the rural economy as there may be fewer people to work on farms and other agricultural activities, leading to a decrease in agricultural production. Rural depopulation may also result in a decline in social amenities, such as schools and health facilities, as well as a decrease in the provision of basic infrastructure such as roads and electricity. This can have a ripple effect on the standard of living of those who remain in rural areas.

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The winds whose direction is reversed from one season to another are called monsoons. Monsoons are characterized by seasonal reversal of wind direction, which are caused by differential heating and cooling of land and water surfaces. During summer, the land gets heated more than the ocean, causing a low-pressure zone over the land and high-pressure zone over the ocean, which leads to moisture-laden winds blowing from the ocean towards the land. In winter, the opposite occurs due to the reversal of the pressure gradient, causing the dry winds to blow from the land towards the ocean. This phenomenon is most commonly observed in South and Southeast Asia.

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Mountains formed as a result of compressional forces in the earth's crust are called fold mountains. Fold mountains are formed when two tectonic plates collide and push up layers of rock into folds, resulting in a series of peaks and valleys. The compression forces cause the rocks to deform and buckle, leading to the creation of folds. The Himalayas and the Alps are examples of fold mountains.

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Tsetsefly infestation least influences population density in Nigeria. Tsetse flies are known to transmit diseases that affect both humans and animals, and as such, their presence has a negative impact on human settlements in affected areas. Areas with high tsetse fly infestation are often avoided by settlers, thereby limiting population density. On the other hand, the other options listed in the question, such as mining, fertile agricultural land, thick forest vegetation, and industrialization, can have both positive and negative effects on population density in Nigeria.

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One relative advantage of water transport over road transport is its suitability for bulky and heavy cargo. Water transport, such as shipping and barges, are capable of carrying large and heavy loads of goods that would be difficult or impossible to transport by road. Water transport can also be more cost-effective than road transport for long-distance transport of heavy goods. This makes water transport a popular choice for industries such as mining and agriculture, where large quantities of goods need to be transported over long distances.

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A large expanse of low, level land, formed due to an uplift of part of the sea floor bordering a continent is called a coastal plain. Coastal plains are characterized by a broad strip of low-lying land adjacent to the coast, often consisting of sand and sediment deposited by rivers and ocean currents. Coastal plains are common features along the edges of continents and can extend for hundreds of kilometers inland. They are important for human settlement and economic activities such as agriculture, fishing, and tourism.

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One characteristic that distinguishes urban settlements from rural settlements is that urban settlements are areas of secondary and tertiary activities. Urban settlements are usually characterized by a higher population density, larger size, and greater economic and social complexity compared to rural settlements. Urban areas are typically centers of commerce, industry, education, and government, and offer a wider range of employment opportunities and services, such as healthcare, transportation, and entertainment, compared to rural areas, which tend to focus more on primary activities such as agriculture, mining, and forestry.

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The best example of a non-renewable resource among the given options is minerals. Minerals are geological materials that exist in a fixed amount in the Earth's crust, and they are formed over millions of years through geological processes. Once these minerals are extracted and used, they cannot be replaced or replenished in a short time. Hence, minerals are considered as non-renewable resources, unlike water, air, and vegetation which can be renewed through natural processes such as the water cycle, photosynthesis, and atmospheric circulation, respectively. Therefore, of the given options, minerals are the best example of a non-renewable resource.

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The equatorial diameter of the Earth is the distance from one point on the equator to the point diametrically opposite on the equator, passing through the center of the Earth. The correct answer is 12.760km.

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Urbanization refers to the process of a significant increase in the proportion of the population of a country or region living in urban areas (cities or towns). It involves the growth of urban areas in terms of both population and physical size, as well as the expansion of urban land use into surrounding rural areas. This can be due to various factors such as industrialization, rural-urban migration, and natural population growth. Option A "growth of towns, especially in terms of human population and physical size" accurately describes urbanization.

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The development of hydro-electric power in Nigeria is least affected by the presence of high mountains. Hydro-electric power is generated by harnessing the potential energy of water stored in dams. The water is allowed to flow through turbines which drives generators to produce electricity. The height from which the water falls and the volume of water flow are the two main factors that determine the amount of electricity generated. High mountains are ideal for the construction of hydro-electric power stations because they provide a high head of water, which means that the water can fall from a greater height, thus producing more energy. However, the presence of high mountains is not an essential requirement for the development of hydro-electric power. Other factors such as a regular supply of water, availability of suitable sites for dams, and the rapid increase in demand for electricity are more critical to the development of hydro-electric power in Nigeria. Additionally, while the high cost of construction may be a limiting factor, it is not necessarily the least affected factor as it can significantly impact the viability of a hydro-electric power project.

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The description given refers to sedimentary rocks. Sedimentary rocks are formed by the accumulation of sediments over time, which may be derived from the erosion of pre-existing rocks or the remains of dead organisms. These sediments are deposited in layers and then compacted and cemented together to form rock. Examples of sedimentary rocks include sandstone, limestone, and shale.

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The best example of a non-renewable resource among the given options is "minerals". Minerals are natural resources that cannot be replaced or regenerated within a short time frame. They are finite and exhaustible. Once they are extracted and used, they are depleted and cannot be replenished easily. Some examples of non-renewable minerals include coal, oil, natural gas, and metals such as iron, copper, and gold. In contrast, renewable resources such as water, air, and vegetation can be replenished naturally and sustainably over time.

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(a) Five distinguishing features of plantation agriculture in East Africa

1. Large-scale, single-crop (monoculture) cultivation: vast estates are devoted to one cash crop such as tea, coffee, sisal, sugar-cane or pyrethrum.
2. Production for export/market: the crops are grown mainly for sale and export, not for subsistence.
3. Heavy capital investment: plantations require large capital for land, machinery, processing plants and infrastructure, and are often owned by companies or foreign investors.
4. Large, permanent labour force: they employ many hired workers and use scientific methods, fertilizers, pest control and irrigation.
5. On-site processing: the crop is usually partly processed on the estate (tea factories, sisal decorticators, sugar mills) before marketing, and estates are well organised with their own settlements and roads.

(b) Five factors that have favoured plantation agriculture in East Africa

1. Favourable climate: the highland areas have moderate temperatures and reliable rainfall suited to tea and coffee, while lowlands suit sisal and sugar.
2. Fertile volcanic soils in the highlands of Kenya, Uganda and Tanzania.
3. Suitable relief: gently sloping, well-drained highlands and plains ease large-scale cultivation.
4. Availability of cheap, abundant labour from the dense local population.
5. Capital, foreign investment and colonial/company involvement, together with transport links (railways and roads) and access to export ports such as Mombasa.

(Also: ready overseas market demand and government/estate support.)

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(a) Sketch map of Nigeria

Key locations shown on the map:

People	Home area	Major town
Fulani	Far North, especially the Kano-Sokoto savanna belt	Kano
Ibibio	South-East coastal area, mainly Akwa Ibom	Uyo
Yoruba	South-West Nigeria	Ibadan
Urhobo	Western Niger Delta, mainly Delta State	Warri

(b) Effects of physical environment on occupation and house type

(i) Yoruba

• The Yoruba live mainly in the humid forest and derived-savanna belt. The fairly high rainfall, fertile soils and long growing season encourage the cultivation of crops such as yam, cassava, maize, cocoa, kolanut and oil palm.
• The availability of forest products also encourages wood carving, furniture making and other crafts. Trading and weaving are common, particularly in towns.
• Clayey soil is available for building, so traditional houses are commonly made of mud walls, often with thatched roofs. In large urban settlements, permanent houses of blocks and corrugated iron roofing are now widespread.

(ii) Fulani

• The Fulani occupy the northern savanna, where open grassland provides extensive pasture for cattle. Their major occupation is cattle rearing, with milk production and the sale of cattle and dairy products.
• The long dry season and seasonal shortage of water and pasture cause many pastoral Fulani to move with their herds in search of grazing land and water. Some settled Fulani also grow grains and engage in trade.
• Because many are mobile pastoralists, their traditional shelters are light, temporary huts or tents made from grass, leaves, mats and branches. Such shelters are easily dismantled and rebuilt when they move. Settled Fulani may occupy round mud houses with conical thatched roofs.

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(a) Sketch map of Nigeria showing selected mineral-producing areas and major towns

Mineral	Mining area located	Major town named
Limestone	Ewekoro area, Ogun State	Ewekoro
Tin	Jos Plateau	Jos
Crude oil	Niger Delta	Port Harcourt
Coal	Udi-Enugu coalfield	Enugu

(b) Importance of crude oil to the economy of Nigeria

1. It earns Nigeria foreign exchange through export.
2. It provides substantial government revenue through taxes, royalties and export proceeds.
3. It provides employment in oil exploration, production, refining, transport and marketing.
4. It supplies essential products such as petrol, diesel, kerosene and cooking gas.
5. It supplies raw materials for petrochemical industries, including plastics, fertiliser, paints and lubricants.
6. Oil revenue assists the provision of infrastructure such as roads, electricity, water supply, schools and hospitals.

(c) Problems facing the mining industry in Nigeria

1. Environmental pollution from mining, oil spills, gas flaring and mine waste damages land and water.
2. Mining operations may cause loss of farmland and land degradation.
3. There is inadequate skilled labour and shortage of modern mining technology.
4. Inadequate transport facilities and poor access roads make movement of machinery and minerals costly.

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Trade relations: Nigeria-United Kingdom compared with Nigeria-Japan

Similarities (comparison)

• In both cases Nigeria's trade is unfavourable/dependent: Nigeria mainly exports raw materials/primary products (crude oil, cocoa, rubber, hides) and imports manufactured goods (machinery, vehicles, electronics, chemicals) from both partners.
• Both the UK and Japan are industrialized nations that sell high-value finished goods to Nigeria, so Nigeria often runs the weaker side of the exchange with each.
• Trade with both moves by sea (and air) over long distances and both are important trading partners of Nigeria.

Differences (contrast)

• Historical basis: Nigeria-UK trade rests on long colonial and Commonwealth ties, long-established commercial links and a common language; Nigeria-Japan trade is more recent, purely commercial, without colonial history.
• Nature of goods: the UK supplies a wide range of manufactures, services and financial links, while Japan concentrates on vehicles, motorcycles, electronics and heavy machinery.
• Direction and distance: the UK is nearer (Europe) with older shipping routes; Japan is much farther (the Far East), so Nigeria-Japan trade involves longer transport routes and higher freight.
• Balance and volume: trade with the UK is broader and long-standing, whereas Japan buys relatively little from Nigeria, so Nigeria's trade deficit with Japan is often wider than with the UK.

Conclusion: In both relationships Nigeria acts mainly as a supplier of raw materials and a market for manufactured goods, but the UK link is older and colonial in origin while the Japanese link is newer, more distant and dominated by machinery and vehicles.

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(a) Three effects of the rotation of the earth include:

(i) It causes the alternation of day and night.

(ii) It causes the deflection of winds and ocean currents (Coriolis effect).

(iii) It causes differences in local time from place to place.

(b)(i) Reasons why all areas north of the Arctic Circle have 24 hours of daylight on June 21:

(i) On June 21, the North Pole is tilted towards the sun.

(ii) The overhead sun is at the Tropic of Cancer.

(iii) The circle of illumination extends beyond the North Pole, leaving all places north of the Arctic Circle within the illuminated half of the earth.

(iv) As the earth rotates, the sun does not set in these areas; hence, they experience continuous daylight.

(b)(ii) Reasons why areas within the tropics have more sunshine than areas outside the tropics:

(i) The sun is overhead or nearly overhead within the tropics at some time during the year.

(ii) The sun’s rays strike the tropics more directly and are concentrated over a smaller area.

(iii) Areas within the tropics have fairly equal lengths of day and night throughout the year, giving relatively long periods of daylight.

(iv) Outside the tropics, the sun’s rays are more slanting, spread over a wider area and pass through more atmosphere; therefore, they receive less intense sunshine.

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(a) Five factors responsible for low population density in some parts of West Africa

1. Harsh climate: areas of very low, unreliable rainfall (the Sahel and desert margins) or excessively wet, humid areas discourage settlement.
2. Poor/infertile soils: thin, leached or sandy soils that cannot support good farming keep population sparse.
3. Difficult relief and terrain: mountains, rugged highlands, swamps, mangrove and dense forest are hard to farm and settle.
4. Prevalence of pests and diseases: the tsetse fly (sleeping sickness), river blindness, malaria and similar hazards drive people away from affected areas.
5. Poor development and lack of amenities: absence of roads, industries, jobs and social services, sometimes worsened by insecurity/conflict, leads to out-migration.

(Also: past slave-raiding that depopulated areas, and infertile flood-prone or waterlogged land.)

(b) Four ways low population density can be an advantage

1. Less pressure on land and resources: more farmland, water and forest are available per person, reducing over-cultivation and land disputes.
2. Larger share of amenities and higher living standards: the available food, jobs, houses and social services are shared among fewer people.
3. Less environmental degradation: reduced deforestation, soil erosion, pollution and overcrowding, keeping the environment healthier.
4. Lower unemployment and less congestion: fewer people competing for jobs, and little overcrowding, slums or traffic pressure in settlements.

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Relative contributions of roads and railways to national development (example: Nigeria)

Contributions of roads

• Flexibility and wide coverage: roads reach nearly every town and village, providing door-to-door movement of people and goods and linking farms to markets.
• Movement of perishable and short-distance goods: roads carry foodstuffs, passengers and light freight quickly over short and medium distances.
• Employment and rural development: road transport supports drivers, mechanics and traders, and opens up remote areas for farming, settlement and trade.
• Feeder function: roads act as feeders that connect railways, ports and airports, integrating the whole transport network.

Contributions of railways

• Bulky and heavy haulage: railways carry heavy, bulky goods such as minerals (coal, tin), petroleum products, cash crops and cement cheaply over long distances.
• Low cost per unit over long distance: rail freight is cheaper for large volumes, aiding industry and export trade.
• Opening up the interior: the lines from Lagos and Port Harcourt to the north opened the interior to commercial agriculture and mining and helped develop towns along the routes.
• Mass movement of people in a safe, relatively reliable manner, reducing pressure on roads.

Comparison/conclusion

Roads are more flexible, more widespread and better for short-distance and perishable traffic, but they are costlier per tonne for bulk goods and prone to congestion and accidents. Railways are cheaper and more efficient for heavy, bulky, long-distance traffic but are fixed in route and limited in coverage. The two are therefore complementary: an efficient national economy needs roads as feeders and for local distribution and railways for bulk long-haul movement, together promoting trade, industry, employment and national integration.

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(a) Outline map of Nigeria showing internal (domestic) trade

A drawn outline map of Nigeria is required. On it, locate and name the source and destination of two major internal-trade items, join each source to its destination with an arrow showing the direction of movement, and name one important town in each area. Suitable examples:

• Foodstuffs/grains (millet, beans, cattle): source area the far North (Kano), moving southward to the destination market of Lagos/Onitsha in the south. Arrow points from north to south. Towns: Kano (source), Lagos (destination).
• Palm oil and kola/timber (or petroleum products): source area the South (Aba/Port Harcourt), moving northward to Kaduna/Kano. Arrow points from south to north. Towns: Port Harcourt (source), Kaduna (destination).

(Other acceptable items: yam/cassava from the middle belt to the cities, salt/imported goods from the coast inland, cement, fish from the coast to the interior.)

(b) Four factors that have favoured the development of internal trade in Nigeria

1. Regional differences in products: the north produces grains, cattle and groundnuts while the south produces oil palm, yam, kola and petroleum, so surpluses are exchanged between regions.
2. Improved transport network: the spread of roads, railways and waterways links producing and consuming areas.
3. Large population and big urban markets: a large home population and growing cities create strong demand for goods.
4. A common currency and a single national market: the same currency, common language of trade and absence of internal customs barriers ease exchange.

(Also: presence of periodic markets and trading networks, and government encouragement/peace and stability.)

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(a) Deforestation

Deforestation is the large-scale clearing or removal of forests and trees from an area, usually without replanting, so that the land is put to other uses or left bare. It is caused by activities such as lumbering (logging), the clearing of land for farming and grazing, bush burning, fuel-wood collection, road building and the growth of settlements. Its effects are largely harmful: it exposes the soil to erosion and leaching, reduces soil fertility, lowers rainfall and destroys the water balance, causes loss of wildlife and biodiversity, and increases carbon dioxide in the air, contributing to global warming. It may also lead to desertification at forest margins. Deforestation can be controlled through afforestation and reforestation, control of bush burning, provision of alternative fuels and enforcement of forestry laws.

(b) Drought

Drought is a prolonged period of abnormally low or no rainfall, during which the water supply falls far below normal for a region, leading to acute shortage of water for plants, animals and people. It is caused by failure or lateness of the rains, persistent dry winds, deforestation and the general drying/advance of desert conditions. Its effects include crop failure and famine, death of livestock, drying up of rivers, streams and wells, migration of people and animals (environmental refugees), and the spread of desertification, as experienced in the Sahel region of West Africa. Its effects may be reduced by irrigation, water conservation and storage (dams), drought-resistant crops, afforestation and shelter belts, and early-warning and relief schemes.

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(a) Meaning of manufacturing industry

A manufacturing industry is an economic activity concerned with the processing or transformation of raw materials or semi-finished goods into finished or more useful (higher-value) products for consumption, using labour, machinery and power, for example turning cotton into textiles or crude oil into refined products. It belongs to the secondary sector of the economy.

(b) Characteristic features of manufacturing industries in Tropical African countries

1. They are mostly light and small-scale industries based on processing local raw materials (food, textiles, soap, beverages).
2. They are few, poorly developed and concentrated in a few large towns and ports (for example Lagos, Nairobi).
3. They rely heavily on imported machinery, spare parts and technical skill, and often on foreign capital.
4. They suffer from inadequate power supply, capital and skilled labour, so they operate below capacity.
5. They produce mainly for the home/local market and add little value, since most raw materials are still exported unprocessed.

(c) Four reasons why countries embark on industrialization

1. To create employment and reduce unemployment.
2. To add value to local raw materials and diversify the economy away from dependence on primary exports.
3. To earn and save foreign exchange by producing goods for export and reducing imports (import substitution).
4. To raise national income and living standards and provide manufactured goods for the population.

(Also: to encourage the growth of towns and infrastructure and to promote technological advancement.)

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(a) Distinction between an ecosystem and a food chain

An ecosystem is a natural unit made up of all the living organisms (biotic components) of an area together with the non-living environment (abiotic components) such as soil, water, air, sunlight and climate, and the interactions and energy flow between them (for example a pond, forest or grassland).

A food chain is much narrower: it is a single line of feeding relationships showing the transfer of energy and nutrients from one organism to the next as one feeds on another, for example: grass \(\rightarrow\) grasshopper \(\rightarrow\) lizard \(\rightarrow\) hawk. A food chain is therefore only one part of the wider ecosystem.

(b) Interdependence of the biotic and abiotic components

• Green plants (producers) depend on abiotic factors, using sunlight, carbon dioxide, water and soil nutrients to manufacture food through photosynthesis.
• Animals (consumers) depend on plants and on other animals for food, and on the abiotic environment for oxygen, water and shelter.
• Decomposers (bacteria and fungi) break down dead plants and animals, returning mineral nutrients to the soil, water and air, which the plants then reuse; this recycles nutrients.
• In turn the biotic components affect the abiotic environment: plants add oxygen and humus, give shade and reduce erosion, while animal respiration returns carbon dioxide.
• Thus a change in one component (for example loss of vegetation or reduced rainfall) upsets the others, showing that biotic and abiotic parts form a single, balanced, interdependent system through cycles of energy and matter.

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(a) Formation of the two features

(i) River capture (river piracy)

• Two rivers flow in roughly parallel valleys, but one (the captor) has a steeper gradient and greater erosive power than its weaker neighbour (the captured/victim).
• The more powerful stream cuts headward (backward) erosion up its valley faster.
• In time its head reaches and taps the channel of the weaker river, diverting the upper part of the victim's water into itself.
• The point of diversion is the elbow of capture; below it the now-dry, water-deprived section of the victim's valley is the wind gap, and the beheaded lower stream is the misfit stream.

Diagram required: two parallel rivers with the captor cutting back at right angles into the victim, marked with the elbow of capture, wind gap and misfit stream.

(ii) Waterfall

• A waterfall forms where a river flows over a band of hard (resistant) rock lying over softer rock, or over an edge such as a fault scarp or a plateau.
• The soft rock downstream is worn away faster than the hard rock, creating a vertical step over which the water plunges.
• At the foot the falling water and load erode a deep plunge pool, and undercut the soft rock, leaving the hard cap-rock overhanging.
• The overhang eventually collapses, and by repetition the fall retreats upstream, leaving a steep-sided gorge below it.

Diagram required: cross-section showing hard rock over soft rock, the vertical fall, plunge pool, overhang and receding gorge.

(b) Usefulness of each feature to man

• River capture: the diverted, increased volume of water in the captor river provides a larger, more reliable supply for water supply, irrigation and navigation, and the wind gap can serve as a routeway for roads and railways.
• Waterfall: the fall of water is harnessed for the generation of hydro-electric power and also serves as a scenic attraction for tourism/recreation.

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Differences between the Equatorial and Tropical Continental climates

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Answer Details

(a) Meaning of migration and three forms it may take

Migration is the movement of people from one place (their place of origin) to another (their destination) with the intention of settling there, either permanently or for a fairly long period. Three forms it may take are:

1. Internal migration: movement within the same country, for example rural-urban migration (from villages to towns) or rural-rural migration.
2. International migration: movement across national boundaries from one country to another (emigration and immigration).
3. Seasonal/temporary migration: movement for only part of the year or a limited period, such as nomadic herders or migrant labourers returning home after the season.

(Others: permanent migration, voluntary and forced migration.)

(b) Four factors responsible for migration

1. Economic factors: search for jobs, higher wages and better economic opportunities (towns pull, rural poverty pushes).
2. Social factors: desire for better education, health and social amenities available elsewhere.
3. Political factors: wars, insecurity, persecution and bad governance drive people away.
4. Physical/environmental factors: natural disasters such as drought, flood, famine and infertile land force movement.

(c) Advantages and disadvantages of rural-urban migration

Three advantages

1. Provides abundant cheap labour for urban industries and services.
2. Migrants send home remittances that raise rural incomes and living standards.
3. Relieves population pressure on rural land, and migrants acquire new skills.

Three disadvantages

1. Creates overcrowding, slums, unemployment and pressure on urban amenities in the towns.
2. Leads to shortage of farm labour and neglect of agriculture in the villages.
3. Encourages social vices and crime in towns and leaves an ageing rural population.