WAEC SSCE - Geography - 1998

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Temperate grasslands, also known as prairies or steppes, are generally important for animal grazing. These vast areas of open grasslands are well-suited for grazing animals such as bison, deer, and antelope, as well as domesticated animals like cattle and sheep. The grasses found in temperate grasslands are typically nutrient-rich and able to support large numbers of grazing animals. In addition, the grasses are adapted to withstand the dry conditions and occasional fires that are common in these regions. The grazing of animals in temperate grasslands has a number of important benefits. First, it provides a source of food for both wild and domesticated animals, which is important for maintaining healthy populations. Second, it can help to maintain the grasslands themselves, by preventing the buildup of dead plant material and promoting the growth of new grasses. Finally, the grazing of animals can also be an important economic activity, providing income for farmers and ranchers who raise livestock on these lands.

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The savanna lands of East Africa are best known for their wildlife. These vast grasslands are home to a diverse array of animal species such as lions, zebras, giraffes, elephants, and many more. Tourists from all over the world visit East Africa to experience the natural beauty of the savanna and to see the wildlife in their natural habitat. The Maasai Mara National Reserve in Kenya and the Serengeti National Park in Tanzania are some of the most popular tourist destinations in East Africa due to their abundant wildlife. The savanna lands also provide grazing areas for cattle and other domestic animals, which are important to the local economy.

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The greatest problem in the use of solar energy is its unreliability from day to day and season to season. Solar panels only generate electricity when exposed to sunlight, which means that energy production varies depending on factors such as weather conditions, time of day, and location. Cloudy or rainy days, as well as winter months with shorter daylight hours, can significantly reduce the amount of energy generated by solar panels. This unpredictability makes it difficult to rely solely on solar energy as a primary source of power. To address this issue, solar power systems often include backup power sources, such as batteries or generators, which add to the overall cost of installation and maintenance. Nonetheless, with advances in technology and the increasing demand for renewable energy, solar energy is becoming more efficient and cost-effective over time.

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The vegetation belt associated with valuable hard wood is the tropical rainforest. The tropical rainforest is characterized by dense vegetation, high rainfall, and high humidity. This biome has a great diversity of species, including many types of hardwood trees that are highly valued for their strength, durability, and beauty. Some examples of valuable hardwoods found in tropical rainforests include teak, mahogany, and rosewood. Due to deforestation and other factors, many tropical rainforests are under threat, and efforts are being made to protect these valuable ecosystems.

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The southernmost latitude in Africa is approximately 34°S. This is the latitude of Cape Agulhas, which is located at the southernmost tip of Africa where the Atlantic and Indian Oceans meet. Cape Agulhas is located in South Africa, and it is considered to be the southernmost point of the African continent. Therefore, the correct answer is option (C) 350S.

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The mode of transportation in Nigeria that is limited by weather is air transportation. This is because airplanes rely heavily on clear weather to operate safely. When there is bad weather such as heavy rain, thunderstorms, fog, or strong winds, it can be difficult or even impossible for planes to take off, land, or fly safely. As a result, flights may be delayed, diverted or cancelled due to poor weather conditions. Therefore, air transportation is the mode of transportation in Nigeria that is most affected by adverse weather conditions.

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Air transportation has a low patronage because it is costly. Air travel is generally more expensive than other forms of transportation such as road or rail. This is because the cost of operating and maintaining aircraft is high, and these costs are often passed on to passengers in the form of high ticket prices. As a result, many people cannot afford to travel by air, and air transportation tends to be used mainly by people who can afford it, such as business travelers or wealthy individuals. This limits the overall demand for air travel and contributes to its relatively low patronage compared to other forms of transportation.

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The figure 1 is a pie chart. A pie chart is a circular statistical graph that is divided into slices to illustrate numerical proportion. Each slice represents a proportionate part of the whole, and the total of all slices should add up to 100%. In figure 1, each slice represents a percentage or proportion of the whole, making it a pie chart.

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One danger about the present rate of increase in world population is an acute food shortage. As the population increases, the demand for food also increases, and if the supply of food does not increase at a corresponding rate, it could lead to a shortage of food. This could result in malnutrition and starvation, especially in developing countries where the majority of the population live below the poverty line. The increase in world population also puts pressure on the available land for agriculture, leading to deforestation and environmental degradation. Therefore, it is essential to control the rate of population growth to ensure that there is enough food to go around, and that the environment is not further degraded.

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One important consequence of Nigeria's location between latitudes 40 and 140 north of the Equator is that she enjoys a hot, wet, tropical climate. The sun's rays are more direct in the tropical region, which makes the temperature high. The hot temperature, combined with high humidity, leads to the formation of clouds that result in heavy rainfall. Therefore, Nigeria's location in the tropical region makes it have a climate that is hot and wet with a lot of rainfall. This climate is good for the growth of vegetation, which makes Nigeria have a luxuriant vegetation cover.

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A rural settlement is a settlement classified by its function. A settlement is a place where people live and carry out various activities, such as farming, trading, or manufacturing. The function of a settlement refers to the main economic activity that takes place within it. In the case of rural settlements, the main economic activity is usually agriculture, which includes activities such as farming, animal husbandry, and fishing. Rural settlements are typically located in rural areas, away from large urban centers. In contrast, urban settlements are classified by their function as well, but their main economic activities are usually trade, commerce, and manufacturing. Urban settlements are typically located in urban areas, where there is a higher concentration of people, infrastructure, and economic activities. Therefore, the main classification of a rural settlement is by its function, which is agriculture, while the main classification of an urban settlement is by its function, which is trade, commerce, and manufacturing.

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The data shown in Figure 1 can be represented in various ways, but the most appropriate ways are a proportional circle or a chloropleth map. A proportional circle graph shows the data as circles with areas proportional to the values they represent. In this case, each circle would represent a country or group of countries and the size of the circle would represent the percentage of the world export commodity they contribute. This type of graph is effective for comparing the contributions of different countries or regions. On the other hand, a chloropleth map shows the data using color-coded regions or countries. Each region is shaded according to the value of the data it represents. In this case, the map would show different shades of color to represent the percentage of the world export commodity contributed by each country or group of countries. Chloropleth maps are useful for displaying data that vary by geographic location.

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Famine is a severe shortage of food in a region, leading to widespread hunger, malnutrition, and death. In Africa, several factors contribute to the occurrence of famine. However, one of the options listed above does not cause famine, and that is unstable prices paid to farmers for their products. Unreliable rainfall is a significant cause of famine in Africa. Many African countries rely on rain-fed agriculture, and erratic rainfall patterns due to climate change or natural variability can lead to crop failures, reduced yields, and food shortages. Civil strife and unrest can also cause famine by disrupting agriculture, trade, and food distribution systems. Conflict can lead to the displacement of people, destruction of crops, and disruption of markets, making it difficult for people to access food. Ravages of crops by pests can cause famine by destroying crops and reducing yields. Insect pests and diseases can lead to significant crop losses, leaving farmers with little or no harvest to sell or consume. Infertile soil and soil erosion can also contribute to famine by reducing agricultural productivity. Poor soil quality and soil erosion can lead to reduced crop yields, leaving farmers with less food to sell or consume. In conclusion, while all the options listed above can contribute to food insecurity, unstable prices paid to farmers for their products is not a direct cause of famine. Nonetheless, achieving stable prices can help to promote food security and support the livelihoods of farmers.

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Coal and mineral oil are usually found embedded in sedimentary rocks. Sedimentary rocks are formed by the accumulation of sediment and organic matter over time, which is then compacted and cemented together. Coal is formed from the remains of plants that were buried in sedimentary basins and subjected to high pressure and heat over millions of years. Mineral oil, also known as petroleum, is formed from the remains of microscopic marine plants and animals that were buried in sedimentary basins and subjected to high pressure and heat over millions of years. Sedimentary rocks are the most common type of rock on the Earth's surface, and they contain a wide variety of minerals, fossils, and other organic matter. They are typically composed of layers or strata, with each layer representing a different period of deposition or environmental conditions. Coal and mineral oil are found in specific types of sedimentary rocks, such as shale and sandstone, which have the necessary characteristics to trap and preserve organic matter. Therefore, coal and mineral oil are usually found embedded in sedimentary rocks, which are formed by the accumulation of sediment and organic matter over time.

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Among the options provided, "Lack of goods to carry along the routes" does not explain the poor development of inland waterways in Africa. The development of inland waterways in Africa has been hindered by several factors. These include the presence of rapids and waterfalls, obstruction by floating vegetation, high seasonality of the rivers, and crossing of many political boundaries by the rivers. Rapids and waterfalls make it difficult to navigate through the rivers, which can limit transportation and trade along the waterways. Floating vegetation can also obstruct the waterways, making them impassable for boats and ships. The high seasonality of the rivers can also hinder the development of inland waterways. Some rivers in Africa are dry for most of the year, making them unsuitable for navigation and transportation. Crossing many political boundaries by the rivers can also hinder the development of inland waterways in Africa. Different countries may have different regulations, making it difficult to develop and maintain a continuous waterway that crosses multiple borders. In summary, the poor development of inland waterways in Africa is due to several factors, including rapids, waterfalls, floating vegetation, seasonality, and political boundaries. However, the lack of goods to carry along the routes is not a direct cause of poor development of inland waterways.

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Trade among West African countries is less developed mainly because they were ruled by different colonial powers, which created a barrier to communication. The arbitrary borders created by European colonizers divided ethnic groups and disrupted traditional trade routes. This has made it difficult for countries to communicate and develop trade relations with each other. Additionally, some of the countries have different languages, currencies, and legal systems, which further complicates trade. The lack of infrastructure, such as international railway lines, also makes it difficult to transport goods across borders. Although the other options may have some impact, the historical and structural barriers created by colonialism have had the most significant impact on hindering trade development among West African countries.

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From the given figure 1, we can see that the crude oil export is represented by the blue-colored bar. To calculate the percentage of the world export commodities represented by crude oil, we need to find the total export value of all the commodities and then find the proportion of the export value represented by crude oil. The total export value of all commodities is the sum of the values of all the bars in the graph. Adding up the values of all the bars, we get: 20.8 + 18.7 + 11.2 + 7.8 + 6.3 + 5.3 + 3.3 + 2.6 + 2.3 + 1.7 = 80.0 Therefore, the total export value of all commodities is 80.0. Now, to find the percentage of the world export commodities represented by crude oil, we need to divide the value of crude oil export (18.7) by the total export value of all commodities (80.0) and then multiply the result by 100. Percentage of crude oil export = (18.7/80.0) x 100 = 23.375 Therefore, the percentage of the world export commodities represented by crude oil is approximately 23.4%. The closest option is 23.74%, which is the correct answer.

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Currently, most manufacturing industries in Nigeria produce consumer goods. These include food and beverages, textiles and clothing, household items, and pharmaceuticals. However, some industries also produce capital goods such as machinery and equipment. While some Nigerian manufacturing companies export their products to other countries, it is not true that large quantities of their products are exported. Nigeria has a significant trade deficit, meaning that the country imports more than it exports. Many Nigerian manufacturing industries rely heavily on imported raw materials due to inadequate local production. This has been a significant challenge to the growth of the sector. However, there are efforts by the government and private sector to promote local sourcing of raw materials. Most Nigerian manufacturing industries were established after the colonial era, with a significant number being set up in the 1970s and 1980s. They are mainly located in the southern and southwestern regions of the country, with some in the northern and eastern regions as well. In conclusion, the correct option is (a) most of them produce consumer goods.

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Irrigation farming is highly practiced in Northern Nigeria because of inadequate rainfall and the presence of many rivers. Northern Nigeria is located in the Sahel region, which is characterized by low and erratic rainfall. Irrigation is a method of watering crops artificially by diverting water from rivers, lakes, or underground sources to the fields. The presence of many rivers such as River Niger, River Benue, and their tributaries provides a reliable source of water for irrigation farming. Additionally, irrigation allows farmers to grow crops throughout the year, regardless of the season. Therefore, the correct answer is option (C) inadequate rainfall and presence of many rivers.

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The settlement type that is strongly associated with tourism is the holiday resort. A holiday resort is a place where people go for leisure activities such as swimming, sunbathing, and sightseeing. Resorts are usually located in scenic areas with natural attractions such as beaches, mountains, or wildlife reserves. They often have amenities such as restaurants, hotels, and recreational facilities like spas or golf courses. Tourists are attracted to holiday resorts because of the opportunity to relax, enjoy the natural beauty of the area, and engage in leisure activities. Therefore, the correct option is (D) Holiday resort.

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(a) Explanation of atmospheric resources

Atmospheric resources are the useful materials and forms of energy provided by the atmosphere (the envelope of air surrounding the earth) which man can harness for his benefit. They include the gases of the air (oxygen, carbon dioxide, nitrogen), sunlight (solar energy), wind and precipitation (rainfall/moisture). They are largely free, renewable and available everywhere.

(b) Six uses of atmospheric resources (with examples)

• Sunlight for photosynthesis and solar power: Solar energy enables green plants to make food and is trapped by solar panels to generate electricity and to dry crops and clothes.
• Oxygen for respiration: Humans and animals breathe in oxygen to stay alive, and it is needed for combustion (burning of fuels).
• Carbon dioxide for plant growth: Green plants use carbon dioxide from the air during photosynthesis to manufacture their food.
• Nitrogen for soil fertility and industry: Nitrogen is fixed into the soil by lightning and bacteria to enrich it, and is used in making fertilizers and other chemicals.
• Wind as a source of power and transport: Wind drives windmills and wind turbines to pump water and generate electricity, and moves sailing boats; it also aids pollination and seed dispersal.
• Rainfall / moisture (water supply): Precipitation supplies water for drinking, farming (rain-fed agriculture and irrigation), rivers and hydro-electric power generation.

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(a)(i) Annual temperature range

Range = highest − lowest = \(23^{\circ}\text{C} - 12^{\circ}\text{C} = 11^{\circ}\text{C}\).

(a)(ii) Mean monthly temperature

Sum of temperatures \(= 23+22+20+17+15+12+13+16+17+19+20+22 = 216\). \[\text{Mean} = \frac{216}{12} = 18^{\circ}\text{C}.\]

(a)(iii) Total annual rainfall

\(200+180+120+45+8+0+0+0+5+35+100+160 = 853\ \text{mm}\).

(b)(i) Climatic region

The station lies in a Tropical wet-and-dry (Tropical Continental / Savanna) region.

(b)(ii) Two supporting reasons

• There is a marked single rainy season in the high-sun months (November to March, peaking at 200 mm in January) and a pronounced dry season with three completely rainless months (June, July, August), which is the classic savanna wet-and-dry rhythm.
• Temperatures are warm throughout the year (mean 18°C, all months above 12°C) with a fairly small range (11°C) and a high annual rainfall total (853 mm), all typical of the tropical continental belt.

(c) Hemisphere

The highest temperatures occur in December to February and the lowest in June to July, so the warm summer season falls in December to February. This places the station in the Southern Hemisphere.

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(a) Ocean currents along the coast of Africa

• Canary Current (cold) - north-west coast
• Benguela Current (cold) - south-west coast
• Guinea Current (warm) - Gulf of Guinea, West Africa
• Mozambique/Agulhas Current (warm) - south-east coast

(Other acceptable currents: the cold Somali Current and the warm Somali Current during the monsoon reversal.)

(b) Effects of the two types of currents on the climate of Africa

Warm currents (e.g. the Mozambique/Agulhas Current):

• Raise the temperature of the coastal areas they wash, giving warmer conditions.
• Warm the air above them so it can hold more moisture, bringing rainfall to the adjacent coast (the south-east coast of Africa is well watered).

Cold currents (e.g. the Benguela and Canary Currents):

• Lower the temperature of the coastal areas, giving cool conditions.
• Cool the air above them so little moisture is released; this produces dryness and coastal deserts (the Namib Desert beside the Benguela Current and the aridity of the north-west coast beside the Canary Current). Cold currents also cause coastal fogs.

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(a) Characteristics of manufacturing industries in Tropical Africa

• They are dominated by light industries such as food processing, textiles, soap and beverage production rather than heavy engineering.
• Most are primary/agro-based processing industries that add value to raw agricultural and mineral products (e.g. palm oil milling, cotton ginning).
• Industries are few, small-scale and unevenly distributed, concentrated in a few large towns, ports and capital cities.
• They rely heavily on imported machinery, spare parts and skilled expertise from outside the region.
• They are largely import-substitution industries producing consumer goods for the local market.

(b) Ways manufacturing industries contribute to economic development

1. Employment generation: they create jobs for skilled and unskilled labour, reducing unemployment.
2. Income and revenue: they raise workers' incomes and provide government revenue through taxes and duties.
3. Foreign exchange: exported manufactured goods earn foreign currency, while local production reduces import bills.
4. Value addition: they process raw materials into finished goods, raising the value of local resources.
5. Infrastructural growth: they stimulate development of roads, power and communication, and encourage growth of allied industries.

(c) Problems facing industrial development

1. Shortage of capital for investment and expansion.
2. Inadequate power supply and poor infrastructure (roads, water, communication).
3. Shortage of skilled manpower and low level of technology.
4. Small home market caused by low purchasing power and poverty.
5. Competition from cheaper, better-quality imported goods, and political instability.

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(a) Four ways in which urban settlements differ from one another

• Function: Settlements differ by their dominant role, for example industrial towns (Kano), administrative/capital cities (Abuja), commercial towns (Lagos), mining towns (Enugu) and port towns (Port Harcourt).
• Size of population: Some are large metropolitan cities of several million (Lagos) while others are small towns of a few thousand.
• Age and origin: Some are ancient, indigenous towns (Ibadan, Benin) while others are modern planned cities (Abuja).
• Site and situation/layout: Some have a planned grid layout with good facilities; others have grown haphazardly with a mixture of unplanned quarters.
• Level of development/infrastructure: Cities differ in the quality of roads, electricity, water and services they provide.

(b) Four ways in which rural settlements depend on urban settlements

• Market for produce: Rural areas sell their farm produce (food crops, livestock) to the urban centres.
• Supply of manufactured goods: Villagers obtain clothing, tools, fertilisers, machinery and other processed goods from the towns.
• Higher social services: Rural dwellers travel to towns for secondary/tertiary education, specialist hospitals, banking and administration.
• Employment and income: Urban centres provide jobs for rural migrants who often send money home (remittances).
• Processing and storage: Farm produce is processed and stored in urban factories and warehouses before final sale.

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(a) Factors which favour lumbering in Nigeria

1. Extensive tropical rain forest in the south with valuable hardwood trees such as mahogany, iroko, obeche and opepe.
2. Heavy rainfall and high temperatures that encourage rapid and continuous tree growth.
3. Rivers and roads that provide means of floating and transporting logs to sawmills and markets.

(b) Contributions of lumbering to the economy

1. Provides timber and wood for building, furniture and construction.
2. Supplies raw materials to saw-milling, plywood, paper and furniture industries.
3. Earns foreign exchange through the export of timber and wood products.
4. Provides employment and income for loggers, sawmill workers and traders.

(c) Problems facing lumbering

1. Mixed forests with valuable trees scattered among many worthless ones, raising the cost of extraction.
2. Dense undergrowth and difficult terrain that make felling and haulage hard.
3. Poor transport facilities from forest to market.
4. Shortage of capital and modern machinery for large-scale logging.
5. Deforestation and slow replacement of trees, plus pests and forest fires, threaten the resource.

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India has one of the most uneven population distributions in the world. Dense clustering occurs in the Ganges plain and along the coasts, while the mountains, deserts and dense forests are sparsely settled.

(a) Factors responsible for the distribution

• Relief: The extensive, low-lying and level Ganges (Indo-Gangetic) plain is easy to cultivate and build on, attracting dense settlement, while the high Himalayas and the Deccan uplands repel population.
• Fertile soils: The rich alluvial soils of the river plains support intensive farming and therefore large rural populations.
• Water supply and rainfall: Areas with reliable monsoon rainfall and river water (Ganges, Brahmaputra) are densely peopled, whereas the arid Thar Desert of the north-west is thinly settled.
• Industrial and commercial development: Cities such as Mumbai, Kolkata, Delhi and Chennai draw people through jobs in industry, trade and services.
• Transport and coastal advantage: Ports and good road/rail networks concentrate people along the coasts and river valleys.
• History and religion: Long-settled river valleys and holy cities along the Ganges have accumulated population over centuries.

(b) Advantages of dense population

• Large supply of cheap labour for agriculture and industry.
• Big internal market that encourages manufacturing and trade.
• Availability of skilled manpower and professionals for development.
• Cheaper provision of social services (schools, hospitals, roads) per person where people are concentrated.
• Strong defence and political influence from a large population.

(c) Problems of dense population

• Pressure on farmland leading to land fragmentation and low output per person.
• Overcrowding, slums and housing shortages in the big cities.
• Unemployment and under-employment.
• Strain on food supply, water, schools, hospitals and other social amenities.
• Environmental problems such as pollution, deforestation and poor sanitation.
• Widening poverty and high rural-urban migration.

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(a) Ways highlands promote economic development in the North Central Highlands (Jos Plateau region)

1. Mining: the highlands contain tin, columbite and other solid minerals whose extraction earns revenue and provides employment.
2. Cool, healthy climate: the higher altitude gives lower temperatures that attract settlement, tourism and resorts (e.g. Jos).
3. Temperate crop farming: the cool climate favours market gardening of vegetables, potatoes and fruits (Irish potatoes, cabbage).
4. Hydro-electric power and water supply: highland rivers provide sites for dams, water reservoirs and power generation.
5. Tourism and grazing: scenic landscapes attract tourists, while highland grasslands support livestock rearing.

(b) Characteristics of highlands that hinder development

1. Steep slopes and rugged relief make construction of roads, railways and buildings difficult and costly.
2. Thin, poor and easily eroded soils on the slopes limit large-scale crop farming.
3. Difficult accessibility isolates settlements and raises transport costs.
4. Rapids and waterfalls on highland rivers interrupt navigation.
5. Cold and misty weather at times, and the danger of soil erosion and landslides, discourage some activities.

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The stem's "sorest" region is read as the forest region. The table below distinguishes agriculture in the forest and savanna regions of Nigeria.

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(a) Shape of the earth

The earth is spherical (round) in shape, but not a perfect sphere. It is slightly flattened at the two poles and bulges at the equator; this true shape is described as an oblate spheroid (geoid).

(b) Four proofs that the earth is spherical

• Circumnavigation: Travellers and ships (from Magellan's voyage onward) who set out in one direction and keep going eventually return to their starting point without turning back, which is only possible on a round body. (Diagram: an arrow going right round a circle back to the start.)
• Ship on the horizon: As a ship approaches from over the sea, the top of its mast is seen first and then the hull; as it sails away the hull disappears before the mast. This is caused by the curvature of the earth's surface. (Diagram: ships at different points on a curved sea surface.)
• Circular shadow during a lunar eclipse: The shadow the earth casts on the moon during a lunar eclipse is always circular, and only a sphere casts a circular shadow in every position. (Diagram: sun, round earth and its round shadow falling on the moon.)
• The widening horizon / view from a height: The higher an observer climbs (a hill, an aircraft), the wider the circular horizon they can see, which shows the surface is curved. Photographs taken from space and aircraft also show the earth as a sphere. (Diagram: an observer at increasing heights with an expanding circular horizon.)

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(a) Why irrigation agriculture is more important in the Nile Basin than in the Niger Basin

1. Aridity of the surrounding land: the Nile flows through the Sahara and Egyptian desert where rainfall is almost nil, so crops depend entirely on irrigation, whereas the lower Niger Basin has enough rainfall for rain-fed farming.
2. Regular, predictable flood and flow: the Nile has a steady regime fed by equatorial and Ethiopian sources, and dams such as the Aswan give a controlled year-round water supply for irrigation.
3. Dense population and long history of irrigation: the Nile valley has ancient, well-developed irrigation systems and canals supporting a large farming population that has always relied on the river.

(b)(i) Other uses of the River Nile

1. Generation of hydro-electric power (Aswan High Dam).
2. Inland water transport and trade.
3. Fishing for food and income.
4. Domestic and industrial water supply, and tourism.

(b)(ii) Characteristics of the river which limit its usefulness

1. Cataracts and rapids interrupt navigation along parts of its course.
2. Seasonal variation in flow with periods of low water.
3. Heavy silting and sedimentation that clogs canals and reservoirs.
4. Evaporation losses and swampy sections (the Sudd) that waste water and hinder movement.

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(a) Four processes of soil formation

• Weathering of parent rock: The breaking down of the underlying rock by physical, chemical and biological weathering produces the mineral particles that form the basis of the soil.
• Addition of organic matter (humification): Dead plants and animals decay and are broken down by micro-organisms to form humus, which is added to the mineral matter and enriches the soil.
• Leaching and eluviation: Rainwater passing down through the soil dissolves and washes soluble minerals and fine material from the upper layers down to the lower layers, helping to develop distinct soil horizons.
• Action of living organisms and climate: Burrowing animals (earthworms, termites), plant roots, and the effects of temperature and rainfall mix the soil, aerate it and speed up the chemical changes that continue soil development over a long time.

(b) Four ways soil is important

• It is the medium for plant growth, supplying anchorage, water and nutrients, and so is the basis of agriculture and food production.
• It provides pasture and grazing land for the rearing of animals.
• It supplies raw materials such as clay for pottery, bricks and building, and holds ground water.
• It supports forests and natural vegetation that provide timber and other products, and it is home to countless organisms that keep the ecosystem going.

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Characteristics and mode of formation (any two)

(a) Yardang

Characteristics: A yardang is a long, narrow, streamlined ridge of hard rock separated by grooves or troughs, found in hot deserts. The ridges run parallel to the direction of the prevailing wind and have a steep, blunt front facing the wind and a tapering tail. They may be several metres high.

Mode of formation: Yardangs are formed by wind erosion (abrasion and deflation). In a desert where soft and hard rocks lie side by side in bands parallel to the wind, the wind, armed with sand, wears away the softer bands into grooves, leaving the harder bands standing up as ridges. Abrasion is strongest near the ground, undercutting the ridges. (Diagram: parallel ridges and grooves aligned with the wind arrow.)

(b) Crater

Characteristics: A crater is a roughly circular, funnel-shaped or basin-shaped depression at the top (summit) of a volcano, surrounding the vent. It has steep inner walls and may hold water to form a crater lake. A very large crater formed by collapse or violent explosion is called a caldera.

Mode of formation: A crater is formed during volcanic eruption. As lava, ash and gases are blown out through the vent, material piles up around the opening, and the funnel-shaped mouth left at the top of the cone is the crater. Collapse of the summit into the emptied magma chamber, or a violent explosion, may enlarge it into a caldera. (Diagram: a volcanic cone with a bowl-shaped crater and central vent.)

(c) Block mountain (horst)

Characteristics: A block mountain is an upstanding block of land with steep fault sides and a fairly level top, bounded by roughly parallel faults. Examples include the Ruwenzori and the Vosges.

Mode of formation: It is formed by faulting. When the crust is subjected to tension or compression, cracks (faults) develop, and a middle block is left standing higher either because it is uplifted or because the blocks on either side subside (sink). The raised block is the block mountain (horst); a sunken block between faults gives a rift valley. (Diagram: a central up-thrown block standing above two down-thrown blocks bounded by faults.)

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Explanatory notes (any two)

(a) Flood plain

A flood plain is the flat, low-lying land bordering a river on either side in its lower course, which is regularly covered with water when the river overflows its banks during floods. It is built up of fine sediment (alluvium) dropped by the river each time it floods, so it is very fertile. It is formed by the deposition of alluvium and the lateral (sideways) swinging of meanders, which widens the valley floor. Features found on it include levees, meanders, ox-bow lakes and marshes. Flood plains are valuable for farming (e.g. rice) and settlement. (Diagram: a river winding across a broad flat plain with levees and an ox-bow lake.)

(b) Hydrological cycle

The hydrological (water) cycle is the continuous circulation of water between the sea, the atmosphere and the land. Water evaporates from oceans, seas, rivers and lakes (and transpires from plants) to form water vapour. The vapour rises, cools and condenses to form clouds. The moisture falls back to the earth as precipitation (rain, snow, hail). Some water flows over the surface as run-off into rivers that return it to the sea, some sinks into the ground as infiltration/ground water, and the cycle repeats endlessly. The total amount of water on earth stays the same. (Diagram: sea, arrows for evaporation up, condensation to cloud, precipitation, run-off and infiltration back to sea.)

(c) River erosion

River erosion is the wearing away and removal of the bed and banks of a river channel by the moving water and its load. It takes place in four main ways: corrasion (abrasion) - the load rubs and grinds against the bed and banks; hydraulic action - the sheer force of moving water dislodges loose material; corrosion (solution) - the water dissolves soluble rocks such as limestone; and attrition - the load particles knock against one another and break into smaller pieces. Erosion may act vertically (deepening the valley, chiefly in the upper course) or laterally (widening it). It produces features such as V-shaped valleys, gorges, waterfalls, potholes and rapids. (Diagram: a V-shaped valley in the upper course with a waterfall.)

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(a) Map of Africa

On an outline map of Africa, locate and name:

• (i) Rivers: the Nile (north-east, flowing to the Mediterranean), the Volta (Ghana, flowing to the Gulf of Guinea) and the Niger (West Africa, flowing to the Gulf of Guinea).
• (ii) Deltas: an inland delta - the inland Niger delta in Mali; and a coastal delta - the Nile delta (or the Niger delta).
• (iii) The Akosombo Dam on the River Volta in Ghana.

(A neat labelled sketch map is required.)

(b) Uses of the Akosombo Dam

1. Generation of hydro-electric power for Ghana and neighbouring countries (and for the Volta aluminium smelter).
2. Creation of Lake Volta, used for inland water transport.
3. Irrigation of farmland and provision of water supply.
4. Fishing on Lake Volta, and tourism/recreation.

(c) Problems facing hydro-electric power generation in Africa

1. Seasonal variation in river flow reduces output in the dry season.
2. Shortage of capital to build and maintain large dams.
3. Silting of reservoirs, high cost of transmission, and low demand in some areas.

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(a) Factors responsible for low volume of trade between Nigeria and other African countries

1. Similarity of products: most African countries produce and export similar primary raw materials (cocoa, coffee, minerals, oil), so they compete rather than trade with one another.
2. Low level of industrialisation: few countries produce the manufactured goods others need, so demand is met from Europe, America and Asia instead.
3. Poor transport and communication links: road, rail and shipping connections between African states are weak, making inter-country movement of goods slow and costly.
4. Different currencies and trade barriers: varying currencies, high tariffs, import duties and border restrictions discourage cross-border trade.
5. Colonial trade orientation: economies were built to trade with former colonial powers rather than with neighbours, a pattern that still persists.

(b) Ways of increasing the volume of trade

1. Industrialisation and product diversification so countries produce different goods that others need.
2. Improving inter-state transport such as the Trans-African highways, rail links and shipping services.
3. Strengthening economic groupings like ECOWAS and the African Continental Free Trade Area to remove tariffs and barriers.
4. Introducing a common currency or convertible payment systems to ease transactions.
5. Establishing common markets and joint ventures, and improving communication and trade information among member states.

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None

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(a) Sketch map of Nigeria showing Rivers Kaduna, Cross and Ogun and their source areas

Key: ★ indicates the source area of each river. The rivers are shown by thick blue lines and labelled clearly.

(b) Characteristics of rivers in Nigeria

1. Many rivers have rapids and waterfalls, especially in their upper courses where they flow across highlands.
2. They have a seasonal regime: water level is high in the rainy season and low in the dry season.
3. Most rivers are short and swift-flowing, particularly those flowing from the eastern highlands to the coast.
4. Many have shallow channels and experience deposition, silting and the growth of water weeds in parts of their courses.

(c) Economic importance of rivers in Nigeria

1. They provide water for irrigation, especially for dry-season farming.
2. They are used for fishing and support fish processing and trade.
3. Navigable sections provide water transport for people and goods.
4. They provide sites for hydro-electric power generation, for example at Kainji, Jebba and Shiroro.

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(a) Map of Nigeria showing solid-mineral-mining towns and refinery towns

Key: ● Solid-mineral-mining town; ▲ Refinery town.

• Jos: tin and columbite
• Enugu: coal
• Itakpe: iron ore
• Refinery towns: Kaduna, Warri and Port Harcourt

(b) Contributions of solid minerals to the economy of Nigeria

1. They provide revenue to government through taxes, royalties, licence fees and export duties.
2. They earn foreign exchange when minerals are exported.
3. They provide employment and income for miners, transporters and workers in allied industries.
4. They supply raw materials to industries, for example iron ore for steel, limestone for cement and coal for industrial use.
5. They promote the development of roads, railways, electricity and other infrastructure in mining areas.
6. They encourage the growth of towns and trading activities around mining centres.

(c) Problems facing the mining of solid minerals in Nigeria

1. Inadequate capital for exploration and large-scale mechanised mining.
2. Low level of technology and shortage of modern mining equipment.
3. Inadequate skilled manpower, such as geologists, engineers and technicians.
4. Poor infrastructure, especially transport routes and electricity supply.
5. Illegal mining and illegal transactions in minerals.
6. Depletion or exhaustion of some mineral deposits.

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(a) Four ways air transportation differs from water transportation

(b) Three major contributions of transportation to national development

• It moves raw materials to industries and finished goods to markets, boosting industry and trade.
• It opens up remote areas, encouraging farming, mining and even settlement of new regions.
• It promotes national unity and administration by linking different parts of the country and easing movement of people.
• It creates employment and generates revenue for the government.

(c) Three problems of water transportation in Tropical Africa

• Many rivers are interrupted by rapids and waterfalls, making them non-navigable for long stretches.
• Seasonal variation in water level: rivers become too shallow in the dry season and flood in the wet season.
• Silting and floating vegetation (water hyacinth) block channels and harbours.
• Few natural deep harbours, and inadequate modern port facilities and dredging.