WAEC SSCE - Geography - 2009

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The answer is Nile. The Nile River is located in northeastern Africa and is generally regarded as the longest river in the world, with a length of approximately 6,650 kilometers (4,130 miles). It flows through eleven countries, including Uganda, Ethiopia, Sudan, and Egypt, before draining into the Mediterranean Sea. The Nile River is an important source of water for irrigation and agriculture, as well as transportation and fishing, and has played a significant role in the development of civilizations throughout history.

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The characteristic that is not applicable to sedimentary rocks is that they are crystalline. Sedimentary rocks are formed by the accumulation and consolidation of sediment or organic matter. They are typically deposited in layers or strata, and often contain fossils. Sedimentary rocks are usually porous, meaning they have many small spaces or holes where fluids, such as water or oil, can be stored. However, unlike igneous and metamorphic rocks, sedimentary rocks are not typically crystalline. Instead, they are made up of small mineral grains or organic material that have been compacted and cemented together over time.

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A great advantage of basin irrigation is that water is not wasted. Basin irrigation is a method of irrigation where a field is surrounded by earthen banks and divided into small basins. The basin is filled with water, and the water is allowed to infiltrate the soil to a certain depth. In basin irrigation, the amount of water applied is just enough to fill the basin, and it stays there until the plants absorb it or it evaporates. This ensures that the water is not wasted by flowing away or evaporating before it can be used by the crops. Another advantage of basin irrigation is that it is a simple and low-cost method of irrigation. It is suitable for small fields and can be easily constructed by farmers themselves. Basin irrigation also helps to reduce soil erosion and nutrient loss, and the basins can trap much alluvium to enrich the soil. In summary, the great advantage of basin irrigation is that water is not wasted, as the water stays in the basin until it is absorbed by the plants or evaporates. Additionally, basin irrigation is a simple, low-cost method that can help to reduce soil erosion and enrich the soil.

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A geyser is best described as a fountain of superheated water and steam that erupts from the ground periodically. It is a natural phenomenon that occurs when groundwater is heated by geothermal activity deep below the Earth's surface. As the water heats up, it expands and rises towards the surface. When the pressure builds up enough, the water and steam erupt in a powerful geyser. The eruption can last from a few seconds to several minutes, and the height of the water and steam can range from a few meters to over 90 meters. Geysers are found in areas of geothermal activity, such as Yellowstone National Park in the United States, Iceland, and New Zealand.

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A soil profile refers to the vertical section of the soil, from the surface to the underlying rock, that shows the different layers (horizons) of the soil. Soil horizons are distinct layers of soil with different physical, chemical, and biological properties that develop over time due to various soil-forming processes. These horizons are arranged in a vertical sequence and can be observed and analyzed by digging a soil pit or hole. The soil profile provides important information about the soil's physical and chemical properties, such as texture, structure, pH, nutrient content, and organic matter content. This information is useful in agriculture, forestry, and environmental science for understanding soil fertility, soil erosion, and land management practices. The zone of eluviation is a specific horizon within the soil profile that refers to the layer where minerals and organic matter are leached or washed out of the soil by water movement.

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The rocks which are formed by the cooling and solidification of molten magma are called igneous rocks. Magma is a hot, molten rock that is found beneath the Earth's surface. When magma cools and solidifies, it forms igneous rocks. Igneous rocks can form either on the Earth's surface or beneath it. If magma cools quickly on the surface, it forms small crystals and is called extrusive igneous rock. If magma cools slowly beneath the surface, it forms large crystals and is called intrusive igneous rock. Examples of igneous rocks include granite, basalt, and pumice. These rocks can be identified by their texture and composition. Igneous rocks have a variety of uses, such as in construction, as building materials, and in jewelry making.

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A line joining places with equal degree of cloudiness is called an isoneph. This statement is incorrect as there is no such term as "isoneph". A line joining places with equal precipitation is called an isohyet, a line joining places with equal temperature is called an isotherm, and a line joining places with equal atmospheric pressure is called an isobar. Therefore, the correct answer is none of the above options.

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The most common mode of transportation in Africa is road. This is because Africa has the most developed road network compared to other transportation modes. Although air, soil and ocean transportation also exist, road transportation is the most widely used because it is cheaper and more accessible to most people. Many parts of Africa still lack rail or water transport systems, making road transport the most practical option for people and goods movement. Additionally, many rural areas in Africa have poor infrastructure, making it difficult to access other forms of transportation, making road transportation the most popular means of movement for people and goods in the continent.

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The statement that is not true of stalagmites and stalactites is that "stalacties are formed on the floor of limestone caves while stalagmites are formed on roofs of limestone caves." In reality, stalactites are formed from the ceiling of a cave, while stalagmites are formed from the ground. Stalactites form when water containing dissolved minerals drips from the ceiling of a cave and the minerals gradually build up over time to form a pointed, icicle-like structure. Stalagmites form when the same water drips onto the floor of the cave and builds up into a mound or column. Therefore, the correct option is the third one.

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Life expectancy refers to the average age at which people are expected to live in a certain population or country. It is a statistical measure of the average amount of time a person can expect to live based on current mortality rates. In other words, it is the number of years a person can expect to live, on average, from birth. Life expectancy is often used as an indicator of the health and well-being of a population or country. Factors that can affect life expectancy include access to healthcare, sanitation, nutrition, and lifestyle choices. Therefore, the answer is option B: average age at which people die.

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The question is asking for the option that is NOT a problem of mining in Africa. Therefore, we need to identify the option that does not fit with the other three options, which are all problems of mining in Africa. - The use of obsolete technology is a problem because it makes mining less efficient and can result in safety hazards for workers. - Inadequate foreign capital is a problem because mining operations require significant investment, and without sufficient funds, mining companies may struggle to maintain or expand their operations. - Shortage of power is a problem because mining operations require large amounts of energy, and without a reliable power supply, mining companies may struggle to operate at their full capacity. - Inadequate unskilled labor is a problem because mining requires a skilled workforce, and without enough trained workers, mining companies may struggle to find the personnel they need to operate effectively. Therefore, the answer to the question is the option that is not a problem of mining in Africa, which is "inadequate unskilled labor."

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Lines joining places with the same mean annual rainfall are called isohyets. These lines are also known as rainfall contours or isopluvials. Isohyets are used to map and study the distribution of rainfall in a region. They are drawn by connecting points on a map that have the same average annual rainfall. By analyzing the patterns of isohyets, we can identify areas that receive high or low amounts of rainfall, as well as seasonal variations in rainfall. The term "isohyet" is derived from two Greek words: "iso," meaning equal, and "hyetos," meaning rain. Therefore, isohyets are simply lines on a map that connect places with the same amount of rainfall. In summary, isohyets are lines that connect places with the same mean annual rainfall. They are useful for studying the distribution and patterns of rainfall in a region.

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The activity that requires a large area of land usually in thousands of hectares, availability of water either in the form of rain or irrigation, and high capital outlay is plantation agriculture. Plantation agriculture involves the large-scale cultivation of a single crop on a large area of land. Examples of plantation crops include coffee, cocoa, tea, rubber, sugarcane, and palm oil. Plantation agriculture requires a lot of land to be economically viable, which is why plantations often cover thousands of hectares. In addition to a large area of land, plantation agriculture also requires a reliable source of water, either from rainfall or irrigation, as most plantation crops need a lot of water to grow. Finally, plantation agriculture requires a significant capital investment to purchase land, equipment, and labor. Therefore, the answer is option A: plantation agriculture.

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The statement "it is often difficult to compare the component parts" is not true of pie charts. A pie chart is a circular chart that is divided into sectors or "slices" to represent the proportion of each category in the data being displayed. It is an effective way to display the relative sizes of different categories, as each slice represents a percentage of the whole. However, it may become difficult to compare the sizes of small slices or slices with similar percentages. Therefore, it is recommended to use pie charts only for simple data sets with a few categories.

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A settlement developed at the meeting point of roads is known as a nodal town. Nodal towns are usually located at the intersection of major roads, which makes them an important transportation hub. As a result, they often attract economic activity such as trade and services. Nodal towns can also serve as centers of administration and governance due to their central location.

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The feature shared by Hong Kong, Java, and Manhattan is high population density. All three areas have a large population in a relatively small area.

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A mercury barometer is a device that is used to measure atmospheric pressure. Atmospheric pressure is the force per unit area exerted by the weight of the Earth's atmosphere on the surface of the Earth. A mercury barometer works by balancing the weight of a column of mercury against the atmospheric pressure. The barometer consists of a long glass tube that is closed at one end and filled with mercury. The open end of the tube is then placed in a dish of mercury. As the atmospheric pressure changes, the pressure on the surface of the mercury in the dish also changes, causing the height of the column of mercury in the tube to rise or fall. The height of the column of mercury in the tube is directly proportional to the atmospheric pressure. Therefore, the answer is option D: atmospheric pressure.

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The statement "The trees are evergreen, forming a canopy with buttress roots, climbers and creepers" refers to the Equatorial vegetation type. The Equatorial vegetation is found near the equator, where the climate is hot and wet throughout the year. The trees in this vegetation type are tall, reaching heights of up to 50 meters, and have a dense canopy of leaves that provide shade to the lower levels. The leaves of the trees are evergreen, which means they do not shed their leaves seasonally, and they have buttress roots that help to support their height. Climbers and creepers are also common in this vegetation type, and they use the trees as support for their growth. This type of vegetation is known for its biodiversity and is home to a wide variety of animal species, including monkeys, birds, and reptiles.

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The environmental hazard primarily due to human activities is ozone depletion. Ozone is a gas that protects life on Earth from the harmful effects of the sun's ultraviolet (UV) rays. The ozone layer is a thin layer of ozone in the Earth's atmosphere. Human-made chemicals, such as chlorofluorocarbons (CFCs) used in refrigerators, air conditioners, and aerosol sprays, contribute to the depletion of the ozone layer. When CFCs reach the ozone layer, they release chlorine atoms, which destroy ozone molecules. As the ozone layer becomes thinner, more UV radiation can reach the Earth's surface, leading to increased skin cancers, cataracts, and other health problems for humans, as well as harm to plants and animals. In summary, ozone depletion is the environmental hazard primarily caused by human activities, specifically the use of human-made chemicals like CFCs.

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The system of cultivation of tropical commercial crops estates is known as plantation agriculture. Plantation agriculture is a form of commercial farming in which crops are grown on large estates or plantations, typically located in tropical or subtropical regions. This type of agriculture is characterized by the extensive use of labor, often in the form of indentured servants or slaves, and the cultivation of cash crops such as coffee, tea, sugar, tobacco, and rubber. The crops grown on plantations are generally intended for export, rather than for local consumption, and are usually produced using intensive farming practices.

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Mercury and Venus lie between the sun and the earth. Mercury is the planet closest to the sun and is the smallest planet in the solar system. Venus is the second planet from the sun and is similar in size to the Earth. Both planets orbit the sun in between the sun and the Earth. Mercury and Venus are known as the inferior planets because they orbit the sun closer than Earth does. In contrast, Mars, Jupiter, Saturn, Uranus, and Neptune are known as the superior planets because they orbit the sun farther out than Earth does. Therefore, the answer is option C: Mercury and Venus.

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Loess is an example of wind-deposited soil. It is a type of soil formed by the accumulation of fine-grained sediment (silt-sized particles) that has been deposited by the wind. The name "loess" comes from the German word for "loose", as the soil is very porous and crumbly. Loess is typically found in areas where there is little vegetation to hold the soil in place, such as in the plains of China and the central United States. It is also very fertile and can support agriculture, making it an important soil type for human societies throughout history.

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Most of the world's lakes are fresh lakes that are fed by rivers with outlets to the sea. These fresh lakes are bodies of water that contain low levels of dissolved salts and minerals. They are often located in areas with high levels of precipitation, such as mountainous regions, and are fed by rivers that bring in fresh water from surrounding areas. The water in these lakes is continually refreshed as water flows in from the rivers and out through outlets to the sea. Glaciers, on the other hand, are bodies of ice that are formed by the accumulation of snow over many years. They slowly move downhill under the force of gravity and may melt to form lakes. However, most of the world's lakes are not fed by melting glaciers. Some lakes may have high levels of salinity due to excessive evaporation, which can occur in arid regions with high temperatures. These lakes are often referred to as saline lakes and are not considered fresh lakes. Finally, most lakes are not constant in volume as they can be affected by changes in precipitation, evaporation, and human activities such as water extraction and damming. However, they are important sources of freshwater for many communities and are also valuable habitats for a variety of plants and animals.

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Copper is an important raw material in the electrical industry. Copper is a good conductor of electricity and heat, making it an essential material for electrical wiring and electrical components such as motors, transformers, and generators. It is also used in electronic devices like computers, smartphones, and televisions. Copper's electrical conductivity and durability make it a valuable resource for the production of electrical equipment and infrastructure, which are critical for modern society's functioning.

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The innermost section of the Earth is the core. The core is the central part of the Earth and is located beneath the mantle. It is the hottest and densest part of the Earth, and it consists of two layers: the outer core and the inner core. The outer core is a liquid layer that surrounds the inner core. It is composed mostly of iron and nickel, and it generates the Earth's magnetic field through the movement of electrically charged particles. The inner core, on the other hand, is a solid layer that is composed mostly of iron and nickel. It is under immense pressure and is extremely hot, with temperatures reaching up to 5,500 °C. The core is the source of the Earth's internal heat, which drives plate tectonics and the movement of the continents. It is also responsible for the formation of the Earth's magnetic field, which protects the Earth from harmful solar radiation. In summary, the innermost section of the Earth is the core, which is composed of two layers: the outer core and the inner core. The core is responsible for generating the Earth's magnetic field, providing the Earth's internal heat, and driving plate tectonics.

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On June 21st, when the sun is directly overhead at the Tropic of Cancer, places in the Northern Hemisphere experience a longer day and a shorter night. This is because the sun's rays are falling more directly on the Northern Hemisphere, causing the day to be longer and the night to be shorter. This is also known as the summer solstice, and it marks the beginning of summer in the Northern Hemisphere. As the Earth rotates on its axis, different parts of the planet receive different amounts of sunlight, which creates different seasons and lengths of days and nights.

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The desert landforms among the given pairs are yardangs and zeugens. Yardangs are long, narrow ridges with steep sides that are carved out of the bedrock by wind erosion. They are formed by the deflation of loose sand and silt, leaving behind harder, more resistant rock formations. Zeugens, on the other hand, are elongated ridges or hills that are formed by the wind erosion of a softer rock layer, leaving behind a more resistant layer on top. They are often found in desert landscapes where there are alternating layers of hard and soft rock. Wave-cut platforms are features formed by the erosion of coastal cliffs by waves, while self-dunes are small, isolated sand dunes that form on a flat surface, often around a single rock or obstacle. Sandbars and sandspits are coastal landforms formed by the deposition of sand by waves and currents, while barchans and tombolos are sand dunes and ridges that form in desert and coastal environments, respectively. Therefore, the correct answer is yardangs and zeugens.

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The climatic belts recognized by the Greeks were torrid, temperate, and frigid. These terms were used to describe the three main climatic zones based on their distance from the equator and the amount of solar radiation they receive. The torrid zone is the area near the equator, where the sun's rays are most direct, and the climate is generally hot and humid throughout the year. The temperate zone lies between the tropics and the polar regions and experiences moderate temperatures and four distinct seasons. The frigid zone, also known as the polar zone, is located near the North and South poles and has a cold climate with little sunlight during the winter months. These climatic belts were recognized by the Greeks as early as the 4th century BCE and were based on their observations of the world around them. The Greeks were among the first to recognize the relationship between geography, climate, and vegetation, which they described as the "oikumene," or the inhabited world. This understanding of the different climatic zones was important for agriculture, trade, and navigation, as it allowed the Greeks to anticipate the climate and weather conditions they would encounter in different parts of the world.

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When a ship appears over the distant horizon, the mast is seen before the hull. This is due to the curvature of the Earth. As the ship approaches, the hull gradually appears above the horizon, and eventually, the whole ship can be seen. This phenomenon is known as "looming". The distance at which a ship can be seen above the horizon depends on the height of the observer and the height of the ship's mast above the water.

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The wind that affects the West Indian Islands of the Caribbean is hurricanes. A hurricane is a tropical cyclone that forms over the Caribbean Sea and can cause severe damage to the islands in the region. It is characterized by strong winds that can exceed 74 miles per hour and heavy rainfall. Hurricanes are usually formed during the warm months of the year, typically from June to November, and can be very destructive, leading to loss of life and property damage.

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The ocean that connects Europe and America is the Atlantic Ocean. The Atlantic Ocean is the second largest ocean in the world and it separates the continents of North and South America to the west from Europe and Africa to the east. The ocean covers an area of approximately 41 million square miles and has an average depth of 12,080 feet. The Atlantic Ocean plays a vital role in global trade, transportation, and climate, with major ports and shipping lanes located throughout the region. The ocean also contains a diverse range of marine life and resources, including fish, oil, and natural gas. Therefore, the answer is option C: Atlantic Ocean.

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The term over-population is best defined as the situation where the population exceeds available resources. Overpopulation occurs when there are too many people living in a particular area relative to the resources and services available to sustain them. This can result in a range of environmental, economic, and social problems, such as food and water shortages, poor sanitation, pollution, and increased competition for resources. High population density is one potential consequence of overpopulation, but it is not the sole factor. Birth rate being equal to death rate, on the other hand, would result in a stable population, but not necessarily an overpopulated one. An increasing birth rate and decreasing infant mortality rate may lead to population growth, but this alone does not necessarily indicate overpopulation. It is the combination of population growth and resource depletion that can result in overpopulation. Therefore, the answer is option C: the population exceeds available resources.

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(a) Outline map reduced to a scale of 1:150,000

The reduction factor is:

\[\frac{1:150\,000}{1:50\,000}=3\]

Thus, every length on the original extract is reduced to one-third. The completed reduced outline is shown below.

(b) Features marked on the outline

1. Nodal settlement: Kaiama. Several roads converge at Kaiama.
2. Secondary road: No secondary road is shown on the map extract. The roads shown are the main road and minor roads or tracks.
3. Trigonometrical station: the trigonometrical station northwest of Kaiama, marked by the trigonometrical-station symbol.

(c) Full length of River Gbesha from point X

Length measured along the winding river course on the map = \(27.4\text{ cm}\).

At a scale of \(1:50,000\):

\[\text{Ground distance}=27.4\times50,000=1,370,000\text{ cm}\]

\[\text{Ground distance}=\frac{1,370,000}{100,000}=13.7\text{ km}\]

Therefore, the full length of River Gbesha from X is 13.7 km.

(d) Identification

(i) Land-use types

1. Agriculture or farming, indicated by scattered cultivation.
2. Animal grazing, indicated by the savanna vegetation.

Other identifiable land uses include settlement and transportation.

(ii) Social amenities in Kaiama

1. Postal agency
2. Market
3. Health centre

Other social amenities shown include a rest house, church and school.

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(a) Sketch map of Africa showing the rivers and irrigation areas

Key locations marked on the sketch map:

• River Niger: Office du Niger irrigation scheme, Mali; and Baguinéda irrigation area, Mali.
• River Nile: Gezira irrigation scheme, Sudan; and the Nile Delta irrigation area, Egypt.

(b) Contributions of irrigation agriculture to the Gezira Scheme, Sudan

1. It provides water for farming throughout the year and permits continuous or multiple cropping.
2. It increases the production of food crops such as wheat, sorghum and vegetables for the growing population.
3. It provides employment and income for farmers, farm labourers, traders and transport workers.
4. It produces cash crops, especially cotton, which supply raw materials to industries and earn foreign exchange.
5. It provides revenue to the government through taxes, export duties and sales of agricultural produce.

(c) Problems facing irrigation agriculture in the Gezira Scheme

1. Salinisation and waterlogging: high evaporation and poor drainage leave salts in the soil and reduce soil fertility.
2. High cost: canals, dams, pumps and irrigation equipment are expensive to construct, operate and maintain.
3. Silting: silt deposited in canals and reservoirs reduces their depth and carrying capacity.
4. Water-borne diseases: stagnant water in canals encourages diseases such as bilharzia and malaria.
5. Fluctuation in water supply: low river flow or drought may reduce the amount of water available for irrigation.

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(a) (i) Main lines of latitude

Lines of latitude are imaginary parallel circles drawn round the Earth and measured north or south of the Equator.

The main lines of latitude are:

• Arctic Circle, \(66\tfrac{1}{2}^{\circ}\text{N}\)
• Tropic of Cancer, \(23\tfrac{1}{2}^{\circ}\text{N}\)
• Equator, \(0^{\circ}\)
• Tropic of Capricorn, \(23\tfrac{1}{2}^{\circ}\text{S}\)
• Antarctic Circle, \(66\tfrac{1}{2}^{\circ}\text{S}\)

(a) (ii) Distance between Addis Ababa and Maseru

Latitude of Addis Ababa = \(10^{\circ}\text{N}\)

Latitude of Maseru = \(30^{\circ}\text{S}\)

Since the two towns are on opposite sides of the Equator:

\[\text{Difference in latitude}=10^{\circ}+30^{\circ}=40^{\circ}\]

\[1^{\circ}\text{ of latitude}=111\text{ km}\]

\[\text{Distance}=40\times111=4,440\text{ km}\]

Therefore, the distance between Addis Ababa and Maseru is \(4,440\text{ km}\).

(b) (i) Revolution of the Earth

Revolution is the movement of the Earth round the Sun in its orbit. The Earth completes one revolution in about \(365\tfrac{1}{4}\) days.

(b) (ii) Effects of revolution on the length of day and night in the Northern Hemisphere

• The Earth’s axis is tilted, and it remains inclined in the same direction as the Earth revolves round the Sun. Consequently, the length of day and night changes during the year.
• About 21 June, the Northern Hemisphere is tilted towards the Sun. It experiences summer, with longer days and shorter nights. At the Arctic Circle there is 24 hours of daylight, and areas north of it experience the midnight sun.
• About 22 December, the Northern Hemisphere is tilted away from the Sun. It experiences winter, with shorter days and longer nights. At the Arctic Circle there is 24 hours of darkness, while areas farther north may not see the Sun.
• About 21 March and 23 September, the Sun is overhead at the Equator. These are equinoxes, when day and night are approximately equal, each lasting 12 hours.

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(a) Four reasons for the concentration of manufacturing industries in the capital cities of Tropical African countries

• Large market - capital cities have dense populations, giving industries a ready market for their products.
• Good infrastructure - they have better roads, rail, ports, water and electricity supply than other areas, which industries need.
• Availability of labour - both skilled and unskilled workers gather in the capital in search of jobs.
• Presence of capital and financial institutions - banks, government offices and investors are concentrated there, making it easy to raise funds.
• Nearness to government - being the seat of government they enjoy favourable policies, contracts and administrative attention.

(b) Three reasons for the predominance of consumer-oriented industries in Tropical Africa

• The economies are still developing and lack the heavy capital and technology needed for capital-goods industries, so light consumer industries are cheaper to establish.
• There is a large and growing population demanding everyday goods such as food, drinks, soap, textiles and footwear.
• Consumer industries use mostly local agricultural raw materials that are readily available.
• They require less skilled labour and yield quick returns on investment.

(c) Three contributions of manufacturing industries to economic development

• They create employment and raise the incomes and living standards of the people.
• They add value to local raw materials and reduce dependence on imported goods, saving foreign exchange.
• They diversify the economy away from over-reliance on agriculture and mineral exports.
• They generate revenue for government through taxes and stimulate the growth of towns and other supporting services.

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(a) Four characteristics of igneous rocks

• Crystalline: they are made of interlocking mineral crystals formed when molten magma or lava cooled and solidified.
• Non-stratified (no layers): they occur in solid masses without bedding planes or strata.
• Contain no fossils, because they were formed from molten material and never laid down as sediments.
• Generally hard, crystalline and non-porous, so they resist weathering; the crystals are large when the rock cooled slowly at depth (e.g. granite) and small/fine when it cooled quickly at the surface (e.g. basalt).

(b) Four ways metamorphic rocks are useful to man (with examples)

• Marble (from limestone) is used for building, floor and wall tiles, statues, monuments and decoration.
• Slate (from shale/clay) splits into thin sheets and is used for roofing, floor slabs and formerly writing boards.
• Quartzite (from sandstone) is very hard and is used as building stone, road-making aggregate and for making glass and abrasives.
• Graphite (from carbon-rich rock) is used for pencil leads, lubricants and electrodes; and gneiss is used as a durable building and paving stone (marble/graphite may also carry valuable minerals).

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(a) Description of survey instruments (any three)

• (i) Ranging poles: straight wooden or metal poles about 2 to 3 metres long, painted in alternate bands of red and white (sometimes black) so that they are easily seen from a distance. They are pointed or shod with iron at the base to be stuck into the ground, and are used for marking survey stations and for ranging (keeping straight lines) during chaining.
• (ii) Chain: a measuring device made of a series of galvanised steel/iron links joined by rings, commonly the 20 m or 30 m chain, with brass tags/tallies at intervals to show the readings. It is used for measuring distances along the survey lines on fairly level ground.
• (iii) Cross staff: a small instrument (an octagonal box or frame with slits/sights, mounted on a pole) used to set out or measure right angles (offsets) from the chain line to features being surveyed.
• (iv) Arrows (chaining pins): pointed steel pins, usually a set of ten, with a ring at the top, used to mark the end of each chain length on the ground so that the number of chains measured can be counted.

(b) Processes involved in carrying out a Chain Survey

1. Reconnaissance: walk over and study the area to be surveyed to plan the survey lines and station positions.
2. Marking stations and drawing a key/index sketch of the framework of survey lines (well-conditioned triangles).
3. Ranging the main (base/chain) line using ranging poles to keep it straight.
4. Chaining the survey lines, measuring distances with the chain and inserting arrows at each chain length.
5. Taking offsets to features on either side of the chain line using the cross staff/tape, and booking all measurements neatly in the field book.
6. Applying check lines/tie lines to verify accuracy, then plotting the survey to scale in the office to produce the map.

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(a) Outline map of West Africa

The map shows:

• Area of dense population: south-western Nigeria (Yorubaland/Lagos area).
• Important town in the dense area: Lagos.
• Area of sparse population: northern Niger, within the Sahara Desert region.
• Important town in the sparse area: Agadez.
• River Niger: from the Guinea Highlands, through Mali and Niger, then south through Nigeria to the Gulf of Guinea.

(b) Factors responsible for the high population density in south-western Nigeria

1. Favourable climate: The area has reliable rainfall, warm temperatures and a relatively humid environment, which favour settlement and agricultural production.
2. Fertile soils and agriculture: Fertile soils support food crops and cash crops such as cocoa, kola nut, oil palm and vegetables. Intensive farming can therefore sustain a large population.
3. Industrialisation and employment: Lagos and other towns contain factories, offices, markets, banks and transport businesses. These provide employment and attract migrants from other areas.
4. Port and commercial functions: Lagos is a major coastal port and commercial centre. Import, export, shipping and trading activities encourage the concentration of people.
5. Social amenities and transport: Good road and rail links, schools, hospitals, electricity, water supply and other services make the area attractive for settlement.
6. Historical and administrative importance: The area has long been occupied and urbanised, while Lagos developed as an important colonial and administrative centre. This has encouraged continuous population growth.

(c) Problems of sparse population density

1. Shortage of labour: There are too few workers to cultivate land fully, exploit mineral resources and undertake major development projects.
2. High cost of providing services: Scattered settlements make roads, schools, hospitals, water supply and electricity expensive to provide; the small population also creates a limited market for goods and services.

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(a) Outline map of Nigeria: soil zones, crops and towns

The map below shows three major soil zones and their associated crops. Kano and Ibadan are the two towns located in the northern sandy-soil zone and the southern forest-soil zone respectively.

Soil zone	Main location	Associated crop	Town shown
Northern sandy soils	Far northern Nigeria	Groundnut	Kano
Interior lateritic soils	Middle Belt and inland areas	Yam	Makurdi
Forest soils	Southern Nigeria	Oil palm	Ibadan

(b) Characteristic features of two soil zones

1. Northern zone of sandy soils

• It occurs mainly in the far northern part of Nigeria, where the climate is arid or semi-arid.
• It is formed under low rainfall and sparse vegetation.
• The soil is loose, friable and porous, with coarse sand grains and a sandy-loam texture.
• It is easy to cultivate and is generally well drained.
• It contains little humus and has low water-holding capacity, so it dries out rapidly.
• It is not heavily leached because rainfall is relatively low.
• It supports crops such as groundnut, millet, cotton and maize, especially where moisture is adequate.

2. Interior zone of lateritic soils

• It is widespread in the interior and Middle Belt of Nigeria.
• It develops under alternating wet and dry tropical conditions and is commonly reddish or brownish in colour.
• Its red colour results from iron compounds; it also contains aluminium compounds.
• It is heavily leached by rainfall and is therefore generally of medium fertility unless manure or fertiliser is added.
• It is sticky when wet but hard and compact when dry, and may become relatively impervious.
• It supports food crops such as yam, cassava, cocoyam and maize.

Detalles de la respuesta

(a) Sketch map of Africa

Key locations: River Nile is in north-eastern Africa and flows northwards to the Mediterranean Sea. River Limpopo is in south-eastern Africa and flows eastwards to the Indian Ocean. Lake Victoria is in East Africa near the Equator, while Lake Chad is in the north-central interior. The Namib Desert lies along the south-western coast, and the Kalahari Desert lies in the interior of southern Africa.

(b) Uses of rivers and lakes in Africa

1. They provide water for domestic purposes such as drinking, cooking and washing.
2. They provide water for irrigation and support livestock farming.
3. They provide fish and employment in fishing, fish processing and boat building.
4. They are used for inland water transport of people and goods.
5. They are dammed for the generation of hydro-electric power.
6. They supply water for industries and serve as tourist and recreational centres.

(c) Factors limiting the use of rivers and lakes in Africa

1. Rapids and waterfalls interrupt river courses and hinder navigation.
2. Seasonal fluctuations in water level cause some rivers to become shallow or dry up in the dry season, while flooding occurs in the wet season.
3. Silting and sand bars, especially at river mouths, obstruct navigation.
4. Aquatic weeds, such as water hyacinth, block waterways and hinder fishing and transport.
5. Many rivers pass through sparsely populated, desert or otherwise unproductive areas, reducing their economic usefulness.
6. Some rivers cross international boundaries, creating problems of joint control, development and use.

Detalles de la respuesta

(a) Sketch map of Nigeria showing cattle rearing and movement to markets

Key: The shaded northern savanna belt is the cattle-rearing zone. Kano is a town within the zone. The arrows show cattle moving southwards from Kano/the northern producing area to the major consuming markets of Lagos and Ibadan.

(b) Factors favouring cattle rearing in northern Nigeria

1. The extensive Sudan and Sahel savanna grasslands provide abundant natural pasture for grazing cattle.
2. The relatively dry climate and low humidity discourage the tsetse fly, thereby reducing trypanosomiasis.
3. The broad, gently undulating plains provide wide open land for grazing and movement of herds.

(c) Problems of cattle rearing in northern Nigeria

1. Rainfall is scanty and unreliable; consequently, pasture and surface water become inadequate during the long dry season.
2. Overgrazing may destroy available pasture and lead to soil erosion and desertification.
3. Diseases such as rinderpest and foot-and-mouth disease, together with inadequate veterinary drugs, vaccines and services, reduce cattle production.

Detalles de la respuesta

None

Detalles de la respuesta

(a) Soil profile

A soil profile is a vertical section of soil from the ground surface down to the parent rock or bedrock, showing the different layers or horizons of the soil.

(b) Well-labelled diagram of a soil profile

(c) Characteristics of the three zones of a soil profile

1. A horizon (topsoil or zone of eluviation)
   • It is the uppermost layer of mineral soil, immediately below the surface litter.
   • It contains decaying plant and animal remains which form humus.
   • It is dark in colour and is usually the most fertile horizon.
   • It is the zone of greatest biological activity, containing many soil organisms and most plant roots.
   • Soluble minerals and fine materials are washed down from this horizon by percolating water.
2. B horizon (subsoil or zone of illuviation)
   • It lies below the A horizon and contains little humus.
   • It is the zone in which clay, iron, aluminium and other mineral materials leached from the A horizon accumulate.
   • It is often reddish, brownish or yellowish because of iron compounds.
   • It is usually denser and more compact than the topsoil.
   • Only deep-rooted plants commonly extend into this horizon.
3. C horizon (parent-material horizon)
   • It consists mainly of partly weathered rock fragments and other parent material from which the soil develops.
   • It contains very little or no humus and has little biological activity.
   • It is coarser and less developed than the A and B horizons.
   • It grades downward into hard, unweathered bedrock.

Detalles de la respuesta

Answer based on Nigeria as the candidate's country.

(a)(i) Two major export items

• Petroleum (crude oil)
• Cocoa (others include rubber, tin, columbite and natural gas)

(a)(ii) Two major import items

• Motor vehicles and machinery
• Electronics and food (rice) (others include tractors, computers and textiles)

(a)(iii) Two major trading partners

• China
• United States of America (others include Britain, Japan, Germany, Italy and South Korea)

(b) Four benefits from trading with other countries

• It provides foreign exchange for the country.
• It fosters international co-operation and friendly relations with other nations.
• It provides employment and generates revenue to government and income to individuals.
• It encourages specialisation in production and makes new products available, thereby improving the standard of living.

(c) Three problems encountered in international trade

• Inadequate foreign exchange and inadequate capital.
• High tariffs imposed on goods and low demand for the country's products abroad.
• Port congestion and the high cost of transportation (with smuggling and economic sabotage adding to the difficulties).

Detalles de la respuesta

Detalles de la respuesta

(a) Outline map of Nigeria showing annual rainfall distribution

Key: Annual rainfall generally decreases from the southern coast northwards. The Niger Delta and coastal belt receive over 2,000 mm; the southern interior receives 1,500 to 2,000 mm; the Middle Belt receives 1,000 to 1,500 mm; while the extreme north receives about 500 to 1,000 mm annually.

(b) Effects of rainfall on the distribution of vegetation in Nigeria

1. Heavy and almost continuous rainfall, especially over 2,000 mm in the south, supports dense tropical rain forest with tall trees. In the coastal swampy areas, it also supports mangrove vegetation.
2. Moderate rainfall of about 1,000 to 1,500 mm in the Middle Belt supports Guinea Savanna, made up of tall grasses and scattered trees.
3. Low and seasonal rainfall in the north supports Sudan and Sahel Savanna, where vegetation consists mainly of short grasses, thorny shrubs and widely spaced drought-resistant trees. Thus, vegetation becomes shorter, less dense and more open from south to north as rainfall decreases.

(c) Characteristics of the Guinea Savanna

1. It has tall grasses, often growing up to about 3 m high. The grasses are green in the rainy season and dry or brown in the dry season.
2. It has few scattered trees, with open grassland between them.
3. Many of the trees are deciduous and shed their leaves during the dry season; they commonly have thick bark and deep roots to withstand drought and bush fires.
4. Gallery forests occur along river valleys and streams where moisture is available throughout much of the year.

Detalles de la respuesta

Characteristics of any two river features (with diagrams)

(i) Meanders

• They are the wide, looping bends or curves of a river, well developed in the middle and lower courses where the valley is gentle and the river swings freely.
• Each bend has an outer (concave) bank that is steep and cut back by erosion (river cliff), where the current is fast and the water deep, and an inner (convex) bank that is a gentle, shelving slip-off slope where deposition takes place and the water is shallow.
• The river erodes sideways (lateral erosion), so meanders slowly grow and shift down-valley; when a loop is cut through at the neck it may be abandoned to form an ox-bow lake.
• Diagram: a plan view of a winding channel showing erosion on the outer bank and deposition (slip-off slope) on the inner bank.

(ii) Flood plain

• A flood plain is the wide, flat, low-lying area of land on either side of a river in its lower course, built up of alluvium (fine silt and mud) deposited when the river overflows its banks in flood.
• It is very fertile and level, and may carry features such as meanders, ox-bow lakes, and natural levees (raised banks of coarser material along the channel).
• It grows wider as the river shifts across it by lateral erosion and deposition, and is often used for farming and settlement.
• Diagram: a cross-section showing the river channel with levees, the flat alluvium-covered plain on both sides, and the valley bluffs at the edges.

(iii) Braided stream

• A braided stream is a river that splits into several separate channels which divide and rejoin around numerous islands or bars of sand and gravel, giving a plaited or interwoven appearance.
• It forms where the river carries a heavy load but has a variable or reduced discharge, so it drops the coarse material to build the mid-channel bars that force the water to divide.
• It is common on gentle gradients with easily eroded banks, for example near glacier snouts and on dry-region river beds.
• Diagram: a plan view showing one river dividing into interlacing channels around sand/gravel bars.

Detalles de la respuesta

(a) Divergence line graph

The monthly temperatures and their departures from the annual mean are:

Month	J	F	M	A	M	J	J	A	S	O	N	D
Temperature (°C)	10	14	22	32	42	48	44	38	32	24	16	10

Annual mean temperature:

\[\bar T=\frac{10+14+22+32+42+48+44+38+32+24+16+10}{12}=\frac{332}{12}=27.7^\circ\text{C}\]

The bold horizontal line on the graph represents the mean temperature, or zero departure. Temperatures above it are positive departures and those below it are negative departures.

(b)(i) Annual range of temperature

\[\text{Annual range}=\text{temperature of hottest month}-\text{temperature of coldest month}\]

\[=48^\circ\text{C}-10^\circ\text{C}=\boxed{38^\circ\text{C}}\]

(b)(ii) One other method of showing the statistics is a simple bar graph.