WAEC SSCE - Geography - 2006

Bayanin Amsa

Continental shelves are important for fishing, the development of harbors, and recreation. However, they are not important for sea piracy. Continental shelves are shallow underwater areas that extend from the shoreline to the edge of the continental slope. They are important for fishing because they are rich in nutrients and support a diverse range of marine life, making them ideal fishing grounds. The development of harbors is also possible on continental shelves because the water is shallow and calm, making it easier for ships to anchor and dock. Additionally, continental shelves are popular destinations for recreation such as diving, snorkeling, and surfing. However, sea piracy is not related to continental shelves. Sea piracy is a criminal act that involves attacking ships on the high seas, and it can happen anywhere in the world's oceans, including areas far from continental shelves. Therefore, continental shelves are not important for sea piracy.

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When it comes to transporting perishable goods or items of high unit value like gold or diamonds, the best mode of transportation is air. This is because air transport is the quickest and most efficient means of transport, which helps to ensure that the goods arrive at their destination in a timely manner. In addition, air transport is also the safest means of transport for such valuable or perishable goods, as it provides a high level of security and reduces the risk of theft or damage during transit. The use of specialized cargo planes and temperature-controlled containers also helps to maintain the quality and freshness of perishable goods during transit. On the other hand, while road, rail, and sea transport are suitable for other types of goods, they are not as efficient or secure when it comes to transporting perishable goods or high-value items. Road transport is slower and can be affected by traffic and weather conditions, while rail transport may not provide the necessary security for valuable goods. Sea transport, on the other hand, is slow and can be affected by rough weather conditions, which can lead to delays and damage to goods.

Bayanin Amsa

Bayanin Amsa

The option that is not a contribution of land transport to the economic development of any country is "depopulation of urban centres." Land transport provides many economic benefits to a country, such as generating income and employment opportunities, as well as diffusing ideas and innovations. However, land transport does not contribute to the depopulation of urban centers. In fact, it can have the opposite effect by making it easier for people to travel to and from urban centers, leading to increased population growth. Therefore, the depopulation of urban centers is not a contribution of land transport to the economic development of any country.

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The ports that specialize in receiving goods from ships and then redistributing them to neighboring countries are called "entrepots." These ports act as a middleman between the importing country and the neighboring countries, where the goods are re-exported. They typically have good transportation connections to the neighboring countries, such as road or rail links, to facilitate the movement of goods. Entrepots are also known as "free ports" or "duty-free ports" because they often offer tax breaks and other incentives to encourage trade. They can be found in strategic locations, such as at the crossroads of major shipping lanes or at the junctions of different transportation routes.

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The greatest problem associated with cattle rearing in West Africa is the presence of tse-tse fly. Tse-tse flies are bloodsucking insects that transmit a parasite causing African animal trypanosomiasis or nagana disease in cattle. This disease reduces the productivity and growth of the animals, resulting in lower milk and meat yields. The presence of tse-tse flies also restricts the areas where cattle can graze, making it difficult for farmers to find suitable grazing land for their herds. This ultimately leads to reduced profits for farmers and hinders the growth of the cattle industry in West Africa.

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Lava plateaux are not examples of intrusive volcanic features. Intrusive volcanic features are structures that form from magma that cools and solidifies beneath the Earth's surface. Dykes and sills are sheet-like intrusions that form when magma intrudes into existing rock layers and solidifies. Batholiths are large masses of rock that form deep within the Earth's crust from slowly cooling magma chambers. These intrusive features are generally characterized by their coarse-grained texture and slow cooling process, which allows for the formation of large mineral crystals. In contrast, lava plateaux form when lava erupts onto the Earth's surface and spreads out in all directions, creating a flat, elevated area of land. Lava plateaux are extrusive features, which means they form from volcanic activity that occurs on the Earth's surface, rather than beneath it.

Bayanin Amsa

Bayanin Amsa

Metamorphic rocks form when other rocks are changed by heat, pressure, and/or chemical reactions. The process of forming metamorphic rocks is called metamorphism. Heat and pressure can come from deep within the Earth or from the weight of overlying rocks. Chemical reactions can occur when fluids seep through rocks, dissolving and re-depositing minerals. This transformation can occur without melting the original rock, and can lead to the formation of new minerals and the rearrangement of existing ones, creating a new rock with unique characteristics. Tension and folding may play a role in the process of metamorphism, but they are not the primary agents of change.

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The major causes of change in population size are births, deaths, and migration. Births increase the population size by adding new individuals to the population. Deaths decrease the population size by removing individuals from the population. Migration can increase or decrease the population size depending on whether people are moving in or out of the area. Overall, population size is influenced by the balance between births, deaths, and migration. If the number of births is greater than the number of deaths and migration, the population will increase. Conversely, if the number of deaths and migration is greater than the number of births, the population will decrease.

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The Mediterranean type of climate is best favored for fruit growing. This is because the climate is characterized by mild, wet winters and hot, dry summers. Such conditions are ideal for growing a variety of fruits, including citrus fruits, grapes, olives, and figs. These fruits require long, warm, and dry summers for ripening and cooler, moist winters for growth. Additionally, the soil in the Mediterranean region is fertile and suitable for fruit growing. While other crops such as wheat and cotton can also grow in this climate, fruit growing is the most favored.

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The option that is not a proof to show that the Earth is spherical in shape is "twilight and dawn." Twilight and dawn occur when the sun is just below the horizon, and the Earth's atmosphere refracts or bends the sunlight. This bending of light makes the sun appear higher in the sky than it actually is, creating an illusion that the Earth's surface is flat. However, this phenomenon can occur on any curved surface, not just a sphere. On the other hand, sunrise and sunset, aerial photographs, and lunar eclipses all provide evidence that the Earth is spherical. During a sunrise or sunset, the sun appears to rise or set on the horizon, and the shape of the shadow cast by the Earth on the moon during a lunar eclipse is curved. Aerial photographs of the Earth also reveal its curvature, as the horizon appears to curve away from the observer's viewpoint. These observations provide evidence that the Earth is not flat, but rather, it is curved in shape.

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The Atlas, Andes, and Himalayas are all examples of fold mountains. However, the Vosges Mountains are not a fold mountain range. Fold mountains are formed when two tectonic plates collide and the crust is crumpled and pushed upward, creating a mountain range. The Atlas, Andes, and Himalayas are all examples of fold mountains because they were formed by the collision of two tectonic plates. The Vosges Mountains, on the other hand, were formed differently. They were created by a combination of volcanic activity and erosion. The Vosges Mountains were once much higher than they are today, but over time, erosion has worn them down. Therefore, the Vosges Mountains are not considered to be a fold mountain range.

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The difference between high tide and low tide is referred to as "tidal range". Tidal range is the vertical distance between the highest water level during high tide and the lowest water level during low tide. It is influenced by various factors, including the gravitational pull of the moon and the sun, the shape and depth of the coastline, and the wind and weather patterns. Understanding tidal range is important for activities such as boating, fishing, and beachcombing, as well as for managing coastal ecosystems and infrastructure.

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Bayanin Amsa

Wind erosion is a natural process that occurs when wind removes particles from the earth's surface. The movement of wind can cause various landforms to form, such as rock pedestals, zeugens, yardangs, and other features. However, rift valleys are not a feature produced by wind erosion. Rift valleys are formed by the movement of tectonic plates and are commonly found at divergent plate boundaries, where the earth's crust is being pulled apart. The separation of the plates causes the formation of a rift valley, which can create a low-lying area between two highland areas. On the other hand, rock pedestals are created by the selective erosion of softer rock layers, while zeugens are formed by the differential erosion of alternating layers of hard and soft rock. Yardangs, meanwhile, are elongated ridges formed by the wind eroding the softer rock layers around them, leaving the harder rock layers behind. In summary, all the given options except rift valleys are features produced by wind erosion.

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The north-easterly wind from the Sahara blowing towards the Gulf of Guinea is called the "harmattan". This wind is a dry and dusty trade wind that blows from the Sahara Desert towards the western coast of Africa during the winter months (November to March). The harmattan is characterized by a hazy and dusty atmosphere, and it can cause low visibility and dryness in the affected areas. It is an important weather phenomenon in West Africa, and it has significant impacts on the environment, agriculture, and human health.

Bayanin Amsa

Bayanin Amsa

Diurnal range of temperature is the difference between the highest and the lowest temperature of a given day. Therefore, to obtain the diurnal range of temperature, we need to subtract the minimum temperature of the day from the maximum temperature of the same day. Option (c) subtracting the minimum temperature of the day from the maximum temperature of the same day, is the correct method to obtain the diurnal range of temperature. This is because it gives us the difference between the maximum and minimum temperature for a given day, which represents the variation in temperature that occurs within a 24-hour period. Options (a) and (b) are incorrect because they involve adding all the temperature readings, which does not give us the range of temperature for a specific day. Option (d) is incorrect because it gives us the range of temperature for a whole month, rather than a specific day. In conclusion, the diurnal range of temperature is obtained by subtracting the minimum temperature of a day from its maximum temperature.

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Zaire (now known as the Democratic Republic of Congo or DRC) is noted for lumbering in Africa. Lumbering, also known as logging, is the process of cutting down trees for commercial use. The DRC has an abundance of forests that cover more than half of the country's land area, and it has one of the largest forest reserves in Africa. The country has an estimated 100 million hectares of forest, which makes up about 10% of the world's tropical forests. The DRC's forests are rich in various species of trees, including hardwoods like mahogany, teak, and ebony. These trees are highly valued for their durability and aesthetic appeal, and they are in high demand in the global market for furniture, flooring, and other high-end products. However, the logging industry in the DRC has faced various challenges due to poor governance, weak regulations, and illegal logging practices. Despite these challenges, logging remains an important economic activity in the DRC, and it contributes significantly to the country's GDP.

Bayanin Amsa

A plunge pool is a feature of waterfalls. When a river falls from a height, the water hits the pool below with great force, causing erosion. Over time, the pool gets deeper, and the rocks at the bottom get smoother. Plunge pools can be dangerous to swim in due to the strong currents and swirling water at the base of the waterfall. However, they can also be beautiful and attract tourists. Many waterfalls are popular tourist attractions because of their plunge pools, which visitors can swim in under the right conditions.

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Koppen's climatic classification was based on both rainfall and temperature. This classification system divides the world's climates into five main groups based on average monthly temperature and precipitation. The groups are tropical, dry, temperate, continental, and polar. Within each group, there are further subdivisions based on variations in climate patterns. Koppen's classification system is widely used in the fields of geography, ecology, and climatology to study and understand the distribution of different climate types across the world. It is helpful for predicting and studying the impact of climate change on various regions and ecosystems, and for identifying suitable areas for agricultural and economic development.

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The Equatorial forests of the Amazon basin are generally referred to as the "selvas." The term "selvas" is Spanish for "jungles" or "forests," and it is used to describe the dense tropical rainforests that cover much of the Amazon basin. These forests are characterized by their high levels of biodiversity, with millions of plant and animal species, many of which are found nowhere else on earth. The Amazon rainforest is also known as the "lungs of the earth" because it produces approximately 20% of the world's oxygen. The Amazon basin spans nine countries in South America, with the largest portion in Brazil.

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Limestone is an example of an organically formed sedimentary rock. It is primarily composed of calcium carbonate, which is the skeletal remains of marine organisms such as coral and shells. Over millions of years, the accumulation of these organisms on the ocean floor is compacted and cemented together to form limestone. Limestone can also be formed through chemical precipitation, where minerals in water are deposited in caves and underground formations. It is a versatile rock and can be used for a variety of purposes, including construction, as a source of lime for agriculture, and in the production of cement. Due to its porous nature, limestone can also be a source of groundwater and is often used as a natural filter for drinking water.

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The farthest planet from the sun in our solar system is Pluto. It is located at an average distance of about 3.7 billion miles (5.9 billion kilometers) from the sun, which is almost 40 times farther away than Earth. Pluto was considered the ninth planet of the solar system until 2006 when it was reclassified as a dwarf planet. Despite its small size, Pluto has a unique place in our solar system due to its location and the mysteries that surround it.

Bayanin Amsa

The major benefit of international trade is revenue generation. This means that countries can sell their goods and services to other countries and generate income that can be used for economic growth and development. International trade also creates jobs and stimulates competition, which can lead to lower prices and higher quality products. While there are other potential benefits to international trade, such as the stabilization of prices, the free movement of people across borders, and increased access to essential goods, revenue generation is considered the most significant benefit.

Bayanin Amsa

Xerophytic plants are usually associated with areas of low rainfall. These plants have adapted to survive in arid or semi-arid environments by developing features such as thick stems or leaves, water-storing tissues, and deep root systems to access water reserves. Xerophytic plants are also able to close their stomata (tiny pores on their leaves) during the day to reduce water loss through transpiration. These adaptations allow xerophytic plants to conserve water and thrive in environments with little rainfall.

Bayanin Amsa

Bayanin Amsa

The river transports its load through three main processes: solution, suspension, and traction. Plucking is not one of the processes through which a river transports its load. Solution occurs when the river dissolves some of the minerals or rocks in its load into the water, creating a solution that can be transported downstream. Suspension occurs when the river carries small particles, such as silt or clay, in the water, giving the water a cloudy appearance. Traction occurs when the river pushes or rolls large particles, such as boulders or rocks, along the riverbed. Plucking, on the other hand, is a process that occurs in glacial environments, not rivers. It happens when ice freezes onto rocks and then pulls pieces of those rocks away as the glacier moves. So, plucking is not a process through which a river transports its load.

Bayanin Amsa

Rural settlements can provide urban settlements with agricultural products such as fruits, vegetables, and grains. These products are essential for sustaining the population of urban settlements, as they provide food and raw materials for various industries. Additionally, rural settlements can also provide employment opportunities for individuals in urban settlements who may seek work in agricultural fields. This can help ease the burden of high unemployment rates in urban areas. While rural settlements may not directly provide manufactured goods or ideas and innovations, their provision of agricultural products and employment opportunities can indirectly contribute to the development and growth of urban settlements.

Bayanin Amsa

The description refers to a dispersed settlement. This type of settlement is characterized by houses that are spaced far apart from each other and are often connected by footpaths or roads. In a dispersed settlement, houses are usually located on individual plots of land, rather than being clustered together in a central area like in a nucleated settlement. This type of settlement is commonly found in rural areas where the population density is low, and people prefer to live in a more isolated and quiet environment.

Bayanin Amsa

The basin you are describing is called an "artesian basin." An artesian basin is a geological formation where permeable rock, such as sandstone, holds water that is trapped by layers of impermeable rock, such as shale. This water is under pressure because it is confined within the layers of rock, so when a well is drilled into the basin, the water will naturally flow to the surface without the need for a pump. Imagine a water balloon that is squeezed between two flat surfaces. The water inside the balloon is trapped and under pressure, just like the water in an artesian basin. When you poke a hole in the balloon, the water will flow out because of the pressure, just like the water in an artesian well. In summary, an artesian basin is a geological formation where water is trapped between layers of rock and is under pressure, allowing it to flow naturally to the surface without the need for a pump.

Bayanin Amsa

Of the options given, ox-bow lakes are not typically found in the upper course of a river. Ox-bow lakes are formed when a meandering river erodes the outer bank of a bend, causing the river to change course and cut off the meander. The abandoned meander then becomes an ox-bow lake. In the upper course of a river, the landscape is characterized by steep gradients, rough terrain, and rapid erosion. V-shaped valleys, interlocking spurs, and waterfalls are common features in this area. Interlocking spurs are ridges of higher land that protrude into the valley and force the river to wind its way around them. Waterfalls are formed when a river falls from a height, creating a plunge pool at the bottom. V-shaped valleys are created by the erosion of the river channel as it cuts its way down through the landscape.

Bayanin Amsa

The direction of wind is recorded by an instrument called a "wind vane". A wind vane, also known as a weather vane, is a simple device that is typically mounted on a rooftop or tower to measure the direction of the wind. It consists of a flat or curved plate that is balanced on a vertical rod or spindle, with one end of the plate wider than the other. The narrow end of the plate is designed to point into the wind, while the wider end is shaped like an arrow to indicate the wind direction on a compass or other directional scale. Wind vanes are often used in combination with other weather instruments, such as an anemometer for measuring wind speed, to provide a complete picture of atmospheric conditions.

Bayanin Amsa

An area is said to be overpopulated when it has more people than the resources available to support them. This means that the population exceeds the capacity of the land to produce enough food, water, and shelter for everyone. Overpopulation can lead to poverty, malnutrition, disease, and other negative consequences. It is not just about the lack of food or migration, but the inability of the area to support the number of people living there.

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Bayanin Amsa

The rock that is used for fuel is called lignite. Lignite is a type of sedimentary rock that is formed from compressed peat. It is brown in color and has a soft texture, which makes it easy to mine. Lignite is used as a fuel because it has a high moisture content and low carbon content, which means it burns easily and produces a lot of heat. Lignite is mainly used to generate electricity in power plants, and it is also used as a fuel in some homes for heating and cooking. So, if you are looking for a rock that is used for fuel, the answer is lignite.

Bayanin Amsa

(a)(i) Formation of erosional plains

Erosional (denudation) plains are formed by the long-continued wearing down of a former highland by agents of denudation. Rivers, ice, wind and weathering slowly strip away the raised land over a very long period until the surface is reduced almost to a low, gently undulating plain (a peneplain). Continuous weathering, erosion and transport of the loosened material lowers the land close to base level, leaving occasional resistant remnants (monadnocks) standing above the plain.

(a)(ii) Formation of a dissected plateau

A dissected plateau is formed when an upland or plateau is cut into (dissected) by rivers. After uplift, active rivers flowing across the plateau erode deep, steep-sided valleys and gorges into it. Continued vertical (down-cutting) erosion by many streams divides the once continuous upland surface into separate blocks, ridges, spurs and flat-topped hills, giving a rugged, broken plateau surface.

(b) Advantages and disadvantages of plains

Advantages

• The flat, gentle land encourages agriculture, since it is easy to cultivate and often has deep, fertile alluvial soils.
• They favour settlement and construction of roads, railways and towns because building is easy and cheap.

Disadvantages

• Low, flat plains near rivers are liable to flooding and may become waterlogged/swampy.
• They may suffer poor drainage and, in dry areas, can be exposed and monotonous, encouraging soil erosion by wind or sheet wash.

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(a) Five reasons why my country (Nigeria) has more trading partners outside Africa

• Similar products within Africa: most African countries produce the same primary goods (cash crops, minerals), so they have little to exchange with one another.
• Demand for manufactured goods: Nigeria imports machinery, vehicles, and technology which are produced mainly in Europe, America and Asia, not in Africa.
• Colonial ties and established links: long-standing trade relations built during the colonial era orient trade toward former colonial powers overseas.
• Ready market for raw materials/oil: industrialised countries outside Africa provide a large market for Nigeria's crude oil and raw materials.
• Poor intra-African transport and communication: weak road, rail and shipping links between African countries make trade with them difficult and costly.

Other reasons: differences in currency and trade barriers within Africa, and the higher purchasing power of countries outside Africa.

(b) Five ways trade between my country and other African countries could be improved

• Improve transport links (roads, railways, shipping and air routes) connecting African countries.
• Remove or reduce trade barriers such as high tariffs and border restrictions, and strengthen bodies like ECOWAS and the AfCFTA.
• Diversify production so that countries produce different goods that can be exchanged.
• Introduce a common currency or better currency-exchange arrangements to ease payment.
• Promote regional cooperation, joint industries and common markets, and improve communication and information about available goods.

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(a) Outline map of Nigeria showing oil palm and cattle rearing areas

On the outline map below, the oil palm production area is shaded in the south-east (the Niger Delta / South-Eastern belt), the cattle rearing area is shaded in the far north (the Sudan / Sahel savanna belt), and the required towns are marked with dots and named.

• (i) Oil palm production area: the South-East / Niger Delta belt (Imo, Abia, Akwa Ibom and Rivers area), shaded green.
• (ii) Cattle rearing area: the far northern Sudan / Sahel savanna belt (Sokoto, Kano, Katsina and Borno area), shaded brown.
• (iii) One town in the oil palm area: Aba.
• (iv) Two towns in the cattle rearing area: Kano and Sokoto.

(b) Three factors that favour cattle rearing in the northern area

1. Abundant pasture and savanna vegetation: the extensive grassland of the Sudan and Sahel savanna provides plentiful natural grass for the cattle to graze on.
2. Absence of the tsetse fly: the dry northern climate is largely free of the tsetse fly, so the cattle are not attacked by trypanosomiasis (sleeping sickness).
3. Favourable climate and wide grazing land: the moderate rainfall of about 50 - 125 cm per year with low relative humidity encourages grass growth, while the vast, flat open plains allow the herds to move and graze freely.

(c) Three ways in which cattle rearing is of importance to Nigeria

1. Source of food: cattle supply meat, milk and other dairy products, providing protein for the population.
2. Source of income and employment: the rearing, sale and processing of cattle provide a livelihood for herders, traders and butchers, and yield revenue to government through cattle tax (Jangali).
3. Source of raw materials: hides and skins from cattle are used in the leather and allied industries, while the dung provides organic manure for farming.

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(a) Sketch map of Africa showing the named rivers

(b) Characteristics of African rivers

1. Most African rivers have rapids, cataracts and waterfalls, especially where they cross plateaux and escarpments.
2. Many rivers show seasonal fluctuation in volume: they have more water and may flood during the rainy season, but their volume falls greatly in the dry season.
3. Many African rivers are shallow and fast-flowing, and their courses are often interrupted by rapids and falls; this limits navigation.
4. They carry much silt, mud and other debris, particularly in the rainy season, and may deposit this material to form flood plains and deltas.

(c) Uses of African rivers

1. They provide water for domestic use, irrigation and industries.
2. They are used for the generation of hydro-electric power at dams, rapids and waterfalls.
3. They support fishing, transport and tourism, and their alluvial deposits provide fertile soils for farming.

Bayanin Amsa

(a) Four advantages of concentrating industries in urban areas

• Availability of labour: large urban population supplies both skilled and unskilled workers.
• Good infrastructure: ready supply of electricity, water, roads, railways and ports serves the industries.
• Large market: the dense urban population and high purchasing power provide a ready market for goods.
• Availability of capital and services: banks, insurance and other financial and repair services are concentrated in towns, and firms benefit from linkages with one another (economies of agglomeration).

(b) Three disadvantages of concentrating industries in urban areas

• Pollution of air, water and land, and noise, harming health.
• Overcrowding, traffic congestion and pressure on housing and services (slums, high rents).
• Regional imbalance: rural areas are neglected and their people migrate to the towns; land and labour costs also rise.

(c) Three factors for the dominance of light industries in developing countries

• Low capital requirement: light industries (food processing, textiles, soap) need little capital, which suits countries short of investment funds.
• Use of local raw materials and simple technology: they process locally available agricultural raw materials and do not need advanced machinery or highly skilled labour.
• Ready local market and small scale: they produce consumer goods for the immediate local population and can operate on a small scale, matching low demand and limited power/energy supply.

Bayanin Amsa

None

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(a) Transportation

Transportation is the movement of people, goods and services from one place to another using various means such as roads, railways, waterways, pipelines and air.

(b) Four advantages of air transportation

• It is the fastest means of transport, ideal for long distances.
• It can reach remote and difficult areas (mountains, deserts, islands) not served by roads or rail.
• It is not restricted by physical barriers on the ground such as rivers, hills or forests.
• It is suitable for carrying perishable, urgent and valuable goods and for emergency/relief services.

(c) Five contributions of transportation to economic development

• Promotes trade and commerce by moving goods from areas of production to markets and consumers.
• Opens up remote areas for farming, mining and settlement, aiding regional development.
• Creates employment for drivers, pilots, mechanics, loaders and transport workers.
• Aids industrialisation by moving raw materials to factories and finished goods to markets.
• Encourages tourism and links, generating revenue, and speeds the movement of labour and information, boosting overall growth.

Bayanin Amsa

(a) Reducing the map to a scale of 1:300,000

The original extract is drawn to a scale of \(1:100{,}000\) and measures 37.5 cm long by 36.6 cm broad. To redraw the outline at \(1:300{,}000\) every distance must be reduced to one-third, because the new denominator is three times larger:

The representative fraction of the reduced outline is therefore

The outline is drawn as a rectangle 12.5 cm long by 12.2 cm wide. On it the four required features are marked: (i) the low, flat land bordering the river channel is outlined and shaded as the area liable to flooding; (ii) the full course of River Rafin Bela is drawn from its source to its mouth with an arrowhead pointing downstream to show the direction of flow; (iii) the settlements of TILLI and ZOGIRMA are each shown by a small circle and named; and (iv) the 800 ft contour enclosing ZANUA HILL is drawn and the ground above it shaded completely.

(b) Four distinct drainage features on the map

1. Meanders - pronounced looping bends along the course of River Rafin Bela.
2. Watersheds - the high ground (including Zanua Hill) separating one drainage basin from the next.
3. Floodable (flood) plains - the wide, flat, low-lying land bordering the river channel.
4. Braiding - the division of the river into several interlacing channels around bars of deposited sediment.

River valleys and a dendritic (tree-like) drainage pattern are also clearly present on the extract.

(c) Six features along the minor road from Rafin Tsaka to Nageda

Human features:

1. Settlements (small nucleated villages along the route).
2. Bench marks (survey height points beside the road).
3. Areas of scattered cultivation (farm plots).

Physical features:

4. Scrub vegetation.
5. An open plain (flat lowland).
6. A hill and the adjoining river valley.

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(a) Outline map of Africa

The sketch map below shows an outline of Africa with the three required features clearly marked and named: the two belts that receive rainfall in winter (Mediterranean north coast and the south-western Cape), the dominant maritime tropical (mT) South-West Monsoon air mass drawn northwards across the Equator in July, and the northernmost July position of the Inter-Tropical Convergence Zone (ITCZ) over the Sahel.

Key to the map

• (i) Winter-rainfall areas (shaded): the Mediterranean coastlands of the extreme north (Atlas region of Morocco, Algeria, Tunisia) and the south-western Cape of South Africa. Both have a Mediterranean climate with hot, dry summers and mild, wet winters.
• (ii) Dominant air mass in July: the moist maritime tropical (mT) South-West Monsoon (equatorial maritime air) is drawn from the South Atlantic north-eastwards across the Equator into West and Central Africa, bringing the summer rains. The hot, dry continental tropical (cT) air dominates the Sahara to the north of the ITCZ.
• (iii) Position of the ITCZ in July: it lies in its northernmost position, well north of the Equator over the Sahel and southern Sahara (about 20°N).

(b) Effects of altitude on the climate of Africa

Altitude (height above sea level) strongly modifies the climate that latitude alone would produce, so that even places on the Equator can be cool. Its main effects are:

1. Temperature falls with height. Temperature decreases at an average rate of about \(6.5^{\circ}\text{C}\) for every \(1000\ \text{m}\) of ascent (the environmental lapse rate). Highland areas such as the Ethiopian Highlands, the Jos Plateau and the Kenya Highlands are therefore markedly cooler than the surrounding lowlands even though they lie near the Equator.
2. Cooler, temperate-like highland climates. Because of this cooling, equatorial highlands enjoy a pleasant, temperate-type climate that has attracted dense settlement and farming (for example the Kenya Highlands and the Jos Plateau).
3. Snow and ice on high peaks. The temperature drop is so great on the highest mountains that Kilimanjaro and Mount Kenya carry permanent snow and ice caps despite standing almost on the Equator.
4. Thinner air causes rapid heat loss. At high altitude the air is thin and contains less dust and water vapour, so it holds little heat and allows the ground's heat to escape (radiate) rapidly, especially at night. This gives large diurnal temperature ranges and cool nights on plateaux such as Jos.
5. Relief (orographic) rainfall. Highlands force moist air to rise, cool and condense, giving heavy relief rainfall on the windward slopes, while the leeward slopes lie in a dry rain-shadow with scanty rainfall.
6. Illustrative comparison. Nairobi and Mombasa lie on almost the same latitude, yet Nairobi, standing high on the plateau at about \(1675\ \text{m}\), has a much lower mean annual temperature than the coastal city of Mombasa near sea level. Using the lapse rate, the altitude difference alone accounts for a cooling of roughly \(\frac{1675}{1000}\times 6.5 \approx 10.9^{\circ}\text{C}\), confirming that altitude, not latitude, explains the contrast.

Bayanin Amsa

None

Bayanin Amsa

(a) The Solar System

The solar system consists of the Sun and all the heavenly bodies held by its gravitational pull and revolving round it. The Sun is at the centre of the system and is the main source of light and heat.

It consists of eight major planets—Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune—which move round the Sun in elliptical orbits. The planets do not produce their own light; they shine by reflecting light from the Sun.

The solar system also contains natural satellites (moons), asteroids, comets, meteoroids and dwarf planets. Pluto, formerly regarded as the ninth planet, is now classified as a dwarf planet. Mercury is the closest planet to the Sun, while Venus is the hottest planet. Jupiter is the largest planet.

(b) Characteristics of Planets

(i) Pluto

• It is a dwarf planet located in the outer region of the solar system.
• It is very far from the Sun and is therefore extremely cold.
• It takes about 248 Earth years to complete one revolution round the Sun.
• It has a highly elliptical and inclined orbit, and it has moons, the largest of which is Charon.

(ii) Mercury

• It is the closest planet to the Sun, at about 58 million kilometres away.
• It is the smallest of the eight major planets.
• It takes about 88 days to complete one revolution round the Sun.
• It has no natural satellite and has very high daytime and very low night-time temperatures. Venus, not Mercury, is the hottest planet.

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(a) Outline map of Nigeria showing the required features

The sketch below is an outline of Nigeria with the four features correctly located: Lake Kainji on the River Niger in the west-central area (Niger State), an area of extinct volcanoes on the Biu Plateau in the north-east, the Udi Hills near Enugu in the south-east, and the River Hadeija flowing eastward across the far north toward the Chad Basin.

(b) Four problems of development in the Eastern Borderland

1. Rugged relief: the highlands and dissected slopes of the Eastern Borderland (Obudu, Mambilla, Oban hills) make road building, mechanised farming and settlement expansion very difficult and costly.
2. Severe soil erosion: the steep slopes and heavy rainfall combine with continuous cropping to produce gully erosion that destroys farmland, roads and buildings.
3. Poor transportation network: the broken terrain leaves the area with few good roads and almost no rail links, so movement of people and evacuation of farm produce is slow and expensive.
4. Remoteness and inaccessibility: the borderland is far from the main urban and industrial centres, which limits access to markets, social amenities and government services and encourages rural-urban migration.

(c) Two solutions to the problems highlighted in (b)

1. Construction of better roads: building and tarring well-engineered roads (with bridges and culverts across the rugged relief) opens up the borderland, reduces remoteness, links farms to markets and gives access to social services.
2. Re-afforestation and terrace/strip farming: planting trees on the bare slopes and cultivating along terraces or contour strips binds the soil, breaks the flow of run-off and checks the gully erosion that is destroying the land.

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A Geographical Account of Tropical Grasslands (Savanna)

(a) Location

Tropical grasslands, also called the Savanna, lie between latitudes 5° and 20° North and South of the Equator, forming a broad belt on either side of the equatorial forest. The main regions are:

• Central America and the Llanos of northern (north-western) South America.
• The interior of Brazil (the Campos).
• The interior of West Africa (the Sudan belt, e.g. northern Nigeria).
• Parts of East Africa (Kenya and Tanzania).
• South-East Asia and Northern Australia.

(b) Climatic factors affecting the distribution

The distribution of the Savanna is controlled by the seasonal migration of the rain-bearing winds, which gives a hot climate with one wet season and one dry season. Its main features are:

1. High mean monthly temperatures of about 27°C throughout the year.
2. A fairly high annual temperature range of up to about 11°C.
3. Moderate annual rainfall of about 600 mm to 1500 mm.
4. Rainfall is seasonal with a single maximum, concentrated in the high-sun (summer) months.
5. Summer rainfall and pronounced winter (low-sun season) drought.
6. Relative humidity is high (above 60%) during the rains and lower (about 40%) in the dry season.

These figures are best shown on a climate graph of a typical Savanna station. The temperature curve stays high all year while the rainfall bars rise sharply to a single peak in the wet season, confirming the wet-and-dry rhythm of the region:

From the graph, total annual rainfall is about 867 mm (within the 600 to 1500 mm range), the wettest month is August (250 mm) while November to February are almost rainless. Temperature ranges from about 22°C in the coolest month to 32°C in the hottest, a range of about 10°C, and the mean is roughly 27°C. The single rainfall maximum and the constantly high temperatures are the two climatic controls that separate the Savanna from the equatorial forest to the south and the desert to the north.

(c) Vegetation characteristics

1. The dominant vegetation cover is grass.
2. Tall grasses with fibrous roots, such as elephant grass, dominate the wetter margins.
3. Short, scattered trees grow among the grasses, giving a park-like appearance.
4. The trees are largely deciduous, shedding their leaves in the dry season to reduce water loss.
5. Many trees have large trunks that store water for the long dry period.
6. Common trees include the Baobab and Acacia.
7. Most trees have rough, thick and thorny bark as protection against drought and fire.
8. Grasses are often succulent during the rains but wither and turn brown in the dry season.
9. A typical grass of the region is the elephant grass.

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(a) Outline map of Nigeria showing areas of population density

(b) Three factors responsible for the dense population of the South-East

1. Fertile soils and favourable climate: the region has fertile land and a reliable rainfall that support intensive farming and a dependable food supply, so it can carry a large number of people.
2. Commercial and industrial activity: busy trading and manufacturing centres such as Onitsha, Aba and Nnewi offer wide employment and business opportunities that attract and hold people.
3. Good social amenities and long settlement: the availability of schools, hospitals, water, electricity and a dense network of roads, together with the long history of settled Igbo communities, has encouraged a heavy concentration of people.

(c) Three problems of the dense population of the South-East

1. Overcrowding and housing shortage: too many people compete for limited housing, leading to high rents, congestion and the growth of slums with poor sanitation.
2. Pressure on land and social amenities: farmland becomes fragmented and scarce, and schools, hospitals, water and other services are overstretched, while unemployment rises as jobs cannot match the number of people.
3. Environmental and social strains: heavy population brings traffic congestion, pollution, poor waste disposal, soil erosion from over-use of land, and a higher crime rate.

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(a) Definition of flooding

Flooding is the overflowing of water beyond its normal channel so that it covers land which is usually dry. It occurs when the volume of water in a river, lake or coastal area exceeds the capacity of its channel or basin and spills onto the surrounding land (the flood plain).

(b) Causes of flooding

• Heavy and prolonged rainfall that supplies more water than the river channel can hold.
• Poor or blocked drainage, for example gutters and channels clogged with refuse.
• Overflowing of rivers and release of water from dams/reservoirs.
• Deforestation and removal of vegetation, which increases surface run-off.
• Building on flood plains and water channels, and rising sea level/storm surges along coasts.

(c) Effects of flooding

• Loss of lives and outbreak of water-borne diseases such as cholera.
• Destruction of property, houses, roads, bridges and other infrastructure.
• Destruction of farmlands and crops, leading to food shortage and hunger.
• Displacement of people (homelessness) and disruption of movement and business.
• Some deposition of fertile silt on flood plains (a positive effect).

(d) Solutions to flooding

• Construct and maintain good drainage channels, dams and embankments.
• Clear blocked drains and stop dumping of refuse in channels.
• Afforestation and protection of vegetation to reduce run-off.
• Prohibit building on flood plains and enforce proper physical planning.
• Public education and an early-warning system for heavy rains.

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(a) Environmental intervention

Environmental intervention refers to the actions, forces or processes (natural or human) that interfere with, alter or modify the natural environment. It is any deliberate or natural interference that changes the condition of the land, water, air or ecosystems.

(b) Types

(i) Natural intervention (two):

• Earthquakes and volcanic eruptions.
• Flooding, drought, erosion or storms.

(ii) Human intervention (two):

• Deforestation and bush burning.
• Mining, dam construction, farming and industrialisation.

(c) Five effects of natural and human interventions on the environment

• Soil erosion and land degradation, for example gully erosion from deforestation and heavy rain.
• Loss of vegetation and wildlife (loss of biodiversity) through clearing, burning and habitat destruction.
• Pollution of air, water and land from industries, mining and waste.
• Flooding and displacement of settlements from heavy rain, dam failure or blocked drainage.
• Desertification and climate change (drought, global warming), plus destruction of property and loss of lives from disasters such as earthquakes and volcanic eruptions.