WAEC SSCE - Geography - 2011

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

The most permanent physical property of the soil is its texture. Soil texture refers to the relative proportions of different-sized mineral particles in the soil, such as sand, silt, and clay. The texture of the soil determines its ability to retain and transmit water and nutrients, as well as the amount of air available for plant roots. Soil texture can change over time due to erosion, weathering, and other factors, but it is generally considered to be a relatively stable characteristic of soil.

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In areas where folding has occurred, oil and natural gas usually collect in synclines. Synclines are trough-like folds in the Earth's crust where the beds dip towards each other. As sediments accumulate in these troughs, they can form reservoirs where hydrocarbons such as oil and natural gas can collect and accumulate. The hydrocarbons are trapped by impermeable rock layers, such as shale or salt, that prevent them from escaping to the surface. Therefore, synclines are often targeted for oil and gas exploration and drilling.

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Tourism is the leading industry in The Gambia. The Gambia is known for its beautiful beaches, wildlife, and rich cultural heritage, which attract tourists from around the world. The tourism industry contributes significantly to the country's economy, providing employment opportunities and generating foreign exchange earnings. In contrast, while Ghana, Liberia, and Nigeria have tourism potential, their leading industries are agriculture, mining, and oil and gas, respectively.

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A warm ocean current is a current that flows from the tropics towards the poles and brings warmer water with it. Among the given options, the Mozambique Current is a warm ocean current. It flows southwards along the east coast of Africa from the equator and transports warm water towards the southern tip of Africa. The California Current is a cold ocean current that flows southward along the western coast of North America, while the Benguela Current is a cold ocean current that flows northward along the southwestern coast of Africa. The West Wind Drift is a cold ocean current that circles Antarctica in the Southern Ocean.

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Soil erosion is a major problem in the highlands of West Africa due to factors such as deforestation, overgrazing, and unsuitable agricultural practices. The options listed in the question provide possible solutions to the problem of soil erosion except for one. Option A, "indiscriminate felling of trees," involves cutting down trees without considering their impact on soil conservation. This practice increases the rate of soil erosion and is, therefore, not a solution to the problem. Option B, "rotational grazing," involves dividing a large pasture into smaller areas and rotating the grazing of livestock between these areas. This helps to prevent overgrazing, reduces soil compaction, and allows grass to grow back. Option C, "strip cultivation," involves planting crops in strips or rows and leaving spaces between them. This method reduces soil erosion by allowing rainfall to infiltrate the soil instead of running off. Option D, "planting of shelter belts," involves planting trees or shrubs around farmlands to provide protection against wind and water erosion. This helps to stabilize the soil, reduce runoff, and provide habitat for wildlife. Therefore, the answer is option A, "indiscriminate felling of trees," as it exacerbates soil erosion rather than solving it.

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The angle of difference between the true North and magnetic North is known as magnetic declination. This angle varies depending on the location on the Earth's surface and changes over time due to fluctuations in the Earth's magnetic field. Magnetic declination is important for navigation, especially when using a compass to find directions. It is necessary to correct for magnetic declination when using a compass to get accurate readings of true North.

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The solar system comprises the Sun and all the objects that orbit around it. These objects include planets, dwarf planets, moons, asteroids, comets, and other small bodies. The most well-known components of the solar system are the eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) and their respective moons. These objects all revolve around the Sun, which is at the center of the solar system. Therefore, the correct option is "the sun and its nine planets."

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Argon in the lower atmosphere is of little use to man, plants, and animals. Argon is an inert gas and it makes up about 0.93% of the Earth's atmosphere. It is colorless, odorless, and non-reactive with other elements, so it has no significant role in supporting life or other natural processes. Carbon dioxide is used by plants during photosynthesis, oxygen is vital for respiration and nitrogen is essential for the growth and development of plants.

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Descending wind does not encourage the formation of rainfall. When air descends, it warms up and becomes drier because its ability to hold moisture increases with temperature. This warm, dry air evaporates moisture from the ground, plants, and other sources, leading to arid conditions. Therefore, descending wind does not lead to the formation of clouds and rainfall, but rather clear, sunny weather. On the other hand, converging and ascending winds bring moist air together and upward, leading to cloud formation and eventually precipitation. Warm winds also contribute to the formation of rainfall by bringing warm, moist air to cooler regions where it can condense and form clouds.

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Light industries predominate in West Africa because of inadequate capital. This is because light industries require less capital and technology to set up and operate compared to heavy industries. The economies of West African countries are largely based on agriculture, which does not generate much income, leading to limited investment capital. Therefore, entrepreneurs in West Africa tend to start small-scale industries that require less capital, such as textile mills, food processing plants, and furniture making. These industries also provide employment opportunities for the rapidly growing population, making them a viable option for economic growth. However, the limited capital also affects the quality and quantity of output as well as the competitiveness of the industries.

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Aluminum is used largely in the aviation industry because of its lightweight and high strength properties. It is also corrosion-resistant and has good electrical conductivity, making it suitable for use in aircraft construction, such as for the manufacturing of aircraft frames, fuselage, wings, and other parts. Aluminum's lightweight properties help in reducing the overall weight of an aircraft, which in turn reduces fuel consumption and operational costs. Therefore, aluminum is a preferred material for the aviation industry.

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The lowest layer of the Earth's atmosphere is called the troposphere. This is the layer closest to the Earth's surface and extends from the ground up to an average height of about 12 kilometers (7.5 miles). The troposphere contains most of the Earth's weather and is where we live and breathe. This is the layer where clouds and precipitation form, and where temperature generally decreases with altitude. The other layers of the atmosphere are the stratosphere, mesosphere, thermosphere, and exosphere, and each of them have different characteristics and functions.

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The harmattan is a dry and dusty West African trade wind that blows from the Sahara towards the Gulf of Guinea between November and February. Therefore, the correct answer is November to January.

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The type of weathering that is common in humid tropical areas is hydrolysis. Hydrolysis is a chemical weathering process in which water reacts with minerals in rocks, causing them to break down and decompose. The warm and moist climate in humid tropical areas accelerates this process, making it the dominant type of weathering in these regions. This type of weathering is important in the formation of clay minerals, which are abundant in tropical soils.

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A conurbation is a build-up area that consists of a number of towns or cities merged together yet maintaining their individual identities. It is a continuous urban area that is formed by the expansion and merging of several cities or towns. This leads to the formation of a larger metropolitan area. Examples of conurbations include the Greater London Urban Area, which consists of London and the surrounding cities and towns that have grown together over time.

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The term "sial" is derived from the words silica and aluminum, which are the two most abundant elements in the upper part of the Earth's crust. The upper part of the Earth's crust is composed mainly of rocks such as granite and basalt, which contain high amounts of silica and aluminum. Therefore, the mineral contents of the upper part of the Earth's crust are collectively called sial. Olivine and phosphate are not major components of the sial.

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Desert areas experience high daily range of temperature mainly because the sky is cloudless. Clouds play an important role in regulating temperature because they reflect some of the incoming solar radiation back into space and trap some of the outgoing heat radiation from the earth's surface. In the absence of clouds, the earth's surface receives a lot of solar radiation during the day, which causes the temperature to rise. At night, the earth's surface loses heat radiation rapidly, which causes the temperature to drop. Therefore, in desert areas where there are no clouds to regulate the temperature, there is a high daily range of temperature, with very hot days and very cold nights.

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The treaty which formally established ECOWAS was signed on May 28th, 1975.

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The correct option is: II and IV. Most large cities are typically commercial centers where business and trade activities thrive due to the high concentration of people and resources. They also tend to be capital cities, serving as administrative centers for government and political activities. However, large cities are not typically associated with large plantations or being religious centers, as these tend to be found in rural areas or smaller towns.

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Maelezo ya Majibu

The correct answer is nitrogen. Nitrogen makes up about 78% of the Earth's atmosphere, which means it is the most abundant gas in terms of total volume. Oxygen is the second most abundant gas, making up about 21% of the atmosphere, and the remaining 1% consists of other gases such as argon, carbon dioxide, neon, helium, and hydrogen.

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Descending wind does not encourage the formation of rainfall. Descending air warms adiabatically (without exchange of heat with the surrounding), leading to an increase in temperature and a decrease in relative humidity. This results in a reduction of cloud formation, leading to clear skies and dry weather. Therefore, option C, descending wind, does not encourage the formation of rainfall.

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A rock through which water cannot easily pass is termed impermeable. Impermeable rocks do not allow water to pass through them easily due to their compact nature and absence of interconnected pores or fractures. Examples of impermeable rocks include clay, granite, and basalt. Impermeable rocks are important in the formation of aquifers, which are underground layers of permeable rock or sediment that hold and transmit water.

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Air pollution is the contamination of the air with harmful substances that affect human health and the natural environment. Evapo-transpiration is a natural process that involves the evaporation of water from the soil and the transpiration of water vapor from plants into the atmosphere, which does not cause air pollution. On the other hand, the fumes from motor vehicles, the discharge of gases from factories, and volcanic eruptions can release harmful substances such as carbon monoxide, sulfur dioxide, and nitrogen oxides into the air, causing air pollution. Therefore, the answer is evapo-transpiration.

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Maelezo ya Majibu

The acacia tree is commonly found in the savannah lands. Acacia trees are well adapted to survive in the hot and dry conditions of the savannah, with their long roots able to tap into underground water sources. They are also able to survive fires, which are common in the savannah, due to their thick bark and the ability to resprout from their roots. Additionally, acacia trees provide important ecosystem services in the savannah, such as providing food and shelter for a variety of animals, as well as nitrogen fixation which helps to enrich the soil.

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Liberia records the highest rainfall among the given options. Liberia is a country located in West Africa and is known for its tropical rainforest climate. This climate is characterized by high temperatures and high rainfall throughout the year. The country receives an average of 4,500 mm (177 inches) of rainfall annually, making it one of the wettest places on earth. In contrast, Algeria, Mali, and Egypt are located in the Sahara desert and are known for their arid and semi-arid climates, which receive very low levels of rainfall.

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The answer is terracing. Terracing is not a common farming system in West Africa. Crop rotation, rotational bush fallowing, and subsistence farming are common farming systems in West Africa. Crop rotation involves planting different crops in the same field in different seasons to maintain soil fertility and control pests and diseases. Rotational bush fallowing is a farming system where a plot of land is cleared of vegetation and farmed for a few years, and then allowed to lie fallow for a longer period to allow the vegetation to regenerate. Subsistence farming is a type of farming where farmers produce only enough food to feed themselves and their families. It is a common farming system in West Africa, where small-scale farmers grow crops and rear animals for their own consumption. Terracing, on the other hand, is a farming practice where steps are constructed on sloping land to create a flat surface for farming. It is more commonly used in mountainous regions such as Asia and South America, where there is a need to farm on steep slopes.

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The roles of transportation in economic development in West Africa include various aspects such as the movement of goods and services, opening up of new lands, and provision of employment opportunities. However, national disintegration is not a role of transportation in economic development. In fact, transportation can promote national integration by connecting different regions and promoting cultural exchange and understanding. Therefore, the correct answer is "national disintegration".

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Wheat is not a plantation crop in West Africa. Plantation crops are crops that are grown on large-scale farms or plantations, typically for export. In West Africa, common plantation crops include rubber, sugar cane, and coffee. Wheat, on the other hand, is not typically grown in large plantations in West Africa. It is a cereal crop that is more commonly grown in other parts of the world, such as North America, Europe, and Asia. Therefore, the answer is (b) wheat.

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Sea waves are the most effective agent of coastal erosion. This is because waves carry a lot of energy and force, which can cause rocks and other materials on the coast to break down over time. As waves approach the shore, they slow down and become taller, causing them to crash onto the beach with more force. This force can cause erosion by breaking down rocks and carrying sediment away from the coast. Sea currents, underground water, and sea tides can also contribute to coastal erosion, but waves are generally considered to be the most significant factor.

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The answer to this question is ecosystem. An ecosystem is a community of living organisms and their physical environment, which includes both biotic (living) and abiotic (non-living) components. The components of an ecosystem, such as the soil, climate, vegetation, and animal population, are all interdependent and interact with each other in a dynamic way. For example, the vegetation in an ecosystem provides food and habitat for the animal population, which in turn helps to pollinate and disperse seeds, thus maintaining the growth and diversity of the vegetation. The climate and soil type also affect the type of vegetation that can grow in an ecosystem, which then affects the animal population that can live there. Overall, an ecosystem is a complex and interconnected web of relationships between living and non-living components that work together to sustain life.

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