WAEC SSCE - Agricultural Science - 2018

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The pest shown in the diagram is a chewing insect pest. Chewing insect pests are pests that feed on crops by chewing and consuming their plant tissue, resulting in damage or destruction of the crops. Examples of chewing insect pests include caterpillars, grasshoppers, and beetles. In the diagram, the pest has visible mandibles, which are used for chewing and consuming the plant material. Therefore, it can be concluded that the pest shown in the diagram is a chewing insect pest.

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To calculate the percentage change in price, we can use the formula: percentage change = ((new value - old value) / old value) x 100 In this case, the old value is the initial price of 12 Naira and the new value is the reduced price of 8 Naira. Using the formula, we get: percentage change = ((8 - 12) / 12) x 100 percentage change = (-4 / 12) x 100 percentage change = -0.33 x 100 percentage change = -33.33% Therefore, the percentage change in price is -33.33%, which represents a 33.33% decrease from the initial price.

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The yield of the groundnut variety on a 10-hectare farm will be 3,500kg. The yield of the groundnut variety is given as 350kg per hectare. Therefore, to find the yield of the variety on a 10-hectare farm, we need to multiply the yield per hectare by the number of hectares. Mathematically, we can represent this as: Yield on 10-hectare farm = Yield per hectare x Number of hectares Yield on 10-hectare farm = 350kg/ha x 10ha Yield on 10-hectare farm = 3,500kg Therefore, the yield of the groundnut variety on a 10-hectare farm will be 3,500kg.

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The group of raw materials used in textile industries is Cotton, jute, and wool. Cotton is a soft, fluffy fiber that grows in a protective case, or boll, around the seeds of the cotton plants. It is one of the most important and widely used textile fibers because of its excellent properties, including its ability to absorb moisture, breathability, and durability. Jute is a long, soft, shiny vegetable fiber that can be spun into coarse, strong threads. It is primarily grown in India, Bangladesh, and China and is used to make various products, including rope, twine, and textiles. Wool is a natural fiber derived from the fleece of sheep or other animals like alpacas and goats. It is a versatile and resilient fiber, making it an excellent material for various textile applications, such as clothing, blankets, and carpets. These three raw materials are widely used in textile industries for producing different types of clothing, household textiles, and industrial fabrics because of their unique properties and versatility.

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Bush burning does not replenish lost soil nutrients. In fact, it can have the opposite effect by releasing carbon and other nutrients into the atmosphere instead of returning them to the soil. This can lead to a decrease in soil fertility over time. Crop rotation involves planting different crops in the same field over time, which can help restore soil nutrients and prevent soil depletion. Fallowing involves leaving fields unplanted for a period of time to allow the soil to recover and rebuild its nutrient levels. Liming involves adding lime to soil to increase its pH levels, which can improve nutrient availability for plants. Therefore, bush burning is the practice that does not replenish lost soil nutrients.

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The sheller is not a tractor-coupled implement. A tractor-coupled implement is an equipment that is designed to be attached or hooked to a tractor to perform a specific task. For instance, a plough is an implement that is attached to a tractor to prepare the soil for planting by turning the soil over, while a harrow is used to smooth and level the soil after ploughing. A ridger, on the other hand, is used to form ridges on the soil for planting crops like potatoes. A sheller, however, is a machine that is used to remove the outer shell or husk of grains such as maize, beans, and peas. It is usually a standalone equipment that is powered by electricity or a diesel engine, and it does not require a tractor to function. Therefore, the sheller is not a tractor-coupled implement.

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An igneous rock is a type of rock that forms from the solidification of molten or partially molten material, such as magma or lava. Basalt is an example of igneous rock because it is formed by the rapid cooling of lava on the Earth's surface. As lava cools, it solidifies and hardens to form solid rock. Basalt is typically dark in color and has a fine-grained texture. On the other hand, Dolomite, Limestone, and Marble are all examples of sedimentary rocks and metamorphic rocks respectively, and are not formed from solidified lava or magma. Dolomite and Limestone are formed from the accumulation of shells, coral, and other organic debris, while marble is formed from the metamorphism of limestone under intense heat and pressure.

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Thinning is a farm operation in which the number of seedlings per stand is reduced to one or two. Thinning is done to ensure that each remaining seedling has enough space, light, water, and nutrients to grow properly. When too many seedlings are growing in a stand, they compete with each other for resources, and this can lead to reduced growth and yields. By thinning the stand, the farmer can improve the overall health and productivity of the crops.

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The part labelled I in the diagram above is responsible for reducing water to droplets. It does this by creating a narrow opening or nozzle that increases the velocity of the water flowing through it, causing it to break up into smaller droplets. This is useful in farming equipment such as sprayers, where the smaller droplets can be more efficiently dispersed over crops or other surfaces.

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The statement "to increase the cost of production" is not a reason for providing tractor-hiring services to farmers. In fact, the main purpose of providing tractor-hiring services is to help farmers with farm mechanization, increase the area of land to be cultivated and boost food production, not to increase the cost of production. The goal is to make farming more efficient and effective, not to make it more expensive.

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A profit and loss account is a document that is usually prepared at the end of the year. This document provides a summary of the farm's income and expenses over a given period of time, usually a year. The profit and loss account shows the farm's revenues, such as sales of crops or livestock, as well as its expenses, such as seed and fertilizer costs, labour costs, and equipment costs. By subtracting the expenses from the revenues, the profit and loss account determines the farm's overall profit or loss for the year. A farm budget is a document that is used to plan and track the farm's finances over a given period of time, usually a year. The farm budget includes projections for income and expenses and is used to help the farmer make decisions about how to allocate resources and manage costs. A labour record is a document that tracks the hours worked and pay for each employee on a farm. This document is used to keep track of employee hours and pay for payroll purposes and can also be used for tax and record-keeping purposes. A farm inventory is a document that lists all of the farm's assets, such as equipment, livestock, and crops. The farm inventory is used to keep track of the farm's resources and to help the farmer make decisions about how to allocate resources and manage costs.

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The practice of growing arable and forage crops alternately on a piece of land is called ley farming. In ley farming, the land is used to grow crops such as wheat or maize for a few years, and then it is left to grow grass for a year or two. This allows the soil to rest and recover, and also adds nutrients to the soil. After the grass has grown, it can be used for grazing animals or cut for hay or silage. This type of farming is sustainable and helps to maintain soil fertility, while also providing food for both humans and animals.

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Rinderpest is a disease that is caused by a virus. The virus infects cattle and other domesticated animals and can cause serious symptoms such as fever, mouth sores, and diarrhea, which can be fatal. It spreads from animal to animal and can also be spread through contaminated food or water. Brucellosis, Trypanosomiasis, and Tuberculosis are all caused by bacteria, not viruses. Brucellosis is a bacterial infection that affects both animals and humans, causing symptoms such as fever, fatigue, and joint pain. Trypanosomiasis is a parasite-borne illness that is spread by the bite of infected insects, and can cause fever, headache, and muscle pain. Tuberculosis is a bacterial infection that primarily affects the lungs and can cause symptoms such as cough, weight loss, and fatigue.

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The digestion of protein starts in part II of the digestive tract illustrated in the diagram. Part II represents the stomach of the farm animal, where protein digestion begins through the action of enzymes and stomach acids. The stomach lining produces enzymes such as pepsinogen, which is converted to the active enzyme pepsin by the acidic environment of the stomach. Pepsin breaks down protein into smaller peptides and amino acids, which can then be further digested and absorbed in the small intestine. Therefore, part II is where the initial breakdown of protein starts in the digestive process of the farm animal.

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The method of herd mating of the animals is not used in collecting semen for artificial insemination. Herd mating involves allowing the animals to mate naturally within a herd, without any human intervention. This method is not appropriate for collecting semen for artificial insemination because it does not allow for the selection of specific, desirable traits in offspring. Also, it is difficult to monitor and control the breeding process in a herd, which can lead to the production of undesirable offspring. On the other hand, the other three methods mentioned are commonly used to collect semen for artificial insemination. - Massage method: This involves manually stimulating the male animal to produce semen, which is then collected in a special container. - Use of artificial insemination: This involves inserting semen into the female animal using a special device, without the need for natural mating. - Electro-ejaculation method: This involves using an electrical probe to stimulate the male animal's reproductive tract to produce semen, which is then collected in a special container. Each method has its advantages and disadvantages, and the choice of method depends on various factors such as the species of the animal, the size of the animal, and the expertise of the person collecting the semen.

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The observation of the day-old chicks clustering around the source of heat in the brooder house is likely due to low temperature. Chicks have a natural instinct to gather around a heat source to maintain their body temperature, which is crucial for their survival and growth. This behavior is known as thermoregulation, and it helps the chicks stay warm and comfortable in their environment.

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Lycopersicon esculentum, also known as the tomato, is usually classified as a vegetable. This classification is based on the way it is used in cooking and food preparation, where it is typically used in savory dishes and as an ingredient in salads, sauces, and other dishes. Although it is botanically a fruit, it is widely considered to be a vegetable due to its culinary uses.

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To calculate the price elasticity of demand, we need to use the following formula: Price elasticity of demand = Percentage change in quantity demanded / Percentage change in price We can calculate the percentage change in quantity demanded by using the following formula: Percentage change in quantity demanded = ((new quantity demanded - old quantity demanded) / old quantity demanded) x 100 From the demand schedule above, we can see that the old quantity demanded is 200 kg when the price is N12, and the new quantity demanded is 240 kg when the price is N8. Therefore: Percentage change in quantity demanded = ((240 - 200) / 200) x 100 = 20% We can calculate the percentage change in price by using the same formula: Percentage change in price = ((new price - old price) / old price) x 100 In this case, the old price is N12 and the new price is N8. Therefore: Percentage change in price = ((8 - 12) / 12) x 100 = -33.33% Note that the negative sign indicates a decrease in price. Now we can substitute these values into the formula for price elasticity of demand: Price elasticity of demand = Percentage change in quantity demanded / Percentage change in price Price elasticity of demand = 20% / -33.33% Price elasticity of demand = -0.6 The price elasticity of demand for this commodity is -0.6. This means that a 1% decrease in price leads to a 0.6% increase in quantity demanded, and vice versa. Since the elasticity is greater than 1, demand is considered elastic, meaning that consumers are relatively sensitive to changes in price. In other words, a small change in price can lead to a relatively large change in the quantity demanded.

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The agricultural extension methods listed involve different ways of providing information and education to farmers. Among the methods listed, a farm visit is the one that is aimed at reaching an individual farmer at a particular time. This method involves an extension agent or expert visiting a farmer's field or farm to provide advice, training, and assistance on various aspects of agricultural production, such as crop management, livestock care, or pest control. During the visit, the agent can observe the farm's specific conditions and needs, and provide tailored recommendations and solutions to the farmer's challenges. Film shows, electronic media, and field trips are other methods that can be used to disseminate information and education to farmers, but they are not aimed specifically at reaching an individual farmer at a particular time. For example, film shows can be used to screen educational videos or documentaries to groups of farmers at a central location, while electronic media, such as radio or TV programs, can reach a wider audience with a variety of topics. Field trips involve taking groups of farmers to visit other farms, research stations or agricultural institutions to learn from demonstrations, lectures or hands-on experiences.

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Hibiscus and croton are examples of hedge plants. Hedge plants are plants that are commonly used to form hedges, which are living fences or boundaries that are often used for privacy, protection, or decoration. Hibiscus and croton are both popular hedge plants because they have dense foliage that can be trimmed and shaped to form a neat, attractive hedge. Hibiscus is a flowering shrub that is known for its large, showy flowers in a variety of colors, including red, pink, white, and yellow. It is often used as a hedge plant in warm, tropical climates. Croton is a tropical shrub that is prized for its colorful foliage, which can range from green and yellow to orange, red, and purple. It is often used as a hedge plant or as a specimen plant in gardens and landscaping. In summary, Hibiscus and croton are examples of hedge plants, which are commonly used to form living fences or boundaries. Hibiscus is a flowering shrub with large, showy flowers, while croton is a tropical shrub with colorful foliage.

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Stylosanthes gracilis is not a pasture grass. Stylosanthes gracilis is a legume, which is a type of plant that fixes nitrogen from the air and adds it to the soil, improving soil fertility. Pasture grasses, on the other hand, are grasses that are grown for livestock to graze on. Examples of pasture grasses include Pennisetum purpureum, Axonopus compressus, and Panicum maximum.

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A disadvantage of vegetative propagation is that diseases are easily transferred to offspring. This is because in vegetative propagation, new plants are grown from a piece of the parent plant, such as a cutting or a runner. If the parent plant is infected with a disease, the disease can be easily passed on to the offspring, as they are genetically identical to the parent plant. This can lead to the spread of the disease throughout a population of plants, and can make it difficult to control the disease. On the other hand, the advantage of vegetative propagation is that the plants are true to type, meaning they have the same genetic characteristics as the parent plant.

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Vitamin K is a fat-soluble vitamin that plays an important role in blood clotting, bone health, and cardiovascular health. In farm animals, a deficiency of vitamin K can cause delayed blood clotting. This means that animals with vitamin K deficiency may experience prolonged bleeding and bruising, which can be life-threatening. However, vitamin K deficiency does not cause night blindness, sterility in both sexes, or delayed ovulation. Night blindness is usually caused by a deficiency in vitamin A, while sterility can be caused by a variety of factors, such as hormonal imbalances, infections, or genetic abnormalities. Delayed ovulation, on the other hand, can be caused by factors such as stress, poor nutrition, or hormonal imbalances.

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Giving the animal access to colostrum is the practice that ensures that a young animal has resistance against diseases. Colostrum is the first milk produced by the mother animal after giving birth, and it contains high levels of antibodies and nutrients that help to protect the young animal against diseases. When a young animal ingests colostrum, these antibodies are absorbed into their bloodstream and help to build up their immune system, providing them with a natural defense against various diseases. This protection is especially important during the first few days of life when the young animal is most vulnerable to infection. Regular visits to the veterinary doctors can help ensure that the animal is healthy and receiving proper care, while giving the animal a maintenance ration can help ensure that it is receiving the proper nutrients to support its immune system. Regular dipping of the animal can help prevent external parasites and bacterial infections. However, access to colostrum is the most critical practice for ensuring that a young animal has resistance against diseases.

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The percentage change in quantity demanded is 20.00%. Percentage change can be calculated using the formula: ((new value - old value) / old value) x 100 In this case, the old quantity demanded is 200 kg and the new quantity demanded is 240 kg. Using the formula, we can calculate the percentage change as follows: ((240 - 200) / 200) x 100 = 40 / 2 = 20.00% Therefore, the percentage change in quantity demanded is 20.00%. This means that the quantity demanded has increased by 20.00% from the old quantity demanded of 200 kg.

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The offspring resulting from the cross of a homozygous brown cowpea and a homozygous black cowpea are called F1 generation. Assuming that brown color is dominant over black color, the genotype of the homozygous brown cowpea can be represented as BB (where B represents the allele for brown color) and the genotype of the homozygous black cowpea can be represented as bb (where b represents the allele for black color). When these two plants are crossed, all the F1 offspring will be heterozygous (Bb) because they receive one allele from each parent. Since brown color is dominant over black color, all the heterozygous offspring will display the brown color. Therefore, the percentage of F1 offspring with brown color will be 100%. In summary, if a homozygous brown cowpea is crossed with a homozygous black cowpea, all the F1 offspring will be heterozygous (Bb) and display the dominant brown color. Thus, the percentage of F1 offspring with brown color will be 100%.

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The structure of loam could be described as crumbly. Loam is a type of soil that is made up of a mixture of sand, silt, and clay particles in roughly equal proportions. This balanced composition gives loam its unique texture, which is crumbly and friable. This means that it can be easily broken down into small pieces or crumbs when you squeeze it in your hand. This crumbly texture allows for good water retention and air circulation, making loam a suitable soil for growing a variety of plants.

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The chemical composition of soil is mostly influenced by its parent material. Parent material is the underlying geological material, such as rock or sediment, that has been weathered and broken down over time to form soil. The chemical composition of the parent material determines the initial chemical composition of the soil, including the types and amounts of minerals present. For example, if the parent material is a type of granite, the soil will likely have a high concentration of minerals such as feldspar and quartz. Other factors such as climate, time, and topography can also influence the chemical composition of soil, but these factors typically have a more indirect or secondary influence. For example, climate can affect the rate of weathering and nutrient cycling, which can in turn affect the chemical composition of soil. Time can also influence the chemical composition of soil as weathering and biological activity continue to break down the parent material and alter the soil over time. Topography, or the physical features of the landscape, can influence the distribution of soil types and the movement of nutrients and minerals within the soil. Overall, the chemical composition of soil is a complex interplay of multiple factors, but the underlying parent material is the most significant determinant of its initial chemical composition.

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The land tenure system which involves the outright purchase of land is called freehold. Freehold is a land ownership system in which an individual or organization has the full and permanent ownership of the land and any property built on it. In other words, when someone buys a property on a freehold basis, they own the land and the buildings on it outright and can use it for any legal purpose. The freehold land tenure system is most common in developed countries like the United States, Canada, and the United Kingdom. It is often seen as a preferred form of ownership as it gives the owner the most control over the land, and they have the freedom to use, sell, or lease the land as they wish. In summary, the freehold land tenure system allows an individual or organization to own land outright, giving them complete control over its use and development.

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One advantage of crossbreeding is that the offspring may perform better than the average of the parents. Crossbreeding is the process of mating two different breeds or lines of animals to produce offspring with desirable characteristics from both parents. The process of crossbreeding can result in offspring that have a combination of the desirable traits from each parent, resulting in offspring that are superior to their parents in terms of traits such as growth rate, disease resistance, and fertility. This is known as hybrid vigor, or heterosis, and it occurs because the offspring inherit different sets of genes from each parent, which can result in complementary gene interactions that enhance the offspring's performance. In contrast to the other options listed, crossbreeding does not necessarily result in offspring resembling the recessive parent, the yield of the offspring may be comparable to those of the parents, and offspring can survive adverse environmental conditions, depending on the specific traits selected for by the breeder.

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The groundnut plant showing stunted growth with yellow or mottled leaves is likely to be infected with Rosette. Rosette is a viral disease that affects groundnut plants and causes stunted growth with yellow or mottled leaves. The virus is transmitted by an eriophyid mite and can also cause the plant to produce smaller pods and fewer nuts. The infected plants also exhibit the formation of small rosettes of leaves at the top of the plant, which is a characteristic symptom of this disease. Unfortunately, there is no cure for Rosette, and the only way to manage it is by preventing the spread of the disease through the use of disease-free seed, controlling the mite population, and removing infected plants from the field.

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Bees are regarded as the friends of farmers because they help in pollination. Pollination is the process by which plants transfer pollen from the male part of a flower to the female part, which results in the fertilization of the plant and the production of fruits and seeds. Bees play a crucial role in pollination, as they move from flower to flower collecting nectar and pollen, and unintentionally transfer pollen between flowers, which leads to the fertilization of the plant. This process helps farmers to increase their crop yields and produce better-quality fruits and vegetables. Additionally, bees also produce honey, which can be harvested and used by humans. While bees may sting if they feel threatened, they are generally not harmful if left alone and respected.

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Ornamental plants are usually grown for their beauty and aesthetic appeal, making them ideal for exterior decorations in gardens, homes, and public spaces. These plants are specifically cultivated for their visual appeal rather than their utility or practical purposes. They are not typically used as sources of perfumes or for providing shade, as their primary function is to enhance the aesthetic value of their surroundings. Additionally, ornamental plants are not commonly used as bedding materials for animals, as they are not suitable for providing the necessary comfort and support for animals to rest on.

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An effective method of preventing viral diseases in crops is by planting resistant varieties. This means selecting crops that have been bred or genetically modified to be resistant to specific viral diseases. When these resistant varieties are planted, they are less likely to get infected with the virus, and even if they do get infected, the symptoms will be milder and the plant will be able to continue growing. This can help to reduce the spread of the virus and minimize crop loss. Treating the seeds with fungicides, practicing crop rotation, and regular spraying of crops are all methods that can be used to control fungal diseases, but they are not as effective for preventing viral diseases. Fungicides are chemicals that are used to kill or control fungal diseases, but they do not work on viruses. Crop rotation involves planting different crops in a field each year to help control pests and diseases, but it may not be as effective for preventing viral diseases. Regular spraying of crops can help to control pests and diseases, but it may not be as effective for preventing viral diseases, especially if the virus is already present in the crop.

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(a) (i) Soil requirements: Maize thrives in well-drained soils that are rich in organic matter, with a pH between 5.5 and 7.5. The soil should be deep enough to allow for good root growth and have adequate nutrients for plant growth. Soil preparation should involve ploughing or tilling to break up compacted soil and remove weeds. (ii) Method of propagation: Maize is propagated by planting seeds directly into the soil. Seeds should be planted at a depth of about 2 to 3 inches, and at a spacing of about 10-15 cm between seeds. (iii) Spacing: Maize plants should be spaced about 60-90 cm apart in rows that are about 75-90 cm apart. This spacing allows for good plant growth and development, and makes it easier to control weeds and harvest the crop. (iv) Weed control: Maize should be kept free of weeds, especially during the early stages of growth, as weeds can compete with the crop for nutrients and water. Weed control can be achieved by hand weeding or using herbicides. Mulching can also be used to suppress weed growth and conserve soil moisture. (v) Two fungal diseases: Two common fungal diseases that affect maize are gray leaf spot and maize streak virus. Gray leaf spot is caused by the fungus Cercospora zeae-maydis and can be controlled by using resistant varieties or applying fungicides. Maize streak virus is transmitted by leafhoppers and can be controlled by using resistant varieties or controlling the leafhopper population. (vi) Harvesting: Maize is ready for harvest when the ears have fully matured and the kernels have turned hard and dry. Harvesting can be done by hand or using a machine, and the ears should be removed from the stalks and dried to prevent mold growth. (b) (i) Production record: A production record is a document that records the quantity and quality of crops or livestock produced on a farm. It includes information such as the type and amount of inputs used, the yield, and any problems encountered during production. (ii) Farm inventory: A farm inventory is a record of all the assets and liabilities of a farm, including land, buildings, equipment, livestock, and supplies. It helps the farmer to keep track of the value of their assets and liabilities, and to plan for the future. (iii) Cash book: A cash book is a record of all the financial transactions on a farm, including income and expenses. It helps the farmer to keep track of their cash flow and to ensure that they have enough money to cover their expenses. (iv) Labour record: A labour record is a document that records the amount of time and wages paid to farm workers. It helps the farmer to keep track of labour costs and to ensure that workers are paid fairly for the work they have done.

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(a) Aim of the experiment

To determine the moisture content (and hence the organic matter content) of a soil sample by heating and drying it.

(b) Parts labelled I to IV

• I - Evaporating dish / crucible
• II - Soil
• III - Tripod stand
• IV - Bunsen burner

(c) Calculations

Mass of fresh soil = 60 g; mass of empty dish = 35 g; mass of dish + dried soil = 80 g.

(i) Weight of the dried soil

\[80\,\text{g} - 35\,\text{g} = 45\,\text{g}\]

(ii) Weight of water lost from the soil

\[60\,\text{g} - 45\,\text{g} = 15\,\text{g}\]

(iii) Percentage of water lost from the soil

\[\frac{15}{60} \times 100 = 25\%\]

(d) Three forms in which water exists in the soil

• Hygroscopic water
• Capillary water
• Gravitational water

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None

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(a) Two types of soil water:

• Capillary water: water held in the small (micro) pores of the soil by surface tension against the pull of gravity. It is the main source of water available to plant roots.
• Gravitational water: water that drains freely downward through the large (macro) pores under the pull of gravity after rain or irrigation. It is not held long enough to be very useful to plants, and its excess causes waterlogging.

(b) Four management practices during the brooding of chicks:

1. Provide adequate warmth with a brooder (about 35 °C in the first week, reduced weekly).
2. Supply clean drinking water and good-quality chick-starter feed.
3. Provide adequate lighting, good ventilation and clean dry litter.
4. Avoid overcrowding and protect the chicks from predators (and vaccinate as scheduled).

(c) Completed table on diseases of farm animals:

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(a) Colostrum

Colostrum is the first thick, yellowish milk produced by a mammal (for example a cow) immediately after giving birth. It is rich in antibodies (immunoglobulins), proteins, vitamins and minerals. It gives the newborn passive immunity against diseases and acts as a natural laxative to clear the gut of the first faeces (meconium).

(b) Transverse section of an egg

A labelled drawing should show the following parts from outside inwards:

• Shell (outer hard protective covering).
• Outer and inner shell membranes.
• Air space (at the broad end).
• Thin albumen and thick albumen (egg white).
• Chalaza (twisted cords holding the yolk in position).
• Vitelline membrane surrounding the yolk.
• Yolk with the germinal disc (blastoderm) on its surface.

(c) Law of diminishing returns

The law of diminishing returns states that as more units of a variable input (for example fertilizer or labour) are added to a fixed input (for example land), the total product first increases at an increasing rate, then increases at a decreasing rate, reaches a maximum, and finally begins to fall. The illustrative table below shows how total product (TP), marginal product (MP) and average product (AP) behave:

Marginal product is the extra output from each additional unit of input; the point where MP begins to fall marks the onset of diminishing returns, and where MP reaches 0 total product is at its maximum.

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(a) Four functions of soil water to crops

• It acts as a solvent, dissolving mineral nutrients in the soil so that plant roots can absorb them.
• It is the medium by which dissolved nutrients are transported into and within the plant.
• It supplies the water needed as a raw material for photosynthesis.
• It maintains the turgidity of plant cells, keeping the plant firm and erect; it also helps to regulate soil and plant temperature and is needed for seed germination.

(b) Five factors that could cause low soil pH (acidity)

• Leaching of basic cations (calcium, magnesium, potassium) by heavy rainfall.
• Continuous use of acid-forming fertilizers such as ammonium sulphate.
• Decomposition of organic matter which releases organic acids.
• Acidic parent material from which the soil is formed.
• Accumulation of acidic ions such as hydrogen, aluminium and iron; acid rain and continuous cropping that removes bases also contribute.

(c) Life cycle of the liver fluke (Fasciola)

1. The adult fluke lives in the bile ducts of the liver of a ruminant (sheep or cattle) and lays eggs.
2. The eggs pass out with the animal's faeces onto pasture.
3. In moist conditions or water, each egg hatches into a ciliated larva called a miracidium.
4. The miracidium enters the intermediate host, a mud snail (Lymnaea).
5. Inside the snail it develops in stages: sporocyst, then redia, then cercaria.
6. The cercariae leave the snail, swim and encyst on grass or vegetation as metacercariae.
7. A grazing animal swallows the metacercariae with the herbage.
8. The young flukes bore through the gut wall, migrate to the liver and bile ducts, mature into adults, and the cycle begins again.

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(a) Characteristics of igneous rocks

1. They are formed by the cooling and solidification of molten magma or lava.
2. They are crystalline and consist mainly of interlocking mineral crystals.
3. They are generally hard, compact and resistant to weathering and erosion.
4. They contain mainly primary minerals and do not occur in layers or strata.

(b)(i) Demand and supply curves for maize

The demand curve slopes downwards from left to right, while the supply curve slopes upwards from left to right. Their point of intersection, E, gives the equilibrium position.

At equilibrium, quantity demanded equals quantity supplied:

\[Q_d=Q_s=200\text{ kg};\qquad P=\text{₦}8\]

Therefore, the equilibrium price is ₦8 per kg and the equilibrium quantity is 200 kg.

(ii) Excess demand at ₦4 per kg

At ₦4, quantity demanded = 350 kg and quantity supplied = 130 kg.

\[\text{Excess demand}=Q_d-Q_s=350-130=220\text{ kg}\]

Excess demand = 220 kg.

(iii) Excess supply at ₦12 per kg

At ₦12, quantity supplied = 250 kg and quantity demanded = 125 kg.

\[\text{Excess supply}=Q_s-Q_d=250-125=125\text{ kg}\]

Excess supply = 125 kg.

Detalles de la respuesta

(a) Cultivation of cassava:

• (i) Soil requirement: a deep, well-drained, loose sandy-loam soil that is fairly rich in organic matter, with a pH of about 5.5 to 6.5; cassava also tolerates fairly poor soils.
• (ii) Land preparation: clear the land, plough and harrow, then make ridges, mounds or heaps to give the developing tubers room to expand.
• (iii) Spacing: plant stem cuttings at 1 m \( \times \) 1 m, giving about 10,000 stands per hectare.
• (iv) Weed control: weed by hoe two to three times during early growth, and use pre-emergence herbicides or mulching to suppress weeds.
• (v) Fertilizer requirement: apply NPK (for example 15:15:15) or organic manure, with adequate potassium for good tuber formation, about 8 weeks after planting.
• (vii) Harvesting: harvest 9 to 12 months after planting, when the lower leaves yellow, by loosening the soil and lifting the tubers.
• (viii) Storage: leave the tubers in the ground until needed, or store fresh roots briefly in moist soil or silos; for long storage, process into gari, flour or dried chips.

(b) Completed disease table:

Detalles de la respuesta

Factors hindering agricultural development in West Africa

(i) Basic amenities

• Poor road network: Feeder roads to farms are few and in bad condition. This makes it difficult and costly to move inputs to the farm and produce to markets, leading to spoilage of perishable crops and low farmer income.
• Lack of electricity: Many rural farming areas have no electricity, so farmers cannot process, store (cold storage) or pump water for irrigation, and agro-industries cannot be sited near production areas.
• Inadequate water supply: Absence of pipe-borne water and irrigation facilities limits dry-season farming and livestock watering.
• Poor storage and processing facilities: Lack of silos, cold rooms and processing plants causes heavy post-harvest losses.
• Absence of social amenities: Poor schools, hospitals and communication discourage people, especially the youth, from staying in the rural areas to farm, causing shortage of farm labour.

(ii) Farm inputs

• Inadequate improved seeds and planting materials: Farmers still use low-yielding local varieties because certified seeds are scarce and costly.
• Scarce and expensive fertilizers: Fertilizers are often unavailable, adulterated or supplied late, so soil fertility and yields remain low.
• Inadequate agrochemicals: Shortage of pesticides, herbicides and drugs leads to heavy losses from pests, weeds and diseases.
• Lack of farm machinery and implements: Farmers depend on crude hand tools, limiting the area they can cultivate and keeping output low.
• Inadequate credit: Without affordable loans, farmers cannot buy the inputs they need, so production remains at subsistence level.

Detalles de la respuesta

Reading the plan. The farmland is a trapezium with two parallel sides, the top boundary of \(70\text{ m}\) and the bottom boundary of \(90\text{ m}\), and a perpendicular distance between them (the left boundary) of \(40\text{ m}\).

(a) Area of the farmland

The area of a trapezium is half the sum of the parallel sides multiplied by the perpendicular distance between them:

The area of the farmland is \(3200\text{ m}^2\) (that is, \(0.32\) hectares).

(b) Population of banana plants

Each plant occupies a square of ground equal to the spacing:

The farm can carry a population of 200 banana plants.

(c)(i) Names of the tools

• Tool I: Ranging pole
• Tool II: Arrow / pin

(c)(ii) Two uses of each tool

I (Ranging pole)

• Marking survey stations.
• Setting out straight lines.

II (Arrow / pin)

• Marking off the length of chains measured during chaining.
• Marking survey stations and points of intersection.

(c)(iii) One general way of maintaining the tools

Clean and dry the tools after use, oil or grease the metal parts to prevent rust, and store them in a cool, dry place.

Detalles de la respuesta

How to read the diagrams. Each drawing shows the diagnostic body plan of a crop pest. Match the visible features (mouthparts, legs, wings, body shape, feathers) to the correct group before answering.

(a) Names of the pests labelled I, II and III

(The pest labelled IV is a grain-feeding bird such as the weaver bird or quelea.)

(b) Life cycle of the pest labelled I (grasshopper)

The grasshopper undergoes incomplete metamorphosis (paurometabolous development) with only three stages: egg, nymph and adult. There is no pupa.

1. Egg stage: The fertilised female uses her ovipositor to lay batches of eggs in a pod inside moist soil. The eggs remain dormant, often through the dry season, before hatching.
2. Nymph (hopper) stage: Each egg hatches into a nymph that closely resembles the adult but is smaller, wingless and unable to reproduce. The nymph feeds on plant leaves and grows by a series of moults (ecdysis), passing through several instars. Wing buds enlarge at each moult.
3. Adult stage: After the final moult the insect emerges with fully developed wings and functional reproductive organs. It flies, feeds, mates and the females lay eggs, so the cycle begins again.

Summary: \[ \text{Egg} \;\rightarrow\; \text{Nymph (several instars)} \;\rightarrow\; \text{Adult} \]

(c) Four damages caused by the pest labelled III (shield/sucking bug) on crops

1. It pierces leaves and stems with its needle-like mouthparts and sucks the sap, causing wilting, yellowing and stunted growth.
2. It feeds on developing fruits, pods and seeds, causing them to become deformed, shrivelled or to drop prematurely.
3. It injects toxic saliva at the feeding points, producing necrotic (dead, discoloured) spots and lesions on the plant tissue.
4. It acts as a vector, transmitting viral, bacterial and fungal diseases from infected to healthy plants, thereby lowering yield and the market quality of produce.

(d) Four ways of controlling the pest labelled IV (grain-feeding bird)

1. Scaring: Use scarecrows, reflective/noise-making bird scarers, or employ people to drive the birds away, especially at grain-filling stage.
2. Netting/covering: Cover maturing crops (for example seedbeds and cereal heads) with nets to physically exclude the birds.
3. Destroying nesting and roosting sites: Locate and destroy the birds' breeding colonies, nests and roosts to reduce their population.
4. Trapping or shooting: Set traps or shoot the birds where the law permits; alternatively grow bird-resistant varieties and practise uniform, early planting so the crop matures together and is exposed for a shorter period.

Detalles de la respuesta

The diagram is the male reproductive system of livestock (for example, a bull or ram). It shows the paired accessory glands at the top, the central bladder region, the two sperm ducts looping down to the two testes (the round bodies wrapped by coiled bands), and the penis extending below.

(a) Names of the labelled parts

(b) One function of each part

• I - Sperm duct (vas deferens): conveys mature spermatozoa from the epididymis to the urethra during ejaculation.
• II - Testis: produces spermatozoa (male sex cells) and secretes the male sex hormone testosterone.
• III - Penis: serves as the copulatory organ that deposits semen into the female reproductive tract; it also passes out urine.
• IV - Epididymis: stores the spermatozoa and provides the site where they mature and become motile.
• V - Urinary bladder: temporarily stores urine before it is passed out through the urethra.
• VI - Seminal vesicle: secretes a fluid (part of the seminal fluid) that nourishes the spermatozoa and provides the medium in which they swim.

(c)(i) Management practice

The practice is castration (the surgical removal or destruction of the testes of the male animal). By removing the source of sperm and testosterone, the male becomes sterile and loses the urge to mate, so it can no longer breed indiscriminately within the herd.

(c)(ii) The two main parts of utmost benefit

The two parts are the two testes (part labelled II and its pair on the opposite side of the diagram). Because the testes produce both the spermatozoa and the male hormone that drives mating behaviour, their removal during castration stops uncontrolled breeding in the herd.

Detalles de la respuesta

(a) Land tenure system

Land tenure system is the system of customs and laws by which land is owned, acquired, held, controlled and used by individuals or a community. It defines the rights a person or group has over a piece of land.

(b) Weed

A weed is any plant growing where it is not wanted, that is, a plant growing out of place and competing with cultivated crops for nutrients, water, light and space.

(c) Groundnut rosette disease

• (i) Causal organism: Groundnut rosette virus (a virus complex).
• (ii) Mode of transmission: Transmitted by the aphid vector Aphis craccivora.
• (iii) Symptoms: Stunted growth; yellowing (chlorosis) and mottling of leaves; curling and reduction in leaf size giving a bushy, rosette appearance; few or no pods; drastic reduction in yield.
• (iv) Control: Plant resistant varieties; early planting; close spacing; control the aphid vector with insecticides; rogue out and destroy infected plants; practise crop rotation.

(d) Characteristics of the factors of production

(i) Land

• It is a free gift of nature.
• It is fixed in supply and immobile.
• It is heterogeneous, varying in quality and fertility.
• It is subject to the law of diminishing returns; its reward is rent.

(ii) Capital

• It is a man-made factor of production.
• It is mobile and its quantity can be increased or decreased.
• It depreciates or wears out with use.
• It is used to produce other goods; its reward is interest.

Detalles de la respuesta

(a) Two examples of each class of crop

• (i) Roots and tubers: cassava, yam (also cocoyam, sweet potato).
• (ii) Oil crops: oil palm, groundnut (also coconut, soya bean).
• (iii) Grain legumes: cowpea (beans), soya bean (also groundnut, pigeon pea).
• (iv) Cereals: maize, rice (also sorghum, millet).

(b) Five differences between the digestive system of a goat and a chicken

(c) Five reasons why farmers keep records

• To determine whether the farm is making a profit or a loss.
• To plan and budget for future production.
• To use as evidence when seeking loans from banks.
• To compare the performance of the farm from one period to another.
• For tax assessment and to detect theft or losses; it also aids sound management decisions.

Detalles de la respuesta

(a) Four management practices in poultry production

• Vaccination against diseases such as Newcastle and fowl pox.
• Debeaking to prevent cannibalism and egg eating.
• Culling of unproductive, sick or weak birds.
• Provision of balanced feed and clean water; brooding of chicks, regular cleaning and disinfection of houses are also carried out.

(b) Four advantages of dehorning in cattle production

• It prevents animals from injuring one another and their handlers.
• It reduces fighting and bullying, so timid animals can feed calmly.
• It allows more animals to be kept in a given space and makes handling and transportation easier.
• It reduces damage to hides and to housing/feeding equipment.

(c) Five marketing services in agricultural production

• Buying and selling (exchange).
• Transportation of produce from farm to market.
• Storage to make produce available all year round.
• Processing to add value and reduce perishability.
• Grading, standardization and packaging; financing and market information are also provided.

(d) Five problems of agricultural marketing in West Africa

• Poor transportation and bad road network.
• Inadequate storage facilities leading to spoilage of produce.
• Perishable nature of most farm produce.
• Price fluctuation and instability.
• Presence of too many middlemen who reduce the farmer's share of the price; lack of market information and grading also hinder marketing.

Detalles de la respuesta

(a) Six problems of agricultural development in West Africa

• Inadequate finance and credit facilities for farmers.
• Poor land tenure system that limits access to large farmland.
• Inadequate storage and processing facilities causing post-harvest losses.
• Poor transportation and bad road network.
• Illiteracy and shortage of trained agricultural personnel.
• Inadequate farm inputs; pests, diseases and unfavourable weather also hinder development.

(b) Explanation of the farm practices

• (i) Crop rotation: The growing of different crops on the same piece of land in a definite order or sequence over the seasons, so that no single crop occupies the land continuously.
• (ii) Mixed farming: The growing of crops and the rearing of livestock together on the same farm at the same time.

(c) Three advantages of each practice

(i) Crop rotation

• It maintains and improves soil fertility, especially when legumes that fix nitrogen are included.
• It helps to control pests and diseases by breaking their life cycles.
• It controls weeds and makes better use of soil nutrients at different depths.

(ii) Mixed farming

• Animal manure improves the fertility of the soil for crops.
• Crop residues and by-products are used to feed the animals.
• It provides diversified income and spreads the farmer's risk.