WAEC SSCE - Agricultural Science - 2014

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

The common name for Andropogon gayanus is "Gamba Grass".

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The correct answer is 31 days. Gestation period is the time between fertilization and birth of offspring. In rabbits, the gestation period ranges from 28 to 35 days, but the average is around 31 days. During this period, the female rabbit or doe will be pregnant and will give birth to a litter of kits. The gestation period may vary slightly depending on factors such as the breed of the rabbit, the age of the doe, and the environmental conditions.

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Improvement of soil structure is not an effect of over-grazing on soil. Over-grazing refers to the continuous or excessive grazing of livestock on a particular area of land, beyond its carrying capacity. This can have several negative effects on the soil, including soil compaction, exposure of soil to erosion, and depletion of soil nutrients. Soil compaction occurs when the soil is compressed, reducing the space between soil particles and making it difficult for air, water, and nutrients to penetrate the soil. Over-grazing can lead to soil compaction due to the trampling of livestock on the soil. Exposure of soil to erosion occurs when vegetation cover is removed, leaving the soil exposed to the elements. Over-grazing can cause this as it leads to the removal of vegetation by livestock, leaving the soil exposed to the sun, wind, and rain, which can cause erosion. Depletion of soil nutrients occurs when the soil loses its fertility due to continuous grazing and trampling. Over-grazing can lead to this by removing plant cover, which reduces the amount of organic matter added to the soil through leaf litter and root decay, and also by causing soil compaction, which reduces soil aeration and water infiltration, making it difficult for plants to grow. In summary, over-grazing has several negative effects on the soil, including soil compaction, exposure of soil to erosion, and depletion of soil nutrients. Improvement of soil structure is not an effect of over-grazing.

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The annual depreciation of the farm machinery can be calculated using the straight-line method of depreciation. This method involves dividing the total depreciation by the useful life of the asset to determine the annual depreciation expense. In this case, the total depreciation of the farm machinery is D63,000 and the useful life is 5 years. Therefore, the annual depreciation can be calculated as: Annual Depreciation = Total Depreciation / Useful Life Annual Depreciation = D63,000 / 5 Annual Depreciation = D12,600.00 Therefore, the annual depreciation of the farm machinery is D12,600.00. Option (c) is the correct answer. It is important to note that depreciation is a method used to allocate the cost of an asset over its useful life. It represents the decrease in the value of the asset due to wear and tear, age, and obsolescence. By calculating the annual depreciation expense, farmers can plan for the replacement of the asset at the end of its useful life and ensure that the costs are properly allocated over time.

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The most common method of acquiring land in West Africa is by inheritance. Inheritance refers to the transfer of land ownership from a deceased person to their heirs. In West African societies, land is often viewed as a communal resource that belongs to the entire community, rather than being owned by individuals. Inheritance of land is governed by traditional customs and practices, and the rules may vary between different ethnic groups and regions. In some cases, the land may be inherited by the eldest son, while in other cases, it may be divided equally among all the children or passed down to a specific family member designated by the deceased. Inheritance of land can also have implications for women's rights and access to land. In some societies, women may be excluded from inheriting land, while in others, they may be entitled to inherit land through matrilineal or patrilineal systems. Overall, inheritance is the most common method of acquiring land in West Africa due to the importance of land as a communal resource and the prevalence of traditional customs and practices that govern land ownership.

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The farm produce that is referred to as "a mass of decayed plant and animal wastes processed in pits" is compost manure. Compost manure is produced by the decomposition of organic matter such as plant and animal wastes in the presence of air, moisture, and microorganisms. The process of composting involves the collection of these materials and their placement in pits or compost bins. The decomposition process is facilitated by turning or mixing the materials periodically, which helps to promote aeration and the breakdown of the organic matter. The resulting product is a nutrient-rich soil amendment that can be used to improve soil fertility and structure, increase water retention, and promote plant growth. Compost manure is an excellent alternative to synthetic fertilizers because it is environmentally friendly, sustainable, and can help reduce waste. In contrast, green manure refers to the practice of growing specific plants, which are then plowed back into the soil to improve soil fertility. Farmyard manure, on the other hand, is a mixture of animal dung, urine, and bedding materials that are allowed to decompose before use as a soil amendment. Inorganic manure, also known as chemical fertilizer, is made from synthetic materials and does not contain organic matter.

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The dissemination of new ideas by agricultural extension workers can be effective if they work with existing local communities. Agricultural extension workers are professionals who provide information and resources to farmers and communities to improve agricultural practices and productivity. They can help to disseminate new ideas by working with local communities to understand their needs and preferences, and to tailor their messages and programs accordingly. By working with existing local communities, extension workers can build trust and rapport with farmers and gain a deeper understanding of their knowledge and practices. This can help to ensure that the new ideas being disseminated are relevant and applicable to local conditions, and that farmers are more likely to adopt and implement them. In contrast, simply supplying farmers with needed inputs or giving financial support may not be sufficient to ensure the success of new ideas. Farmers may not have the necessary knowledge or skills to use the inputs effectively, and financial support may not address underlying issues such as lack of knowledge or access to markets. Similarly, being politically active may not necessarily lead to effective dissemination of new ideas, as it may not address the needs and preferences of local communities. Therefore, working with existing local communities is crucial for the effective dissemination of new ideas by agricultural extension workers. It can help to ensure that the ideas are relevant, applicable, and adopted by farmers, leading to improved agricultural practices and productivity.

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Nutrient replenishment in soil can be enhanced by crop rotation. Crop rotation is the practice of growing different crops on the same land in a specific order over time. This method has been used for centuries by farmers to improve soil health and productivity. Different crops have different nutrient requirements, and they also contribute different nutrients back to the soil when they decompose. By rotating crops, the nutrients in the soil are used more efficiently, and the risk of depletion is reduced. For example, legume crops such as beans and peas can fix nitrogen from the air and add it to the soil, while other crops like corn and wheat require large amounts of nitrogen to grow. Crop rotation also helps to break pest and disease cycles by interrupting the life cycles of pests and diseases that are specific to certain crops. This reduces the need for pesticides and herbicides, which can have negative impacts on the environment and human health. Overall, crop rotation is a sustainable and effective way to enhance nutrient replenishment in soil, improve crop yields, and protect the environment.

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Control of maize stem borer is most effective when affected crops are uprooted and burnt. This is because the maize stem borer is a pest that bores into the maize stem, thereby causing damage to the crop. When the affected crops are uprooted and burnt, it helps to prevent the spread of the pest to other crops in the farm. This method is considered more effective than the application of rodenticides, nematicides or fertilizers.

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The main objective of flushing in animal production is to promote multiple births. Flushing is a feeding practice used in animal production to improve the reproductive performance of female animals. During flushing, the animal is given a diet that is higher in energy and nutrients than the normal maintenance diet, for a period of time prior to mating. This is done to increase the body condition score of the animal and stimulate the reproductive system, leading to increased ovulation rates and multiple births. Thus, flushing is an important management practice used to increase the reproductive efficiency and profitability of animal production.

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An example of fungal disease of stored grain is mould. Mould is a type of fungus that grows on stored grain, especially in damp conditions. It can cause discoloration of the grain, foul odors, and produce harmful toxins that can affect both human and animal health. Mould is a major problem in the storage of grains and can lead to significant losses in quality and quantity if not properly managed.

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Monoculture is the practice of cultivating a single crop species over a large area of land. A major disadvantage of monoculture is that it creates an environment where diseases and pests can build up easily. This is because the large area planted with the same crop provides a perfect breeding ground for pests and pathogens that can destroy the crop. In addition, monoculture reduces the diversity of soil microbes that are essential for healthy soil. Over time, the continuous cultivation of a single crop can deplete the soil nutrients, leading to poor soil texture. Although it may be possible to mechanize a monoculture farm, this is not a major disadvantage.

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The agricultural sector in West Africa is plagued with poverty primarily because yields obtained per annum are relatively low. This low yield can be attributed to various factors such as poor soil fertility, inadequate or inappropriate use of inputs, inadequate access to water resources, and poor management practices. These factors lead to low productivity, low income, and a vicious cycle of poverty, which makes it difficult for farmers to invest in their farms, access credit facilities, and improve their livelihoods. Additionally, unpredictable weather conditions such as droughts, floods, and other natural disasters also contribute to the low productivity of the agricultural sector in West Africa, exacerbating the already existing problems. While cooperative societies can be helpful in promoting agricultural development, they alone are not sufficient to overcome the poverty challenge faced by West African farmers.

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The appropriate farm tool for lifting tomato seedlings for transplanting is the hand trowel. A hand trowel is a small gardening tool that is designed for digging and scooping soil. It has a pointed blade that is perfect for getting under the roots of seedlings, and a comfortable handle that allows the user to grip it firmly. When transplanting tomato seedlings, it is important to be gentle and avoid damaging the roots as much as possible. The hand trowel is the right tool for this task because it allows the user to lift the seedling out of the ground with minimal disturbance to the roots. A dibber is a tool that is used to make holes in the soil for planting seeds or seedlings, but it is not suitable for lifting seedlings out of the ground. A hoe and hand fork are larger tools that are used for cultivating and breaking up soil, and are not appropriate for the delicate task of lifting seedlings. Therefore, the hand trowel is the appropriate farm tool for lifting tomato seedlings for transplanting.

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Out of the four options given, the farm produce that does not require fermentation during processing is rice grains. Fermentation is a process that involves the breakdown of carbohydrates into simpler compounds like acids, gases, or alcohol by microorganisms such as yeast or bacteria. This process is commonly used in the production of various food and beverage products, such as bread, cheese, wine, and beer. However, rice grains do not require fermentation during processing. The process of producing rice involves several steps, such as threshing, hulling, milling, and polishing. These processes remove the outer layers of the rice grain, leaving behind the starchy endosperm, which is the edible part of the rice. Therefore, rice grains can be processed without the need for fermentation. In contrast, cocoa beans, coffee beans, and cassava tubers may require fermentation during processing to achieve desirable flavors, colors, or textures.

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Maelezo ya Majibu

The causal organisms of diseases in crop production do not include protozoa. Protozoa are single-celled microorganisms that are usually found in water and soil. Although they can cause diseases in animals and humans, they are not known to be significant pathogens in crop production. In contrast, viruses, bacteria, and fungi are all known to cause diseases in crops. Viruses are extremely small infectious agents that can only replicate inside living cells. They can cause a wide range of diseases in crops, including mosaic and yellowing diseases. Bacteria are also microscopic organisms that can cause diseases in crops, such as blight and wilt diseases. Fungi are multicellular organisms that can cause diseases in crops such as rust, smut, and powdery mildew. Therefore, the causal organisms of diseases in crop production do not include protozoa, while viruses, bacteria, and fungi are all significant pathogens in crop production.

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Water in a fish pond needs to be of good quality for fish to grow and thrive. One way to achieve this is by making it suitable through a process called liming. Liming involves the addition of a material, such as agricultural lime or calcium carbonate, to the water to adjust its pH level. This is important because fish require a specific pH range in the water they live in to be healthy. In addition to liming, other methods like fertilization and manuring can be used to promote the growth of aquatic plants and algae, which provide food for fish. Silting is not a method for making water suitable for fish, as it involves the accumulation of sediment and organic matter, which can reduce water quality and oxygen levels, making it unsuitable for fish to live in.

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Theobroma cacao, the plant from which cocoa beans are harvested for chocolate production, grows best in the humid rainforest zone. Theobroma cacao requires a warm, humid climate with abundant rainfall and good drainage. The humid rainforest zone provides these conditions, with an annual rainfall of 1500-2500mm and an average temperature of 25-28°C. In addition to the climate, the soil also plays an important role in the growth of cocoa. Cocoa plants require well-drained soils with a pH between 6.0 and 7.5. The soils in the humid rainforest zone are generally fertile and have good drainage, which makes them suitable for cocoa cultivation. Other factors that can affect the growth and yield of cocoa plants include pests and diseases, as well as proper management practices such as pruning, fertilization, and weed control. However, the climate and soil conditions in the humid rainforest zone provide the ideal environment for Theobroma cacao to grow and produce high-quality cocoa beans.

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Wind can be beneficial to crop production because it aids in the pollination of crops. Wind moves the pollen from the anthers of flowers to the stigma, which helps in fertilizing the flowers and producing seeds. This process is known as wind pollination or anemophily. Wind also helps in the dispersal of pollen from one plant to another. Some crops that benefit from wind pollination include maize, wheat, and rice. However, excessive wind can also cause lodging of crops, which can lead to yield loss, and can cause rapid drying of wet soils, leading to water stress in crops.

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Ruminants are mammals that have a four-chambered stomach specialized for digesting tough plant materials. The passage of feed through the digestive system of a ruminant begins in the rumen, where bacteria and other microorganisms break down the plant material through fermentation. The partially digested feed then passes into the reticulum, where it is regurgitated and rechewed (cud), before being swallowed again and passed through the omasum, which absorbs water and some nutrients. Finally, the feed enters the abomasum, which is the true stomach of the ruminant and functions like the stomach of other mammals, secreting acids and enzymes to further break down the feed. Therefore, the correct sequence of the passage of feed through the digestive system of a ruminant is rumen → reticulum → omasum → abomasum.

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The practice of using insecticides is not considered a cultural control measure for crop diseases. Cultural control of crop diseases involves various farming practices that aim to reduce the incidence and severity of plant diseases. Planting disease-resistant crop varieties and practicing crop rotation are common cultural control practices that farmers use to manage plant diseases. Crop rotation involves alternating crops grown in a particular field over time, which helps to disrupt the life cycle of plant pathogens and reduce the build-up of disease-causing organisms in the soil. Fallowing farmland is another cultural practice where farmers leave their farmland unplanted for a season or more, allowing the soil to rest and the build-up of disease-causing organisms to decrease. This practice also helps to reduce soil erosion and maintain soil fertility. Insecticides are chemical agents used to kill insects and other arthropods that may attack crops. While insecticides can help control insect pests, they are not considered a cultural practice as they do not aim to reduce the incidence or severity of plant diseases. Therefore, the practice that is not considered a cultural control measure for crop diseases is the use of insecticides.

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In hook and line fishing, the bait is fixed onto the hook. The hook is attached to the fishing line, which is held by a fishing rod or pole. The hook is usually baited with live or artificial bait to attract the fish. When the fish bites the bait, the angler can feel the tug on the line and use the rod to reel in the fish. The hook is designed to catch the fish by piercing its mouth or throat, allowing it to be lifted out of the water.

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Continuous soil tillage can lead to the breakdown of soil structure. Soil structure refers to the arrangement of soil particles into aggregates or clumps. A good soil structure is important for healthy plant growth as it allows for air, water, and nutrient movement through the soil, as well as providing a habitat for soil organisms. Continuous soil tillage involves the regular disruption of the soil by plowing or digging to prepare the soil for planting. While this can initially improve soil aeration and water infiltration, over time it can lead to the breakdown of soil structure. This is because soil tillage can break up soil aggregates, leading to the loss of pore spaces and the creation of smaller particles that can become compacted over time. This can make it difficult for air, water, and nutrients to penetrate the soil, leading to reduced plant growth and yield. Additionally, continuous soil tillage can also lead to increased soil erosion, as the soil is left exposed to the elements without any cover or protection. This can result in the loss of topsoil and soil fertility, further exacerbating the negative effects on plant growth. In summary, continuous soil tillage can lead to the breakdown of soil structure, reduced plant growth and yield, and increased soil erosion.

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The major factor affecting the distribution of crops in West Africa is climate. Climate is the long-term pattern of weather conditions that prevail in a particular region. In West Africa, the climate is characterized by two main seasons, the rainy season and the dry season. The length and intensity of these seasons vary from place to place, and this affects the type of crops that can be grown in each region. For example, in areas with a long and intense rainy season, crops such as rice and maize can be grown successfully. These crops require a lot of water and can only grow in areas where there is enough rainfall to sustain them. In areas with a shorter rainy season, crops such as millet and sorghum are more common. These crops are able to tolerate drought conditions and can survive with less water. In addition to rainfall, temperature is another important factor that affects the distribution of crops in West Africa. Some crops, such as cocoa and coffee, require a specific temperature range to grow successfully. These crops are typically found in areas with a moderate climate. Therefore, climate is the major factor affecting the distribution of crops in West Africa. The type of crops that can be grown in a particular region is determined by the amount and distribution of rainfall, as well as the temperature range.

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Fowls are debeaked in order to reduce cannibalism. Debeaking, also known as beak trimming, is a process of removing part of the beak of poultry birds like chickens, turkeys, and ducks. It is done to prevent the birds from pecking at each other and causing injuries or death, which can occur due to aggressive behaviour or stress in overcrowded conditions. By reducing the size and sharpness of the beak, debeaking can help to reduce the severity of injuries that may result from pecking, thereby reducing cannibalism. It is not done to make them grow faster or to increase the intake of vitamin A.

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The plant that is not a forage grass among the given options is Calopogonium mucunoides. Forage grasses are plants that are primarily grown to be used as food for grazing animals, such as cows, sheep, and horses. Pennisetum purpureum, Panicum maximum, and Axonopus compressus are all examples of forage grasses that are commonly used for this purpose. On the other hand, Calopogonium mucunoides is a legume that is used as a cover crop or for soil improvement, but not typically used as a forage grass for grazing animals. Therefore, Calopogonium mucunoides is the plant that is not a forage grass among the given options.

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Forest regulations are formulated in order to encourage afforestation. Afforestation refers to the process of establishing a forest or stand of trees in an area where there was no forest before. Forest regulations aim to encourage afforestation by setting guidelines and rules for how forests can be managed and used. These regulations can include measures to protect existing forests from deforestation and degradation, such as limiting logging or clearing of land for agriculture or development. They may also encourage the planting of new trees and the establishment of new forests through programs such as reforestation or afforestation initiatives. Forest regulations can also promote sustainable forest management practices that balance the needs of economic development with environmental conservation. This can include guidelines for responsible logging, forest certification programs, and incentives for conservation and restoration of degraded forests. In contrast, forest regulations do not encourage deforestation, which is the permanent destruction of forests for non-forest uses such as agriculture or development. Bush burning, which involves deliberately setting fire to forests or other vegetation, is also not encouraged by forest regulations as it can have negative impacts on soil fertility, wildlife habitat, and air quality. Taungya farming, which is a type of agroforestry system where crops are grown in the understory of a newly established forest, may be encouraged by some forest regulations as a way to promote reforestation and provide livelihoods for local communities. Therefore, forest regulations are formulated primarily to encourage afforestation and sustainable forest management practices, while discouraging deforestation and harmful practices such as bush burning.

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Weeds that produce large hollow seeds are most likely to be dispersed by the wind. This is because the seeds are light in weight and have a cavity, which makes them easy to be carried away by even the slightest breeze. As the wind blows, the seeds are lifted into the air and carried over long distances, where they can fall onto new soil and grow into new plants. The other options - water, insect, and explosion - are less likely for weeds with large hollow seeds as their seeds are not adapted for those forms of dispersal.

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The farming system that uses bush fallowing is shifting cultivation, which involves cutting down and burning a plot of land to create a farm, planting crops for a few years until the soil is depleted, then moving on to a new plot and allowing the old one to regenerate through natural vegetation for a few years before returning to it. Therefore, the correct answer is "shifting cultivation and land rotation."

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Based on the symptoms observed in the bull, the disease that the bull is most likely suffering from is "Foot and Mouth Disease" (FMD). FMD is a highly contagious viral disease that affects cloven-hoofed animals such as cattle, pigs, sheep, and goats. The symptoms of FMD in animals include watery discharge from the eyes and nostrils, soreness in the mouth and nostrils, excessive salivation with offensive odor, and severe diarrhea with blood-tinged feces. While there are other diseases that may cause similar symptoms, FMD is characterized by the combination of these symptoms in cloven-hoofed animals. FMD is a significant threat to animal health and agriculture as it can cause large-scale outbreaks and economic losses due to trade restrictions. Therefore, based on the symptoms described, the most likely disease that the bull is suffering from is Foot and Mouth Disease (FMD). It is essential to isolate and treat the infected animal promptly to prevent the spread of the disease to other animals.

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Commercial agriculture is characterized by the use of machines for various agricultural operations such as planting, cultivation, harvesting, and processing of crops. This is because commercial agriculture involves the production of crops and livestock on a large scale for commercial purposes, such as for sale to markets, processing plants, or export. In contrast, small farm holdings are typically associated with subsistence farming, where crops are grown primarily for personal consumption and not for sale. Low capital investment is also not typically associated with commercial agriculture, as it often requires significant investment in land, equipment, and labor to establish and maintain large-scale agricultural operations. Moreover, commercial agriculture often involves significant research activity to improve crop yields, develop new crop varieties, and address challenges such as pests and diseases. This research is often conducted by government agencies, universities, and private companies to support and enhance the productivity and profitability of commercial agriculture. Therefore, commercial agriculture is characterized by the use of machines, large-scale farming operations, significant capital investment, and significant research activity to improve productivity and profitability.

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It is important to clean and grease plough discs after use to prevent rusting. Plough discs are made of metal and are exposed to moisture, which can cause them to rust over time. Rusting can weaken the discs and make them less effective at cutting through the soil, which can reduce the quality of the ploughing. Cleaning the discs and applying grease after use helps to protect them from moisture and prevent rusting, ensuring that they last longer and perform better in the future. Sharpening the discs or reducing friction are not the main reasons for cleaning and greasing plough discs after use.

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The average gestation period in rabbits can be controlled to 31 days. Gestation period refers to the time period between conception and birth of offspring. In rabbits, the average gestation period is around 31 days, although it can vary slightly depending on factors such as breed, age, and environmental conditions. Controlling the gestation period in rabbits is important for managing breeding and reproduction. By controlling the gestation period, breeders can plan for when offspring will be born and ensure that they are born during favorable seasons or market conditions. One method for controlling the gestation period in rabbits is through hormonal manipulation. This involves administering hormones to female rabbits to induce ovulation and synchronize breeding. By carefully timing the administration of hormones, breeders can control the timing of conception and therefore the gestation period. Therefore, the average gestation period in rabbits can be controlled to 31 days through hormonal manipulation, which can be an important tool for managing breeding and reproduction in rabbits.

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The offspring which will result from a cross between heterozygous and homozygous dominant plants will be 50% heterozygous and 50% homozygous dominant. When we talk about genetic traits, an individual can have two copies of the same gene or two different versions (alleles) of the gene. In this case, the homozygous dominant parent has two copies of the dominant allele (AA), while the heterozygous parent has one copy of the dominant allele and one copy of the recessive allele (Aa). During reproduction, each parent contributes one copy of their alleles to the offspring. Therefore, the possible combinations of alleles that can be inherited from these parents are AA, Aa, and Aa. If we look at the ratio of genotypes (genetic makeup) among the offspring, we can see that 50% will inherit one copy of the dominant allele from the heterozygous parent (Aa), while the other 50% will inherit the dominant allele from both parents (AA). Therefore, all of the offspring will have the dominant phenotype (observable traits), but only half of them will be heterozygous. This pattern of inheritance is known as Mendelian inheritance and follows the principles established by Gregor Mendel in his studies of pea plants in the 19th century.

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The factors that affect the supply of agricultural produce are: I. Improvement in technology: This refers to the use of modern and advanced methods of farming such as mechanization, improved seeds, and fertilizers which can increase crop yields and ultimately increase the supply of agricultural produce. II. Increase in rainfall: This is a natural factor that affects agricultural production as it influences the growth of crops. When there is an increase in rainfall, it creates a favorable condition for crops to grow and develop which can lead to an increase in the supply of agricultural produce. III. Decrease in temperature: A decrease in temperature can have a negative impact on the growth of crops and can lead to a decrease in the supply of agricultural produce. IV. Input cost: The cost of inputs such as fertilizers, seeds, pesticides, labor, and machinery can have a direct impact on the supply of agricultural produce. An increase in input cost can reduce the supply of agricultural produce as farmers may not be able to afford the cost of production. Therefore, the factors that affect the supply of agricultural produce are I, II, III, and IV. The correct option is "l, ll, lll and lV".

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The machine used for removing seeds from maize cobs is called a sheller. A sheller is a device that is specifically designed to remove the kernels or seeds from the cob of maize. The machine works by mechanically separating the kernels from the cob using a rotating cylinder or a set of rollers with ridges or teeth that grip and remove the seeds as they pass through. Once the kernels are separated, they can be used for a variety of purposes, such as for human or animal consumption, or for further processing into products like cornmeal or corn syrup.

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Pigs wallow in muddy pools of water primarily to lower their body temperature. Pigs cannot sweat and they have a limited number of sweat glands which makes it difficult for them to regulate their body temperature. By wallowing in mud or water, pigs are able to cool themselves down as the water evaporates from their skin. Additionally, the mud acts as a form of sunscreen and protects their skin from the sun's harmful rays.

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The function of the seed-tube of a seed drill is to transport seeds from the metering device to the furrow opener. A seed drill is a machine that is used for planting seeds in rows at a specific depth and spacing. The seed-tube is a component of the seed drill that connects the metering device, which measures and dispenses the seeds, to the furrow opener, which creates a groove in the soil for the seeds to be placed in. The seed-tube is responsible for transporting the seeds from the metering device to the furrow opener through a series of tubes or channels. It ensures that the seeds are delivered accurately and consistently to the correct location in the soil, which is important for ensuring uniform crop emergence and growth. Therefore, the function of the seed-tube is to transport seeds from the metering device to the furrow opener, where they can be placed in the soil at the correct depth and spacing for optimal plant growth.

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(a) Explanation of terms

• (i) Farmstead: the part of a farm on which the farm buildings and their immediate surroundings stand, such as the farmhouse, barns, stores, pens and yards where the day-to-day activities of the farm are based.
• (ii) Secondary tillage: the lighter cultivation operations carried out after primary tillage to break the soil into a fine tilth, level it and prepare a good seed bed (for example harrowing, ridging and levelling).

(b) One function of each part of a mouldboard plough

(c) One natural process that takes carbon away from the atmosphere

Photosynthesis: green plants absorb carbon dioxide from the atmosphere and use it, in the presence of sunlight and chlorophyll, to manufacture carbohydrates, thereby removing carbon from the air.

(d) Three ways of replenishing plant nutrients in the soil

1. Application of organic manure (farmyard manure, compost, green manure).
2. Application of inorganic (chemical) fertilisers.
3. Practising crop rotation with legumes and allowing the land to fallow.

(e) Two deficiency symptoms of calcium in crops

1. Death of the growing points (terminal buds) and poor root development.
2. Young leaves become deformed, curled or show scorching/dieback of their tips and margins.

(f) Four soil organisms

1. Earthworm
2. Termite
3. Bacteria
4. Fungi (nematodes and millipedes also acceptable)

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(a) Commercial farming

Commercial farming is the large-scale production of crops and/or livestock mainly for sale and profit, rather than for the farmer's own consumption.

(b) Two agricultural produce used by each agro-based industry

• (i) Canning industry: tomatoes and fruits (for example pineapple/orange); fish and vegetables are also acceptable.
• (ii) Beverage industry: cocoa and coffee (also tea).
• (iii) Feed mill: maize and groundnut cake (also soya bean, fish meal, bone meal).

(c) Two aims of each organisation

(i) International Livestock Centre for Africa (ILCA):

1. To carry out research aimed at improving livestock production in Africa.
2. To train personnel and provide information for the development of the livestock industry.

(ii) International Institute for Tropical Agriculture (IITA):

1. To carry out research to improve the yield and quality of tropical food crops.
2. To develop improved crop varieties and better farming systems, and to train agricultural scientists.

(d) Surface irrigation

Surface irrigation is a method of applying water to crops by allowing it to flow over and spread across the surface of the land by gravity (for example through furrows, basins or flooding).

(e) Soil horizons

• (i) Horizon A (topsoil): the uppermost layer; it is dark in colour, rich in humus/organic matter and soil organisms, and is the most fertile layer where most plant roots grow.
• (ii) Horizon D (bedrock/parent rock, R horizon): the deepest layer consisting of solid, unweathered parent rock from which the soil above is formed.

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(a) Elasticity of demand

Elasticity of demand is the degree of responsiveness of the quantity of a commodity demanded to a change in one of the factors affecting demand, especially a change in its price. It is expressed as:

\[ \text{Price elasticity of demand} = \frac{\text{percentage change in quantity demanded}}{\text{percentage change in price}} \]

(b) Terms in agricultural production

• (i) Collateral: a valuable asset or property (such as land, buildings or a certificate of occupancy) that a borrower pledges to a lender as security for a loan, which the lender can take if the loan is not repaid.
• (ii) Farm inventory record: a record that shows a complete list of all the assets (property and stock) on the farm, together with their values, at a particular time.

(c) Three merits and three demerits of the retailer

Merits:

1. Sells produce in small quantities that consumers can afford.
2. Brings goods close to consumers in their localities.
3. Sometimes gives credit and useful information to consumers.

Demerits:

1. Charges higher prices, increasing the cost to the consumer.
2. Handles only small quantities, so the range of goods may be limited.
3. May sell inferior or adulterated produce and add to the number of middlemen who reduce the farmer's share.

(d) Two roles of each hormone in animal reproduction

• (i) Testosterone: (1) brings about the development of male secondary sexual characteristics; (2) stimulates the production of sperm and male sexual behaviour (libido).
• (ii) Progesterone: (1) prepares and maintains the uterus (womb) for pregnancy; (2) maintains pregnancy and prevents further ovulation, and prepares the mammary glands for milk secretion.

(e) Four ways of preserving fish

1. Smoking
2. Drying (sun-drying)
3. Salting
4. Freezing/refrigeration (canning also acceptable)

Maelezo ya Majibu

(a) Animal nutrition

Animal nutrition is the branch of animal science concerned with the intake, digestion, absorption and utilisation of food nutrients (carbohydrates, proteins, fats, vitamins, minerals and water) by farm animals for growth, maintenance, reproduction and production.

(b) Four functions of oestrogen in animal reproduction

1. It brings about the signs of heat (oestrus) and the sexual receptivity of the female.
2. It promotes the development of the female secondary sexual characteristics.
3. It stimulates growth and repair of the lining of the uterus (endometrium) in readiness for the fertilised egg.
4. It aids development of the mammary (milk) glands and the birth canal for parturition.

(c) Methods of animal improvement

(i) Selection: Choosing and keeping for breeding only those animals with the most desirable traits (high milk, fast growth, disease resistance) while culling inferior ones, so that good genes are passed to the offspring.

(ii) Breeding: Deliberate mating of selected animals to combine or fix desirable characters. It includes in-breeding, out-breeding, cross-breeding and up-grading to produce superior offspring.

(iii) Introduction: Bringing in improved breeds or stock from another area or country to replace or upgrade the local, lower-yielding animals.

(d) Ornamental plants

Ornamental plants are plants grown mainly for their beauty, that is for the decoration of homes, gardens, offices and surroundings because of their attractive flowers, leaves, form or scent, rather than for food.

(e) Four vegetative methods of propagating ornamental plants

1. Stem cuttings
2. Layering
3. Budding
4. Grafting (also division of clumps/suckers)

Maelezo ya Majibu

(a) Five roles of agricultural extension in agricultural development in West Africa

1. Transfer of improved technology: Extension carries research findings such as improved seeds, fertilizers and better husbandry practices from research stations to the farmer.
2. Farmer education and training: It teaches farmers modern skills through demonstrations, field days and lectures, thereby raising their competence.
3. Increasing productivity and income: By promoting good practices it helps raise crop and animal yields, improving farmers' earnings and living standards.
4. Feedback link to researchers: It relays farmers' problems and needs back to research institutes so that research is made relevant to real field conditions.
5. Encouraging adoption of innovations and cooperation: It motivates farmers to form cooperatives, obtain credit and adopt new inputs, marketing and processing methods.

(b) Four problems faced by agricultural extension workers in West Africa

1. Poor transport and bad roads make it difficult to reach farmers in remote rural areas.
2. Inadequate funding for salaries, inputs and demonstration materials limits their work.
3. Illiteracy and conservatism of farmers cause resistance to new ideas.
4. Shortage of trained personnel gives too many farmers per extension worker (high farmer-to-agent ratio).

(c) Cultivation of groundnut

(i) Soil requirements: Groundnut thrives on deep, well-drained, loose sandy-loam soil that is loose enough for the pegs to penetrate; a slightly acid to neutral soil (pH about 5.5 to 6.5) rich in calcium is best. Waterlogged, heavy clay soils should be avoided.

(ii) Method of propagation: Groundnut is propagated sexually by seeds (the shelled kernels), sown directly at stake on ridges or flat beds.

(iii) Two methods of storage:

• Storage in the pod (unshelled) in well-ventilated cribs, barns or jute bags in a cool dry store.
• Storage of shelled, well-dried seeds in air-tight containers or treated bags to keep moisture and pests out.

(d) Pests of maize

Two field pests: maize stem borer and army worm (also grasshoppers, birds such as the quelea).

Two storage pests: maize weevil (Sitophilus zeamais) and the grain moth / rust-red flour beetle.

Maelezo ya Majibu

(a) Cultivation of cassava

• (i) Soil requirements: deep, loose, well-drained sandy-loam soil, fairly fertile and free of waterlogging.
• (ii) Spacing: about 1 m x 1 m (one metre between rows and one metre within rows).
• (iii) One disease: cassava mosaic disease.
• (iv) One pest: cassava mealybug (or grasshopper/variegated grasshopper).

(b) Difference between natural and artificial pasture

A natural pasture is grassland made up of grasses and herbs that grow on their own without being deliberately planted by man, whereas an artificial (established) pasture is one that is deliberately planted and managed by man using selected grasses and legumes.

(c) Disease as used in crop production

A disease is any abnormal condition that disturbs the normal structure or functioning of a crop plant, caused by pathogens such as fungi, bacteria and viruses or by unfavourable conditions, leading to reduced growth and yield.

(d) Mendel's law of independent assortment

It states that when two or more pairs of contrasting characters (genes) are considered together, each pair separates and is inherited independently of the others during the formation of gametes.

(e) Regeneration as a forest management practice

Regeneration is the renewal or re-establishment of a forest, either naturally (from seeds and shoots of existing trees) or artificially (by deliberately planting seedlings), to replace trees that have been removed and keep the forest productive.

(f) Five effects of deforestation

1. It leads to soil erosion.
2. It reduces soil fertility (loss of organic matter and leaching).
3. It destroys the habitat of wildlife, reducing biodiversity.
4. It reduces rainfall and alters the climate.
5. It causes desertification and loss of timber and forest products.