WAEC SSCE - Agricultural Science - 1989

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The process of meiosis in plants ensures the production of reproductive cells with half the number of chromosomes of the parent plant. During meiosis, the cell undergoes two rounds of division, which results in the production of four haploid cells (cells with half the number of chromosomes). This is important for sexual reproduction, as it ensures that when the sperm and egg cells unite, the resulting offspring will have the correct number of chromosomes.

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The minerals contained in oyster shells help animals to develop their bones and teeth. Oyster shells are a rich source of minerals such as calcium, phosphorus, and magnesium that are essential for the growth and development of bones and teeth in animals. These minerals are also important for maintaining strong bones and teeth throughout an animal's life. Therefore, consuming oyster shells or adding them to an animal's diet can help ensure that they are getting enough of these important minerals to develop and maintain healthy bones and teeth.

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The day-to-day record of work on a farmer's farm is called a "labour diary." This record is used to keep track of the work done on the farm each day, including tasks performed, hours worked, and the number of workers involved. It is an important tool for the farmer to monitor the progress of work and ensure that tasks are completed on schedule. The other options listed - crop yield book, farm inventory, produce account, and profit and loss account - are all different types of records that a farmer might keep, but they do not specifically track the day-to-day work on the farm.

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The part of the ruminant stomach from which digestive juices are secreted is the abomasum. The abomasum is also called the "true stomach" of the ruminant because it functions similarly to the monogastric stomach found in non-ruminant animals. In contrast, the rumen, reticulum, and omasum are specialized compartments of the ruminant stomach where fermentation of ingested food occurs, with the aid of microorganisms. The paunch is another name for the rumen.

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The correct option is "poor utilization". Preventive and control measures of diseases and pests of crops are taken to ensure healthy and abundant crop yields. These measures include the use of pesticides, fungicides, and herbicides. While these chemicals may have adverse effects on the environment, such as air pollution and water poisoning, they do not directly lead to poor utilization of crops by humans. The other options, such as food contamination and poor health, are potential negative effects of the use of these chemicals.

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Rhizobium is a type of bacteria that lives in the root nodules of leguminous plants. It is able to fix atmospheric nitrogen, which means it can convert nitrogen gas from the air into a form of nitrogen that plants can use. This process of nitrogen fixation is very important for leguminous plants because it allows them to obtain nitrogen without having to rely on external sources such as fertilizers. The nitrogen that Rhizobium supplies to the plant is in the form of ammonium ions which the plant can absorb and use to synthesize amino acids, proteins, and other important compounds. So, the correct answer is "fixing atmospheric nitrogen".

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Maelezo ya Majibu

Maelezo ya Majibu

The crop that is a raw material for the production of chocolate is cocoa. Cocoa beans are extracted from the cocoa plant, which are then processed into cocoa powder and cocoa butter - both essential ingredients for making chocolate. Therefore, option D - cocoa - is the correct answer.

Maelezo ya Majibu

Maelezo ya Majibu

The answer is "Rhode Island Red" because it is a breed of chicken, not a breed of rabbit. The question is asking for the exotic breeds of rabbits found in Nigeria, and all the other options are breeds of rabbits, except for Rhode Island Red which is a breed of chicken.

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Out of the given options, only "loans" can be considered as direct monetary cash assistance from the government to farmers. Agricultural development programmes, extension services, supply of inputs, and tractor hiring services do not involve direct monetary cash assistance, but rather provide various forms of support such as training, technical assistance, or equipment. Loans, on the other hand, involve the government providing money to farmers, which can be used for various purposes such as buying inputs, equipment, or other farming-related expenses.

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Forage crops are plants that are primarily grown to feed animals. They are a crucial source of nutrients for animals such as cows, sheep, goats, and horses. When selecting forage crops, farmers look for certain desirable characteristics that can ensure maximum yield and good nutrition for their animals. Palatability refers to the taste and smell of the forage crop, which affects whether animals will eat it or not. Dependability refers to the ability of the forage crop to produce consistent yields, even under variable environmental conditions. High yield is another important characteristic that ensures that there is enough forage to feed the animals. Resistance to trampling is also a desirable characteristic because animals may walk over the forage crop, which can damage or destroy it. On the other hand, poor reproductive ability is not a desirable characteristic for forage crops. This is because forage crops are typically harvested before they can produce seeds, so their reproductive ability is not important. Instead, farmers look for plants that produce a lot of biomass and are able to regrow quickly after harvest. Therefore, "poor reproductive ability" is the characteristic that is not desirable among forage crops.

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The expression of a gene in the phenotype irrespective of whether the cell is homozygous or heterozygous is known as dominance. In genetics, dominance is a concept that describes how some alleles (versions of a gene) are expressed over others. If one allele is dominant, it will be expressed in the phenotype even if it is paired with a different allele that is recessive. This means that the presence of a dominant allele can mask the expression of a recessive allele in the phenotype. Dominance can be complete, where the dominant allele completely masks the expression of the recessive allele, or it can be partial, where the dominant allele only partially masks the expression of the recessive allele.

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The breed of cattle regarded as the best dairy breed in Nigeria is the White Fulani. This breed of cattle is known for its high milk yield and adaptability to different environments. White Fulani cows are usually large and have a white coat with a hump on their back. They are found in many parts of Nigeria and are preferred by dairy farmers because of their milk production efficiency.

Maelezo ya Majibu

Maelezo ya Majibu

The instrument used to measure the relative humidity is a hygrometer. A hygrometer is an instrument used to measure the amount of water vapor in the air or the humidity. There are different types of hygrometers, such as mechanical and electronic, but they all measure the humidity of the air.

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Maelezo ya Majibu

Maelezo ya Majibu

A seed-producing farmer should spray insecticides on his crops only when the bees are not around because bees are important for pollination of his crops. Bees are responsible for transferring pollen from male flowers to female flowers, which leads to the fertilization of the plant and the production of seeds. If the insecticide is sprayed when the bees are around, it may kill them or deter them from visiting the flowers, which would negatively impact the pollination process and ultimately reduce the yield of the crop. Therefore, it is important for farmers to time their insecticide application carefully and avoid spraying when bees are present. This helps to ensure that the crops receive adequate pollination and that the yield is maximized.

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Peasant farmers sell almost all their produce immediately after harvesting because of inadequate storage facilities. They do not have proper storage facilities to preserve their produce, and stored produce may be lost to pests, lose their quality or may not fetch high prices in the market. Additionally, the commonest method of land tenure in Nigeria is communal landholding, and peasant farmers may not have exclusive rights to the land they farm. As a result, they may not have the resources to invest in storage facilities. Therefore, they choose to sell their produce immediately after harvest to avoid losses due to poor storage.

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Coccidiosis is a protozoan disease of livestock that is not transmitted by a vector. This disease is caused by a parasite that multiplies in the intestine of animals such as cattle, sheep, and goats. It is usually spread through contaminated feed or water, and it affects the absorption of nutrients, causing diarrhea and dehydration. Although it is not transmitted by a vector, coccidiosis can still spread quickly within a herd if proper sanitation measures are not taken. Treatment usually involves the use of drugs to control the parasite and supportive care to manage the symptoms.

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Shearing is not used for identification purpose in livestock. Shearing is the process of removing wool, hair or fur from the body of an animal, usually for commercial purposes. On the other hand, tattooing, branding, tagging and notching are commonly used methods of identifying livestock for various purposes such as ownership, breeding, health management and monitoring, and disease control.

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Maelezo ya Majibu

Maelezo ya Majibu

It is best to plant a mixture of grasses and legumes in the establishment of pastures. This is because grasses and legumes complement each other in terms of nutrient content, growth habit, and ecological requirements. Legumes have the ability to fix atmospheric nitrogen, which is important for the growth of both grasses and legumes. Additionally, the legumes provide protein-rich forage for livestock, which can improve their productivity. On the other hand, grasses provide the bulk of the forage and can help to reduce weed growth by shading out weed seeds. Therefore, a mixture of grasses and legumes is ideal for sustainable pasture management.

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Maelezo ya Majibu

Among the environmental factors listed, moisture is likely to have the greatest influence on crop production in Nigeria. Nigeria has a tropical climate with distinct wet and dry seasons, and rainfall is generally the most limiting factor for agricultural production. Insufficient rainfall or prolonged droughts can cause crops to wither and die, leading to reduced yields and even crop failure. On the other hand, excessive rainfall can cause flooding and waterlogging, which can also damage crops. Therefore, moisture management is critical for successful crop production in Nigeria.

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The act of giving birth in rabbits is known as "kindling". It is important to note that different animals have specific terms for giving birth. For rabbits, the term kindling is commonly used.

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Low fibre and high energy feeds are classified as "concentrates". Concentrates are feeds that are high in energy and low in fibre, with a low content of crude fiber, and include grains and oilseeds. They are used to supplement the diets of animals and are typically given in smaller amounts than roughages or basal feeds, which are high in fibre and low in energy. The main function of concentrates is to supply energy and protein to meet the animal's nutritional requirements. They can be used to supplement grazing or forage diets, or as the main source of nutrition in confinement feeding systems.

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The question is asking which of the following is NOT a factor that can predispose animals to diseases. The correct answer is "immunity", as immunity is a protective factor that can prevent animals from contracting diseases, rather than a factor that can predispose them to diseases. In simple terms, the other options - poor housing, malnutrition, physical injuries, and unfavorable weather - can all weaken an animal's immune system and make them more susceptible to contracting diseases.

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The disease that most commonly attacks groundnut is called rosette. It is a viral disease transmitted by aphids, and it causes severe damage to the leaves, stems, and roots of the plant. The disease gets its name from the characteristic rosette-like growth pattern of the plant, with small, deformed leaves clustered at the top. Rosette disease can lead to stunted growth, reduced yield, and in severe cases, death of the plant.

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The parent material of a soil is formed from the disintegration of rock. Over time, physical and chemical weathering of rocks lead to the formation of parent materials which eventually form soils. The composition and characteristics of the parent material contribute to the properties of the soil, including texture, structure, nutrient content, and water-holding capacity. The type of rock that breaks down and the extent of weathering that occurs influences the type of soil that will be formed.

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Maelezo ya Majibu

The most important limitation of agricultural mechanization is small holdings. Agricultural mechanization requires significant capital investment in machinery and equipment, and it is more economical when practiced on large-scale farms. Small-scale farmers, who often have limited resources and land, may find it difficult to invest in such equipment. As a result, they may not be able to enjoy the benefits of mechanization, such as increased productivity, efficiency, and reduced labor costs.

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The question is asking for an option that is NOT an advantage of the sprinkler method of irrigation. Based on the options provided, the last option "method may be difficult for local farmers to use" is the answer. The sprinkler method of irrigation has several advantages, including the ability to control the rate of water application, the portability of the sprinkler system, and the option to make the system automatic. Additionally, this method can be used on land with varying topography where traditional furrow irrigation is difficult to implement. However, one disadvantage of the sprinkler method is that it may be difficult for some local farmers to use due to the high cost of equipment and maintenance.

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To measure out a large farm accurately, a farmer should use tools that provide precise measurements and cover large distances. Therefore, a measuring tape and ranging poles would be the best tools to use. A measuring tape provides accurate measurements, while ranging poles help cover large distances, which makes it easier to measure large farms. A garden line may not be long enough to cover large distances accurately, and using it alone may not provide accurate measurements. Therefore, options 1, 3, and 4 may not be the best tools to use. may be effective, but it may not be as accurate as using ranging poles and a measuring tape.

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The average seed rate for maize is 25 kg per hectare, which means 25 kg of maize seeds are required to plant 1 hectare of farmland. Now, to plant 10 hectares of farmland, we need to multiply the seed requirement for 1 hectare by 10. So, Seed requirement for 10 hectares = 25 kg/ha x 10 ha = 250 kg However, we also need to account for the seed wastage of 5%. This means that 5% of the total seed requirement will be wasted, and we need to add this to the original requirement. Seed wastage = 5% of 250 kg = (5/100) x 250 kg = 12.5 kg Total seed requirement with wastage = 250 kg + 12.5 kg = 262.5 kg Therefore, the answer is 262.5 kg, which is option E.

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The factor that does not influence land use is population graph. While topography, population pressure, forest establishment, and soil type are all factors that can affect land use, population graph is not a recognized term or concept in the context of land use. It is unclear what is meant by population graph in this context. Therefore, it cannot be considered a factor that influences land use.

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Maelezo ya Majibu

Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from shale through a low-grade regional metamorphism process. The original shale deposits were subjected to heat and pressure, causing them to transform into slate. This transformation process involves the recrystallization of the minerals in the shale, resulting in the formation of a dense, fine-grained rock with excellent cleavage. Therefore, the correct option is shale.

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Most farmers in Nigeria are hesitant in adopting new farming techniques because they are poor and cannot afford to take risks. This is because trying out new techniques may involve additional expenses and there is no guarantee of success. Many farmers in Nigeria live on subsistence farming and their income may not be sufficient to cover their basic needs, let alone to invest in new technologies. Additionally, they may not have access to credit facilities to support their farming activities. Therefore, they tend to stick to traditional farming techniques that they are familiar with and have been using for generations.

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Maelezo ya Majibu

Gilts are female pigs that have not yet given birth. Normally, they are mated between the ages of 8-12 months. At this age, they have reached sexual maturity and are able to conceive and carry a pregnancy to full term. Mating them earlier than 8 months may result in poor conception and litter sizes, while waiting until they are over 12 months may result in reduced fertility and increased risk of complications during pregnancy and farrowing. Therefore, the best age range for mating gilts is between 8 and 12 months.

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The commonest method of land tenure in Nigeria is inheritance. Inheritance involves the transfer of land from parents to children, and it is a traditional method of land transfer that has been in existence for generations. Land is considered a family asset that is passed down from one generation to another, and it is governed by customary laws and practices. This method of land tenure is prevalent in rural areas where there is a strong attachment to family land and cultural practices. However, there are also other methods of land tenure in Nigeria, including lease, outright purchase, pledge, and state allocation, but they are not as common as inheritance.

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A forest established for watershed management will perform all of the functions listed except for controlling fish population. Forests can help to reduce water pollution, control erosion, maintain a steady stream flow, and reduce evaporation by increasing infiltration and slowing down the movement of water across the land. However, controlling fish population is not a typical function of a forest established for watershed management, as this is generally managed through other means such as fishing regulations and habitat restoration projects.

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The option that is not an effect of burning on the soil is "increasing the organic matter in the soil". Burning of vegetation, also known as bush burning, has negative effects on soil fertility and ecosystem in general. It reduces soil organic matter, exposes the soil to erosion, increases soil acidity, and can lead to the loss of beneficial soil microorganisms. Therefore, burning of vegetation is generally discouraged in agriculture and land management practices.

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Maelezo ya Majibu

The term used to describe the growing of both forest and agricultural crops on the same piece of land is "taungya system". This is a type of agroforestry system in which farmers establish and maintain agricultural crops in the understory of a forest while the forest trees are still growing. The agricultural crops are typically planted in the forest during the first few years of its establishment and are later harvested as the forest matures. This system is commonly used in tropical regions to provide both food and income for farmers while also promoting forest conservation and management.

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The factor of improvement in breeding cattle refers to the traits that breeders aim to enhance through selective breeding. These traits include high milk yield, fast growth, disease resistance, and good temperament, among others. Among the options provided, bloat, night blindness, milk fever, infertility, and anemia are all health conditions that can negatively impact the breeding potential of cattle. Bloat is a condition where the animal's stomach fills with gas and can be fatal if not treated quickly. Night blindness, caused by vitamin A deficiency, can reduce the animal's ability to see and lead to accidents or difficulty finding food. Milk fever is a metabolic disorder that can occur after calving and cause muscle weakness and decreased milk production. Infertility can affect both male and female cattle, and it can be caused by various factors such as disease, genetics, or poor nutrition. Anemia is a condition where the animal lacks sufficient red blood cells to transport oxygen to body tissues, which can cause weakness, fatigue, and decreased productivity. Therefore, the answer to the question is that "bloat" is not a factor of improvement in breeding cattle. Rather, it is a health condition that needs to be prevented or treated in order to maintain the health and productivity of the animal.

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Maelezo ya Majibu

Thrips cause serious mechanical damages to crops by their feeding activities on flowers, leaves, and fruits. Thrips are small insects that feed on the surface of plants by piercing and sucking the sap out of the cells. This can cause deformities, stunted growth, discoloration, and even death of the plants. Thrips also scrape the surface of the plants with their mouthparts, which can create scarring, silvering, or bronzing of the leaves. These damages can reduce the quality and quantity of the crop yield, and can also make the plants more susceptible to secondary infections by fungi and bacteria.

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The question is asking for a by-product of fish that is NOT listed among the options. The correct answer is "leather", as it is not typically considered a by-product of fish. Fish by-products are often obtained from processing fish for food or other uses. Fish meal, fish silage, glue, and oil are all examples of common by-products of fish. Fish meal is a high-protein supplement used in animal feed, while fish silage is used as a fertilizer or soil conditioner. Fish glue can be used as a wood adhesive or in the manufacture of paper, and fish oil is commonly used as a nutritional supplement for humans and animals. However, leather is not typically produced from fish, making it the correct answer to the question.

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The correct answer is "profile". A soil profile is a vertical section of the soil, from the surface down to the parent material, that displays a sequence of soil layers or horizons. These layers are differentiated from each other by their physical, chemical, and biological properties, and are used to study and classify soils. A soil profile is an important tool for understanding soil characteristics, such as soil structure, texture, depth, and fertility, and for identifying soil management practices that can be used to improve soil health and productivity.

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Maelezo ya Majibu

The best method(s) of regulating fish capture is/are quota and mesh-size control. Quotas refer to the limits set on the amount of fish that can be caught during a particular period, while mesh-size control refers to the use of fishing nets with a specific mesh size to prevent catching undersized or juvenile fish. These methods aim to maintain sustainable fishing practices by ensuring that fish populations are not overexploited or depleted. Gill netting and electro-fishing, active netting, and passive netting can lead to unintended bycatch and harm to non-target species. The beach seine method is also known to have negative impacts on the environment and other marine organisms. Therefore, quota and mesh-size control are considered the best methods for regulating fish capture.

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The process whereby rocks are broken down into small particles through both physical and chemical factors is known as weathering. Physical factors that cause weathering include temperature changes, wind, and water, while chemical factors include acid rain, oxidation, and plant roots. These factors work together to break down the rock into smaller particles that eventually form soil.

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Maelezo ya Majibu

(a) Selective exploration refers to the process of extracting resources from an area by selectively removing only certain trees or other natural resources, while leaving the rest of the area undisturbed. This is commonly used in forestry and mining operations to minimize environmental damage and ensure sustainability.

(b) Deforestation is the process of clearing forests and trees on a large scale, usually to make room for agriculture, urbanization, or other forms of human development. Deforestation has significant environmental impacts, including soil erosion, loss of biodiversity, and climate change.

(c) Regeneration refers to the natural regrowth and recovery of an ecosystem after it has been damaged or disturbed. This can happen after a natural disaster, such as a forest fire or hurricane, or as a result of human activities like logging or mining. Regeneration is important for maintaining ecosystem health and biodiversity.

(d) Afforestation is the process of planting trees in an area where there was no previous forest cover. Afforestation can help combat climate change by sequestering carbon dioxide from the atmosphere, as well as provide habitat for wildlife, protect soil from erosion, and improve air and water quality.

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a) Irrigation and drainage are two distinct processes in agriculture. Irrigation is the process of applying water to plants through various methods to supplement natural rainfall and ensure optimal plant growth and yield. On the other hand, drainage is the process of removing excess water from the soil or land to prevent waterlogging, soil salinity, and other problems that can lead to poor plant growth.

b) There are several systems of irrigation and drainage, and some of them are:

Systems of Irrigation:

1. Flood Irrigation: In this system, water is allowed to flood the entire field, and it is left to infiltrate the soil by gravity. It is a traditional and less efficient method of irrigation.
2. Sprinkler Irrigation: This system involves the use of sprinklers to distribute water on the plant leaves or over the field. Water is delivered to the plants in a spray-like manner, which simulates rainfall. It is suitable for areas with high temperatures and low humidity.
3. Drip Irrigation: In this system, water is applied slowly and directly to the root zone of plants. Water is delivered to the plants through a network of pipes and emitters that release water in droplets. It is a highly efficient irrigation method that saves water and energy.
4. Center Pivot Irrigation: This is a mechanized irrigation system that involves the use of a large sprinkler that rotates around a pivot point. Water is sprayed over the field as the sprinkler moves in a circular pattern. It is ideal for large, flat fields.

Systems of Drainage:

1. Surface Drainage: This system involves the use of surface channels or ditches to remove excess water from the land surface. It is useful in flat areas with poor drainage.
2. Subsurface Drainage: In this system, pipes or drain tiles are installed beneath the soil surface to remove excess water from the soil profile. It is useful in areas with high water tables and heavy soils that are prone to waterlogging.

In summary, irrigation involves the application of water to plants, while drainage involves the removal of excess water from the soil. Flood, sprinkler, drip, and center pivot irrigation are some of the systems of irrigation, while surface and subsurface drainage are some of the systems of drainage.

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Land tenure refers to the system of rules and regulations that govern the use, ownership, and transfer of land. In Nigeria, there are four major systems of land tenure, which are:

1. Traditional/Communal land tenure: This system of land tenure is based on the communal ownership of land by families or communities. It is characterized by the absence of private ownership and the existence of customary rules and regulations governing land use, transfer, and inheritance.
2. Individual land tenure: This system of land tenure involves the ownership of land by individuals, who have exclusive rights to use, transfer, and inherit the land. The land may be acquired through purchase, inheritance, or allocation by the government.
3. Leasehold land tenure: This system of land tenure involves the leasing of land for a specified period of time, usually between 50-99 years. The lessee has exclusive rights to use and benefit from the land, but ownership remains with the lessor.
4. Government land tenure: This system of land tenure involves the ownership and control of land by the government. The government may allocate land to individuals or organizations for specific purposes such as agriculture, housing, or industrial development.

Each system of land tenure has its advantages and disadvantages. For instance, traditional/communal land tenure promotes social cohesion and community development, but may not be conducive to individual investment and economic growth. Individual land tenure, on the other hand, encourages individual investment and economic growth, but may lead to land speculation and inequality. Leasehold land tenure provides a middle ground between individual and communal ownership, but may limit long-term investment and development. Government land tenure can facilitate planned development and control over land use, but may be prone to corruption and misuse of power.

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(a) Agricultural extension refers to the process of transferring knowledge and technology related to agriculture from research centers to farmers. It involves the use of various methods and techniques to teach farmers how to adopt new and improved farming practices, technologies, and innovations.

(b) The following methods can be used to disseminate new ideas and techniques to farmers in Nigeria:

1. Mass media: This method involves the use of electronic and print media to reach a large number of farmers. For instance, radio and television programs can be used to disseminate information on new farming techniques, market prices, weather forecasts, and government policies. Similarly, agricultural magazines and newspapers can be used to provide information on farming practices and innovations.
2. Individual method: This method involves one-on-one interactions between agricultural extension workers and farmers. It involves visiting farms to assess the problems faced by farmers and to provide advice on how to solve them. The method is effective in situations where farmers are scattered across a wide area, and it helps to provide personalized attention to each farmer's needs.
3. Group method: This method involves organizing farmers into groups or associations, and then training them collectively on new farming techniques and innovations. The method is effective in situations where farmers are concentrated in a particular area. It allows for the exchange of ideas and experiences among farmers, which can enhance learning and adoption of new techniques. Group method can also create a platform for collective bargaining and accessing credit facilities.

In conclusion, agricultural extension is crucial in disseminating new ideas and techniques to farmers in Nigeria. The use of various methods and techniques such as mass media, individual method, and group method can enhance the effectiveness of agricultural extension services.

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(a) Farm records refer to the systematic recording of important information related to farming activities, such as crop production, livestock management, and financial transactions. Farm accounts, on the other hand, refer to the systematic recording and management of financial transactions related to farm operations.

(b) There are several reasons for keeping farm records and accounts, including:

1. Planning: Farm records help farmers to plan their activities, such as deciding which crops to plant or when to breed their animals.
2. Monitoring performance: Farm records allow farmers to monitor the performance of their crops and animals over time, which can help them to make informed decisions about how to improve their operations.
3. Budgeting: Farm accounts help farmers to create and manage budgets for their operations, which can help them to control costs and improve profitability.
4. Tax reporting: Farm accounts are important for tax reporting purposes, as they provide the necessary financial information for filing tax returns.
5. Obtaining credit: Farm records and accounts are often required when applying for loans or other forms of credit.
6. Evaluating profitability: By keeping detailed records of their expenses and income, farmers can evaluate the profitability of their operations and identify areas for improvement.
7. Compliance: Farm records and accounts may be required to comply with regulations related to environmental and food safety, as well as labor and employment laws.

Overall, keeping accurate and up-to-date farm records and accounts is essential for effective farm management and decision-making.

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(a) Stem borers of cereal: Stem borers are a group of insects that cause significant economic losses to cereal crops such as maize, rice, and sorghum. They bore into the stems of these plants and feed on the vascular tissues, causing stunting, wilting, and even death of the plants. This can result in reduced yields and quality of the affected crops. Control measures include the use of resistant varieties, cultural practices such as crop rotation, and the application of insecticides.

(b) Grain weevils of stored produce: Grain weevils are a common pest of stored grains such as maize, rice, and wheat. They feed on the kernels of these grains, reducing their quality and making them unsuitable for consumption or sale. Control measures include proper storage techniques such as drying and fumigation, as well as the use of insecticides.

(c) Cotton stainer: Cotton stainers are insects that feed on cotton plants and stain the fibers with a reddish-brown color, reducing the value and marketability of the cotton. They also reduce yields by damaging the developing bolls. Control measures include the use of resistant varieties, cultural practices such as crop rotation and weed control, and the application of insecticides.

(d) Cassava mealy bug: Cassava mealy bug is a serious pest of cassava, a staple crop in many African countries. It feeds on the leaves and stems of cassava, causing stunting and reduced yields. Control measures include the use of resistant varieties, cultural practices such as intercropping with legumes, and the application of insecticides. In addition, the introduction of natural enemies such as parasitic wasps has been successful in controlling the pest in some areas.

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(a) Weathering is the process by which rocks and minerals are broken down into smaller pieces or dissolved by physical, chemical or biological processes, in response to the conditions of the environment in which they exist.

(b) The three processes involved in rock weathering are:

1. Mechanical or physical weathering: This process involves the physical breakdown of rocks into smaller pieces without changing their chemical composition. Examples of mechanical weathering include freeze-thaw cycles, root wedging, abrasion, and exfoliation.
2. Chemical weathering: This process involves the chemical breakdown of rocks and minerals by the action of water, air, and other chemicals. Examples of chemical weathering include oxidation, hydrolysis, carbonation, and acid rain.
3. Biological weathering: This process involves the breakdown of rocks and minerals by the action of living organisms such as plants, animals, and microorganisms. Examples of biological weathering include root penetration, burrowing by animals, and decay by microorganisms.

(c) The agents of mechanical weathering are physical forces such as temperature changes, wind, water, and ice. For example, freeze-thaw cycles occur when water freezes in rock crevices and then expands as it turns into ice, causing the rock to crack and break apart.

The agents of chemical weathering are chemical compounds such as water, oxygen, carbon dioxide, and acids. For example, carbon dioxide in the air combines with water to form carbonic acid, which can dissolve minerals in rocks such as limestone, leading to their erosion and breakdown over time. Another example is acid rain, which results from the combination of rainwater with pollutants such as sulfur dioxide and nitrogen oxides, leading to the corrosion and breakdown of rocks and other structures.

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(a) Causal organism: Rinderpest is caused by a virus called the rinderpest virus, which belongs to the Paramyxoviridae family.

(b) Transmission: The virus is highly contagious and is transmitted through contact with infected animals, their bodily fluids or excretions, and contaminated equipment or surroundings.

(c) Symptoms: Rinderpest has an incubation period of about 3-9 days, after which the animal starts to exhibit symptoms such as fever, loss of appetite, nasal and ocular discharges, diarrhea, and severe dehydration. The animal may also develop sores in the mouth and on the skin. In the later stages of the disease, the animal may show neurological signs such as paralysis and convulsions.

(d) Effects and economic importance: Rinderpest is a highly fatal disease that can wipe out entire herds of cattle, buffalo, and other cloven-hoofed animals. It has caused devastating losses in the past, leading to famine and poverty in many regions of the world. The disease has also had a significant impact on the economies of affected countries, reducing the availability of meat, milk, and draft power.

(e) Control: The most effective way to control rinderpest is through vaccination. Mass vaccination campaigns have been successful in eradicating the disease from many parts of the world. Other control measures include quarantine of infected animals, movement restrictions, and disinfection of contaminated equipment and surroundings.

Maelezo ya Majibu

(a) Work animals: Animals such as oxen, horses, and donkeys have been used as a source of farm power for centuries. They can be used for plowing, harrowing, planting, and transportation of farm produce. The advantage of work animals is that they do not require fuel and can be fed on farm-grown crops. However, they require proper care and maintenance, and their use can be limited by their physical strength and endurance.

(b) Machine engines: Machine engines such as tractors, combine harvesters, and tillers are popular sources of farm power in modern agriculture. They are efficient, reliable, and can perform a wide range of tasks. The engines are powered by diesel, gasoline, or electricity. Their advantages include increased productivity, reduced labor requirements, and faster completion of farm tasks. However, they require significant capital investment and skilled operators to maintain them.

(c) Water: Water can be used as a source of farm power through the use of watermills and hydroelectric generators. Watermills can be used to grind grains and pump water for irrigation. Hydroelectric generators can provide electricity for farm operations. The advantage of water power is that it is renewable and does not require fuel. However, it is limited by the availability of water sources and the topography of the farm.

(d) Sun: Solar power can be used to provide electricity for farm operations. Solar panels can be used to power lights, pumps, and other electrical equipment. The advantage of solar power is that it is renewable and does not produce greenhouse gas emissions. However, it requires significant capital investment and is limited by the availability of sunlight.

Maelezo ya Majibu

(a) Five factors required for establishing a fish pond are:

1. Location: A suitable location for a fish pond should be chosen, which has adequate water supply, good soil quality, and is free from pollution.
2. Topography: The land should be properly leveled to prevent water from accumulating in certain areas and to allow for even distribution of water in the pond.
3. Water supply: An adequate and reliable source of water is necessary for the fish pond. This can be from a natural spring, stream, or well.
4. Pond design: The pond should be designed in a way that allows for easy water circulation, adequate depth for fish growth, and proper aeration.
5. Fish species: The type of fish to be reared should be chosen based on the water conditions, climate, and market demand.

(b) Six management practices for maintaining high fish yield are:

1. Feeding: Proper feeding of the fish is essential for growth and development. The type of feed and frequency of feeding should be based on the fish species and size.
2. Water quality: Maintaining good water quality is important for the health of the fish. Regular water testing and monitoring should be done to ensure the pH level, temperature, and oxygen levels are optimal.
3. Harvesting: Fish should be harvested at the right time to avoid over-crowding and to ensure maximum yield. Harvesting should be done carefully to avoid stress and injury to the fish.
4. Disease control: Proper sanitation, quarantine procedures, and regular health checks should be done to prevent and control disease outbreaks.
5. Pond maintenance: Regular pond maintenance, including removing debris and dead fish, and repairing leaks and damaged equipment, is important for maintaining a healthy environment for the fish.
6. Record keeping: Keeping accurate records of feed usage, water quality, and fish growth is important for tracking performance and identifying areas for improvement.