WAEC SSCE - Agricultural Science - 2013

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Rhizobium is the species of bacteria that lives symbiotically in root nodules of legumes. Rhizobium forms a mutualistic relationship with leguminous plants such as peas, beans, and alfalfa, among others. The bacteria colonize the root hairs of the legume and stimulate the development of specialized structures called nodules. Inside the nodules, the Rhizobium bacteria convert atmospheric nitrogen into a form that the plant can use, in exchange for carbohydrates produced by the plant. This symbiotic relationship is essential for the growth of leguminous crops and also contributes to the nitrogen balance in soil.

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All of the factors mentioned in the options should be considered when sowing seeds in the field. (i) Time of sowing: The appropriate time of sowing depends on the type of crop and the climate of the region. Some crops are sown in the rainy season, while others are sown in the dry season. Sowing at the right time ensures that the seeds germinate and grow properly. (ii) Plant density: The density at which seeds are sown affects the yield and quality of the crop. If the seeds are sown too closely, the plants will compete for nutrients and space, resulting in stunted growth and reduced yield. On the other hand, if the seeds are sown too far apart, the yield will be lower than expected. (iii) Depth of sowing: The depth at which seeds are sown affects germination, emergence, and seedling vigor. Seeds that are sown too deeply may not germinate, while those sown too shallowly may dry out or be damaged by pests. (iv) Method of sowing: There are different methods of sowing seeds, including broadcasting, drilling, and transplanting. The choice of method depends on the type of crop, the soil type, and the available resources. The method of sowing affects the distribution and density of the seeds, as well as the efficiency of fertilizer and water application. In summary, all the options provided in the question stem should be considered when sowing seeds in the field to ensure optimum yield and quality of the crop. Therefore, the correct answer is: l, ll, lll, and IV.

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Meat obtained from cattle of less than one year old is called "veal". Veal is the meat obtained from young calves that are usually between 4 and 16 weeks old. The meat is tender, lean, and pale pink in color. Veal is often used in cooking because of its delicate flavor and texture. It is usually more expensive than beef because of the special care and feeding required to produce it. Beef, on the other hand, is the meat obtained from adult cattle, usually over one year old. Chevon is the meat obtained from goats, and pork is the meat obtained from pigs.

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The group of cattle that are tropical breeds is N' dama, Sokoto Gudali, and Muturu. These breeds have adapted to the hot and humid climate of tropical regions and are generally resistant to common tropical diseases like trypanosomiasis, tick-borne diseases, and other parasitic diseases. They also have a high level of tolerance to heat and can survive in areas with limited water resources.

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Population growth is a socio-economic factor that affects the availability of land for agricultural use in West Africa. As the population of West Africa continues to grow, there is increased pressure on the available land for agricultural use. The land that was once available for farming is being used for other purposes such as housing and infrastructure development. As a result, farmers have to make do with smaller land sizes or move to areas that are not suitable for agriculture. This situation can lead to decreased agricultural productivity and food insecurity.

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The correct answer is (a) l only. Blood is not an excretory product, as it is a vital fluid in the circulatory system that carries oxygen and nutrients to the body's tissues and removes waste products. Sweat and urine are excretory products, as they contain metabolic waste products such as urea, salt, and other substances that are eliminated from the body.

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The characteristic of draught animals that does not influence traction effort is meat quality. This is because meat quality refers to the characteristics of the meat produced by an animal and has no direct impact on its ability to exert pulling force. The age, sex, and breed of an animal are factors that can affect its traction effort. For example, young animals may not have fully developed muscles, while male animals may be stronger than female animals. The breed of an animal can also affect its strength and endurance.

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The processes by which animals release carbon dioxide into the air are respiration and decay. Respiration is the process by which animals take in oxygen and release carbon dioxide as a waste product. This process occurs continuously in animals as they use oxygen to release energy from the food they consume. As a result, carbon dioxide is released into the air as a byproduct. Decay, on the other hand, is the process by which dead organic matter breaks down and decomposes. During this process, microorganisms break down the organic matter and release carbon dioxide as a byproduct. This carbon dioxide is then released into the air.

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The practice that leads to land degradation in the savanna zones of West Africa is overgrazing of grassland, cutting of woody species for fuelwood, and constant annual bushfires. Overgrazing leads to the removal of vegetation cover, exposing the soil to erosion. Cutting of woody species for fuelwood reduces vegetation cover, which leads to soil erosion. Constant annual bushfires destroy vegetation cover and cause soil erosion. The application of cattle manure, on the other hand, helps to improve soil fertility, which is beneficial for agriculture. Therefore, the correct answer is option B: l, ll, and lV only.

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When building a rabbit hutch, it's important to consider the safety and comfort of the rabbits as well as the ease of maintenance and cleaning. These factors ensure that the rabbits are kept in a healthy and hygienic environment, reducing the risk of disease and injury. The safety and comfort of the rabbits should be the top priority when designing the hutch. This means ensuring that the hutch is big enough for the rabbits to move around, jump, and play, as well as providing adequate ventilation and protection from predators. The hutch should also be made from non-toxic materials to avoid harm to the rabbits. Ease of maintenance and cleaning is also crucial when building a rabbit hutch. The hutch should be designed in a way that makes it easy to clean and maintain hygiene, as this is important for the health of the rabbits. This means that the hutch should have removable trays and easy access to all areas for cleaning. Day length is not a factor that needs to be considered when building a rabbit hutch. Therefore, the correct answer is l and ll only.

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To facilitate mechanical harvesting of cereals, it is better to ensure they all have a uniform height. Mechanical harvesting of cereals, such as wheat and maize, involves the use of specialized harvesting equipment, such as combines or harvesters, which are designed to cut the crop at a specific height above the ground. If the crop height is not uniform, the harvesting equipment may not be able to cut the crop effectively and efficiently, resulting in yield losses and increased harvesting costs. Therefore, to facilitate mechanical harvesting of cereals, it is essential to ensure that the crop has a uniform height. This can be achieved by planting seeds that have the same genetic characteristics and by ensuring that the crop is grown under the same conditions, such as irrigation, fertilization, and weed control. In summary, uniform crop height is critical in facilitating mechanical harvesting of cereals, and it can significantly reduce harvesting costs and increase yields.

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"Magnetic attraction" could lead to wrong reading on a prismatic compass. A prismatic compass is a device used in surveying to measure horizontal angles between different points. It works by using a magnetic needle to align with the Earth's magnetic field, allowing the user to determine the direction of the needle relative to the cardinal directions (North, East, South, West). However, if there are magnetic materials or objects nearby, they can interfere with the Earth's magnetic field and cause the needle to deflect from its correct position. This is known as "magnetic attraction" and can lead to errors in reading the compass. A big tree, wind direction, or a pond do not affect the accuracy of a prismatic compass. However, it is important to ensure that the compass is properly leveled and that there is no metallic or magnetic material nearby that could interfere with its function.

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Marble is a metamorphic rock formed from limestone. Limestone is a sedimentary rock made of calcium carbonate, which is the primary mineral component in marble. Through intense heat and pressure, limestone undergoes a metamorphosis, which transforms it into marble. This process causes the mineral crystals in the limestone to recrystallize and interlock, resulting in the characteristic veined appearance of marble.

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"Increased appetite" is not a sign of ill-health in farm animals. Uncoordinated gait, dull eyes, and high body temperature are all commonly observed in animals that are sick or unwell. Uncoordinated gait or difficulty in moving can indicate neurological problems or weakness, dull eyes can indicate fever, stress, or dehydration, and high body temperature can indicate infection or inflammation in the animal's body. However, an increased appetite is not typically a sign of ill-health in farm animals. In fact, it is often an indicator of good health and well-being in animals. A healthy animal with a good appetite will typically eat well and maintain its weight, which is essential for growth and productivity. Conversely, a decrease in appetite or refusal to eat is a common symptom of many illnesses in animals, and can lead to weight loss, weakness, and other health problems.

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The consequence of pasture littered with polythene materials is that it can block the alimentary canal of farm animals. When farm animals such as cows or goats graze on littered pasture, they may accidentally ingest the polythene materials along with the grass, which can cause obstruction in their digestive system. This can lead to serious health problems or even death of the animal. Therefore, it is important to keep the pasture free of any harmful materials like polythene to prevent harm to the animals.

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One disadvantage of vegetative propagation is that viral diseases can be transferred to offspring. When propagating a plant through vegetative means, it is important to ensure that the original plant is free of any viral diseases that could be passed down to its offspring. If the parent plant is infected, the clones produced through vegetative propagation will also be infected, resulting in a decrease in yield or poor quality crops. It is therefore important to carefully select healthy parent plants and to take proper precautions to prevent the spread of disease.

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One disadvantage of using bamboo troughs for poultry water is that they are susceptible to algal growth. Bamboo troughs are not able to withstand regular cleaning and disinfection, which makes them a favorable environment for the growth of algae. Algae can cause various health problems to the birds, leading to reduced growth rate, low egg production, and increased susceptibility to diseases. Furthermore, algal growth makes the water less palatable and increases the likelihood of contamination by harmful microorganisms. Therefore, it is essential to use appropriate materials for poultry water troughs, such as plastic or metal, which are easier to clean and maintain hygiene.

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The main disadvantage of mechanical tillage is the use of heavy equipment that leads to soil compaction. Soil compaction can occur when heavy machinery repeatedly moves over the soil surface, causing the soil particles to be tightly packed together. This can reduce soil porosity and limit water infiltration and air circulation, which can negatively affect plant growth and development. Therefore, mechanical tillage can have a negative impact on soil health and agricultural productivity.

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The filler makeup weight of a compound fertilizer refers to the weight of the inert materials added to the fertilizer to bulk it up to a desired weight. It has no nutrient value and does not contribute to the fertility of the soil. To find the answer to this question, we need to use the ratio of the fertilizer which is 15:15:15, representing the percentages of nitrogen, phosphorus, and potassium. The total percentage of nutrients in the fertilizer is 15+15+15=45%. Since the weight of the fertilizer is 100kg, the weight of the nutrients in the fertilizer is 45kg. Therefore, the weight of the filler makeup is the difference between the weight of the fertilizer and the weight of the nutrients. Filler makeup weight = Total weight of the fertilizer - Weight of the nutrients Filler makeup weight = 100kg - 45kg Filler makeup weight = 55kg Therefore, the filler makeup weight of the NPK 15:15:15 compound fertilizer is 55kg.

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Insect damage to crops takes the form of chewing, sucking, and piercing. This means that insects can cause damage to crops by either chewing through the plant tissue, sucking out the sap or piercing the plant tissue to feed on the inside. Some insects may even use a combination of these methods to feed on crops. This damage can lead to reduced yield and quality of crops, making it important for farmers to take measures to control insect populations.

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Price elasticity of demand is a measure of how responsive the quantity demanded of a good is to a change in its price. If the absolute value of price elasticity of demand is greater than one, then the demand is said to be price elastic. This means that a small change in the price of the good will result in a relatively larger change in the quantity demanded of the good. In other words, the demand for the good is sensitive to changes in price.

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The cattle breed in West Africa tolerant to trypanosomiasis is the "N'dama". N'dama is a cattle breed that originated in West Africa and is known for its tolerance to trypanosomiasis, a parasitic disease that affects cattle in the region. The breed is also resistant to ticks and other parasites, making it well-suited for the tropical climate of West Africa. N'dama cattle are smaller in size compared to other breeds and have distinctive long and curved horns. They are also known for their docile temperament and ability to survive on poor quality forage. In contrast, the White Fulani and Sokoto Gudali breeds are known for their milk production, while Friesian is a breed of dairy cattle originating from the Netherlands. These breeds are not known for their tolerance to trypanosomiasis or other parasitic diseases common in West Africa.

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To calculate the number of yam setts planted at a spacing of 1.0m by 1.0m on a hectare of land, we need to first determine the area of land in hectares and then calculate the number of setts required to plant the area. One hectare of land is equivalent to 10,000 square meters. To calculate the area in square meters, we can use the formula: Area = length x width Since the spacing is 1.0m by 1.0m, the length and width are both 100 meters (1.0m x 100 rows = 100m and 1.0m x 100 columns = 100m). Therefore, the area is: Area = 100m x 100m = 10,000 square meters To convert this to hectares, we divide by 10,000: Area in hectares = 10,000 square meters ÷ 10,000 = 1 hectare Since we are planting at a spacing of 1.0m by 1.0m, each yam sett will occupy an area of 1.0m x 1.0m = 1 square meter. Therefore, the number of yam setts required to plant one hectare of land is: Number of setts = Area in square meters ÷ Sett spacing in square meters Number of setts = 10,000 square meters ÷ 1 square meter = 10,000 setts Therefore, the correct answer is (d) 10,000 setts.

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Inadequate financing is a problem facing agricultural development in West Africa. This refers to the insufficient funding and investment in the agricultural sector, which hinders its growth and productivity. The lack of adequate financing may result in a shortage of funds for the purchase of necessary inputs, such as fertilizers, pesticides, and farm equipment, which could lead to a decrease in crop yields and livestock production. Additionally, inadequate financing may discourage farmers from expanding their operations and adopting modern technologies and practices that could improve their productivity and profitability.

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To determine the crop population per hectare, we first need to calculate the area of one plant, which is the product of the spacing along the rows and between the rows. Area of one plant = 3.6m x 4.5m = 16.2m² Next, we need to convert the area of one plant to the area per hectare (10,000 m²). Number of plants per hectare = (10,000 m²/16.2m²) = 617 Therefore, the crop population per hectare is 617. Hence, the answer is.

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The most important objective of agricultural extension education is to help farmers to produce more efficiently. Agricultural extension education is a system of transferring agricultural knowledge and skills from research institutions to farmers. The goal is to improve agricultural production and efficiency, which can be achieved by providing farmers with information on modern farming techniques, new crop varieties, improved animal husbandry practices, and other relevant information that can help them increase productivity and income. By providing farmers with this knowledge, agricultural extension education can help to enhance food security, reduce poverty, and promote sustainable agricultural development.

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The common name of Axonopus compressus is "carpet grass". This is a type of grass that is often used in lawns and landscapes because it forms a dense, low-growing carpet-like mat that can withstand heavy foot traffic. It is also drought-tolerant and can grow in both sun and shade. The name "carpet grass" comes from its ability to form a thick, uniform mat, similar to a carpet.

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An example of a piercing and sucking insect-pest of crops is a mealybug. Mealybugs are small, soft-bodied insects that feed on plant sap using their piercing and sucking mouthparts. They are called mealybugs because they have a powdery, white, waxy coating that resembles meal. Mealybugs are found on a wide range of crops and ornamental plants, and they can cause significant damage by sucking the sap from the plant's tissues. They also secrete honeydew, a sweet, sticky substance that can promote the growth of sooty mold on plant surfaces. In summary, mealybugs are a good example of a piercing and sucking insect-pest of crops due to their feeding behavior and the damage they can cause to plants.

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The characteristic that is not important in beef cattle production is increased butter-fat percentage. Beef cattle are not raised for their milk production, so their butter-fat percentage is not important. High feed conversion efficiency and high yield of lean meat are important characteristics as they are related to the efficiency and profitability of beef production. Therefore, the answer is (a) l only.

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During the fallow period, plant nutrients are restored through the accumulation of soil organic matter. Fallow period refers to the period when a field is left uncultivated or unplanted. During this time, natural processes such as the decomposition of plant residues and the growth of cover crops can enhance the accumulation of organic matter in the soil. This organic matter is rich in essential plant nutrients such as nitrogen, phosphorus, and potassium, which can be released into the soil as they decompose. Therefore, the accumulation of soil organic matter during the fallow period helps to restore the fertility of the soil for future crop production.

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The advantages of the communal land ownership system are l and ll only. Under the communal land ownership system, every member of the community has a piece of land on which to farm. This ensures that everyone has access to land, which is a valuable resource for farming. Additionally, co-operative farming is possible under this system, allowing members of the community to pool their resources and work together to increase productivity. This can lead to better utilization of land and resources, as well as increased yields and profits. However, large-scale farming is not encouraged under the communal land ownership system because the land is divided among the members of the community, limiting the amount of land available for large-scale commercial farming. Land cannot also be used as security for loans since it is communally owned. Therefore, the advantages of the communal land ownership system are l and ll only.

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The correct option is "low blood temperature". When farm animals are exposed to high temperatures, their body temperature increases, and they try to dissipate this heat by various means such as sweating, panting, and seeking shade. The redness of the vulva in females is a sign of heat, which occurs due to increased blood flow to the reproductive system. Loss of appetite and increased water intake are also signs of heat stress in animals. However, low blood temperature is not a sign of heat stress, as the body temperature of an animal experiencing heat stress would be high, not low.

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The statement that colostrum is an evaporated milk is false. Colostrum is actually the first milk that is produced by mammals, including humans, after giving birth. It is different from regular milk because it is packed with high amounts of antibodies, which help to protect newborns from infections and diseases. Colostrum is also rich in proteins and vitamins, making it a vital source of nutrition for newborns in their early days of life. So, to sum up, colostrum is the first milk produced after parturition that is high in antibodies, proteins, and vitamins.

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(a) Four benefits of agriculture to the economy of West African countries

1. It provides food for the growing population.
2. It provides employment and income for a large part of the population.
3. It supplies raw materials to agro-based industries.
4. It earns foreign exchange through the export of cash crops and generates government revenue.

(b) Four functions of agro-service centres

1. Supply farm inputs such as improved seeds, fertilizers and agrochemicals.
2. Hire out farm machinery and equipment to farmers.
3. Provide extension/advisory services and training.
4. Provide credit facilities and assist in marketing farm produce.

(c) Four routine tractor maintenance practices

1. Check and top up the engine oil level regularly.
2. Check and top up the radiator coolant/water.
3. Check the tyre pressure and adjust it correctly.
4. Grease and lubricate moving parts, and clean/replace the air filter.

(d) Two functions of each part of the farm tractor

(i) Three-point linkage:

• It attaches (hitches) mounted implements to the tractor.
• It raises and lowers the mounted implements and transfers their weight to the tractor for stability.

(ii) Hydraulic lever:

• It controls the raising and lowering of mounted implements.
• It regulates and controls the depth of operation of the implement.

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(a) Two sources of irrigation water

• Rivers and streams.
• Dams/reservoirs, lakes or underground water (boreholes and wells).

(b) Two advantages and two disadvantages of irrigating farmlands

Advantages:

• It allows crop production during the dry season and in areas of low rainfall.
• It increases crop yield and allows continuous (all-year) production.

Disadvantages:

• It is expensive to install and maintain.
• It may cause waterlogging and salinity, and can spread water-borne pests and diseases.

(c) Two ways by which the soil loses nutrients

• Leaching of soluble nutrients beyond the root zone.
• Soil erosion and removal of nutrients through harvested crops.

(d) Two reasons for manuring in crop production

• To replenish and add nutrients to the soil.
• To improve soil structure, water-holding capacity and organic-matter content, thereby raising yield.

(e) Two ways each environmental factor affects agricultural production

(i) Temperature:

• It affects the rate of germination, photosynthesis and growth of crops.
• Extreme temperatures affect flowering, ripening and the feeding and reproduction of animals.

(ii) Soil micro-organisms:

• They decompose organic matter and fix atmospheric nitrogen, releasing nutrients for crops.
• Some cause plant diseases while others cause denitrification, leading to loss of nitrogen.

(iii) Wind:

• It aids pollination and dispersal of seeds, and helps in drying of produce.
• Strong wind causes lodging of crops, wind erosion of soil and the spread of pests and diseases.

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(a) Farm mechanization

Farm mechanization is the use of machines and engine-powered equipment (such as tractors and their implements) to carry out farm operations, thereby reducing the reliance on human and animal labour.

(b) Three advantages and three disadvantages of farm mechanization

Advantages:

• It ensures timeliness and speed in performing farm operations.
• It makes it possible to cultivate large areas of land.
• It reduces drudgery and the need for human labour, and raises productivity.

Disadvantages:

• It involves a high cost of purchase and maintenance.
• It causes unemployment by displacing farm labour.
• It can cause soil compaction and is unsuitable for small, fragmented lands.

(c) Two merits of using draught animals

• They are cheaper to acquire and maintain than machines and require no fuel.
• They provide manure and can be used on small farms and on rough terrain.

(d) Roles of science and technology in agricultural development

(i) Pest and disease control:

• Development of chemicals (pesticides, herbicides and fungicides) for control.
• Breeding of pest- and disease-resistant varieties.
• Provision of biological control methods and improved diagnosis of pests and diseases.

(ii) Meteorology and climatology:

• Weather forecasting to guide the planning of farm operations.
• Provision of rainfall and temperature data to guide choice of crops and planting dates.
• Early warning of drought and flood to reduce losses.

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None

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(a) Four cereal crops grown in West Africa

1. Maize
2. Rice
3. Sorghum (guinea corn)
4. Millet

(b) Three benefits of forests to the economic development of a country

1. Forests supply timber, fuel wood and other raw materials for industries such as sawmilling, paper, gum and latex industries.
2. They provide employment and income for rural people and also generate revenue and foreign exchange for government.
3. Forests protect the environment by checking erosion and desertification, protecting water catchment areas and serving as windbreaks.

(c) Life cycle of the variegated grasshopper (Zonocerus variegatus)

The variegated grasshopper undergoes incomplete metamorphosis. The female lays egg pods in the soil, usually at the beginning of the rainy season. The eggs hatch into wingless nymphs. The nymphs resemble small adults and feed actively, moulting through several instars as wing buds develop. After the final moult, a fully winged adult emerges. The adult mates and lays eggs in the soil, thereby repeating the cycle. There is no pupal stage.

(d) Three cultural methods of controlling crop pests

1. Crop rotation.
2. Timely planting and harvesting.
3. Regular weeding and destruction or burning of crop residues that harbour pests.

(e) Two uses of oil palm

1. The palm oil obtained from the fruit mesocarp is used for cooking and for making soap.
2. Palm kernel oil is used in making soap, margarine and other industrial products.

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(a) Animal improvement

Animal improvement is the application of scientific principles and breeding techniques to develop farm animals that possess desirable/superior characteristics such as higher yield, faster growth and disease resistance.

(b) Three aims of animal improvement

1. To increase yield of animal products (meat, milk, eggs).
2. To improve resistance to pests and diseases.
3. To improve feed-conversion efficiency and adapt animals to the environment (also improve fertility and growth rate).

(c) Definition of terms

• (i) Parturition: The act or process of giving birth to young ones in animals.
• (ii) Gestation period: The length of time from conception (fertilization) to the birth of the young, during which the offspring develops in the womb.

(d) Three systems in the body of farm animals

• Digestive system.
• Respiratory system.
• Reproductive system (also circulatory, nervous or excretory system).

(e) Four advantages of castration in animal production

1. It makes the animals docile and easy to handle.
2. It improves the quality of meat (tender and free of objectionable odour).
3. It prevents indiscriminate/uncontrolled breeding by inferior males.
4. It promotes fattening and faster weight gain.

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(a) Three reasons why fish farming is important

1. It is a source of animal protein/food.
2. It is a source of income, employment and foreign exchange.
3. It provides raw materials such as fish meal and makes productive use of waterlogged land.

(b) Three factors influencing the choice of a fish-pond site

1. Availability of a reliable and adequate source of clean water.
2. Soil that holds water well (clay or loam with low permeability).
3. A gently sloping topography that allows easy filling and draining, and nearness to market and security from flooding/pollution.

(c) Two sources of each feed nutrient

(i) Water: fresh drinking water (streams/rivers/rain); succulent green feeds.

(ii) Proteins: animal sources (fish meal, blood meal); plant sources (groundnut cake, soybean meal).

(iii) Carbohydrates: cereals (maize, guinea corn); roots and tubers (cassava, yam) and cereal brans.

(iv) Vitamins: green leafy vegetables/leaf meal; fruits, cod-liver oil or vitamin premix.

(d) Two ways roundworm infestation is of economic importance in livestock production

• It causes poor growth, emaciation and reduced productivity (meat, milk, eggs), and may lead to death of animals.
• It increases the cost of production through treatment and causes condemnation of infected organs at slaughter, lowering market value.

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(a) Definition of terms

• (i) Assets: These are the items or properties of value owned by a business or farmer, such as land, buildings, machinery, livestock and cash.
• (ii) Liabilities: These are the debts or financial obligations owed by the business to others, such as loans, unpaid wages and taxes payable.

(b) Three problems encountered by farmers in obtaining agricultural credit

1. Lack of collateral/security to guarantee the loan.
2. High interest rates and complex, bureaucratic loan procedures.
3. Inadequate credit institutions in rural areas and delay in loan approval/disbursement.

(c) Four roles of an agricultural extension agent

1. Teaches farmers improved farming techniques and demonstrates new practices.
2. Introduces improved seeds, breeds and inputs to farmers.
3. Organizes farmers into cooperatives/groups.
4. Conveys farmers' problems to researchers and disseminates research findings to farmers.

(d) Five roles of farmer cooperative societies

1. Provide credit and loans to members.
2. Supply farm inputs to members at reduced cost.
3. Provide storage and marketing facilities for members' produce.
4. Provide extension education and encourage savings among members.
5. Process members' produce and provide social welfare services.

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(a) Three edaphic factors that influence crop growth

• Soil texture.
• Soil structure.
• Soil pH (soil reaction) and nutrient/organic-matter content.

(b) Explanation of terms

• (i) Gravitational water: This is the water that drains freely through the soil under the force of gravity after the soil has been saturated. It moves down to the water table and is not available for plant use.
• (ii) Hygroscopic water: This is the very thin film of water held tightly around soil particles by adhesive forces. It is held so firmly that it is not available for plant use.

(c) Two deficiency symptoms of each nutrient element

(i) Nitrogen:

• Stunted growth.
• Yellowing (chlorosis) of leaves, starting with the older leaves.

(ii) Phosphorus:

• Stunted growth with delayed maturity.
• Purple/reddish colouration of leaves and stems, and poor root development.

(iii) Potassium:

• Scorching/browning of leaf margins (marginal necrosis).
• Weak stems that lodge easily.

(d) Three benefits derived from draining farmlands

1. It removes excess water and prevents waterlogging.
2. It improves soil aeration and warms the soil.
3. It promotes root development and improves the workability of the soil.

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(a) Nursery

A nursery is a specially prepared bed or place where seeds are sown and young seedlings are raised and cared for before they are transplanted to the permanent field.

(b) Three reasons for establishing a nursery

1. It allows easy and close care/management of the young seedlings.
2. It enables the farmer to select only healthy and vigorous seedlings for transplanting.
3. It gives the seedlings a head start while the permanent land is being prepared, and helps economize on seeds.

(c) Three characteristics of weeds that make them difficult to control

1. They produce large numbers of seeds with long viability and dormancy.
2. They propagate vegetatively through rhizomes, stolons and suckers.
3. They have rapid growth rates and their seeds are easily dispersed.

(d) Two methods of controlling weeds

• Cultural/mechanical control (hand weeding, hoeing, mulching, cover cropping).
• Chemical control using herbicides.

(e) Three ways by which diseases are spread among crops

1. Through wind.
2. Through water (rain splash and irrigation water).
3. Through insect vectors, infected planting materials and contaminated tools.

(f) Three effects of diseases on crops

1. They reduce crop yield.
2. They lower the quality and market value of produce.
3. They may cause the death of the plants.