WAEC SSCE - Agricultural Science - 2005

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The total land area of a country available for farming depends on the climate of the area. The suitability of land for agriculture depends on various climatic factors such as temperature, rainfall, and humidity. Some crops require specific climatic conditions to grow, and thus, the availability of land for farming depends on the climate of the area. The level of literacy of farmers, sex distribution of the population, and the number of houses and other structures may impact the productivity of the land but not the availability of land for farming. Therefore, the climate of the area is the most critical factor that determines the total land area available for farming.

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The best way to control viral diseases of crop plants is by planting resistant varieties. Viral diseases can spread rapidly through a crop, causing significant damage to the plants and reducing crop yield. While fungicides and insecticides can be effective against fungal and insect infestations, they are not effective against viruses. Therefore, the most effective way to control viral diseases is by planting crop varieties that have been specifically bred to be resistant to the virus. Resistant varieties have been developed through a process called genetic modification, in which genes that confer resistance to the virus are introduced into the crop plant. This enables the plant to fight off the virus and prevent the disease from spreading. By planting resistant crop varieties, farmers can significantly reduce the impact of viral diseases on their crops and improve their yield. Additionally, this approach is more environmentally friendly than using pesticides, as it reduces the need for chemical sprays on the crops.

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Most viral diseases of plants are transmitted by insects. Insects such as aphids, leafhoppers, and whiteflies can feed on infected plants and then transmit the virus to healthy plants by injecting saliva or piercing the plant's tissue with their mouthparts. This process is known as vector transmission. When the insect feeds on a virus-infected plant, it ingests some of the virus particles along with the plant sap. The virus particles then replicate in the insect's gut and salivary glands, where they can be transmitted to other plants when the insect feeds again. Insects can transmit the virus in a persistent or non-persistent manner depending on the virus type and insect species. Viral diseases can also be transmitted through infected seeds, plant debris, or by humans who handle infected plants. However, vector transmission by insects is the most common and efficient way that viruses spread between plants. This is why it is important for farmers to control insect populations and to use virus-free planting materials to prevent the spread of viral diseases in their crops.

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Farm mechanization refers to the use of machines and equipment to perform farming activities. It involves the adoption of various technologies and techniques to improve agricultural production, efficiency, and profitability. However, it is important to note that farm mechanization does not necessarily involve the use of motorized equipment only. It can also involve simple tools and implements that are manually operated. Furthermore, farm mechanization does not require much capital, and it can be adopted at different scales, from smallholder farmers to large commercial farms. Contrary to popular belief, farm mechanization does not necessarily lead to unemployment. While it may reduce the demand for manual labor in some areas, it can also create new jobs in areas such as equipment maintenance, repair, and operation. Additionally, mechanization can help to improve working conditions for farmers and reduce drudgery associated with manual labor. Lastly, farm mechanization does not only involve the use of heavy machinery. It can also involve the use of lightweight machines such as power tillers, planters, and harvesters. These machines are often more affordable and accessible to small-scale farmers, and they can help to improve productivity and reduce post-harvest losses.

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Mastitis is a disease that affects the udder of female mammals, including cows, goats, and sheep. It is an inflammation of the mammary gland, which can be caused by bacterial infections, injury, or other factors. Mastitis can cause swelling, pain, and changes in the appearance and quality of milk produced by the affected animal. If left untreated, it can lead to serious health problems and even death in some cases. Therefore, prompt diagnosis and treatment are important for the health and well-being of both the animal and the people who depend on their milk.

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Limestone does not contain phosphorus. Phosphorus is an essential mineral for animal growth and is typically found in many feedstuffs, including blood meal, fish meal, and oyster shell. However, limestone is primarily composed of calcium carbonate and does not contain significant amounts of phosphorus. Limestone is often used as a source of calcium in animal diets, as calcium is another essential mineral for animal growth and development. In addition, limestone can also be used to adjust the pH of feed and drinking water to ensure that it is at an appropriate level for animals to digest and absorb nutrients effectively. Therefore, out of the given options, limestone is the feedstuff that does not contain phosphorus.

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The most effective method of controlling ectoparasites in farm animals is by regular dipping of animals in a solution of pesticides. Ectoparasites are external parasites such as ticks, mites, and lice that live on the skin of animals and feed on their blood. These parasites can cause significant damage to the health and productivity of farm animals. Dipping is a method of controlling ectoparasites by submerging animals in a solution of pesticides. This method is effective because it covers the entire body of the animal and kills parasites that are not visible to the naked eye. Dipping also has a residual effect, meaning that it continues to protect the animal from parasites for a period of time after the treatment. Exposure of animals to sunlight is not an effective method of controlling ectoparasites because most ectoparasites prefer dark, moist environments and can survive in direct sunlight. Hand-picking of ectoparasites is not an effective method of control because it is time-consuming and can only remove visible parasites, leaving behind hidden ones. Isolation of infested animals is not an effective method of control because it does not address the underlying problem and can lead to the spread of parasites to other animals. In summary, regular dipping of farm animals in a solution of pesticides is the most effective method of controlling ectoparasites because it covers the entire body of the animal, kills hidden parasites, and has a residual effect.

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Weed plants which grow on other plants without deriving nutrients from them are called epiphytes. Epiphytes are plants that grow on other plants, but they do not depend on them for their nutrients. Instead, they derive their nutrients from the air, rain, and debris that accumulates around them. This allows them to live in areas where the soil is poor or non-existent, such as in the canopies of trees. Sedges are a type of grass-like plant that typically grow in wet areas, decomposers are organisms that break down dead organic matter, and saprophytes are plants that obtain nutrients from dead or decaying matter. Therefore, the most appropriate option for the given question is "epiphytes".

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Fertilizers are added to soils to increase the nutrient level available to plants. Plants require a range of nutrients to grow and develop, including nitrogen, phosphorus, and potassium. While these nutrients are naturally present in soils, they can become depleted over time as plants use them up. Fertilizers are added to soils to supplement the available nutrients and ensure that plants have access to the nutrients they need to thrive. Fertilizers typically contain a combination of nitrogen, phosphorus, and potassium, as well as other micronutrients that may be lacking in the soil. When added to the soil, these nutrients are absorbed by plant roots and used to support growth and development. While fertilizers can have other benefits, such as improving water retention capacity and increasing organic matter content, their primary purpose is to increase the nutrient level available to plants. Therefore, the correct option to choose from the given reasons is "increasing the nutrient level".

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Clay particles hold cations because they are negatively charged. Clay particles have a net negative charge due to the presence of various chemical components in their structure. This negative charge attracts positively charged cations, such as calcium, magnesium, and potassium, which are important nutrients for plant growth. The smaller size of clay particles also means that they have a larger surface area relative to their volume, which enhances their ability to attract and hold cations. The fact that clay particles can become hardened when dry or have definite shapes is not directly related to their ability to hold cations.

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Drainage refers to the removal of excess water from the soil. This can be done through various methods such as through drainage pipes or ditches. The excess water can cause harm to plants by suffocating their roots, which can eventually lead to their death. Additionally, waterlogged soil can also lead to the growth of harmful microorganisms and can prevent the growth of beneficial microorganisms. Therefore, drainage is important to maintain a healthy and fertile soil for plants to grow in.

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Topographical survey reveals the physical features of farmlands. A topographical survey is a type of survey that involves measuring and mapping the physical features of a piece of land, including its elevation, slope, and natural features such as hills, valleys, and water bodies. This type of survey can provide important information about the characteristics of a farmland, such as its drainage patterns, soil erosion potential, and suitability for different crops. Soil survey, on the other hand, focuses specifically on the properties and characteristics of the soil in a given area. Chain survey and compass survey are also types of surveys, but they are generally used for different purposes, such as measuring distances and angles for mapping and construction purposes.

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The most inappropriate means of disseminating new ideas and techniques to the peasant farmer is through the internet. While the internet has revolutionized communication and made it easier to share information across the globe, it may not be the best means of disseminating new ideas and techniques to the peasant farmer. This is because most peasant farmers live in rural areas where access to the internet is limited or non-existent. Even in areas where internet access is available, the cost of data and devices may be prohibitive for many farmers. Furthermore, many peasant farmers may not be familiar with the technology or the language used on the internet. This can make it difficult for them to understand and implement the new ideas and techniques being shared. Other means of disseminating new ideas and techniques, such as radio and television, may be more appropriate for reaching peasant farmers. These mediums are often more accessible and can be broadcast in local languages, making them easier to understand for farmers who may not be fluent in the national language. In summary, while the internet has many benefits, it may not be the most appropriate means of disseminating new ideas and techniques to the peasant farmer. Other mediums, such as radio and television, may be more effective in reaching this audience.

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To ensure that crop and animal diseases are not transferred across international boundaries, governments must have and enforce quarantine services. Quarantine services involve strict measures to prevent the spread of diseases by controlling the movement of people, animals, and goods across borders. This can include screening and testing at ports of entry, mandatory quarantine periods for animals and plants, and strict regulations on imports and exports. By implementing these measures, governments can help to prevent the spread of diseases that could have devastating impacts on their agricultural industries, economies, and public health. While agricultural education and the development of disease-resistant species can also be important, quarantine services are a critical first line of defense against the spread of diseases across borders. Increasing surveillance of borders by security agents can also help to enforce quarantine measures and prevent the illegal movement of goods and animals that could carry diseases.

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Streak disease is a type of crop disease caused by a virus that affects the leaves and stems of plants. The virus is transmitted by insect vectors, such as leafhoppers, and can result in reduced crop yield and quality. Among the crops listed, sorghum and maize are most commonly affected by streak disease. However, it is important to note that other crops such as sugarcane and wheat can also be affected by this disease. So to answer your question, streak disease commonly attacks sorghum and maize crops.

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The purpose of vaccination is to prevent disease infection. It involves administering a small, harmless part of a pathogen or a weakened version of the pathogen to the body, which stimulates the immune system to produce antibodies against that pathogen. These antibodies provide immunity to the individual, which helps to protect them from getting sick if they are exposed to the actual pathogen in the future. Vaccination is an effective and safe way to protect individuals and communities from a wide range of infectious diseases.

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Fossil materials such as coal, oil, and natural gas contain stored energy from ancient sunlight that was captured through photosynthesis millions of years ago. This energy can be harnessed in the form of fuel energy by burning these materials to produce heat, which can then be used to generate electricity. This process involves burning the fossil material, which creates heat, which then boils water to produce steam. The steam is then used to turn a turbine which generates electrical energy. While wind and water can also be used to generate electricity, these are not directly related to fossil materials.

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Heterosis in animal breeding is referred to as hybrid vigor. It is a phenomenon where the offspring of two different breeds or strains of animals show improved performance or characteristics compared to their parents. This occurs because the offspring inherit different versions of genes from each parent, resulting in new combinations of genes that can lead to superior traits such as growth rate, disease resistance, and reproductive performance. Hybrid vigor is commonly observed in crossbred animals such as beef cattle, dairy cattle, pigs, and chickens. It is an important aspect of animal breeding because it can increase the productivity and profitability of livestock production by producing animals with improved performance and quality traits.

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An animal infected by trypanosomiasis usually develops anaemia and swollen lymph glands. Trypanosomiasis, also known as African sleeping sickness, is a disease caused by parasitic protozoa of the genus Trypanosoma. The parasites are transmitted by the tsetse fly and can infect a wide range of domestic and wild animals. In infected animals, the parasites can cause a variety of symptoms, including fever, weakness, and poor coordination. However, one of the most common and significant symptoms is anaemia, which occurs when the parasites destroy red blood cells faster than the animal can produce them. This can lead to weakness, lethargy, and other complications. Swollen lymph glands are also a common symptom of trypanosomiasis, as the parasites can cause inflammation and enlargement of these important immune system structures. Bloat and diarrhea, sore legs and running nose, or swollen legs and constipation are not typically associated with trypanosomiasis.

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Soils in forest areas would normally have a high proportion of humus. This is because the forest floor is covered in organic matter such as leaves, twigs, and fallen trees that slowly decompose and contribute to the buildup of humus in the soil. Humus is a dark, organic material that is rich in nutrients and helps to improve soil structure, water-holding capacity, and nutrient availability. Additionally, forest soils tend to have a high microbial activity as decomposers such as bacteria and fungi thrive in the organic-rich soil, breaking down organic matter and recycling nutrients. The moisture content of forest soils can vary depending on factors such as rainfall, topography, and soil type, but they generally tend to have higher moisture content than soils in drier environments. The proportion of sand in forest soils can also vary but tends to be lower than in sandy environments, as the organic matter tends to bind with the mineral particles and improve soil structure.

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The livestock endoparasite that is a hermaphrodite is the tapeworm. Hermaphroditism refers to an organism that has both male and female reproductive organs. Tapeworms are a type of flatworm that live inside the intestines of animals, including livestock, where they can cause health problems. Unlike other parasites on the list, tapeworms are hermaphrodites, which means that each individual worm has both male and female reproductive organs. This allows them to fertilize their own eggs and reproduce without needing a partner. Tapeworms can grow quite long and consist of many segments, each of which contains reproductive organs. When mature, the segments break off and are passed out of the host's body in its feces, allowing the tapeworm to spread to other animals. It is important for livestock owners to be aware of the potential for tapeworm infections in their animals and to take steps to prevent and treat them to ensure the health and productivity of their livestock.

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Mulching is a farming technique where a layer of organic or inorganic material is spread on the soil surface around plants. This layer helps to conserve soil moisture by reducing the rate of evaporation of soil water. Mulching also helps to prevent the growth of weed, which competes with crops for water and nutrients. In addition, mulching can improve soil texture by preventing soil compaction and erosion. The organic materials in the mulch decompose over time, adding nutrients to the soil and increasing soil fertility. Mulching also helps to maintain soil temperature and reduce fluctuations that can stress plants. However, it's important to note that not all types of mulch are suitable for all crops, and some types of mulch can increase soil acidity which can affect the growth of certain crops. Mulching can also prevent the growth of seedling diseases by creating a barrier between the soil and the young plants, reducing their exposure to pathogens.

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The group of basic amenities that should be provided in rural areas for improved agricultural productivity are water, electricity, and healthcare centers. Water is essential for irrigation, which is critical for farming activities. Without water, crops will not grow well, leading to poor harvests, food shortages, and decreased agricultural productivity. Electricity is also crucial for rural areas since it is required for powering farm machinery, lighting, and refrigeration. This can increase agricultural productivity by improving the efficiency of agricultural practices and reducing post-harvest losses. Healthcare centers are essential in rural areas because they provide access to medical care and can help prevent illnesses and diseases that may impact agricultural productivity. Healthy farmers and their families can work longer and more efficiently, leading to increased agricultural productivity. Therefore, these three basic amenities (water, electricity, and healthcare centers) are critical for improving agricultural productivity in rural areas.

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Inadequate food production in most developing countries is mainly due to inadequate technology. Developing countries often rely on traditional and less efficient methods of farming, such as hand tools and animal-drawn plows, which can lead to low yields and limited food production. In addition, these countries often lack access to modern agricultural technologies, such as advanced machinery, irrigation systems, and fertilizers, which can improve efficiency and productivity. Furthermore, developing countries may also face challenges such as poor infrastructure, limited access to credit, and lack of training and education for farmers, which can further hinder their ability to adopt and use modern technologies effectively. While factors such as high population growth, infestation of farms by pests, and scarcity of labor may also contribute to inadequate food production, the lack of adequate technology is often the root cause of the problem.

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When an animal eats wood and licks iron railing instead of the diet given to it, it is likely that the diet is deficient in essential elements. Animals require a balanced and nutritious diet to maintain good health and productivity. When they lack certain essential nutrients in their diet, they may exhibit strange eating behaviors, such as chewing on wood or licking metal objects. These behaviors are known as "pica," and they are often a sign that the animal is seeking nutrients that are missing from their diet. For example, if an animal is deficient in minerals such as iron or magnesium, they may seek out these minerals by licking metal objects or chewing on wood. In addition, animals may also exhibit pica if they are deficient in vitamins, protein, or other essential nutrients. Therefore, when an animal eats wood and licks iron railing instead of the diet given to it, it is likely that the animal is experiencing pica due to a deficiency of essential elements in its diet. It is important to identify and correct the deficiency to ensure the animal's health and well-being.

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The sign that is not an indication of ill-health in farm animals is "bright eyes". Bright eyes are generally a sign of good health in animals, and it indicates that the animal is alert and aware of its surroundings. On the other hand, watery faeces, loss of appetite, and nasal discharge are all signs of ill-health in farm animals. These symptoms may indicate that the animal has an infection, is suffering from a disease, or is experiencing some other health issue. It is important for farmers to monitor their animals closely and to seek veterinary care when necessary to ensure that their animals are healthy and thriving.

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Cover crops are important because they can suppress weed growth. When fields are left bare, weeds can easily grow and compete with crops for nutrients, water, and sunlight, reducing yields. However, cover crops can help prevent weeds from growing by shading the soil and competing with them for resources. This can result in better crop yields and a healthier soil ecosystem. Additionally, cover crops can improve soil health by adding organic matter, increasing nutrient availability, and preventing erosion.

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The factor that does not affect the distribution of pasture grasses is "pests". While pests can certainly impact the health and growth of individual plants, they are not a significant factor in determining the distribution of pasture grasses as a whole. On the other hand, wind, temperature, and soil are all important factors that can affect the distribution of pasture grasses. For example, some species of grass may be better adapted to grow in hot, arid climates, while others may thrive in cooler, wetter environments. Similarly, different types of soil may be more or less suitable for supporting certain species of grass, depending on their nutrient requirements and other factors. Wind can also play a role in determining where pasture grasses are found, as it can impact the dispersal of seeds and the growth patterns of individual plants. Therefore, the most appropriate option for the given question is "pests".

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The by-product in plant photosynthesis is oxygen. During photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose (a type of sugar) and oxygen. This process occurs in the chloroplasts of plant cells, where the pigment chlorophyll captures sunlight and converts it into energy. The carbon dioxide is taken in through tiny pores in the leaves called stomata, and the water is absorbed by the roots and transported to the leaves through specialized tubes called xylem. With the help of the energy from the sunlight, the carbon dioxide and water are broken down into glucose and oxygen. The glucose is used as a source of energy for the plant, while the oxygen is released into the atmosphere as a by-product. This oxygen is essential for the survival of many organisms, including humans, as we breathe in oxygen to survive. Therefore, plants play a critical role in maintaining the balance of oxygen and carbon dioxide in the Earth's atmosphere through photosynthesis.

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An indication that chicks are comfortable in a brooder is that they spread themselves uniformly under the hover. Chicks need warmth to survive, especially during the first few weeks of their lives. A brooder provides warmth through a heat source, usually a heat lamp or hover. Chicks that are too cold will huddle together under the hover to conserve heat, while chicks that are too warm will move away from the source of heat or pant and sit with their mouths open. However, when chicks are comfortable in the brooder, they will spread themselves uniformly under the hover. This indicates that the heat is evenly distributed and that the chicks are not too cold or too hot. When chicks are comfortable, they will also be active and alert, eating and drinking regularly, and moving around the brooder freely. Therefore, spreading themselves uniformly under the hover is a good indication that the chicks are comfortable and healthy in their brooder.

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Cassava tubers can be poisonous to non-ruminants because they contain hydrocyanic acid. Hydrocyanic acid, also known as hydrogen cyanide, is a toxic chemical that can cause serious health problems when ingested. While cassava is a staple food crop in many parts of the world, some varieties contain high levels of hydrocyanic acid, which can make them poisonous to non-ruminant animals, such as pigs and chickens. When consumed in large quantities, hydrocyanic acid can cause a range of health problems, including respiratory failure, seizures, and even death. Therefore, it is important to process cassava tubers properly before consuming them, to remove as much of the hydrocyanic acid as possible. One common method of processing cassava is to peel and soak the tubers in water for several hours or overnight, which can help to reduce the hydrocyanic acid content. The tubers can then be boiled, roasted, or fried, and consumed safely. In summary, cassava tubers can be poisonous to non-ruminant animals because of their high hydrocyanic acid content. Proper processing and preparation of cassava tubers can help to reduce the risk of poisoning and make them safe for consumption.

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A protozoon organism can cause coccidiosis, which is a disease that affects the digestive tract of animals. Protozoa are single-celled organisms that can live in different environments, including soil and water, and can infect animals and humans. In the case of coccidiosis, the protozoan parasite infects the intestines of the host animal, causing diarrhea, weight loss, and other symptoms. Protozoa do not cause anthrax, rinderpest, or aspergillosis, which are caused by bacteria, viruses, and fungi, respectively.

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The first vegetation zone that runs across the coast of most West African countries is the mangrove forest. This vegetation zone is characterized by a group of salt-tolerant trees and shrubs called mangroves, which grow in intertidal zones along the coast. The mangrove forest is an important ecosystem that provides a habitat for a variety of plant and animal species, including fish, crustaceans, and birds. It also serves as a natural barrier against coastal erosion and storm surges, and plays a key role in carbon sequestration and climate regulation. However, mangrove forests are threatened by human activities such as deforestation, coastal development, and pollution, which can have negative impacts on the health and functioning of this important ecosystem.

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The main aim of preparing a farm income and expenditure statement is to calculate the profit or loss of the farm over a particular period of time. The statement outlines all the income received by the farm during the period and all the expenses incurred in running the farm. This includes both sales and purchases, such as sales of crops or livestock, purchases of seeds or feed, and any other expenses related to the operation of the farm. By subtracting the total expenses from the total income, farmers can calculate their net profit or loss. This information is important for farmers to make informed decisions about their farm operations, such as which crops or livestock to prioritize, which expenses to reduce, and whether to invest in new equipment or infrastructure. In summary, while preparing a farm income and expenditure statement involves recording all purchases and outlining the sales of the farm, its primary aim is to calculate the profit or loss of the farm.

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The role of science and technology in the development of agriculture has been significant in various ways. However, among the options provided, "setting up produce marketing boards" is the only option that does not relate to the role of science and technology in agriculture. Science and technology have played a crucial role in agriculture by providing various innovations that have increased efficiency and productivity. For example, science and technology have enabled the provision of insecticides and drugs that help farmers control pests and diseases that attack their crops and livestock. It has also led to the development of good road networks, which has made it easier for farmers to transport their produce to markets. Moreover, science and technology have led to the introduction of artificial insemination centers that provide better breeding opportunities for livestock farmers. This helps to improve the quality of livestock breeds and increase the number of livestock. Therefore, science and technology is an essential tool in the development of agriculture, which helps to enhance productivity and efficiency in the sector.

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The accessory sex gland in a bull refers to the gland that is responsible for producing seminal fluid, which is a component of semen that helps to nourish and transport sperm. The gland in question is the prostate gland, which is located near the bladder and the rectum. The prostate gland produces a fluid that is alkaline and contains nutrients that are necessary for sperm motility and survival. During ejaculation, the fluid from the prostate gland is mixed with sperm from the testes and fluid from other accessory sex glands, and together they form semen. Therefore, the prostate gland plays an important role in the reproductive system of a bull by producing seminal fluid that is necessary for fertilization.

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If a farmland is heavily infested with striga, it may be concluded that the farmland may have been used for growing guinea corn in the past. This is because striga is a parasitic weed that is commonly found on guinea corn and other crops in the sorghum family. Striga can cause significant yield losses in affected fields and can persist in the soil for several years, making it difficult to control. Therefore, if a farmland is heavily infested with striga, it is important to implement appropriate management strategies such as crop rotation, intercropping, and the use of resistant crop varieties to prevent further infestation and reduce the impact on crop yield.

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Selective exploitation means felling trees of specific ages and girths. It involves identifying and removing only those trees that are mature enough to be harvested and leaving the younger ones to continue growing. This approach is considered more sustainable than clear-cutting, where all trees in an area are harvested regardless of their age or size. By selectively harvesting trees, the forest can be regenerated naturally, ensuring that the ecosystem remains intact and that future generations will have access to the same resources.

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(a) Five aims of crop improvement:

1. To increase crop yield per unit area.
2. To produce varieties that are resistant to pests and diseases.
3. To produce varieties that are tolerant of adverse conditions such as drought and poor soils.
4. To improve the quality of produce (for example higher nutrient, oil or protein content).
5. To produce early-maturing varieties and improve other desirable characters such as ease of harvesting and better market qualities.

(b) Selection. Selection in crop improvement is the process of choosing and keeping plants (or seeds) that have desirable characters, such as high yield or disease resistance, for propagation, while rejecting and discarding the undesirable ones.

(c) Three methods of selection:

1. Mass selection.
2. Pure-line selection.
3. Pedigree selection (progeny selection).

(d) Genetic terms:

• (i) Homozygotes: individuals that carry two identical alleles of a gene for a particular character (for example TT or tt); they breed true for that character.
• (ii) Back cross: a cross between an F₁ offspring (a hybrid) and one of its parents (or an individual genetically identical to a parent); a cross with the homozygous recessive parent is a test cross used to find the genotype of the offspring.
• (iii) Dominance: the condition in which one allele (the dominant allele) masks or suppresses the expression of its partner (the recessive allele) in a heterozygote, so that only the dominant character is shown in the individual.

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(a) Climate. Climate is the average weather condition of a place taken over a long period of time (usually 30 years or more). It is the composite of elements such as rainfall, temperature, humidity, sunshine and wind for a given area.

Three importances of climate in agriculture:

1. It determines the type of crops and livestock that can be produced in an area.
2. It determines the farming season and the timing of operations such as planting and harvesting.
3. It affects the growth, yield, spread of pests and diseases, and the distribution of vegetation.

(b) Five ways in which high rainfall affects agricultural production:

1. It causes leaching, washing away soluble plant nutrients from the topsoil and reducing soil fertility.
2. It promotes soil erosion, removing the fertile topsoil.
3. It causes water-logging and flooding of farmland, which damages crops and roots.
4. It encourages the spread of pests, diseases and rapid weed growth.
5. It leaches out nutrients and can make land tillage and harvesting difficult, and causes spoilage of harvested produce; however, adequate rainfall also supplies the water crops need for growth.

(c) Forms in which water exists in the soil: gravitational water (drains away freely under gravity), capillary water (held in the soil pores and available to plants) and hygroscopic water (held tightly as a thin film around soil particles and unavailable to plants).

(d) Three ways soil water may be lost:

1. Evaporation from the soil surface.
2. Transpiration through plants.
3. Drainage/percolation (deep drainage) and run-off.

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(a) Seven characteristic features of a good layer:

1. It has a bright, red and well-developed comb and wattles.
2. It has bright, prominent and alert eyes.
3. It has a large, moist, soft and expanded vent (cloaca).
4. It has a wide span between the pubic (pelvic) bones, able to admit two to three fingers.
5. It has a soft, pliable and large abdomen (well-developed egg-laying capacity).
6. It is active, alert and has a good appetite (feeds well).
7. It has smooth, well-bleached shanks/beak (in yellow-skinned birds) and a good, healthy body condition free from disease.

(b) Preparations for receiving day-old chicks:

1. Clean, wash and disinfect the brooder house and all equipment thoroughly and allow it to rest before the chicks arrive.
2. Spread clean, dry litter (such as wood shavings) on the floor and set up the brooder guard (chick guard) in a circle.
3. Provide and test the source of heat (brooder/lamp) and warm the house to the correct brooding temperature (about 35 degrees Celsius) before the chicks arrive.
4. Arrange clean feeders and drinkers, and provide feed (chick mash) and clean water (with glucose/vitamins) ready for the chicks.
5. Ensure the house is well ventilated, rodent-proof and predator-proof, and count and inspect the chicks on arrival, placing them gently under the brooder.

(c) How poor storage facilities affect agricultural marketing: Without adequate storage, farmers cannot hold their produce, so they are forced to sell perishable produce quickly and cheaply immediately after harvest; much produce spoils, rots or is attacked by pests, causing heavy losses. This leads to gluts and low prices at harvest and scarcity and high prices off-season, unstable prices, poor produce quality, reduced farmers' income and difficulty in storing goods to await better market prices.

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(a) Manual labour.

Three advantages:

1. It has a low initial (capital) cost and requires no fuel or expensive machinery.
2. It is suitable for small farms, rough or hilly land and for delicate operations such as transplanting and harvesting where machines cannot work well.
3. It provides employment for many people and causes less damage to the soil structure.

Two disadvantages:

1. It is slow and has low output, so large areas cannot be covered quickly.
2. It is tedious and tiring, and labour is often scarce and costly at peak periods.

(b) Four qualities of good draught animals:

1. They should be strong, healthy and muscular with good stamina.
2. They should be docile, gentle and easy to train and control.
3. They should be well adapted to the local climate and resistant to diseases and pests.
4. They should be of good body size and weight, with sound legs and hooves.

(c) Two precautions when using draught animals:

1. Do not overwork the animals; give them rest, adequate feed and water.
2. Use well-fitting, comfortable harnesses/yokes to avoid injury and sores.

(d) Harnessing power:

(i) Sun (solar energy): sunlight is trapped by solar panels (photovoltaic cells) which convert it into electricity that can be stored in batteries and used to pump water, power electric fences, dry crops and light farm buildings; solar dryers also use the sun's heat directly to dry produce.

(ii) Biogas: animal dung and other farm wastes are put into an airtight digester where bacteria decompose them (anaerobic digestion) to produce biogas (mainly methane). The gas is collected and piped out to be burned for cooking, heating, lighting and running gas engines/generators on the farm, while the slurry left behind is used as manure.

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(a) Seven objectives of agricultural extension:

1. To teach farmers improved farming practices and modern technologies.
2. To increase agricultural production and productivity.
3. To raise the income and improve the standard of living of farmers and their families.
4. To disseminate the results of agricultural research to farmers.
5. To convey farmers' problems and needs back to research institutes for solution.
6. To encourage farmers to form cooperatives and other self-help organisations.
7. To improve rural home and community life, including nutrition, health, sanitation and youth development.

(b) Three main types of extension teaching methods:

1. Individual (person-to-person) methods.
2. Group methods.
3. Mass (mass-media) methods.

Explanation of any two:

Individual methods: the extension worker deals with one farmer at a time, giving direct, personal advice suited to that farmer's particular situation. Examples include farm and home visits, office calls and personal letters. The method allows a close relationship and detailed attention, but it is slow and reaches only a few farmers.

Group methods: the extension worker teaches a number of farmers together at the same time. Examples include result and method demonstrations, group discussions, lectures, field days and farm tours. It reaches more farmers than individual methods, encourages the sharing of ideas and is fairly convincing through practical demonstration.

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Three advantages and one disadvantage of each marketing agent are given below.

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(a) Four reasons for rearing goats in West Africa:

1. They provide meat (chevon) which is a valuable source of animal protein.
2. They provide milk, skin (hides for leather) and manure.
3. They are a source of income and a form of savings/wealth to farmers.
4. They are small, cheap to acquire and easy to manage, and they can feed on a wide range of vegetation and thrive under harsh conditions.

(b) Extensive system of rearing goats.

Three advantages:

1. It is cheap, requiring little capital, housing or equipment.
2. The animals feed themselves on natural range/browse, so feeding costs are low.
3. It requires little labour and management, and the animals exercise freely and are generally healthy.

Three disadvantages:

1. The animals are exposed to predators, theft, accidents and bad weather.
2. Diseases and parasites spread easily and are difficult to control.
3. Feeding, breeding and record-keeping cannot be controlled, so growth and productivity are low.

(c) Six general characteristics of West African cattle breeds:

1. They are generally small to medium in body size (dwarf types are small).
2. Many are trypanotolerant (resistant to trypanosomiasis) and adapted to the humid zone.
3. They are hardy and well adapted to the local climate and poor feeding.
4. They are mostly of the humpless (taurine) type such as the N'Dama and Muturu, though zebu (humped) types occur in the north.
5. They are dual-purpose (kept for meat and, in some, milk and work) but are generally low in milk yield.
6. They mature slowly and have relatively low meat and milk productivity, but resist local diseases well.

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None

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(a) Ten poultry equipment and the main use of each:

(b) Two parts of a tractor involved in coupling and operation of implements:

1. The drawbar / three-point hitch (linkage) for coupling (attaching) implements.
2. The power take-off (PTO) shaft for transmitting power to drive the implements.

(c) Four maintenance practices of a tractor:

1. Check and top up the engine oil, hydraulic oil, coolant (water) and fuel regularly, and change the oil at the recommended intervals.
2. Grease and lubricate all moving parts and check the tyre pressure regularly.
3. Clean the air, oil and fuel filters and the radiator; wash the tractor after work.
4. Service the battery and check nuts, bolts and belts; carry out repairs promptly and keep the tractor under shelter when not in use.

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

(b) Four methods of weed control:

1. Cultural (mechanical/manual) method: weeds are removed by hand-pulling, hoeing, slashing, mulching, crop rotation, close spacing and good tillage practices.
2. Chemical method: weed-killers (herbicides) such as pre-emergence and post-emergence herbicides are sprayed to kill the weeds.
3. Biological method: living organisms (insects, animals or pathogens) are used to feed on or destroy specific weeds; for example grazing animals or introduced insect predators.
4. Physical method: weeds are destroyed by burning, flooding or by covering (smothering) with materials to deprive them of light.

(c) Six reasons for controlling weeds on the farm:

1. Weeds compete with crops for nutrients, water, light and space, reducing crop yield.
2. Weeds harbour pests and diseases that attack crops.
3. Some weeds are parasitic on crops (for example Striga) and reduce their vigour.
4. Weeds lower the quality and market value of harvested produce when mixed with it.
5. Weeds obstruct farm operations such as harvesting and increase the cost of production.
6. Some weeds are poisonous to livestock, and weeds can cause water loss from the soil through transpiration.