WAEC SSCE - Agricultural Science - 2006

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Hybrid vigor in crop improvement is brought about through crossbreeding. Hybrid vigor, also known as heterosis, is the phenomenon where the offspring of two genetically diverse parents exhibit superior characteristics than their parents. Crossbreeding is a method of plant breeding that involves crossing two genetically different varieties to create a hybrid with desirable traits such as improved yield, quality, or disease resistance. Introduction, mass selection, and inbreeding are plant breeding methods, but they do not produce hybrid vigor. Introduction refers to the introduction of new varieties into an area for cultivation. Mass selection involves selecting the best plants from a population for breeding. Inbreeding refers to the mating of closely related individuals, which often leads to decreased genetic diversity and reduced plant vigor. Therefore, the correct option for the process that brings about hybrid vigor in crop improvement is "crossbreeding."

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A simple farm layout survey involves the measurement and mapping out of a farm into different areas or sections for proper planning and management. One method used in conducting this survey is the 3:4:5 method, also known as the Pythagorean triangle method. This involves using a tape measure to mark out a 3-meter length along one side of the area to be surveyed, then marking out a 4-meter length along the adjacent side, and finally measuring the diagonal between these two points to get a length of 5 meters. This forms a right-angled triangle with sides of 3, 4, and 5 meters, which can be used as a reference point for the layout of the farm. This method is based on the Pythagorean theorem, which states that the square of the hypotenuse of a right-angled triangle is equal to the sum of the squares of the other two sides.

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Soil erosion caused by water can be controlled by afforestation and erection of bunds. Afforestation involves planting trees in areas where there is soil erosion, especially on steep slopes. Trees help to hold the soil together with their roots and reduce the force of raindrops on the soil surface. Erection of bunds involves building a barrier made of soil, stones or other materials across the slope to slow down the flow of water and trap sediments, thus reducing soil erosion. This technique is often used in combination with other erosion control measures such as grass strips and contour ploughing.

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When different breeds of animals are mated, the process is known as crossbreeding. Crossbreeding involves the mating of two different breeds or types of animals in order to produce offspring that possess traits from both parents. This process is used to combine the desirable traits from each breed and create a new breed that is superior to its parents in terms of productivity, disease resistance, and other important traits. Crossbreeding is widely used in animal husbandry to improve the quality and quantity of meat, milk, and other animal products.

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Détails de la réponse

The correct answer is "small brown spot first appears on the pod". Black pod disease is a major fungal disease of cacao plants that causes damage to the pods and beans, leading to significant economic losses. The initial symptom of black pod disease is the appearance of small, water-soaked brown spots on the surface of the pods. These spots then enlarge and become sunken lesions, causing the pods to rot and turn black, hence the name "black pod disease." The disease can spread quickly and cause significant damage to the crop, leading to reduced yields and quality of cacao beans. Therefore, timely detection and management of the disease is essential for successful cacao production.

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Mosaic disease affects cassava and tobacco. Mosaic disease is a viral disease that causes mottling and discoloration of leaves. In cassava, mosaic disease can cause stunted growth, reduced yields, and even plant death. In tobacco, mosaic disease can cause yellow or green mottling of leaves and can reduce the quality of the tobacco. The disease is spread by infected plant material and by sap-sucking insects such as aphids.

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Nagana in cattle is otherwise known as trypanosomiasis. Nagana is a disease that affects livestock, particularly cattle, in Africa. It is caused by the parasite Trypanosoma, which is transmitted to the animals through the bite of the tsetse fly. The disease can cause a range of symptoms, including fever, weakness, and anemia, and can be fatal if left untreated.

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To calculate the annual depreciation of the equipment, we need to find the total depreciation first. The farmer purchased the sprayer for N12,500 in 1974 and sold it for N4,300 at the end of the fourth year. The total depreciation of the equipment = Purchase price - Sale price = N12,500 - N4,300 = N8,200 The equipment was used for four years, so the annual depreciation is: Annual depreciation = Total depreciation / Number of years of use = N8,200 / 4 = N2,050 Therefore, the annual depreciation of the equipment is N2,050. Option C is the correct answer.

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The main aim of wildlife management is to prevent the extinction of species. Wildlife management is the process of ensuring the conservation and sustainable use of wild animal populations and their habitats. The primary goal of wildlife management is to maintain healthy and stable populations of species in their natural habitats. This includes protecting endangered species and their habitats from human activities, preserving biodiversity, and promoting sustainable use of wildlife resources. The other options do not accurately describe the main aim of wildlife management. Providing cheap protein, generating foreign exchange through meat exportation, and reducing trypanosome parasites are all potential benefits of wildlife management, but they are not the primary goal. Therefore, the best option is "prevent extinction of species."

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The forage crop that is not a leguminous plant is Panicum maximum. Leguminous forage crops are plants that belong to the legume family and are known for their ability to fix nitrogen from the atmosphere into the soil, which makes them important for soil fertility and productivity. Examples of leguminous forage crops include Centrosema pubescens, Stylosanthes gracilis, and Pueraria phaseoloides. Panicum maximum, on the other hand, is a grass species that is not classified as a legume. It is a common forage crop in tropical regions and is valued for its high productivity and good nutritional quality. However, unlike leguminous forage crops, it does not have the ability to fix nitrogen and therefore does not contribute to soil fertility in the same way.

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The process of removing a young animal from its mother is referred to as "weaning." Weaning is the process of gradually reducing a young animal's dependence on its mother's milk or maternal care and transitioning it to a different diet or care routine. This process usually takes place over several weeks, during which the young animal learns to eat solid food and becomes more independent. Culling, breeding, and isolation do not describe the process of removing a young animal from its mother. Culling refers to the selective removal of animals from a group based on specific criteria, such as health or productivity. Breeding refers to the process of producing offspring through controlled mating. Isolation refers to separating an animal from others for various reasons, such as disease control. Therefore, the correct option is "weaning."

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An unproductive animal permanently removed from a productive stock is said to be "culled". Culling is the process of selectively removing animals from a herd or flock based on certain criteria, such as poor productivity, poor health, age, or genetic defects. Culling unproductive animals helps to maintain the health and productivity of the remaining animals in the stock. For example, culling a cow that is not producing enough milk will allow the farmer to focus resources on the more productive cows, leading to better overall milk production. Similarly, culling sick animals can prevent the spread of disease to the rest of the herd.

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Subsistence agriculture is best described as the small-scale production of crops and livestock. It is a type of agriculture that is practiced to meet the basic needs of the farmer and their family, rather than for commercial purposes. The crops and livestock produced are primarily for home consumption, with any surplus sold or traded locally. Subsistence agriculture typically involves the use of traditional farming methods, such as hand tools and manual labour, rather than modern machinery. This type of agriculture is common in rural areas of developing countries, where farmers may not have access to modern technology or the financial resources to invest in large-scale commercial agriculture. Therefore, the option "small-scale production of crops and livestock" is the best description of subsistence agriculture.

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The reason why clayey soils are not good for most agricultural crop production is that they are too compact and poorly aerated. Clay soils are composed of very small particles that pack tightly together, leaving little space for air or water to move. As a result, they tend to become waterlogged and poorly aerated, which can make it difficult for plant roots to grow and absorb nutrients. This compactness also makes it harder for farmers to till and manage the soil. Although clay soils are rich in nutrients, they can become too compact for most agricultural crops, making them unsuitable for cultivation. The other options do not correctly explain the reason why clayey soils are not suitable for most agricultural crop production.

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Iodine is applied to the severed umbilical cord of a piglet to prevent the entry of microorganisms into the piglet. The umbilical cord is the connection between the piglet and the placenta through which the piglet receives nutrients from the mother. After the piglet is born, the umbilical cord is cut, leaving an open wound that can be susceptible to infection. By applying iodine to the umbilical cord, it disinfects the area and prevents the entry of microorganisms such as bacteria into the piglet, reducing the risk of infection and disease.

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The agronomic practice that is not applicable to rice production is staking. Staking is a practice of providing support to the stem of some crops like tomatoes, pepper, and beans, among others, to prevent the stems from breaking due to the weight of the fruit. Rice, on the other hand, is not staked because it is not a climbing plant. Threshing is a process of separating the grains from the straw or chaff after harvesting. Transplanting is the practice of uprooting seedlings from the nursery bed and replanting them on a well-prepared field. Puddling is the practice of churning the soil in a waterlogged field to make it muddy and reduce water loss. These practices are commonly used in rice production to achieve high yields.

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The act of giving birth in farm animals is called "parturition". When a female animal becomes pregnant, the fetus develops inside her uterus until it is ready to be born. During parturition, the animal goes through a series of contractions that push the fetus out of her body through the birth canal. This process is necessary for the continuation of the species and the production of offspring for meat, dairy or other purposes.

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The insect group that readily attacks dry grains is "boring insects". Boring insects are insects that make holes or tunnels in wood, plant stems, and dry grains. They are named boring insects because they bore into the food or materials to live and reproduce. Some examples of boring insects that attack dry grains include the rice weevil, maize weevil, and lesser grain borer. These insects can cause significant damage to stored grains, making them unfit for human or animal consumption. Therefore, proper storage techniques should be employed to prevent infestation by boring insects.

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Green manure refers to plants grown and then plowed under to improve soil fertility. Some plants are better suited as green manure than others. To answer the question, the plant not normally used as green manure is Sida acuta. Sida acuta is not commonly used as a green manure crop because it has a low biomass production, and it's difficult to manage due to its bushy growth habit. On the other hand, the other three options (Mucuna utilis, Centrosema pubescens, and Pueraria phaseoloides) are commonly used as green manure crops due to their high biomass production, nitrogen fixation capacity, and easy management.

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Bush burning is a farming practice that encourages soil degradation. When farmers burn their fields, the topsoil, which is the most fertile layer of soil, is destroyed, making it difficult for crops to grow in the future. The fire also destroys soil organisms and beneficial microbes, reducing the soil's fertility. In addition, bush burning can cause soil erosion and contribute to climate change by releasing carbon dioxide into the atmosphere. Therefore, it is important for farmers to avoid bush burning and adopt sustainable farming practices that help maintain soil health and fertility.

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The correct answer is "rapid cooling and solidification of rocks". When a liquid rock (magma) cools and solidifies, it undergoes a chemical change, but not a physical change. However, the other options mentioned in the question can lead to physical disintegration of rocks. Heating and cooling of rock surfaces, for example, can cause the outer layer of a rock to expand and contract, leading to the formation of cracks and fissures. Expansion and contraction of rock minerals due to temperature changes can also cause the rock to break apart. Similarly, the formation of cracks and crevices through the process of weathering and erosion can lead to the physical disintegration of rocks.

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The inscription 27:10:10 on a fertilizer bag represents the percentage by weight of the three major macronutrients present in the fertilizer, namely nitrogen (N), phosphorus (P), and potassium (K) in the order of N:P:K. Therefore, a bag of fertilizer with the inscription 27:10:10 would contain 27% by weight of nitrogen, 10% by weight of phosphorus, and 10% by weight of potassium.

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Irrigation water is passed underneath the soil through pipes. Pipes are used in a type of irrigation called sub-surface irrigation or sub-irrigation. In this method, water is distributed to the roots of plants through pipes that are buried underground. The pipes are usually made of porous material, such as clay, which allows water to seep through and reach the roots. Sub-surface irrigation has several advantages over other irrigation methods. It reduces water loss through evaporation and runoff, saves energy by requiring less water pressure, and prevents soil erosion. It is particularly effective in areas with high water tables, where excess water can be collected and reused. Therefore, irrigation water is passed underneath the soil through pipes in sub-surface irrigation.

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The two main elements of climate that affect soil formation are rainfall and temperature. Rainfall and temperature are important factors in the formation of soil because they influence the rate at which chemical and physical weathering occurs. Chemical weathering involves the breakdown of rocks and minerals through chemical processes, while physical weathering involves the breakdown of rocks and minerals through physical processes such as freeze-thaw cycles. Rainfall is important in soil formation because it helps to break down rocks and minerals through chemical weathering. It also provides the water necessary for plant growth, which contributes to the formation of organic matter in the soil. Temperature is also important in soil formation because it influences the rate at which chemical and physical weathering occurs. Higher temperatures generally lead to faster rates of weathering, while lower temperatures lead to slower rates of weathering. Therefore, the correct option is A, "rainfall and temperature", as these two elements have the most significant impact on the formation of soil. The other options, air, light, wind, and relative humidity, are also important factors in soil formation, but they are not as significant as rainfall and temperature.

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The urethra in the male animal is described as a urinogenital duct because it is a common pathway for urine and sperm. The urethra is a tube-like structure that connects the urinary bladder to the outside of the body through the penis. It serves as a passage for both urine and semen in male animals. Urine is produced by the kidneys and stored in the urinary bladder, while semen is produced by the testes and accessory sex glands. During ejaculation, both urine and semen pass through the urethra and exit the body through the penis. Therefore, the correct option is C, "is a common pathway for urine and sperms". The other options, opening to the outside through the penis, being attached to accessory sex glands, and being the site for the storage of sperm, are not accurate descriptions of the function of the urethra.

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A spade is mainly used for digging. It is a tool with a flat, rectangular-shaped blade and a long handle, designed for cutting into the soil and lifting it out to create holes or trenches. It can be used to dig holes for planting trees, shrubs, and other plants, as well as for preparing garden beds, turning soil, and harvesting root crops like potatoes. While it can be used for light weeding and pruning, its primary function is to dig and move soil.

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The function of the scraper on a disc plough is to remove adhering soil from the disc. As the disc plough cuts through the soil, soil particles stick to the disc due to the pressure and friction. The scraper, which is usually located behind the disc, scrapes the adhering soil off the disc, preventing it from accumulating and reducing the effectiveness of the plough. This helps to maintain the depth and width of the furrow and ensures that the plough functions optimally.

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The vitamin which is essential for the growth of spermatozoa in males and the development of the fetus in females is vitamin E. Vitamin E is a fat-soluble vitamin that acts as an antioxidant, protecting cells from damage caused by free radicals. It is also important for maintaining healthy skin and eyes, as well as boosting the immune system. In males, vitamin E helps to increase the production of healthy sperm and improve their motility. In females, it helps to prevent complications during pregnancy, such as pre-eclampsia and miscarriage.

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A telescope is not a survey equipment. A telescope is an optical instrument used for viewing distant objects. Cross staff, prismatic compass, and offset poles are all surveying equipment used in land surveying to make accurate measurements and collect data about the shape, contour, and size of a piece of land. The cross staff is used to measure angles, the prismatic compass is used to measure bearings, and the offset poles are used to mark points along a straight line.

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Rosette disease of groundnut is transmitted by an aphid. Aphids are tiny insects that feed on the sap of plants and can transmit viruses and other diseases from plant to plant. In the case of groundnuts, the aphids spread the rosette virus from infected plants to healthy plants as they feed on them. The virus then spreads throughout the plant, causing stunting, yellowing of leaves, and the characteristic rosette or bunching of leaves at the top of the plant. If left unchecked, the disease can significantly reduce the yield of groundnuts. Therefore, it is essential to take preventive measures to control the spread of aphids and the disease they transmit.

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The use of fungal pathogens to control dodder weed is a biological method. This method involves the use of living organisms, such as fungi, bacteria, and viruses, to control pests or weeds. In this case, fungal pathogens are used to attack and kill the dodder weed, which is a parasitic plant that feeds on other plants. This method is often considered an environmentally friendly alternative to chemical pesticides because it does not harm non-target organisms and does not leave harmful residues in the environment.

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The sequence of events in the reproductive process of a dairy animal is as follows: 1. Copulation: This is the process of mating between the male and female dairy animal, which is necessary for fertilization to occur. 2. Gestation: After fertilization, the female animal undergoes a period of gestation, during which the fertilized egg develops into a fetus. The length of gestation varies depending on the species of the animal, but is typically several months long. 3. Parturition: Parturition, also known as giving birth, is the process of delivering the fetus from the female animal's reproductive tract. This typically involves the animal going into labor and delivering the newborn calf. 4. Lactation: Following parturition, the female dairy animal begins to produce milk to feed her offspring. This period of milk production is known as lactation and typically lasts for several months until the calf is weaned. Therefore, the correct sequence of events in the reproductive process of a dairy animal is copulation, gestation, parturition, and lactation.

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The replacement of traditional farming methods with modern methods is a step in agricultural development. Traditional farming methods often involve the use of rudimentary tools, such as hoes and cutlasses, and rely heavily on human labor. Modern farming methods, on the other hand, involve the use of mechanized tools and equipment, such as tractors and harvesters, and advanced techniques like precision farming and biotechnology. Modern methods lead to higher yields, better quality crops, and increased efficiency in farm operations. This results in improved food security, increased income for farmers, and overall growth in the agricultural sector. Therefore, the replacement of traditional farming methods with modern methods is considered a significant step in the development of agriculture.

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The total depreciation of the sprayer is N8,200. Depreciation refers to the decrease in the value of an asset over time due to wear and tear or obsolescence. To calculate the total depreciation of the sprayer, we need to determine the annual depreciation rate and multiply it by the number of years the farmer owned the sprayer. Annual depreciation rate = (Purchase price - Sale price) / Useful life Useful life = 4 years (since the sprayer was sold at the end of the fourth year) Purchase price = N12,500 Sale price = N4,300 Annual depreciation rate = (N12,500 - N4,300) / 4 = N2,050 Total depreciation = Annual depreciation rate x Number of years Total depreciation = N2,050 x 4 = N8,200 Therefore, the total depreciation of the sprayer is N8,200.

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A good drought bull should not have long legs. This is because long legs increase the surface area for heat loss, making it difficult for the animal to retain body water during drought conditions. In contrast, a deep barrel is desirable as it indicates good body condition and ability to store fat reserves that can be used during periods of low feed availability. A sloping rump is also desirable as it indicates good muscle development which can help the animal in its search for water and foraging for food. Strong hooves are important for mobility over rough terrain, which is essential during drought periods when food and water sources are scarce.

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The correct answer is: - is not refundable while a loan is refundable Subsidy and loan are both forms of financial assistance, but they differ in several ways. A subsidy is a grant or financial assistance given by the government or an organization to support a particular industry, business, or individual. Subsidies do not have to be repaid and are not considered as debt. On the other hand, a loan is a sum of money that is borrowed and must be repaid with interest. Loans often require collateral or a guarantee of repayment. The main difference between a subsidy and a loan is that a subsidy is not refundable, while a loan is.

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The answer is "increased production cost". Efficient combination of factors of production in agriculture refers to the optimal use of resources such as land, labor, and capital to achieve the highest level of output. This results in lower production costs, increased profit margins, and higher gross revenue. However, increased production costs would mean that the optimal use of resources has not been achieved, which would lead to lower profit margins and gross revenue. Therefore, increased production costs are not an advantage of efficient combination of factors of production in agriculture.

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The statement that is not an impediment to the development of agriculture in West Africa is "aggressive agricultural extension." Agricultural extension refers to the transfer of agricultural knowledge and technology to farmers, and an aggressive extension service can be beneficial to the development of agriculture in the region. However, the other options, such as teeming population of insect pests, chaotic marketing systems, and pollution of the environment, can hinder the growth and productivity of agriculture in West Africa.

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A piece of red cloth is tied to an arrow when it is being used in surveying. The arrow is a survey equipment used to mark points on the ground. The red cloth makes it easier to spot and identify the arrow from a distance. It is usually tied to the top of the arrow, making it visible even from afar.

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The plant nutrient essential for the formation of tubers is potassium. Potassium plays a vital role in many plant processes, including the development of strong stems and roots, photosynthesis, and the movement of water and nutrients through the plant. When it comes to tuber formation, potassium helps to increase the size, quality, and number of tubers produced. A lack of potassium can result in poor tuber formation and reduced crop yields. Therefore, it is important for farmers to ensure that their potato plants have sufficient potassium throughout the growing season.

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The factor that is not considered in the selection of fish for stocking is the color of the fingerlings. When selecting fish for stocking, there are several factors that are considered, such as the marketability of the species, the ease of caring for the fingerlings, and the ability of the fish to be reared in captivity. These factors are important because they can affect the success of the stocking program and the profitability of the fish farmer. The marketability of the species ensures that there is demand for the fish, while the ease of caring for the fingerlings and the ability to rear them in captivity ensure that the fish can be raised successfully. However, the color of the fingerlings is not an important factor in the selection process, as it does not affect the growth or survival of the fish.

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Mechanical power generates the highest amount of energy compared to human power, animal power, and wind power. Mechanical power involves the use of machines and equipment powered by engines or motors. These machines can produce a high amount of energy and are capable of performing tasks that would be impossible or difficult for humans or animals to accomplish. Human power and animal power are limited by the physical capacity of the human or animal, while wind power is dependent on the strength of the wind. Therefore, mechanical power is the most efficient and reliable source of farm power for heavy-duty agricultural activities.

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Agricultural information flows from research institutes through the extension officer to the farmer. Agricultural research institutes generate new knowledge and technologies that are disseminated to farmers through extension officers. Extension officers serve as intermediaries between researchers and farmers by providing information, training, and technical assistance to farmers. Farmers receive the latest agricultural information from extension officers who translate the research findings into practical advice that farmers can use to improve their farming practices. This flow of information helps farmers to adopt new and improved farming technologies and practices that can increase their productivity and profitability.

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The correct sequence of pre-planting operations is bush clearing, burning and stumping, farm layout. This is because the first operation is usually to clear the farm of any bushes or trees that might hinder planting activities. After the clearing, the next operation is to burn any remaining vegetation and stumps to provide ashes and nutrients for the soil. The farm layout is then marked out, indicating the rows and planting spots, to ensure proper spacing and arrangement of crops. Therefore, option D, which starts with bush clearing, followed by burning, stumping and farm layout is the correct sequence of pre-planting operations.

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The correct answer is "proventriculus." The digestive tract of pigs is composed of several structures, including the oesophagus, stomach, small intestine, cecum, colon, and rectum. The oesophagus is the muscular tube that connects the mouth to the stomach, while the stomach is divided into several compartments, including the cardiac region, fundus, body, and pylorus. The small intestine is the longest part of the digestive tract and is further divided into the duodenum, jejunum, and ileum. The cecum is a pouch-like structure that connects the small and large intestine, while the colon is the final part of the large intestine. The rectum is the terminal portion of the digestive tract where feces are stored before being eliminated from the body. The proventriculus, however, is not a structure found in the digestive tract of pigs. Instead, it is a glandular stomach found in birds and some other animals that secretes digestive enzymes and acid to break down food. Therefore, the correct answer is "proventriculus."

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Government ensures continuous availability of fish through fish regulation. Fish regulation refers to the set of policies, laws, and regulations put in place by the government to control the fishing industry. The main objective of fish regulation is to conserve fish stocks and ensure their sustainable utilization, thereby ensuring that fish remains available in the long term. The government achieves this by enforcing regulations such as fishing quotas, size limits, gear restrictions, and closed fishing seasons. These regulations help to control the amount and size of fish caught, as well as the methods used in fishing. Additionally, the government may establish protected areas where fishing is restricted or prohibited altogether, to allow fish stocks to recover. By regulating the fishing industry, the government ensures that fish populations remain healthy and abundant, thereby maintaining a continuous supply of fish for consumption and other purposes.

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The reason for afforestation is to plant trees on land that did not previously have trees or where trees were cut down. The options provided all provide good reasons for afforestation except one: population pressure. Population pressure refers to the increased demand for resources as a result of an increase in population, which can lead to deforestation as more land is cleared for agriculture or settlements. Therefore, population pressure is not a reason for afforestation.

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(a) Five reasons why farm accounts are kept:

• To find out whether the farm is making a profit or a loss.
• To help the farmer plan and budget for the future.
• To serve as a basis for obtaining loans/credit from banks and other lenders.
• To help in assessing tax payable and settling disputes.
• To compare the performance of the farm from one year to another and between enterprises.

(b) Profit and Loss Account for UNITY FARM for the year ending December 2005:

Produce consumed on the farm and given out as gifts are treated as farm income (benefits in kind).

Working:

\[ \text{Total income} = 29{,}000 + 7{,}000 + 5{,}500 + 300 + 1{,}000 = D42{,}800.00 \]

\[ \text{Total expenditure} = 1{,}400 + 1{,}200 + 1{,}900 + 2{,}000 + 1{,}100 + 1{,}200 + 1{,}500 + 6{,}000 + 4{,}400 = D20{,}700.00 \]

\[ \text{Net profit} = 42{,}800 - 20{,}700 = D22{,}100.00 \]

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(a) Four ways by which diseases are spread on a crop farm:

• Through infected planting materials (seeds, cuttings, suckers).
• By wind, which carries fungal spores and bacteria.
• By water (rain splash and irrigation water) that washes pathogens from plant to plant.
• By insect vectors and other animals that carry pathogens.
• Through contaminated farm tools, implements and the hands/clothing of workers.

(b)(i) Onion twister:

Three symptoms:

• Twisting and curling of the leaves.
• Yellowing and dieback of the leaves.
• Stunted growth and rotting/reduction of the bulbs.

Three control measures:

• Plant clean, disease-free seeds/setts and resistant varieties.
• Practise crop rotation and field sanitation (remove and burn infected plants).
• Apply appropriate fungicides.

(b)(ii) Root-knot of tomato (root-knot nematode):

Three symptoms:

• Swellings, galls or knots on the roots.
• Stunted growth of the plant.
• Yellowing of leaves and wilting during hot periods.

Three control measures:

• Practise crop rotation with non-host crops.
• Use resistant varieties and clean, nematode-free seedlings.
• Apply nematicides and/or solarise or flood the soil before planting.

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(a) Three characteristics of agricultural non-governmental organizations (NGOs):

• They are non-profit making; they are not established to earn profit for owners.
• They are voluntary and privately owned, that is, they are not owned or run by government.
• They are usually funded through donations, grants, membership dues and international aid.
• They operate in specific areas of agriculture such as research, funding, or extension.

(b)(i) Five objectives of the West Africa Rice Development Agency (WARDA / AfricaRice):

• To carry out research aimed at increasing rice production in West Africa.
• To develop improved, high-yielding rice varieties (for example NERICA).
• To train rice farmers and national research staff in modern rice production techniques.
• To reduce the region's dependence on imported rice and improve food security.
• To collect, store and distribute improved rice seeds and information to member countries.

(b)(ii) Five objectives of the International Institute of Tropical Agriculture (IITA):

• To conduct research to increase the production of tropical food crops such as yam, cassava, cowpea, maize and soybean.
• To develop improved and disease-resistant crop varieties.
• To develop sustainable farming systems that conserve soil and the environment.
• To train agricultural scientists, technicians and farmers.
• To maintain a gene bank and conserve the genetic resources of tropical crops.

(c) Three other non-governmental organizations involved in agricultural development:

• Food and Agriculture Organization (FAO).
• Sasakawa Global 2000.
• International Fund for Agricultural Development (IFAD).

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(a) Four target groups of the extension agent:

• Crop farmers
• Livestock (animal) farmers
• Rural women/farmers' wives
• Youths and school leavers
• Farmers' cooperatives and organisations

(b) Five important qualities of a good extension worker:

• Good knowledge of agriculture: he must be well trained and understand modern farming practices so as to teach farmers correctly.
• Good communication skill: he must be able to pass information clearly in the local language the farmers understand.
• Patience and tolerance: he must be patient with farmers who learn slowly or resist new ideas.
• Honesty and good character: he must be trustworthy so that farmers will believe and accept his advice.
• Ability to relate well with people (good human relations): he must be friendly, approachable and able to win the confidence of the farmers.

(c) Four functions of an extension worker:

• To teach farmers improved and modern farming methods.
• To carry farmers' problems to research stations and bring research findings back to farmers.
• To organise demonstrations, field days, shows and training for farmers.
• To help farmers form and run cooperative societies and obtain inputs and credit.

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(a) Definition of farmstead: A farmstead is the part of the farm on which the farm buildings and structures (such as the farmhouse, barns, stores, animal houses, processing sheds and roads) are sited and arranged for the efficient running of the farm.

(b) Four factors to be considered in planning a farmstead:

• Topography (nature/slope of the land)
• Source of water supply
• Nature and type of soil
• Accessibility and nearness to roads/market

(c) Importance of the factors listed above:

(d) Two reasons for planning a farmstead:

• To make efficient use of the available land and avoid waste of space.
• To reduce the cost of labour and movement and so improve the efficiency of farm operations.

Détails de la réponse

(a) Candling in chick production: Candling is the process of passing a bright light through an egg in a dark room to examine its interior. It is used to check whether an egg is fertile, to follow the development of the embryo during incubation, and to detect and remove infertile or dead (addled) eggs.

(b) Intensive method of managing poultry:

(i) Sanitation:

• The house, feeders and drinkers should be cleaned and disinfected regularly.
• Litter should be kept clean and dry, and wet or caked litter removed to prevent disease.
• Dead birds should be removed and properly disposed of, and a foot-dip/disinfectant used at the entrance to control disease spread.

(ii) Feeding:

• Birds are fed balanced rations appropriate to their age (chick mash, growers' mash, layers' mash or broiler finisher).
• Clean, cool water must be provided at all times, and feed given in the right quantity to avoid waste.
• Feeders and drinkers should be well spaced so that all birds have easy access.

(c) Six breeds of pigs:

• Large White (Yorkshire)
• Landrace
• Duroc
• Hampshire
• Berkshire
• Tamworth

Détails de la réponse

(a) Four asexual methods of crop propagation:

• Propagation by cuttings (for example cassava, sugar-cane)
• Propagation by budding
• Propagation by grafting
• Propagation by layering
• Propagation by suckers, tubers, bulbs or corms

(b) Definitions:

• (i) Mixed farming: The practice of growing crops and rearing animals together on the same piece of land at the same time, where each enterprise supports the other.
• (ii) Inter-cropping: The practice of growing two or more different crops together on the same piece of land at the same time.
• (iii) Ley farming: A system in which land is put under arable (crop) cultivation for some years and then put under grass or pasture for grazing for a period before returning it to crops, in rotation.

(c) Four advantages of mixed farming:

• Animal dung is used as manure to improve soil fertility for the crops.
• Crop residues and by-products are used to feed the animals.
• It provides a steady, all-year-round income from both crops and animals.
• It spreads the risk of total farm failure and makes fuller use of land and labour.

Four advantages of inter-cropping:

• It gives a higher total yield and better use of the land per unit area.
• Leguminous crops in the mixture add nitrogen to the soil for the other crops.
• The ground cover reduces soil erosion and suppresses weeds.
• It insures the farmer against total loss if one crop fails.

Détails de la réponse

(a) Annotated diagram of the water cycle

(b) Importance of water to crops

1. Water is a raw material used in photosynthesis.
2. It dissolves mineral salts in the soil, making them available for absorption by roots.
3. It serves as a medium for the translocation of mineral nutrients and manufactured food in the plant.
4. It maintains the turgidity of cells, thereby keeping leaves and stems firm.
5. It is required for seed germination.
6. It cools the plant during transpiration.

(c) Ways of conserving water in the soil

1. Mulching the soil surface to reduce evaporation.
2. Adding humus or organic manure to improve the water-holding capacity of the soil.
3. Growing cover crops to shade the soil and reduce evaporation and run-off.
4. Practising contour ridging or terracing to reduce surface run-off and increase infiltration.

Détails de la réponse

(a) Life cycle of the liver-fluke (Fasciola hepatica): An annotated diagram should be drawn as a cycle with arrows linking the stages below. The liver-fluke needs two hosts: the primary host (sheep, cattle, goat) and the intermediate host (a mud/water snail).

• Adult flukes live in the bile ducts/liver of the primary host and lay eggs.
• Eggs pass out with the faeces of the animal onto wet pasture.
• In water, each egg hatches into a ciliated larva called a miracidium.
• The miracidium enters a mud snail (intermediate host) and develops through the sporocyst and redia stages, multiplying.
• These develop into tadpole-like cercariae which leave the snail.
• The cercariae encyst on wet grass as metacercariae (the infective stage).
• A grazing animal swallows the metacercariae, which travel to the liver, grow into adult flukes, and the cycle repeats.

Preventing the fluke from completing its life cycle in the field:

• Drain marshy/water-logged grazing land to destroy the snail habitat.
• Kill the mud snails using molluscicides (for example copper sulphate).
• Avoid grazing animals on wet, low-lying pastures, especially in the early morning.
• Deworm (drench) infected animals regularly and dispose of their dung properly to break the cycle.

(c) Three effects of lice on animal production:

• They suck blood and cause anaemia and loss of condition.
• Their bites cause irritation and restlessness, reducing feeding and growth.
• They damage the skin/hide and transmit diseases, lowering the value of the animal.