WAEC SSCE - Agricultural Science - 2007 (Objective)

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The relative proportion of each fraction of soil in a soil sample determines its texture. Soil texture refers to the composition of different sizes of mineral particles in the soil, which include sand, silt, and clay. The proportion of these particles affects soil properties such as water holding capacity, nutrient retention, and aeration. Soil texture is determined by the relative proportions of these soil particles in the sample, with sand particles being the largest, followed by silt, and then clay. Therefore, the soil sample with a higher proportion of sand particles will have a coarser texture than the soil sample with a higher proportion of clay particles, which will have a finer texture. Texture is one of the most important soil properties, and it influences several soil processes and properties, including fertility, drainage, and erosion.

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The gestation period of ewe is 149 days. This means the time between when a female sheep gets pregnant and when she gives birth to a lamb is approximately 149 days.

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The correct answer is option D: uprooting the weeds. Biological methods of weed control involve the use of living organisms to control or suppress weed growth. Options A, B, and C are all examples of biological weed control methods. In contrast, uprooting the weeds is a physical method of weed control that involves physically removing the weeds from the soil.

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The correct answer is liver flukes. Snails are intermediate hosts of liver flukes, which are a type of parasitic flatworm that infects livestock such as cattle, sheep, and goats. These liver flukes can cause serious damage to the liver and other organs, and can even be fatal in severe cases. By eradicating snails from pastures, farmers can help control the spread of liver flukes and protect their livestock. Therefore, the farmer is attempting to control liver flukes by controlling the snail population.

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The livestock disease that affects the reproductive system is brucellosis. Brucellosis is a bacterial disease that commonly affects cattle, sheep, and goats, and it can also infect other animals and humans. The bacteria can cause abortions, stillbirths, and infertility in infected animals. It can be transmitted from animals to humans through direct contact with infected animals or consumption of contaminated animal products such as unpasteurized milk. Therefore, it is important to regularly test and vaccinate livestock to prevent the spread of the disease.

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Layering is advantageous because it avoids the possible failure of fertilization. In layering, a stem or branch of a plant is bent down and buried in the soil while still attached to the parent plant. The buried section of the stem or branch will eventually develop roots and grow into a new, independent plant. This method ensures that the new plant will be genetically identical to the parent plant, unlike sexual reproduction where the offspring may vary genetically. Since layering does not require fertilization or pollination, the chance of failure due to poor pollination or genetic variability is minimized.

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Fertilizing a fish pond with compost manure would most likely increase phytoplankton population and increase fish yield. This is because the compost manure serves as a source of nutrients for the phytoplankton, which are the primary food for fish in the pond. The increased availability of food for the fish leads to increased growth and productivity, resulting in a higher yield. However, excessive use of compost manure may lead to overgrowth of phytoplankton, leading to reduced oxygen levels in the water and ultimately, reduced fish yield.

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Silos ensure good storage because of the air-tight environment created. Silos are designed to be airtight, which helps to prevent moisture and air from entering, which can lead to spoilage or insect infestation. By keeping the stored grains or other agricultural produce in an air-tight environment, the quality and shelf life of the produce can be preserved for longer periods of time. This is particularly important for long-term storage of produce to prevent spoilage, which can result in losses for farmers.

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Deforestation is the clearing of forests, which results in the removal of trees from the land. This can have negative impacts on the environment and ecosystems, and can eventually lead to the loss of soil organic matter. Trees play an important role in maintaining soil organic matter, as they help to store and cycle nutrients, prevent soil erosion, and provide habitat for soil organisms. When trees are removed, the soil can become exposed to the elements, which can cause it to dry out and become more prone to erosion. This can lead to a decline in soil quality, which can reduce the fertility and texture of the soil, and eventually lead to desertification in some cases. Additionally, deforestation can contribute to climate change, as trees absorb carbon dioxide from the atmosphere and release oxygen. When trees are removed, the amount of carbon dioxide in the atmosphere can increase, leading to global warming and other negative impacts on the environment.

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Urea cannot be used for liming. Liming is the process of adding materials to soil to increase its pH level, which makes the soil less acidic and more alkaline. Urea is a nitrogen-based fertilizer that is commonly used to provide plants with nitrogen. It does not have any liming properties and will not increase the pH level of the soil. Therefore, urea is not a suitable material for liming. The other options (gypsum, basic slag, and chalk) can be used for liming because they contain calcium or magnesium carbonate, which can react with the soil to increase its pH level.

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Assuming that in sheep, the allele for black coat colour is dominant over that for brown coat colour, crossing a heterozygote black with a homozygote brown will result in 50% of the offspring having a black coat colour and 50% having a brown coat colour. This is because the heterozygote parent carries one dominant black allele and one recessive brown allele, and the homozygote brown parent carries two recessive brown alleles. Therefore, the possible combinations of alleles for the offspring are BB (black), Bb (black), and bb (brown). The probability of each outcome is 50% black and 50% brown.

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The deficiency symptom described in the question is the yellowing or whitening of the areas between the veins of leaves, known as chlorosis. This chlorosis has a distinctive pattern of parallel white or yellow streaks along the veins. This is a symptom of magnesium deficiency in plants. Therefore, the correct answer to the question is option B: magnesium.

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Golden brown lesions on peeled yam tuber indicate infection by fungi. Fungal infections in yam tubers can lead to various postharvest losses. The fungi penetrate the yam skin, and lesions or spots appear on the surface of the yam tuber. These lesions can develop into a sunken, dark, and dry rot that can spread throughout the yam. Golden brown lesions can be caused by several types of fungi, including Fusarium and Aspergillus species.

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Ruminants do not normally show deficiency symptoms of vitamin B complex because the bacteria present in their rumen synthesize the vitamins. These bacteria are able to produce the vitamin B complex in adequate amounts, which is then absorbed by the ruminant's body. This process is made possible due to the unique four-chambered stomach of the ruminants, which allows for the fermentation of plant materials by the bacteria in the rumen. As a result, ruminants are able to derive their vitamin B complex requirements from the microbial synthesis in their rumen, and do not rely on dietary sources for these vitamins.

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The option that is excluded from the list of side effects of various preventive and control measures of pests and diseases of crops is "improved quality of farm produce." Explanation: The other options listed - environmental pollution, poisoning of wildlife, and disruption of the ecosystem - are potential negative effects of using certain pest and disease control measures such as synthetic pesticides and herbicides. While these measures can effectively control pests and diseases, they can also harm the environment and non-target organisms. Improved quality of farm produce is not a negative side effect, but rather a desired outcome of using these measures. For example, using disease-resistant crop varieties can lead to improved quality and yield of the crop.

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The practice of burning of trash can lead to loss of soil water because it exposes the soil to direct sunlight, which can cause rapid evaporation of water from the soil. Slashing of undergrowth and seed bed preparation can help to conserve soil moisture by providing mulch cover and reducing soil erosion. Soil tillage can either help to conserve or enhance loss of soil water depending on the timing, depth and frequency of tillage operations. Therefore, the correct answer is option A - I and II.

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The statement that is true about soil water is: "crops utilize capillary water in the soil." Capillary water is the water held in the soil pores and is available to plants for use. The roots of plants absorb water from the soil through the process of osmosis. Capillary water is held in the soil by the surface tension of the water and the adhesion forces between water molecules and the soil particles. It is the most important source of water for plants, and its availability in the soil affects plant growth and crop yield. Therefore, farmers need to manage soil moisture levels to ensure that the plants have access to the required amount of capillary water.

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The false statement about farm settlement schemes is that they are set up for research and publicity. Farm settlement schemes are typically established to encourage young people to take up farming, provide employment for young school leavers, and develop rural infrastructure. While research may be conducted on these schemes, and they may receive some publicity, these are not the primary purposes for their establishment.

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Delayed harvesting of maize may result in a high incidence of pest infestation. This is because when maize is left in the field for too long, it becomes more susceptible to attack by pests such as weevils, borers, and rodents. These pests can cause significant damage to the crop, leading to losses in yield and quality. Additionally, delayed harvesting may also lead to grain shattering, which can result in low seed viability and reduced yields. Furthermore, the longer maize is left in the field, the more likely it is to be exposed to adverse weather conditions, which can lead to yellow colouration of the grains and further reduce their quality.

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A farmstead is best described as the farmer's abode, which includes the main farmhouse, outbuildings, and other structures related to the living and management of the farm. It is the central hub of activity on a farm, where the farmer and their family live and work, and where most of the daily farm activities are carried out. The farmstead can also include areas for animal pens, crop production, and equipment and storage facilities, but its primary function is to serve as the farmer's home and base of operations for the farm.

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The correct answer is elephant grass. Elephant grass is a tall tropical perennial grass with broad hairy leaves that can grow up to 3-6 meters tall. It is commonly used for pasture and silage production for livestock feeding due to its high yield potential and nutrient content. It is also used as a source of bioenergy, and for erosion control and soil improvement.

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The standard length of a Gunter's chain is approximately 20 meters. A Gunter's chain is a measuring tool that was used in the past to measure land, and it consists of 100 links, with each link measuring 0.2 meters or 20 centimeters. Therefore, the total length of a Gunter's chain is 100 links x 0.2 meters per link = 20 meters.

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Agricultural credits are funds made available to farmers or agribusinesses to finance their activities. The purpose of agricultural credits is to enhance agricultural productivity and help farmers overcome financial constraints. Agricultural credits should be used to finance activities that will increase agricultural productivity, and not for personal or non-agricultural purposes. Therefore, agricultural credits should not be put towards meeting family needs, such as paying for household expenses, or towards improving structures that are not directly related to agricultural productivity, such as building a new house. Instead, agricultural credits should be used to purchase inputs, such as seeds, fertilizers, or pesticides, and to adopt innovations, such as new farming techniques or technologies that can increase yields and efficiency.

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To calculate the production cost of maize per kg, we need to first calculate the total revenue and then subtract the profit from it. Total revenue = 260 kg * N5.50/kg = N1,430.00 Profit = N430.00 Therefore, the production cost of maize per kg is: Production cost = (Total revenue - Profit) / Total quantity = (N1,430.00 - N430.00) / 260 kg = N1000.00 / 260 kg = N3.85/kg So, the answer is N3.85.

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The system of poultry management in which the spread of diseases can be kept to a minimum is the battery cage system. In this system, birds are kept in individual cages, which reduces the chances of them coming into contact with each other's feces or bodily fluids, and thus limits the spread of diseases. The other systems, such as deep litter, fold, and free range, involve birds having more contact with each other and their environment, which increases the risk of disease transmission.

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A glue-processing industry would require cassava as an agricultural raw material. Cassava contains a high amount of starch which can be extracted and processed into glue. Cotton is a fiber crop, coconut is used for oil production and kola is a nut used for medicinal and cultural purposes.

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The statement that is not an advantage of drainage is "supplies moisture for plant growth". This is because drainage is meant to remove excess water from the soil, which can be harmful to plant growth by reducing the amount of oxygen available to the roots. While drainage can indirectly improve soil moisture levels by preventing waterlogging, its main purpose is to prevent excess water accumulation, not to supply moisture. Drainage can improve soil structure by reducing compaction and allowing better root penetration. It can also reclaim waterlogged land and swamps by making the soil more suitable for plant growth.

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The factor that will not influence the yield of crops is wind direction and speed. While the other factors listed can affect crop growth and development, wind direction and speed typically do not have a direct impact on crop yield. However, it is worth noting that extreme wind conditions, such as strong winds or tornadoes, can physically damage crops and lead to yield losses.

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The most versatile source of farm power in West Africa is animal power. This is because animals can be used to perform a wide range of tasks on the farm, such as plowing, harrowing, weeding, and transporting goods. They are also relatively easy to maintain and can be fed with locally available feedstuffs. In contrast, biogas, wind, and water power may not be as widely available or may require more specialized equipment and maintenance, making them less versatile.

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The hormone that influences the movement of the pelvic ligaments during parturition in farm animals is known as relaxin. Relaxin is a hormone produced in the ovaries and placenta of pregnant animals, including cows, pigs, and dogs. It causes the ligaments that support the pelvic bones to soften and stretch, allowing the pelvic opening to widen during birth. This allows the offspring to pass through the birth canal more easily. Relaxin is also involved in other aspects of pregnancy, such as regulating the growth and development of the fetus and preparing the mammary glands for lactation.

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Micronutrients are essential nutrients required in small quantities by plants for their proper growth and development. They include elements such as zinc, boron, iron, manganese, copper, and molybdenum. These nutrients are likely to be deficient in soils with low pH levels because acidic conditions in the soil limit the availability of micronutrients to the plants. This means that even though these nutrients may be present in the soil, the plant cannot access them in sufficient quantities for their growth and development. Additionally, the use of high-phosphate fertilizers and excessive irrigation can also cause micronutrient deficiencies in plants. Soils with high organic matter content or fine texture are not necessarily deficient in micronutrients. In fact, organic matter can contribute to the availability of micronutrients in the soil, while fine texture soils generally have a higher nutrient holding capacity. Cleared virgin forest soils can also have varying levels of micronutrients depending on the soil type and the amount of weathering that has occurred.

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The group of macro-nutrients that is a constituent of protein is nitrogen, phosphorus, and sulfur. Proteins are made up of building blocks called amino acids, which consist of nitrogen, carbon, hydrogen, and oxygen. Nitrogen is a key component of amino acids, and it is obtained by plants through the soil in the form of nitrate or ammonium. Phosphorus and sulfur are also important components of amino acids and are necessary for the synthesis of proteins in plants. Therefore, the correct option is nitrogen, phosphorus, and sulfur.

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Drying of harvested crops is necessary because it reduces the moisture content and allows for better storage. When crops are harvested, they contain a lot of moisture which can cause spoilage, mold growth, and insect infestation during storage. Drying the crops reduces the moisture content, which slows down these processes and allows the crops to be stored for longer periods without spoiling. Drying also helps to prevent the growth of microorganisms, which can cause diseases and spoilage of the crops. In addition, dried crops are easier to transport and can be sold to consumers when they are dry, making them more appealing and easier to handle. Therefore, drying harvested crops is an important step in ensuring food security and reducing post-harvest losses.

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In this scenario, we are crossing two heterozygotes (Bb x Bb) where B represents the dominant allele for black coat color and b represents the recessive allele for brown coat color. Each parent has one dominant allele and one recessive allele. When we cross these two heterozygotes, their offspring will inherit one allele from each parent. The possible combinations are BB, Bb, Bb, and bb. BB represents homozygous dominant, which means the offspring will have black coat color. Bb represents heterozygous, which means the offspring will also have black coat color because the dominant allele masks the recessive allele. bb represents homozygous recessive, which means the offspring will have brown coat color. Therefore, out of the four possible combinations, 3 have at least one dominant allele, which will produce black coat color. So, the percentage of the F1 generation that will have black color is 75% (3 out of 4 possible combinations). Hence, the answer is 75%.

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The correct option is: "improves soil structure". This statement is not true because farm mechanization does not directly improve soil structure. Instead, it can cause soil compaction if heavy machinery is used excessively or when soil moisture content is high. However, farm mechanization has many advantages, including saving labour, reducing drudgery, and increasing output. Mechanization can also lead to improved efficiency, timeliness, and precision in farming operations.

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The correct sequence of land preparation for planting yam is option II, I, IV, and III, which is "slashing of undergrowth, burning of trash, soil tillage, and seed bed preparation" respectively. Slashing of undergrowth is done to clear the farm of any unwanted plant debris or weeds that could interfere with the growth of yam. Burning of trash is done to further clear the farm and also to provide the soil with some nutrients from the ashes. Soil tillage is done to loosen the soil and make it easier for the yam to penetrate and spread its roots. Seed bed preparation is done to create mounds or ridges where the yam can be planted, as well as to create spaces for applying fertilizers or mulch.

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To improve soil fertility status, the combination of practices should aim at increasing soil nutrients and organic matter, reducing soil erosion, and promoting soil microorganisms. Out of the given options, applying organic fertilizer (II), growing legumes (IV), and allowing land to fallow (I) are practices that can improve soil fertility. Organic fertilizers increase soil organic matter content and nutrient availability, legumes improve soil nitrogen levels through nitrogen fixation, and allowing land to fallow promotes soil conservation by reducing soil erosion and increasing organic matter content. Practicing monoculture (III) can lead to soil depletion and reduction of soil nutrients over time. Therefore, the correct combination of practices that can help to improve soil fertility status is I, II, and IV only.

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The structure that is not connected to the urethra of a bull is the rectum. The urethra is a tube that connects the urinary bladder to the external environment, allowing for the passage of urine. In bulls, the urethra passes through the penis and is responsible for the transportation of both urine and semen during ejaculation. However, the rectum is not connected to the urethra and is part of the digestive system, responsible for the storage and elimination of fecal matter.

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Tomato plants are primarily staked to raise the fruits from the ground. When tomato plants are not staked, the fruits may come in contact with the soil and become susceptible to diseases, pests, and rotting. Staking allows the fruits to hang freely in the air, reducing the likelihood of damage and disease. Staking also facilitates air circulation and exposes the plants to more sunlight, which can increase crop growth and yield.

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When poultry flock pass out green, foul-smelling faeces with nervous symptoms, it means that the farmer has neglected to treat them against gumboro disease. Gumboro disease, also known as infectious bursal disease, is a viral infection that primarily affects young chickens. It can cause diarrhea, depression, and nervous symptoms in affected birds. The disease is highly contagious and can spread rapidly through a flock, leading to significant economic losses for poultry farmers. Therefore, it is important for farmers to take preventative measures, such as vaccination, to protect their flocks from gumboro disease.

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Water-logged soils impede good crop growth and development because crop roots are deprived of sufficient oxygen. When the soil is water-logged, the spaces between soil particles become filled with water, which displaces the air in the soil. Roots need oxygen to respire and to convert sugars into energy for growth, so without it, the roots cannot function properly. As a result, the crop may experience stunted growth or even die.

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