WAEC SSCE - Agricultural Science - 1997

Which of the following is not a characteristic of a good pasture?

Détails de la réponse

The answer is "slow growth". A good pasture is one that can support the grazing needs of animals by providing high quality grasses and legumes with a high leaf to stem ratio. It should also have the ability to withstand trampling from the animals and be drought-resistant. Slow growth, on the other hand, would be a disadvantage as it means that the animals would have to wait longer for the grass to grow back after grazing. This would result in overgrazing and eventually lead to the depletion of the pasture.

Which of the following does not influence rock weathering?

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The answer is "ammonification". Ammonification is a biological process that converts organic nitrogen to ammonia and ammonium ions, which can contribute to soil fertility. However, it is not directly involved in rock weathering. The other options - water, carbonation, roots, and temperature - all play significant roles in the weathering of rocks. Water can cause physical weathering through erosion and can chemically weather rocks through dissolution and oxidation. Carbonation is the reaction of carbon dioxide with minerals in rocks, which can dissolve and break down the rock. Roots can grow into cracks in rocks and exert pressure, causing physical weathering. Temperature can also cause physical weathering through thermal expansion and contraction.

Effects of overgrazing on soil include the following except

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Overgrazing can have negative effects on the soil. The options given in the question are possible effects of overgrazing except for one. One of the effects mentioned is the "improvement of soil structure", which is not a negative effect of overgrazing. Overgrazing can lead to the exposure of soil to erosion, which is the removal of the topsoil layer by wind or water. This can result in soil infertility, as the topsoil is rich in nutrients necessary for plant growth. Overgrazing can also lead to the depletion of soil nutrients, as the plants are not given enough time to replenish the soil with their root system. In addition, overgrazing can lead to soil compaction, as the constant pressure of animal hooves on the soil can cause it to become tightly packed. Finally, overgrazing can lead to the exposure of soil to direct rays of the sun, which can cause the soil to dry out and become less fertile.

The forest trees growing in the Sudan savanna zone of Nigeria include the following except

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Crops grown in nitrogen deficient soil show the following characteristics except

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When crops are grown in nitrogen deficient soil, they suffer from a lack of nitrogen which is an essential nutrient for plant growth. As a result, they exhibit several characteristics including poor growth, stunted growth, chlorosis in growing crops, and yellowing of lower leaves. The nitrogen deficiency slows down the plant's metabolic processes, which can delay the ripening of the fruit. Therefore, the correct option is (E) timely ripening of fruits, as it is not a characteristic of crops grown in nitrogen deficient soil.

The roles of government in the development of agriculture include the following except

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The question asks for an option that is NOT a role of government in the development of agriculture. Therefore, we need to look for an option that is not a responsibility of the government in the development of agriculture. The correct option is "training of farmers' children" because it is not a direct role of the government in agriculture development. While the government may provide education and training opportunities for farmers, it is not specifically responsible for the education of their children. The other options listed are all roles that the government can play in promoting and supporting agricultural development.

Reforestation is the

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Reforestation is the organised planting of trees in areas from which forest trees have been removed. It is a deliberate effort to restore the ecological function and structure of deforested or degraded land. The objective of reforestation is to establish a forest with a structure and composition that is as similar as possible to the original forest. It is a crucial process for mitigating the negative impacts of deforestation on the environment, including soil erosion, loss of biodiversity, and climate change.

Commodity boards were responsible for the marketing of the following crops except

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Commodity boards were responsible for the marketing of various crops, especially cash crops. However, yams are not typically considered cash crops, but rather subsistence crops. Therefore, it can be concluded that commodity boards were not responsible for the marketing of yams.

Cultural methods of controlling pests include the following except

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The aims of crop improvement include the following except

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The question is asking which option is not an aim of crop improvement. Crop improvement involves the application of scientific techniques to produce crops with desired characteristics. The options listed are aims of crop improvement, except for "improving the infrastructural facilities in a farm". While infrastructure may facilitate crop production, it is not considered an aim of crop improvement. Therefore, the answer is "improving the infracstructural facilities in a farm".

Which of the following is not a reason for converting a piece of land into a forest reserve?

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Cassava is cultivated in many ecological zones because of its

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Cassava is a popular crop that is cultivated in many ecological zones due to its tolerance to low rainfall and poor soil fertility. Unlike other crops, cassava can grow in areas with low rainfall and in soils that are not very fertile. Additionally, cassava has a relatively short growth period, making it possible to harvest the crop after about 8 to 18 months of planting. Cassava can be used for both industrial and domestic purposes, and it is also resistant to some diseases and pests. Its low production costs make it a suitable crop for smallholder farmers, contributing to food security in many regions.

The causal organism of mastitis in cattle is

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The causal organism of mastitis in cattle is a bacterium. Mastitis is an inflammation of the mammary gland in cows which can be caused by various bacteria, but the most common ones are Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli. Bacteria can enter the udder through the teat canal and cause an infection which results in swelling, pain, and the production of abnormal milk.

High fibre and low energy feeds are classified as

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High fibre and low energy feeds are classified as roughages. Roughages are feed materials that are high in fibre and low in energy, such as hay, straw, and silage. These feeds are often bulky and take longer to digest, providing sustained energy over a longer period of time. Roughages are an important component of the diet for ruminants like cows and sheep, as their digestive systems are adapted to break down fibrous plant material. In contrast, concentrates are feed materials that are high in energy and low in fibre, such as grains and oilseed meals. They provide a quick source of energy and are often used to supplement roughages in an animal's diet.

The agent of controlled pollination in crops is

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The agent of controlled pollination in crops is man. Controlled pollination is the process of transferring pollen from one plant to another with a specific goal in mind, such as developing a new variety or increasing yield. In this process, humans intervene to manipulate the transfer of pollen, rather than relying on natural pollination by wind or insects. This is done by using tools such as brushes or by physically transferring the pollen by hand. Hence, the answer is "man".

Which of the following is not a function of organic matter in the soil?

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The function of organic matter in soil is very important for soil health and productivity. The options (a), (b), (c) and (e) are all functions of organic matter in the soil. Organic matter helps to retain moisture in the soil, reduces soil erosion, prevents nutrient leaching and improves soil structure. However,, "inhibiting seed germination", is not a function of organic matter in the soil. In fact, organic matter helps to provide nutrients and a favorable environment for seed germination and plant growth.

The amount of air and water in the soil is mostly affected by the

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The amount of air and water in the soil is mostly affected by the structure of the soil. Soil structure refers to the arrangement of soil particles into aggregates or clumps. The spaces between these aggregates determine the amount of air and water in the soil. If the soil has a good structure with well-formed aggregates, there will be more spaces for air and water to move through the soil. On the other hand, if the soil has poor structure, with few or no aggregates, the soil will have poor aeration and drainage. The other options, such as location, rainfall, chemical composition, and living organisms, can also have an impact on soil air and water content, but they are not the primary factors.

The branch of crop production which is normally concerned with crop improvement is

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The branch of crop production that is normally concerned with crop improvement is plant breeding. Plant breeding involves selecting and crossing plants with desirable traits, such as increased yield, disease resistance, or improved quality, in order to develop new and improved varieties. This is done through careful selection of parent plants, controlled pollination, and evaluation of offspring. Plant breeding is an important aspect of agriculture as it helps to develop crops that can better meet the needs of farmers and consumers.

Ice causes rock weathering

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The following are functions of farm manager except

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The farm manager has several roles to play on the farm, but planting crops and vegetables is not one of them. The farm manager is responsible for planning the farm programme of work, co-ordinating the farm activities, organizing sales of farm products, controlling farm workers and managing the resources of the farm to ensure maximum productivity. The farm manager is also responsible for managing the finances of the farm, including budgeting, accounting, and financial reporting. In addition, the farm manager is responsible for managing risk and making strategic decisions to ensure the long-term sustainability of the farm.

Most of the land used for agriculture in Nigeria are acquired through

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In cattle, high fever and sudden death are symptoms of

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In cattle, high fever and sudden death are symptoms of anthrax. Anthrax is a highly infectious bacterial disease that affects mainly animals, especially cattle, sheep, and goats. The disease is caused by the bacterium Bacillus anthracis, which forms spores that can survive in the soil for many years. In cattle, the disease can cause high fever, depression, and sudden death, with little or no warning. Other symptoms may include bloody discharge from the body orifices and difficulty breathing. Anthrax is a zoonotic disease, meaning it can be transmitted from animals to humans, and therefore, it is important to take necessary precautions to prevent its spread.

Farm financing may be obtained from the following except

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The following are characteristics of quartz except

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Quartz is a mineral that has a glass-like appearance, is granular in nature, semi-translucent, and has a shiny surface. However, one characteristic that does not apply to quartz is having cleavage. Cleavage is the tendency of a mineral to break along specific planes of weakness, producing smooth surfaces. Quartz lacks cleavage, and instead has a conchoidal fracture, which is a type of fracture that produces curved, shell-like surfaces when the mineral is broken.

Which of the following is not correct about the importance of agriculture?

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Night blindness in an animal is caused by a deficiency of

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Night blindness in animals is caused by a deficiency of vitamin A. Vitamin A is an essential nutrient that is necessary for maintaining normal vision. Animals that do not have enough vitamin A in their diet may experience a range of vision problems, including night blindness. Night blindness is the inability to see clearly in low light or at night, which can be dangerous for animals that are active during these times. Therefore, ensuring that animals have a diet that is rich in vitamin A is important for maintaining their vision and overall health.

New-born animals should be fed with colostrum because it

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New-born animals should be fed with colostrum because it contains antibodies protecting them against diseases. Colostrum is the first milk produced by the mammary glands of female mammals after giving birth. It is rich in antibodies, growth factors, and other essential nutrients that are important for the development and survival of the newborn. The antibodies present in colostrum provide passive immunity to the newborn, protecting them against diseases and infections. Colostrum is essential for the health and survival of the newborn animal.

The following crops can be grown as cover crops except

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The crop that cannot be grown as a cover crop is Nicotiana tabacum. Cover crops are crops that are grown primarily to provide ground cover to protect the soil against erosion, suppress weed growth, and improve soil health. They are usually grown between periods of regular crop production. The other options listed - pueraria phaseoloides, stylozanthes gracillis, centrosema pubescens, and calopogonium mucunoides - are all examples of crops that can be grown as cover crops.

Progeny selection involves selection of breeding stock on the basis of

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Progeny selection involves selecting breeding stock based on the performance of their offspring. This means that the offspring of a particular breeding pair are evaluated for specific traits or characteristics, such as growth rate, meat quality, milk production, or disease resistance. The animals that perform well in these traits are then selected as breeding stock for future generations. By selecting based on offspring performance, the breeder can improve the overall genetic quality of the herd or flock over time. This is in contrast to other forms of selection, such as selection based solely on the merits of the parents or on pedigree, which may not necessarily result in the desired traits being passed on to the offspring.

Which of the following breeds of cattle is an imported breed?

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The hormone generally called pregnancy hormone in farm animals is

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The hormone generally called pregnancy hormone in farm animals is progesterone. Progesterone is a hormone that is essential for the maintenance of pregnancy in mammals. It is produced by the corpus luteum in the ovary and later by the placenta after implantation of the fertilized egg. It helps to prepare the uterus for implantation and maintain the pregnancy by inhibiting contractions of the uterus. In farm animals, progesterone is used to synchronize estrus cycles and to support pregnancy in breeding programs.

Pigs are normally classified into the following group except

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Dissemination of new ideas and techniques to farmers can only be effective if the agricultural extension officer

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For effective dissemination of new ideas and techniques to farmers, the agricultural extension officer must work with existing community organizations and local leaders. This is because the agricultural extension officer needs to understand the cultural, social, and economic factors that affect the farmers' practices and behavior. By working with local leaders and organizations, the extension officer can gain the trust and support of the community, which is necessary for the successful adoption of new practices. The extension officer can also use these local networks to disseminate information and provide support to the farmers. Giving financial support, equipment or inputs alone is not sufficient without working with the community and local leaders.

The difference between the total assets and total liabilities of a farm enterprise within a specified period before taxation is known as

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The difference between the total assets and total liabilities of a farm enterprise within a specified period before taxation is known as "net worth". This is because it represents the residual interest of the owner(s) in the assets of the farm after all liabilities have been settled. In other words, net worth is the value of the farm to its owners. It is calculated by subtracting the total liabilities from the total assets.

A farm practice which assists in maintaining the structure and fertility of soil and reduction in risk of the sun infestation is

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Which of the following is the primary function of the gizzard?

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The primary function of the gizzard is to grind ingested food into smaller particles. This is necessary for the mechanical breakdown of food in the digestive system of birds and some other animals, since these animals lack teeth to chew and grind their food. The gizzard is a muscular, thick-walled organ that contracts rhythmically to break down food particles by grinding them against each other and against small stones or grit that the animal has ingested. The ground-up food then passes on to the rest of the digestive system for further processing and absorption of nutrients.

Drainage types include the following except

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Energy for photosynthesis in crops is provided by

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Energy for photosynthesis in crops is provided by the sun. Photosynthesis is the process by which plants use energy from sunlight, carbon dioxide, and water to produce glucose and oxygen. The process of photosynthesis occurs in specialized structures in plant cells called chloroplasts, which contain chlorophyll pigments that absorb light energy from the sun. This light energy is then used to convert carbon dioxide and water into glucose and oxygen, which the plant uses as a source of energy for growth and development. Therefore, the energy for photosynthesis in crops is provided by the sun.

The most important pests of vegetable crops are

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The most important pests of vegetable crops are insects. Insects are the most common and harmful pests that attack vegetable crops, causing damage to leaves, stems, roots, and fruits. They feed on the plant tissues, sucking the sap or chewing the leaves, and can also transmit diseases. Some of the most common insects that attack vegetable crops include aphids, caterpillars, whiteflies, thrips, mites, and beetles. Insects can cause significant damage to crops, resulting in reduced yields and economic losses for farmers. Therefore, effective pest control measures are necessary to protect vegetable crops from insect damage.

The proportion of the different types of feed given to an animal daily is known as

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The proportion of the different types of feed given to an animal daily is known as a ration. It is the total amount of feed provided to an animal in a day, including roughages, concentrates, supplements, and additives. The correct balance of each component in a ration is critical for the animal's health, productivity, and overall well-being. The proper ration will vary depending on the animal's species, breed, age, weight, and level of activity. The goal of formulating a balanced ration is to provide the animal with all the essential nutrients it needs to maintain health, growth, and production.

Milling of rice is usually done

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Which of the following is a pasture grass?

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The pasture grass among the options given is Cynodon dactylon. This is because Cynodon dactylon, also known as Bermuda grass or African couch grass, is a well-known and widely used pasture grass that is native to Africa but is now found in many parts of the world. It is a highly valued grass because it is drought-tolerant, grows well in warm climates, and can withstand heavy grazing pressure. The other options listed are legumes that are often grown alongside grasses in pastures to improve soil fertility and provide additional nutrition for grazing animals.

Which of the following is a soil micro-nutrient?

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Iron is a soil micro-nutrient. Micro-nutrients are essential elements required by plants in small amounts for their growth and development. Iron is required for the formation of chlorophyll in plants, which is necessary for photosynthesis, and it also plays a vital role in the respiration process of plants. Although iron is required in small quantities, its deficiency can lead to chlorosis or yellowing of leaves, which can reduce the plant's growth and yield.

Gestation period is defined as the time

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Which of the following group of crops can be attacked by smut diseases?

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Smut diseases are a group of fungal diseases that affect various crops. The symptoms include the formation of black soot-like masses of spores on the affected parts of the plant. Based on the options given, the group of crops that can be attacked by smut diseases include rice, maize, and guinea corn.

Common pasture grasses include the following except

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An aquarium contains all the following except

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The tree species widely used in afforestation programme is

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The factors which affect the number and the activities of soil micro-organisms include the following except

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The act of mating in cattle is known as

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Which of the following in not an effect of the North-East trade winds on agriculture?

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The effect of North-East trade winds on agriculture are well-known. However, one of the options listed is not a direct effect of these winds, which is "causing heavy rainfall." While North-East trade winds bring moisture and precipitation to some regions, they do not typically cause heavy rainfall. Therefore, the correct answer is "causing heavy rainfall."

The effects of practicing rotational grazing in a livestock farm include the following except

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Which of the following statement is not true about rearing livestock under the free range system?

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The statement that is not true about rearing livestock under the free-range system is "adequate veterinary care." In a free-range system, livestock are allowed to move freely and fend for themselves, which makes it difficult to provide adequate veterinary care. This is because the animals are not confined in a specific location, and it is challenging to monitor their health and provide them with necessary treatments. As a result, livestock under the free-range system are at higher risk of infestation by parasites, and the young animals may have a high mortality rate due to lack of care. Also, since the animals are free to move around, there is a higher chance of loss due to predators or accidents.

Cassava is normally planted at a spacing of about

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When granting loans to farmers, the credit officer should consider mostly the

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When granting loans to farmers, the credit officer should consider mostly the production and essential needs of the farmers. This means that the loan should be granted based on the farmer's intended use of the funds to produce crops or raise livestock. The credit officer should assess the viability of the project, the potential yield, and the marketability of the product to ensure that the loan will be used for a profitable venture that will enable the farmer to repay the loan. Factors such as the age, consumption needs, family size, and experience of the farmer may also be considered, but they are secondary to the production and essential needs of the farmers in assessing the viability of the loan.

The main component of egg shell is

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The main component of egg shell is calcium. Egg shell is a hard, protective covering that surrounds the egg and serves as a source of calcium for the developing embryo. Calcium is an essential nutrient for bone growth and strength, and it is also required for muscle function, nerve transmission, and other physiological processes in the body. Therefore, calcium is an important nutrient for both the developing embryo and for the health of the adult bird.

Which of the following feed stuffs will not supply carbohydrate?

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The answer is "bone meal". Bone meal is a feed ingredient made of ground animal bones and is used as a source of minerals such as calcium and phosphorus. It does not contain carbohydrates, which are a major source of energy for animals. The other options listed are all feedstuffs that supply carbohydrates to animals, such as maize, guinea corn, rice bran, and palm kernel cake.

(a) Explain briefly each of the following types of credits in agricultural production: (i) short term credit (ii) mediunfo term credit (iii) long term credit.

(b) (i) List four sources of agricultural credit. (ii) Explain briefly four reasons why farmers find it difficult to get loans from banks

Détails de la réponse

(a)

(i) Short term credit: This is a type of credit given to farmers to finance their immediate agricultural needs. It usually has a repayment period of less than one year and is used to purchase inputs like seeds, fertilizers, and pesticides.

(ii) Medium-term credit: This type of credit is used to finance agricultural activities that have a longer gestation period. It is usually repaid within a period of one to five years and is used for activities such as land development, farm mechanization, and purchase of livestock.

(iii) Long-term credit: This is a type of credit used to finance long-term agricultural projects like the construction of irrigation systems, purchase of farmland, and setting up of processing plants. It has a repayment period of more than five years.

(b)

(i) Four sources of agricultural credit are:

1. Commercial banks: These are the most common sources of agricultural credit. They provide short, medium, and long-term loans to farmers.

2. Agricultural development banks: These banks are specifically set up to provide credit to farmers. They provide long-term loans for agricultural development projects.

3. Microfinance institutions: These institutions provide small loans to farmers who do not have access to formal banking services.

4. Government schemes: The government provides various credit schemes to farmers through its agencies. These schemes include crop loans, farm mechanization loans, and livestock development loans.

(ii) Four reasons why farmers find it difficult to get loans from banks are:

1. Lack of collateral: Banks usually require collateral to provide loans. Many farmers do not have the necessary collateral to obtain loans.

2. Lack of credit history: Farmers who have never borrowed before may not have a credit history, which makes it difficult for banks to assess their creditworthiness.

3. High-interest rates: The interest rates charged by banks on agricultural loans are usually high, which makes it difficult for farmers to repay the loans.

4. Complex application process: The application process for agricultural loans is often complex and time-consuming, which discourages many farmers from applying for loans.

Write short notes on four of the following: (a) deforestation (b) regeneration (c) afforestation (d) selective exploitation (e) Taungya system.

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(a)

Deforestation refers to the removal of trees and other vegetation from a forested area, either by natural or human activities. This process results in significant environmental impacts, including soil erosion, loss of biodiversity, and climate change.

(b)

Regeneration refers to the natural process of restoring a forested area to its original state after being disturbed or destroyed by natural or human activities. This process involves the natural regrowth of trees and other vegetation, as well as the restoration of ecological processes and functions.

(c)

Afforestation refers to the deliberate planting of trees in an area where there was no forest previously. This process is often used to combat deforestation, soil erosion, and climate change by increasing the number of trees and other vegetation in an area.

(d)

Selective exploitation refers to the sustainable harvesting of timber from a forested area, while ensuring that the overall health and productivity of the forest are maintained. This process involves careful planning and management of the harvesting activities to minimize the impacts on the environment.

(e)

The Taungya system is a traditional agroforestry system that combines the cultivation of crops with the establishment of new forested areas. This system involves the collaboration between farmers and foresters, where the farmers are allowed to cultivate crops in newly established forested areas while also helping in the maintenance and management of the forested area. This system has been successful in promoting sustainable land use and reducing deforestation in many regions.

Explain the following terms: (a) salvage value (b) farm inventory (c) farm assets (d) point of diminishing return (e) depreciation.

Détails de la réponse

(a) Salvage value: This refers to the estimated value of an asset at the end of its useful life, when it is expected to be sold or disposed of. It is the value that can be recovered from the asset after it has been fully depreciated or written off.

(b) Farm inventory: This refers to the list of goods and materials owned by a farm enterprise. It includes both finished goods and raw materials used in the production process.

(c) Farm assets: These are the resources owned by a farm enterprise that have monetary value and can be used to generate income. They include land, buildings, equipment, livestock, and crops.

(d) Point of diminishing return: This refers to the point at which the additional input of a factor of production (e.g. labor, fertilizer, capital) results in a smaller increase in output. Beyond this point, adding more of the input may actually decrease output or result in a loss.

(e) Depreciation: This is the gradual decrease in value of an asset over time due to wear and tear, obsolescence, or other factors. Depreciation is often used to calculate the decline in value of a fixed asset over its useful life, and is usually recorded as an expense on the income statement.

Discuss briefly four sources of farm power

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There are several sources of farm power that farmers can utilize to operate their agricultural machinery and equipment. Here are four common sources of farm power:

1. Human power: This is power generated by human labor. Farmers can use their own muscle power or employ farm laborers to operate manual tools and equipment like hoes, shovels, rakes, and wheelbarrows.

2. Animal power: This involves the use of animals like horses, mules, donkeys, oxen, and even dogs to power farm machinery and equipment. Farmers can use these animals to pull plows, harrows, carts, and wagons.

3. Mechanical power: This is power generated by engines, machines, and equipment like tractors, harvesters, irrigation pumps, and threshers. Mechanical power is typically more efficient and faster than human or animal power and is commonly used on large farms and commercial operations.

4. Electrical power: This involves the use of electricity to power farm machinery and equipment. Electrical power is typically supplied by a generator or power grid and is used to power irrigation pumps, milkers, feed mixers, and other electrical equipment.

Overall, the choice of farm power source depends on several factors like the size of the farm, type of farming operation, and availability and cost of the power source.

Discuss briefly the essential features of the following (a) communal land tenure (b) individual land tenure and their effects on Agriculture

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(a) Communal land tenure refers to a system of land ownership where land is owned and managed by a group of people in a community. In this system, individuals do not have exclusive ownership rights over the land. The land is typically used for subsistence agriculture and other communal activities. This type of land tenure encourages cooperation and sharing of resources within the community, but it may also result in overuse or neglect of the land if there is no effective system of management or decision-making in place.

(b) Individual land tenure refers to a system of land ownership where individuals or families have exclusive rights over a piece of land. The owner is free to use, transfer or sell the land as they see fit. This system encourages individual initiative and investment in the land, as the owner is motivated to maximize the benefits they can derive from the land. However, it may also lead to inequality in land distribution if some individuals are unable to acquire land or if there is concentration of land ownership in the hands of a few.

In agriculture, the type of land tenure system in place can have significant effects on agricultural practices and outcomes. Communal land tenure may lead to a lack of investment in the land or overuse, as no individual is held responsible for its management. On the other hand, individual land tenure may encourage investment in the land, but may also lead to unequal land distribution and potential land speculation.

(a) Define the term hybridization (b) State five aims of crop improvement. (c) Describe a monohybrid cross as explained by Mendel's Law of segregation. Illustrate your answers with clearly labelled diagrams.

(a) Hybridization is a process of cross-breeding two different varieties or species of plants or animals to create a hybrid offspring that possesses desirable traits from both parents.

(b) The five aims of crop improvement are:

1. To increase yield and productivity of crops.
2. To improve the quality of crops for better nutrition and taste.
3. To develop resistance to diseases, pests, and environmental stresses.
4. To reduce input costs, such as fertilizers and pesticides.
5. To develop new varieties with desirable traits, such as drought tolerance, early maturity, or high oil content.

(c) A monohybrid cross is a type of genetic cross that involves the study of one trait in which the parents differ by one pair of contrasting traits. According to Mendel's law of segregation, during gamete formation, the alleles for a trait segregate and each gamete receives only one allele from each parent. This means that when two individuals with different alleles for a trait are crossed, their offspring will receive one allele from each parent, and the two alleles will segregate during gamete formation.

For example, if we cross a pea plant with yellow seeds (YY) with a pea plant with green seeds (yy), the resulting F1 generation will all have yellow seeds because the Y allele is dominant over the y allele. However, the F1 generation will be heterozygous (Yy) because they received one Y allele from the yellow-seeded parent and one y allele from the green-seeded parent. When the F1 plants self-pollinate, their offspring (F2 generation) will exhibit a 3:1 ratio of yellow-seeded to green-seeded plants, with the green-seeded plants being homozygous recessive (yy).

The following Punnett square shows the possible genotypes and phenotypes of the F1 and F2 generations in a monohybrid cross:

Read lesson note on Crop Improvement (JAMB)

Read lesson note on Maintenance Practices And Precautionary Measures (WAEC)

Read lesson note on Genetics (JAMB)

Détails de la réponse

(a) Hybridization is a process of cross-breeding two different varieties or species of plants or animals to create a hybrid offspring that possesses desirable traits from both parents.

(b) The five aims of crop improvement are:

1. To increase yield and productivity of crops.
2. To improve the quality of crops for better nutrition and taste.
3. To develop resistance to diseases, pests, and environmental stresses.
4. To reduce input costs, such as fertilizers and pesticides.
5. To develop new varieties with desirable traits, such as drought tolerance, early maturity, or high oil content.

(c) A monohybrid cross is a type of genetic cross that involves the study of one trait in which the parents differ by one pair of contrasting traits. According to Mendel's law of segregation, during gamete formation, the alleles for a trait segregate and each gamete receives only one allele from each parent. This means that when two individuals with different alleles for a trait are crossed, their offspring will receive one allele from each parent, and the two alleles will segregate during gamete formation.

For example, if we cross a pea plant with yellow seeds (YY) with a pea plant with green seeds (yy), the resulting F1 generation will all have yellow seeds because the Y allele is dominant over the y allele. However, the F1 generation will be heterozygous (Yy) because they received one Y allele from the yellow-seeded parent and one y allele from the green-seeded parent. When the F1 plants self-pollinate, their offspring (F2 generation) will exhibit a 3:1 ratio of yellow-seeded to green-seeded plants, with the green-seeded plants being homozygous recessive (yy).

The following Punnett square shows the possible genotypes and phenotypes of the F1 and F2 generations in a monohybrid cross:

Explain briefly four of the following terms in animal production (a) oestrus cycle (b) heat period (c) gestation period (d) parturition (e) colostrum.

Détails de la réponse

(a) Oestrus cycle: The oestrus cycle refers to the reproductive cycle in female mammals, characterized by the periodic occurrence of oestrus or heat. It involves hormonal changes in the female's body, leading to the release of an egg from the ovaries and preparation of the reproductive tract for potential fertilization.

(b) Heat period: The heat period or oestrus period refers to the stage of the oestrus cycle during which the female is sexually receptive and able to conceive. This is when the female displays certain behaviours and physical changes, such as restlessness, vocalization, and swelling of the vulva.

(c) Gestation period: The gestation period refers to the time period between conception and birth in mammals. It varies between species, but in general, it is around 9 months in humans and can range from a few weeks to over a year in other animals.

(d) Parturition: Parturition is the process of giving birth in mammals, which involves the expulsion of the foetus and placenta from the uterus through the birth canal. It is triggered by hormonal changes and can be accompanied by strong contractions of the uterus.

(e) Colostrum: Colostrum is the first milk produced by female mammals after giving birth, which is rich in antibodies and other immune-boosting substances. It provides important nutrients and immunity to the newborn and is crucial for their survival and healthy development.

(a)(i) State six uses of lime in Agriculture (ii) List four common liming materials

(b) State (i) Three examples of nitrogenous fertilizer: (ii) three examples of a phosphorous fertilizer

Détails de la réponse

(a)

(i) Six uses of lime in Agriculture are:

1. To increase soil pH: Lime is used to neutralize acidic soils and increase the pH of the soil, making it more suitable for crop growth.
2. To provide calcium and magnesium: Lime contains calcium and magnesium, which are essential nutrients for plant growth.
3. To improve soil structure: Lime reacts with the soil particles to form stable aggregates, which improves soil structure and reduces erosion.
4. To release nutrients: Lime helps to release nutrients such as phosphorus, potassium, and micronutrients from the soil, making them available to plants.
5. To control soil-borne diseases: Lime can reduce the severity of certain soil-borne diseases such as clubroot and fusarium wilt.
6. To enhance the effectiveness of fertilizers: Lime can increase the effectiveness of certain fertilizers by improving nutrient uptake and reducing nutrient leaching.

(ii) Four common liming materials are:

1. Agricultural limestone: This is the most common type of lime used in agriculture. It is made from crushed limestone and is relatively inexpensive.
2. Dolomitic limestone: This type of lime contains both calcium and magnesium and is used in soils that are deficient in both nutrients.
3. Hydrated lime: This is a quick-acting lime that is often used to correct severe soil acidity problems.
4. Burnt lime: This is a form of lime that is produced by heating limestone in a kiln. It is often used to make lime mortar for building construction.

(b)

(i) Three examples of nitrogenous fertilizer are:

1. Urea: Urea is the most commonly used nitrogen fertilizer worldwide. It is a white crystalline substance that contains 46% nitrogen.
2. Ammonium nitrate: This is a high-nitrogen fertilizer that contains both ammonium and nitrate ions. It is often used as a top-dressing for crops.
3. Ammonium sulfate: This is a nitrogen fertilizer that also contains sulfur. It is often used on crops that require both nitrogen and sulfur.

(ii) Three examples of a phosphorus fertilizer are:

1. Triple superphosphate: This is a highly concentrated phosphorus fertilizer that contains about 46% phosphorus.
2. Di-ammonium phosphate: This is a fertilizer that contains both nitrogen and phosphorus. It is often used on crops that require both nutrients.
3. Mono-ammonium phosphate: This is a fertilizer that contains both nitrogen and phosphorus. It is often used on crops that require both nutrients.

Differentiate between the digestive systems of the sheep and poultry. Illustrate your answers with clearly labelled diagrams.

Détails de la réponse

Sheep and poultry have different digestive systems based on their feeding habits, digestive organs, and processes involved in digestion.

The digestive system of sheep is adapted to grazing on roughage such as grass and hay. The system consists of a mouth, esophagus, four-chambered stomach, small intestine, large intestine, and anus. Sheep do not have upper front teeth, instead, they have a dental pad that helps them to bite off and grind coarse fibrous feed. The food is mixed with saliva and passed down the esophagus into the rumen, which is the first chamber of the stomach. The rumen contains millions of microorganisms such as bacteria, protozoa, and fungi that break down the fiber in the feed into volatile fatty acids (VFAs) and gases like methane. The food then passes through the reticulum, omasum, and abomasum, where it is further digested by enzymes and acids produced by the animal. Finally, the food moves to the small and large intestines, where nutrients are absorbed and waste is eliminated.

The digestive system of poultry, on the other hand, is adapted to a high-energy diet consisting of grains and seeds. It consists of a mouth, esophagus, crop, proventriculus, gizzard, small intestine, ceca, and cloaca. Poultry do have teeth but instead, they have a muscular gizzard that helps them to break down food. The food enters the mouth and is stored in the crop, where it is moistened and softened. From there, it moves to the proventriculus, which secretes digestive enzymes and acids to break down the food. The food then enters the gizzard, where it is mechanically broken down by the muscular contractions of the gizzard walls. The small intestine is where nutrients are absorbed, and waste is eliminated. Poultry also have a pair of ceca, which are pouches located at the junction of the small and large intestines, where fermentation takes place. Finally, the waste is eliminated through the cloaca, which is a common opening for the digestive, urinary, and reproductive systems.

Here are two diagrams illustrating the digestive systems of sheep and poultry:

Sheep digestive system diagram:

Poultry digestive system diagram:

(a) (i) Define weathering (ii) State two types of weathering 

(b) Discuss briefly four factors which influence weathering

Détails de la réponse

(a)
(i) Weathering is the physical or chemical breakdown of rocks, soils, and minerals into smaller particles or substances through natural processes.
(ii) The two types of weathering are mechanical or physical weathering and chemical weathering.

(b)
Four factors that influence weathering are:
1. Climate: Weathering processes are influenced by climatic conditions such as temperature, rainfall, and humidity. High temperatures and rainfall accelerate chemical weathering while low temperatures and low rainfall lead to slow weathering.
2. Topography: The relief or topography of a region affects the intensity of weathering. Mountains, for instance, are prone to mechanical weathering due to their steep slopes while low-lying areas experience chemical weathering as a result of water accumulation.
3. Vegetation: Plants and other organisms affect weathering by producing acids and organic compounds that contribute to chemical weathering. Plant roots also cause mechanical weathering by breaking up rocks.
4. Time: The length of time that rocks and minerals are exposed to weathering agents determines the extent of weathering. Rocks that have been exposed to weathering for long periods are more susceptible to erosion and breakdown than those that have not been exposed for long.

Overall, these factors interact and work together to influence the type and extent of weathering that occurs in a particular region.