WAEC SSCE - Agricultural Science - 2013 (Essay)

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(a) Animal improvement

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

(b) Three aims of animal improvement

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

(c) Definition of terms

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

(d) Three systems in the body of farm animals

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

(e) Four advantages of castration in animal production

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

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(a) Definition of terms

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

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

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

(c) Four roles of an agricultural extension agent

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

(d) Five roles of farmer cooperative societies

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

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(a) Three reasons why fish farming is important

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

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

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

(c) Two sources of each feed nutrient

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

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

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

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

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

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

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

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

(b) Four functions of agro-service centres

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

(c) Four routine tractor maintenance practices

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

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

(i) Three-point linkage:

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

(ii) Hydraulic lever:

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

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(a) Three edaphic factors that influence crop growth

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

(b) Explanation of terms

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

(c) Two deficiency symptoms of each nutrient element

(i) Nitrogen:

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

(ii) Phosphorus:

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

(iii) Potassium:

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

(d) Three benefits derived from draining farmlands

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

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(a) Nursery

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

(b) Three reasons for establishing a nursery

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

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

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

(d) Two methods of controlling weeds

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

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

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

(f) Three effects of diseases on crops

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

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(a) Farm mechanization

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

(b) Three advantages and three disadvantages of farm mechanization

Advantages:

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

Disadvantages:

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

(c) Two merits of using draught animals

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

(d) Roles of science and technology in agricultural development

(i) Pest and disease control:

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

(ii) Meteorology and climatology:

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

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(a) Two sources of irrigation water

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

(b) Two advantages and two disadvantages of irrigating farmlands

Advantages:

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

Disadvantages:

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

(c) Two ways by which the soil loses nutrients

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

(d) Two reasons for manuring in crop production

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

(e) Two ways each environmental factor affects agricultural production

(i) Temperature:

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

(ii) Soil micro-organisms:

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

(iii) Wind:

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

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(a) Four cereal crops grown in West Africa

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

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

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

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

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

(d) Three cultural methods of controlling crop pests

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

(e) Two uses of oil palm

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