WAEC Agricultural Science 2024 Theory Past Questions

Model answer

(a)(i) Cooperative farming: farmers pool their resources together for efficiency and obtain higher income; enables farmers to obtain credit facilities at low interest rates; helps farmers to store farm produce. (ii) Farm settlement scheme: reduces unemployment among youths; helps make agriculture attractive to youths; settlers are taught better/improved farming techniques and provided with agricultural extension services. (iii) Agricultural research institute: develops new varieties of crops and breeds of animals; develops better methods of controlling pests and diseases; develops crops resistant to pests and diseases; improves storage and processing facilities. (b)(i) Dibber -> Seed drill/planter/combine drill. (ii) Hoe -> Plough/Harrow/Ridger/Cultivator. (iii) Sickle -> Mower/slasher/Harvester. (iv) Wheelbarrow -> Trailer/cart/wagon/Bucket loader. (v) Watering can -> Boom sprayer/Sprinkler irrigation system. (c)(i) Advantages of mouldboard plough: can be used in temperate light soils; can be used in soils free from stumps/stones; shares can be resharpened by grinding; buries weeds/crop residues deeply. (ii) Disadvantages of mouldboard plough: not adapted to tropical soil; loses its sharp point easily when in contact with obstacles; predisposes the soil to erosion; frequent usage leads to soil compaction/formation of hard pan.

Model answer

(a) Soil pH is defined as a measure of the degree of acidity or alkalinity of the soil, i.e. a measure of the concentration of hydrogen ions (H+) or hydroxyl ions (OH-) in the soil. A pH scale is graduated from 1-14. A soil whose pH is below 7 is said to be acidic. A soil whose pH is above 7 is said to be alkaline. A soil with pH 7 is said to be neutral. (b)(i) Cover crops are crops that are grown specially to cover the soil and protect it from erosion and leaching for a given length of time. (ii) Advantages: effective in controlling weeds; reduces soil temperature through vegetative cover/reduces direct effect of sunlight on the soil; leguminous cover crops help fix nitrogen in the soil; serves as green manure when ploughed back into the soil; could be harvested as food crop after harvesting the cash crop; prevents soil erosion; reduces soil compaction; improves soil structure; could serve as forage for livestock; controls pests. (c) Wild marigold -- Aspilia africana. Spear grass -- Imperata cylindrica. Stubborn grass -- Eleusine indica. Pig weed -- Amaranthus spp/Boerhavia diffusa. Carpet grass -- Axonopus compressus.

Model answer

(a)(i) Rhizobium: fixation of nitrogen in the root nodules of leguminous crops. (ii) Nitrosomonas: oxidation of ammonium compounds to nitrites (NO2-). (iii) Pseudomonas: reduction of soil nitrates to gaseous nitrogen/denitrification. (iv) Nitrobacter: oxidation of nitrites to nitrates (NO3-). (b)(i) Effects of aphids on cowpea: reduces yield; reduces yield of seeds; reduces germination of seeds/seed viability; serves as vectors of diseases; may result in death of plants. (ii) Cultural control: planting resistant varieties; planting insect-free seeds; practising crop rotation; inter-planting of crops. (c)(i) Forestry is the study and management of forests and forest resources -- the art and science of managing trees, forests and forest products for human use. (ii) Products from forests: Timber/wood; Fuelwood/firewood; Woodpulp; Honey; Snail/Mushroom; Chewing stick; Palm wine/palm oil/Kolanut; Wild fruits; Bamboo; Gum/Latex; Medicinal herbs; Dye; Wild vegetables; Fibre; Resin; Bush yam; Long pole; Wax; Wild spice (any five).

Model answer

(a)(i) Area of farmland = Length x Breadth = 300m x 150m = 45,000 sq.m. Since 1 ha = 10,000 sq.m, area = 45,000/10,000 = 4.5 ha. (ii) Quantity of sorghum seeds required = Seed rate x Area = 60 kg/ha x 4.5 ha = 270 kg. (iii) Quantity of fertilizer required = Fertilizer rate x Area = 20 kg/ha x 4.5 ha = 90 kg. (b)(i) Budding uses a small bud as scion, with a T-shaped or inverted T-shaped cut commonly made on the stock, commonly done during the active growing season of the stock, and the stock and scion do not need to be of the same age/size for successful budding. Grafting uses part of a stem/branch as scion, with a slant or V-shaped cut commonly made on both the stock and scion, usually performed when the stock is dormant e.g. during harmattan, and the stock and scion should be of approximately the same age/size for successful grafting. (ii) Crops propagated by budding: Citrus/named citrus; Cherry; Cashew; Avocado pear; Mango; Almond; Cocoa Apple; Ornamental plants; Rubber; Tea; Peach (any four). (c)(i) Production ration: Pregnant animals; Weaned animals; Layers; Broilers; New born animals; Breeding males/females; Fatteners; Growers; Wool producing sheep; Beef cattle; Dairy cow/lactating animals (any two). (ii) Maintenance ration: Spent layers; Old animals; Culled animals; Dry cows; Non-lactating animals; Non-breeders (any two).

Model answer

(a)(i) Removal of excessive vegetation: allows sunlight to reach the bottom of the pond for growth of phytoplankton; prevents breeding of fish pests; ensures adequate supply of dissolved oxygen; prevents breeding of fish diseases. (ii) Removal of silt: makes the pond water clear/reduces turbidity; facilitates free movement of fish; maintains normal depth of the pond; ensures adequate supply of dissolved oxygen. (iii) Supplementary feeding: promotes rapid growth of fish; improves the health of fish; provides variety of feeds to fish/balanced diet/adequate nutrition. (iv) Fertilizer application: encourages growth of phytoplankton; provides nutrients to fish; improves growth of fish in ponds. (b) Conditions necessitating culling: low productivity/poor feed conversion; old age; aggressiveness; lameness/parturition problems; diseases/severe injury; egg pecking/sucking; poor mothering/piglet eating; reproductive failure/sterility; cannibalism. (c) Effects of excess nitrogen in soil on crops: causes excessive vegetative growth; decreases reproductive growth/delays fruiting; weakens plant stems; causes lodging in crops; reduces resistance of crops to diseases; reduces the yield of some crops.

Model answer

(a) Agricultural insurance is the policy that provides farmers with financial protection against specific risks that may arise during agricultural production. (b)(i) Insurance policy: a contract/document in which the insurance company/insurer agrees to indemnify/compensate the insured/farmer against losses from specific risks/disasters of agricultural production. (ii) Insurance premium: the amount of money that the insured/farmer pays the insurer/insurance company for an insurance policy. (c)(i) Advantages of the extension method (meeting/demonstration): saves costs; saves time; enables the extension agent to reach a large number of farmers; influences reluctant farmers to try the new idea/encourages farmers to develop interest in new ideas; directs attention to group problems and possible solutions; encourages and trains local leaders. (ii) Other dissemination methods: Workshop; Field trip; Debate; Symposium; Lecture; Demonstration; discussion; Agricultural show. (d) Operations in rice processing after harvesting: Cleaning; Parboiling; Drying; Milling/hulling/dehusking; Winnowing; Polishing; Grading; Sorting/destoning; Packaging; Threshing (any five).