WAEC Agricultural Science 2022 Theory Past Questions

Model answer

(a) Reasons for enacting laws to regulate agricultural land use: - Security of tenure: to safeguard farmers against unreasonable eviction - Land litigation: to reduce the number of land disputes among citizens - Government projects: to make large portions of land available for government-sponsored development of large-scale farms - Freedom of enterprise: to encourage freedom of farming where there are regulations or traditional views that militate against such freedom - Ensuring proper land use: to ensure agricultural land is not unnecessarily diverted to non-agricultural purposes (b)(i) Mechanical power should be recommended (e.g. tractor) for tillage on 10 hectares. (ii) Reasons: it works faster and more efficiently; it reduces labour cost; it makes farm work less tedious; it saves time. (c)(i) Seed tube: conducts/directs the seeds from the base of the hopper into the hole dug. (ii) Furrow opener: digs holes/furrows in front into which the seeds drop. (iii) Hopper: contains the seeds to be planted. (iv) Seed metering device: meters seeds at the desired depth and desired location. (v) Furrow wheel: presses the soil to cover the seeds dropped into the hole. (d) Common postharvest processing machines: shellers, decorticators, driers, grain mills, etc.

Model answer

(a)(i) Monocropping: the practice of growing a single crop year after year on the same land. (ii) Mixed cropping: a practice that involves planting two or more types of crops simultaneously on the same piece of land. (iii) Mixed farming: a type of farming that involves both the growing of crops and the raising of livestock. (iv) Crop rotation: the practice of growing different crops in succession on the same land, in a regular recurring sequence. (b)(i) The nutrient deficient is Phosphorus. (NB: Phosphorus deficiency results in a reddish-purple discolouration of leaves, and premature fall of leaves, flower buds and fruits.) (ii) Inorganic fertilizers to correct phosphorus deficiency: Single Superphosphate (SSP); Triple Superphosphate (TSP); Monoammonium phosphate (MAP); Diammonium phosphate (DAP). (c) Materials to attract bees to a new beehive: beeswax; granulated sugar; lavender; lime; sweet juices/lemon grass.

Model answer

(a) Causes of damage to maize during storage: insect pests; rodents; fungi (moulds); poor storage conditions (e.g. hot and humid conditions). (b)(i) Genetic cross Tt × Tt: Parents: Tt × Tt Gametes: T, t × T, t Offspring genotypes: TT, Tt, Tt, tt (ii) I. Genotypic ratio = 1 TT : 2 Tt : 1 tt (1:2:1) II. Phenotypic ratio = 3 tall : 1 short (3:1) (c) Mendel's first law (Law of Segregation): the characteristics of an organism are controlled by genes which occur in pairs; only one of such a pair of genes can be carried in a single gamete. Mendel's second law (Law of Independent Assortment): alleles of one trait assort independently from the alleles of another trait, and are distributed to daughter nuclei with equal probability. (d) Forage grasses: Guinea grass; Elephant grass; Fescues; Bromegrasses.

Model answer

(a) Completed table: Onion — Botanical name: Allium cepa; Classification: Spices; Propagation: Through bulbs Ginger — Botanical name: Zingiber officinale; Classification: Spices; Propagation: Through rhizome Jute — Botanical name: Corchorus spp.; Classification: Fibre; Propagation: Through seeds (b) Total floor area of the litter house = 36m × 10m = 360 m². Since a floor space of 0.36 m² is required per chicken: Number of broilers = 360 ÷ 0.36 = 1,000 broilers. (c) Advantages of introducing legumes in a pasture: - Legumes have a higher protein content than grasses - They improve digestibility - They improve palatability - They offer rich amounts of calcium and minerals - They have a nitrogen-fixing ability (improving soil fertility)

Model answer

(a)(i) Balanced diet: feed that contains all the nutrients required in the right proportion. (ii) Maintenance ration: the amount of feed given to an animal to sustain/maintain its live weight (with no gain or loss). (iii) Production ration: the amount of feed supplied to an animal, in addition to maintenance ration, to promote growth and production (e.g. milk, eggs, meat, growth). (iv) Malnutrition: an unhealthy condition that manifests in farm animals when they are fed with inadequate, excess, or unbalanced feed/diet. (b) Effects of malnutrition on farm animals: - Retarded growth - Low production - High mortality rate in young animals - Emergence of diseases - Weight loss - Physical deformities (also constipation) (c) Nursery practices for tomato production: - Nursery beds/seed boxes/trays are prepared with top soil mixed and sterilized - Seeds are sown in drills 5cm apart and 2.5cm deep - Shading, watering, weeding and mulching are regularly done - Transplanting is done when seedlings are 3 weeks old on the nursery

Model answer

(a)(i) [See graph: quantity of fertilizer (bags) plotted on the x-axis against tomato yield (kg) on the y-axis, showing yield rising from 2kg at 0 bags to a peak of 11kg at 6 bags, then declining to 4kg at 12 bags.] (ii) As the quantity of fertilizer increases, tomato yield initially increases; then after a point (6 bags), additional fertilizer results in a lower yield. This shows the law of diminishing returns — both insufficient and excessive fertilizer use negatively affect yield. (iii) Since the optimum yield of tomato (11kg) is recorded when 6 bags of fertilizer are applied, the most appropriate quantity of fertilizer to apply on the tomato farm is 6 bags. (b) Effects of subsidy withdrawal on agricultural production: - Decrease in cost effectiveness (higher input costs) - Increase in risks absorbed by farmers - Decrease in agricultural productivity (c) Print media for disseminating information about a new maize variety: - Pamphlets - Posters - Newspapers - Booklets/Magazines/Journals (d)(i) Maize insect pests: Grasshopper, aphids, earworm, army worm (ii) Orange insect pests: Fruit borer, white louse, citrus psyllid, mealybug