WAEC Agriculture 2020
Questions & Answers

Distractor check: Learners might confuse decomposition with weathering or erosion, but those processes involve physical rock breakdown or soil movement rather than organic decay. Reasoning to the answer: Decomposition is carried out by biological agents like bacteria and fungi to break down organic matter, which ultimately yields humus to enhance soil structure and fertility. Common mistake: Confusing the biological breakdown of organic matter into humus with inorganic weathering processes.

Distractor check: Students might think of budding or grafting since they are common tree-crop practices, but cocoa relies primarily on a different propagation method for nurseries. Reasoning to the answer: Cocoa (Theobroma cacao) is predominantly propagated using seeds planted in nurseries because this approach preserves genetic diversity and remains cost-effective for large-scale farming. Common mistake: Assuming all tree crops are propagated vegetatively through cuttings rather than seeds.

Distractor check: Candidates might choose deeper planting depths like 3-5 cm or more, which are suitable for larger seeds but detrimental to rice establishment. Reasoning to the answer: Rice seeds must be sown at a shallow depth of 1-2 cm to guarantee rapid germination and emergence, since placing them deeper causes poor crop establishment and lower yields. Common mistake: Planting rice seeds too deeply, which hinders proper emergence.

Distractor check: Students often default to nitrogen, which promotes vegetative leaf growth, but reproductive development requires a different primary nutrient. Reasoning to the answer: Phosphorus is essential for energy transport via ATP and robust root development, making it the key nutrient that directly drives seed and fruit formation in plants. Common mistake: Confusing nitrogen's role in vegetative growth with phosphorus's role in seed and fruit formation.

Distractor check: Learners might select hydroponics or aquaponics, which involve water and nutrients, but miss the specific detail about roots suspended in a mist. Reasoning to the answer: Aeroponics suspends plant roots directly in the air and applies a nutrient-rich mist, which maximizes oxygen access and accelerates nutrient uptake for faster growth. Common mistake: Confusing aeroponics, which uses a mist, with general hydroponics where roots are submerged in liquid.

Distractor check: Students might pick root rot, leaf blight, or anthracnose, which affect yams or other crops, but are not viral in origin. Reasoning to the answer: Yam mosaic virus causes mottled foliage, reduced yields, and stunted growth in yams (Dioscorea spp.), and it is spread primarily by aphids or infected planting stock. Common mistake: Confusing fungal or bacterial yam afflictions with the yam mosaic virus.

Distractor check: Candidates might point to rainfall, temperature, or human activity as primary drivers, overlooking the fundamental geological foundation of soil. Reasoning to the answer: Parent material, consisting of underlying rock or sediment, supplies the original minerals that dictate soil composition and govern how quickly weathering transforms it into soil. Common mistake: Overlooking the foundational role of parent material in favor of climatic factors when considering soil formation.

Distractor check: Students might consider goats, sheep, or pigs, but these livestock types are raised primarily for meat or milk rather than egg production. Reasoning to the answer: Ducks (Anas platyrhynchos domesticus) are specifically raised for high-volume egg production, yielding larger eggs than chickens alongside quality meat. Common mistake: Assuming poultry like ducks are kept exclusively for meat instead of recognizing their high egg yield.

Distractor check: A student might choose erosion or tilling, but those describe natural degradation or cultivation rather than the mechanical removal of the upper layer for land use. Reasoning to the answer: Topsoil stripping involves the deliberate mechanical removal of the nutrient-dense topsoil layer for activities like mining or construction, which destroys fertility if neglected. Common mistake: Confusing natural soil erosion with intentional topsoil stripping for industrial projects.

Distractor check: Options like drying, smoking, or salting use dehydration or curing, but the prompt specifically highlights cooling as the preservation method. Reasoning to the answer: Freezing exposes vegetables to temperatures below -18°C to stop enzymatic action and microbial growth, thereby maintaining their texture and nutritional value over time. Common mistake: Confusing freezing with drying or other methods that do not rely on low-temperature cooling.

Distractor check: Candidates might confuse inbreeding with crossbreeding or outcrossing, which involve mixing different breeds or lines rather than keeping matings strictly within the same breed. Reasoning to the answer: Inbreeding involves mating closely related animals within the same breed to lock in desirable traits, though it carries the trade-off of increasing homozygosity and genetic abnormalities. Common mistake: Confusing inbreeding within a single breed with crossbreeding different breeds.

Students might mistakenly choose Zinc, Copper, or Iron because they are all well-known plant nutrients. However, Sulphur is the correct macro-element because plants require it in larger quantities than micronutrients, making it essential for protein synthesis—such as forming amino acids like cysteine—as well as for chlorophyll formation. Common mistake: confusing macronutrients, which are needed in larger amounts, with micronutrients required only in trace amounts.

Apiculture or Pisciculture might look plausible to students thinking of general animal-rearing industries like bees or fish. The correct answer is Sericulture, which specifically involves the rearing of silkworms like Bombyx mori on mulberry leaves to produce silk cocoons, serving as a key agro-industry across many Asian countries. Common mistake: mixing up specialized animal rearing terms like sericulture for silkworms and apiculture for bees.

Students might incorrectly pick leaf drop or stunted roots, thinking of general stress responses in crops. The right choice is interveinal chlorosis, which happens because manganese is vital for photosynthesis and enzyme activation, leading to yellowing specifically between the veins while the veins themselves stay green in young leaves. Common mistake: assuming all nutrient deficiencies cause overall leaf loss rather than specific patterned discoloration like interveinal chlorosis.

Deep ploughing or slash and burn might seem like effective ways to clear or manage land quickly. Minimum tillage is actually the most sustainable choice for small farms because it reduces soil disturbance, thereby preserving soil structure, organic matter, and microbial life while minimizing erosion and boosting long-term sustainability. Common mistake: confusing intensive land clearing techniques with sustainable practices that preserve soil structure.

Options like Elephant grass or Guinea grass are common grasses that might mislead students looking for forage types. Stylo is the correct answer because it is a tropical legume used as forage, which fixes nitrogen to boost soil fertility while simultaneously supplying high-protein feed for livestock. Common mistake: failing to distinguish between standard tropical grasses and leguminous forage crops that fix nitrogen.

Students might lean toward Rickets or Scurvy due to familiarity with vitamin deficiencies in general. Anemia is the correct answer because a lack of vitamin B12 leads specifically to pernicious anemia in animals, which impairs the production of red blood cells and results in fatigue, weakness, and poor growth. Common mistake: attributing general vitamin-related bone or tissue disorders like rickets or scurvy to vitamin B12 instead of blood-related anemia.

Increases pest infestation or encourages erosion might be chosen by someone misinterpreting agricultural management practices. Improving soil fertility is correct because crop rotation systematically alternates crops to replenish nutrients—such as legumes fixing nitrogen—while also suppressing weeds and pests and enhancing overall soil health for sustained productivity. Common mistake: assuming that rotating crops would degrade soil quality rather than replenish it.

Students might mistakenly select Extensive system or Ranching, confusing confined settings with open grazing. Intensive system is correct because it confines animals in barns or pens with high-output feeds, maximizing production per unit area though it demands careful waste management. Common mistake: mixing up extensive and intensive livestock farming systems regarding confinement and feed inputs.

Whitefly, Aphid, or Mealybug might seem plausible if students think of general sap-sucking plant pests. Stem borer is the correct choice because the larvae of the sugarcane stem borer, Chilo sacchariphagus, specifically tunnel into the stems, causing wilting, reduced juice content, and yield losses reaching up to 30%. Common mistake: confusing general sap-feeding insects with stem-boring larvae that physically tunnel into crop stalks.

Nitrification or Nitrogen fixation might look correct to students seeing nitrogen cycle terms. Denitrification is the correct answer because anaerobic bacteria like Pseudomonas convert soil nitrates back into nitrogen gas, which completes the nitrogen cycle even though it can potentially cause leaching losses. Common mistake: confusing the process of converting nitrates into gas (denitrification) with the process of adding nitrogen to the soil.

Adding sand, increasing irrigation, or using herbicides might be incorrectly chosen as quick fixes for poor soil conditions. Applying lime is the right choice because lime (CaCO3) neutralizes soil acidity, which promotes the flocculation of clay particles into crumbs to enhance aeration, water infiltration, and root penetration. Common mistake: thinking soil structure can be improved merely by adding sand or water instead of addressing acidity and particle flocculation.

Options like 30cm x 30cm or 90cm x 90cm could be guessed by students unfamiliar with specific legume measurements. The correct spacing for groundnut is 60cm x 30cm, which means 60 cm between rows and 30 cm between plants, optimizing light exposure, reducing competition, and facilitating peg formation for pod development. Common mistake: guessing uniform square spacing dimensions instead of the specific row-to-plant ratio required for groundnut growth.

Newcastle disease, Marek's disease, or Infectious bronchitis are well-known poultry ailments that might confuse students since they affect birds. Fowl cholera is the correct answer because it is specifically a bacterial disease caused by Pasteurella multocida, inducing acute septicemia in chickens with symptoms like swollen wattles, pneumonia, and high mortality that can be controlled by vaccination. Common mistake: failing to distinguish between viral poultry diseases like Newcastle and bacterial infections like fowl cholera.

Fermentation or digestion of proteins might seem reasonable if students confuse the reticulum with the rumen or abomasum. Trapping foreign objects is the correct function because the honeycomb walls of the reticulum catch indigestible items like nails in ruminants such as cattle, preventing physical damage to the rumen and lower digestive tract. Common mistake: assuming the reticulum handles chemical digestion or fermentation rather than acting as a physical trap for foreign debris.

Herbicide application or crop rotation might be selected by students thinking broadly about weed management techniques. Hoeing is the correct mechanical method because it physically uproots or cuts weeds using hand tools or machinery without chemicals, making it ideal for small-scale farms. Common mistake: confusing chemical weed control or long-term cultural practices with mechanical uprooting methods like hoeing.

Intercropping or Monoculture might trick students who confuse ground-level planting arrangements with tree integration. Agroforestry is correct because it specifically integrates trees with crops and livestock, providing shade, windbreaks, soil conservation, and diversified income while boosting biodiversity. Common mistake: mixing up agroforestry with simple intercropping that does not involve trees.

Nitrogen or Phosphorus might be picked by students guessing common macronutrient deficiency symptoms. Potassium is the right choice because a deficiency in K leads to marginal necrosis and premature leaf drop, since potassium regulates the water balance and enzyme activations essential for retaining leaves. Common mistake: confusing nitrogen deficiency yellowing with potassium deficiency-related leaf drop and marginal necrosis.

Storing maize in a humid room, wet store, or under sunlight would obviously ruin the crop, but students might guess based on poor preservation habits. Airtight container is correct because airtight storage deprives pests like weevils of oxygen, stopping infestations and successfully preserving maize quality for up to a year. Common mistake: storing grains in damp or open environments that encourage pest survival rather than using oxygen-depriving airtight containers.

Flea, Lice, or Mite might seem plausible since all are external pests found on livestock. Tick is the correct answer because ticks, such as Amblyomma species, are major external parasites on goats that transmit diseases like anaplasmosis and cause anemia by feeding on blood. Common mistake: confusing minor external pests with ticks that are notorious disease vectors for livestock.

Drainage or Irrigation might be confused with salt removal by students thinking about water movement. Leaching is the correct answer because it uses excess water to flush soluble salts down below the root zone in saline soils, thereby restoring soil fertility for proper crop growth. Common mistake: confusing general water management practices like irrigation with the specific salt-flushing action of leaching.

Sorghum or Groundnut might be selected by students thinking of general tropical crops or oilseeds. Cassava is the correct answer because Manihot esculenta tubers contain up to 80% starch, making them a major tropical staple that is processed into garri, flour, and industrial starch. Common mistake: confusing protein- or oil-yielding crops with major starch-heavy staples like cassava.

Options like 20-25°C or 40-45°C are either too cold or dangerously hot for delicate birds. The ideal temperature is 35-37°C because day-old chicks need this brooder warmth to mimic maternal heat, which prevents chilling and encourages uniform growth before the temperature is gradually reduced. Common mistake: misjudging chick brooding temperatures and exposing young birds to chilling or overheating risks.

Overgrazing, Monocropping, or Deforestation are actually practices that worsen land degradation. Contour bunding is correct because it creates earthen ridges along field contours to slow down water runoff, trap sediment, and successfully reduce erosion on sloping lands. Common mistake: choosing land management practices that accelerate soil loss instead of protective structures like contour bunds.

Foot rot, Scours, or Bloat might be chosen by students thinking of common physical or digestive ailments in sheep. Peste des petits ruminants is the correct answer because it is a highly contagious viral disease affecting sheep and goats, causing fever, severe diarrhea, and mortality rates up to 90%, though it can be controlled through vaccination. Common mistake: confusing non-viral digestive disorders with highly contagious viral diseases like PPR.

Human labor, Animal draft, or Windmill might be recognized as traditional or alternative forms of energy. Tractor is the correct answer because tractors supply heavy mechanical power for plowing, planting, and harvesting, which greatly increases operational efficiency and decreases labor dependency in modern farming. Common mistake: confusing traditional power sources like animal draft with modern mechanical tractor power.

Students might mistakenly pick Terracing or Contour plowing because they are also soil conservation practices used on slopes, but they involve building earth steps or plowing along elevation lines rather than alternating crop types. Strip cropping protects against soil loss by placing grass strips and row crops perpendicular to slopes, which works by slowing down water flow and trapping soil particles to minimize erosion. Common mistake: confusing strip cropping with other slope management techniques like terracing.

Students might mistakenly select Yellowing of leaves or Leaf scorching since these are general signs of nutrient stress in many crops. Molybdenum deficiency is specifically linked to whiptail disease, which causes narrow, strap-like leaves in brassicas such as cauliflower because the element is required for nitrate reduction to proteins. Common mistake: assuming all nutrient deficiencies result in identical general chlorosis rather than specific structural deformities like whiptail.

Students might mistakenly choose Provide loans, assuming that agricultural support always involves financial credit or banking services. The primary role of agricultural marketing boards is to stabilize produce prices by regulating supply, setting minimum prices, and intervening in markets to prevent fluctuations, thereby ensuring fair returns for farmers. Common mistake: confusing marketing boards with agricultural banks or financial lending institutions.

Students might mistakenly select Soil type or Water salinity, thinking environmental constraints relate primarily to the ground or irrigation water. Climate is the correct factor because it heavily influences breed selection, such as utilizing heat-tolerant breeds in tropical regions, which directly affects adaptability, productivity, and disease resistance. Common mistake: overlooking broad climatic impacts in favor of local soil characteristics when choosing livestock.