WAEC Agricultural Science 2025 Theory — Question 3

Model answer

(a) Completed table: Maize smut - Causal organism: Fungus (Ustilago maydis); One symptom: Large galls on the ear; One preventive/control measure: Plant resistant varieties. Damping off of tomato - Causal organism: Fungus (Pythium spp.); One symptom: Stunted growth/stems at soil level become weak, seedlings collapse resulting in death of plants; One preventive/control measure: Treat seeds with fungicides/use disease-free seeds, practice crop rotation, ensure good drainage in the nursery, avoid over-watering, soil sterilization, use resistant varieties. (b)(i) Ways wind affects crop production (any four): - Affects the rate of transpiration/evaporation in crops - Facilitates pollination of crops - Necessary for seed dispersal/dispersal of weed seeds - Transmits diseases - Facilitates pest infestation, e.g. grasshopper (ii) Ways light affects crop production (any four): - Supplies energy needed for photosynthesis - Affects the growth rate of crops - Determines the species of crops that grow in areas with different day length/photoperiodism - Enhances the ripening of fruits - Responsible for phototropism in crops (c) Human activities that promote deforestation (any four): - Logging/timber exploitation - Mining/oil exploration - Urbanization/industrialization - Road construction - Farming activities/agriculture