Theory question 106
Plant Forms and Crop Classification(a) List four cereal crops grown in West Africa.
(b) State three benefits of forests to the economic development of your country.
(c) With the aid of a diagram, describe the life cycle of the variegated grasshopper.
(d) List three cultural methods of controlling crop pests.
(e) Give two uses of oil palm.
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(a) Any four: maize; rice; sorghum (guinea corn); millet; wheat; acha (fonio).
(b) Any three: timber and wood products for industry and export; employment; foreign exchange; raw materials (pulp, gum, latex); tourism (game reserves); fuel wood; medicinal products.
(c) Diagram: incomplete metamorphosis egg → nymph (several moults) → adult. Description: adults mate and lay egg pods in the soil at the start of the dry season; eggs hatch at the start of the rains into nymphs (hoppers) that look like small wingless adults; nymphs feed and moult about five to six times, growing wings; they become adults which feed on crops, mate and lay eggs.
(d) Any three: crop rotation; early planting/harvesting; field sanitation and burning residues; use of resistant varieties; trap crops; proper spacing; tillage to expose pests.
(e) Any two: palm oil for cooking; palm kernel oil for soap and margarine; palm wine; fronds for brooms and thatch; kernel cake for animal feed.
The grasshopper has no pupal stage: egg, nymph, adult.