This question was fairly attempted by the candidates.  Majority of the candidates could state two effects of diseases on crop production as required in 5(a) but most of them in 5(b) could not discuss the swollen shoot disease of cocoa under causal organism, mode of transmission, two symptoms and two preventive and control measures.  Also, majority of the candidates could not list two effects of each of afforestation and deforestation on the environment.  However, majority of the candidates were able to mention four grasses and four legumes commonly found in natural pastures in West Africa as required in 5(d).

The expected answers include:
  5(b)     Discussion on swollen shoot disease of Cocoa
              (i)   Causal organism
               -       Cocoa swollen shoot virus                                           

            (ii)   Mode of transmission
       -    Nymphs of mealy bugs and white flies transfer the virus from infected plants to healthy ones
     (iii)  Symptoms

• veins become red
• mottling of pods occurs
• swelling of growing parts of stems and or roots
• chlorosis of leaves with veins remaining green
• wilting and death of plant

(iv)  Prevention and Control Measures

• Use of resistant varieties
• Regular inspection and  destruction of infected plants
• Use of quarantine

                                                               
  (c)         Effects of activities on the environment

         (i)   Effects of Afforestation on the environment

• reduces soil erosion
• increases water infiltration
• leads to increase in soil nutrients/increases humus content of the soil
• Increases the amount of rainfall in the area
• increases the population soil micro-organisms/macro-organisms
• checks desertification
• enhances the growth of wildlife population in the habitat.
• purifies the atmospheric air in the environment
• modifies the microclimate of the area
• reduces leaching
• improves soil moisture retention
• trees planted serve as wind breaks

                                                         
(ii)  Effects of Deforestation on the environment
                      -        encourages/increases soil erosion
                      -        reduces water infiltration
                      -        results in loss of soil nutrients through erosion

• reduces the humus content of the soil
• reduces the amount of rainfall in the area
• hinders soil micro-organic activities
• reduces wild life population in the area concerned
• may lead to desertification.