This question was fairly attempted by the candidates.  In 6(a), most of the candidates were able to name the cereal crops grown in the country.  But in 6(b), majority of them could not state the advantages and disadvantages of afforestation.  Further to this, majority of the candidates were able to list the major groups of insect-pests of crops on the basis of their mouth parts but could not give the examples of the major groups of insect-pests of crops as required in 6(c)(i) and (ii) respectively.
The expected answers include:
(6)(b)Advantages and disadvantages of afforestation
Advantages
         -     Leads to addition of organic matter, resulting in an increase in soil fertility
         -     Prevents desert encroachment
         -     Prevents the leaching of plant nutrients
         -     Increases soil moisture retention
         -     Increases the amount of rainfall in the area
         -     Improves soil structure through the addition of organic matter
         -     Increases the forest fauna (wildlife) in the area concerned
         -     Protects the soil against agents of erosion
         -     Helps to purify the air
         -     Modifies micro climate of the area
         -     Provides shelter belt/wind break                                                  
Disadvantages
 Capital intensive
 Labour intensive
 Takes a long time to establish a tree plantation
 Deprives farmers of fertile lands for arable crop production
 Process is tedious

(c)(ii) Examples of insect pests of crops on the basis of their mouthparts
Piercing and sucking insects
  Cotton stainers
  Green shield bugs
  White flies
  Mealy bugs
  Mirids/capsids
  Fruit-piercing moths
  Coreid bugs
  Scale insects
  Aphids
  Cocoa thrips
Biting and chewing insects
Locusts
Grasshoppers
Termites
Leaf worms
Armyworms
Budworms
Crickets
Stick insects
Caterpillar
Rhinoceros beetles
Mantids

Boring insects
Bean beetles
Yam beetles
Maize weevils
Rice weevils
Sorghum weevils
Stem borers
Larvae of Lepidoptera e.g. butterfly, moth