Observation

Question 5 (a) was also popular among candidates although many candidates could
not state economic importance of roundworms to farm animals. Many candidates
likened roundworms to earthworms or maggots cultured from animal dung; thus the
benefits to maggots in animal production.

The expected answers include:

(a)       Explanation of terms as used in animal improvement

(i)    Phenotype
-    This refers to the trait/character manifested in the physical appearance of
the animal
-    It is influenced by the interaction of genes with the environment
-    Phenotypic traits include height, body size, coat colour
         
(ii)    Chromosome
-    Chromosome is a rod-like /thread-like structure found in the nucleus of
an animal cell
-    It carries the genetic information of a farm animal
-    It is made up of proteins and DNA organised into genes
-    Chromosomes are inherited by offsprings from their parents
         
(iii)    Hybrid
-    Hybrid refers to the offspring from the crossbreeding of two or more
pure breeds of an animal species
-    It combines the qualities of two animals of different breeds
               
(iv)    Gametes
-    Gametes are matured sex cells which could either be male or female
-     Male gametes are called sperms and female gametes are called ova
-     Gametes exist as haploid cells which fuse together to form diploid
cells/zygote during sexual reproduction

       
(v)    Filial generation
-    These are offspring(s) of parents
-     The first filial generation (F1) results from the cross of the first set
of parents
-    The first, second and third generations of offsprings are known as F1, F2,
and F3
                                                                                                                    
(b)        Uses of lime in agriculture
 -     Neutralizes soil acidity
-     Improves soil structure
-     Releases calcium to plants for tissue development
-     Increases rate of water percolation in clay soil
-     Serves as additional source of calcium for bone development in fish
-     Reduces the toxicity of dissolved copper and manganese in the soil
-     Reduces turbidity in fish ponds
-     Enhances the release of some nutrient elements e.g. phosphorus
-     Enhances the activities of microorganisms in the soil
-     Destroys leeches on fish skin in ponds
-     Encourages the growth of phytoplanktons in fish ponds
                                                                                              
(c)        Ways in which roundworms are of economic importance to farm animals
-     Loss of appetite/anorexia                                    -    Anaemia
-     Reduced growth rate                               -    Respiratory distress
-     Indigestion                                              -    Constipation
-     Diarrhoea                                                 -    Loss of weight/emaciation
-     Reduced production in livestock e.g. meat, egg
-     Destroy many organs during migration
-     May result in death of the host