Question 4
(a) Identify the stage of growth of specimen L. [ 1 mark ]
(b) (i) State one observable difference between specimens M and N. [ 2 marks ]
(ii)  Identify  the sex of each of specimens M and N based on the observation in   
      4(b)(i)  above.                                                                                       [ 2 marks ]
(c) Describe the artificial process of obtaining specimen L from specimens M and N.[ 10 marks ]
Observation
         This question was well attempted by  the candidates.  Most of the candidates  were able to 
          identify the stage of growth of  specimen L(Fingerling) as required  in 4(a). Furthermore, 
          majority of the candidates were able  to state the observable difference between
          specimens M (Adult female Clarias) and N (Adult male Clarias) and identify the sex of 
          specimens M(Adult female Clarias)  and N(Adult male Clarias) based on  observation 
          as required in 4(b)(i) and 4(b)(ii)  respectively. 
          Finally, most of the candidates were unable  to describe the artificial process of obtaining 
          specimen L(Fingerling) from specimens M(Adult  female Clarias)  and N(Adult male 
          Clarias) as required in 4(c).
The expected answers include:
4 (c) Artificial process of obtaining Specimen L from Specimens M and N
 -        Specimen M is injected with  hormone/specimens M and N are injected with hormone to  hasten egg and milt maturatio 
 -        Ovulation takes place 10 – 12 hours after injection
-      Specimen M is stripped to release egg/ spawn  into a dry bowl by gently pressing the abdomen 
    -      Specimen N is sacrificed to obtain the testes 
 -            Specimen N is squeezed to obtain the milt
    -      The  eggs and milt are mixed together with feather or plastic spoon to effect fertilization
    -      Water  is added/saline water is added
    -      The  eggs are then incubated and hatched in a flow-through trough/on kakaban/netting material
    -      The  hatchlings will start swimming out after 24 – 36 hours depending temperature
    -      Dark  area is created for the hatchlings to congregate in/move to
    -      The  hatchlings are separated/removed from the unhatched eggs or siphon out 
    dead/unhatched eggs
    -      Feeding  of hatchlings commences immediately yolk sacs are absorbed
    -      The  hatchlings develop into fry which develop into fingerlings/Fry develops into  
    fingerling