Social Science
Literature Arabic Islamic Studies C.R.K MusicVisual Art Clothing/Textile House Management Shorthand
Biology Paper 2, May/Jun 2014  
Questions:   1 2 3 4 5 6   Main
General Comments

Question 2

1.(a)     Define the following terms:
            (a)        elimination;
            (b)        excretion;
            (c)        secretion.    [6 marks]                                                                                           
   (b)     Describe the digestion of boiled fish in the gut of humans.   [6 marks]                                            
   (c)    Make a diagram 8 cm – 10 cm long of a longitudinal section of a villus and label fully.    [8 marks]


This was one of the most unpopular questions.  A few candidates were able to correctly
 define elimination, excretion  and secretion.  Majority of the candidates could not
 efficiently describe the digestion of boiled fish in the gut of humans.  The few
candidates that attempted the diagram of villus did not draw it properly.                           
 The expected answers are:

           (a)     Definition of terms     

  1. Elimination:  Removal of undigested food; from the body of living organisms.                                                           

Excretion:    Removal of waste products of metabolism; from the cells/tissues
                    of an organism; may be toxic if retained in the body.                                                                                                                             

  1. Secretion:    Production and release of substances; useful to the body; by

                specialised glands of living organisms.                                                                                                                                
   (b)   Digestion of Boiled Fish in the Gut of Humans

         Boiled fish is a source of protein; chewed and swallowed into the stomach; digestion
         of protein starts from the stomach; stomach secretes gastric juice; containing pepsin,
         rennin and hydrochloric acid; pepsin in acidic medium acts on the boiled fish and convert
         it to peptides; peptides move into the duodenum / small intestine; into which pancreatic
         juice is secreted; undigested protein is acted upon by trypsin in alkaline medium; into
         peptides/peptones; erepsin finally acts on peptides/peptones in alkaline medium; and
         converts it into amino acids.                                           

     (c)    Diagram of Villus

Title (TL) - Longitudinal section of villus                                                     
             Size  (Sz)(8 – 10cm long)                                                                              

             Quality (Q)
            Clarity of lines (CL)                                                                                       
            Neatness of Labels (NL)                                                                                

            Details (D)
            Epithelium layer shown (EL)                                                                         
            Conical shape of villus (One cell thick) (CV)

Labels (L)  
     Epithelium layer, blood capillary, lacteal, lymphatic vessels, goblet cells,

     venule, arteriole, Crypt of Lieberkuhn, cells of Paneth, Muscularis mucosa.
Powered by Sidmach Technologies(Nigeria) Limited .
Copyright © 2015 The West African Examinations Council. All rights reserved.