Biology Paper 3 Questions and Answers - Catholic Diocese of Kakamega Mock Exams 2023

INSTRUCTIONS TO CANDIDATES:

1. Answer ALL the questions in this paper
2. You are required to spend the first 15 minutes of the 1 3/4 hours allowed for this paper reading the whole paper carefully before commencing your work.
   
   

Biology paper 3

1. You are provided with; Liquid cooking oil.
   
   • Solution Bl
   • Solution B2
   • Irish potato.
     Label two test tubes X and Y.Into each test tube, put 2cm3 of water and 8 drops of liquid cooking oil. To the test tube labeled X add 8 drops of liquid B1.Shake both test -tubes and allow the content to
     stand for 20 minutes.
     
     1. 1. Record your observation in 
           Test tube X
           Test tube Y
           (2 marks)
        2. Name the process that has taken place in test tube X.
           (1 mark)
        3. State the significance of the process named in (ii) above in digestion.
           (1 mark)
        4. Name the digestive juice in human that has same effect on oil as liquid B1.
           (1 mark)
        5. Name the region in the digestive system into which the juice is secreted.
           (1 mark)
     2. Label two test tubes E and F.Place 2cm 3 of liquid B2 into each. Add a drop of Iodine solution. into each test tube.
        
        1. Record your observation.
           (1 mark)
        2. Suggest the identity of liquid B2.
           (1 mark)
     3. 1. Cut a cube whose sides are 1cm from the Irish potato and crush it. Place the crushed paste into a test tube. Carry out food test with reagents X provided. Record the procedure and
           results.
           (2 marks)
           

           Food being tested	Procedure	observation	conclusion

        2. Account for the results in c (i) above.
           (3 marks)
2. Figure 1 represents a bat wing, Figure 2 a whale paddle and Figure 3 an insect wing. Study the
   diagrams and answer the questions that follow.
   
   
   1. Name the parts labeled E,F and G.
      (3 marks)
      E
      F
      G
   2. State the type of skeleton found.
      
      1. In the bat wing.
         (1 mark)
      2. On the part labeled S.
         1 mark)
   3. Suggest the type of structures represented in figure 1 and 2.Give a reason for your answer.
      (2 marks)
   4. What type of evolution is represented by existence of bat and insect wing? Explain your
      answer.
      (2 marks)
   5. The wing of a Kiwi unlike those of a bat are greatly reduced.
      
      1. Name the type of structure represented by wings of kiwi.
         (1 mark)
      2. Why are the wings of kiwi greatly reduced?
         (1 mark)
   6. Name the type of joint found at
      
      1. Proximal end of bone marked H.
         (1 mark)
      2. Distal end of bone marked H.
         (1 mark)
3. Examine photograph B1 and a section through mammalian organ below.
   
   
   
   
   1. Focusing on photograph B1;
      
      1. Name the agent of pollination for specimen B1.
         (1 mark)
      2. Give a reason for your answer in (a) above.
         (1 mark)
      3. Describe the external features of leaves of specimen B1.
         (3 marks)
      4. Based on the floral parts, state the class to which specimen B, belongs.
         (1 mark)
      5. Give a reason for your answer in (d) above.
         (1 mark)
   2. Focusing on the section through mammalian organ;
      
      1. Identify the section.
         (1 mark)
      2. Name the parts labeled A,B and C.
         (3 marks)
         A
         B
         C
      3. State two functions of the photographed specimen.
         (2 marks)
      4. Name one renal disease.
         (1 mark)

MARKING SCHEME

1.  
   1.  
      1. Test tube X
         liquid becomes cloudy/suspension is formed/oil broken up into small droplet which are spread
         throughout the liquid/oil is emulsified
         Test tube Y
         Oil floats on water/two separate layers are formed/immiscible layers are formed.
      2. Emulsification
      3. Increases surface area of fats for efficient digestion by lipase.
         Note: tied to (ii)
      4. Bile.
      5. Duodenum
         tied to (iv)
   2.  
      1. Iodine solution changes from brown to blue-black.
      2. Starch solution
   3.  
      1.  

         Food being tested	Procedure	Observation	Conclusion
         Reducing sugar (1⁄2mk)	Add equal amount of Benedicts solution and boil (1⁄2mk)	Blue-Green-yellow-orange  Accept green,yellow,orange  (1⁄2mk)	Reducing sugar present. (1⁄2mk)

      2. Starch in potato is converted to maltose; then glucose ;(a reducing sugar)by enzyme amylase/maltase/diastase; because potato is a living tissue that requires energy to sustain their metabolic processes;
         (max 3 mrks)
         Reject ptyalin.
2.  
   1. E-Radius
      F- Humerus
      G-Wing veins
   2.  
      1.  Endoskeleton
      2.  Exoskeleton
   3. Homologous structures-presence of pentadactyl pattern/five digit structure/similar bone anatomy
   4. Convergent evolution - They have different embryonic origin but are modified to perform the same function of flight.
   5.  
      1.  Vestigial
      2. They ceased to function.
   6.  
      1. Ball and socket. (joint)
      2. Hinge (joint)
3.  
   1.  
      1. Insect
      2. Brightly coloured petals;tied to (a)
      3. • Net veined
         • serrated blade/margin
         • pointed apex
      4. Dicotyldonae reject dicotyledon.
      5. Floral parts are in 5/ multiple of 5s.
   2.  
      1. Longitudinal (section)
      2. A-Cortex
         B-Medulla
         C-Pelvis
      3.  
         • ionic balance in the body/osmoregulation
         • Excretion of metabolic wastes.
         • Regulate pH of body fluids.
      4.  
         • Proteinuria
         • Nephritis
         • Kidney stones
         • Kidney failure    (Any first 3)