KCSE 2011 Biology Paper 3 Questions with Marking Scheme

1. Below is a diagram of a fish. Examine it and answer the questions that follow.
   
   
   
   
   1. Name the parts labeled K, L, M and N. (4 marks)
      
      
   2. The actual length of the pair of scissors next to the fish is 12.5cm. Using this information, calculate the actual length of the fish. (3 marks)
      
      
   3. Name the fins that prevent the following movements of fish during swimming. (3 marks)
      1. Yawing
      2. Pitching; 
         
         
   4. The photograph below shows visible structures after removing the part labeled P.
      The inset is a magnified view of one of the structures.
      
      
      
      
      1. Name the parts labeled R, S and T. (3 marks)
         
         
      2. Explain how each of the following parts named in (d) (i) above is adapted to its function. (3 marks)
         
         
2. The photographs labeled D and E shows two types of leaves.
   
   
   
   
   
   
   1. With a reason, state the classes of plants from which the leaves in photographs D and E were obtained. (4 marks)
      
      
   2. State three features in the leaf shown in photograph D that adapt it to its functions. (3 marks)
      
      
   3. The photographs below show the structures observed in cross sections of parts of two types of plants as seen under a light microscope.
      
      
      
      
      1. Name the parts labeled U,V and W. (3 marks)
         
         
      2. Identify five differences between cross sections F and G. (5 marks)
         
         
         
3. You are provided with a food sample X in solution form, solution J (Iodine solution), solution K (Benedict’s) and solution L (Biuret’s reagent). Carry out tests on the food sample to identify the type of food substances present. (9 marks)
   
   

   Food being tested for	Procedure	Observations	Conclusion

MARKING SCHEME

1.      
   1. K - Pectoral fin
      L - Dorsal fin
      M - Anal fin
      N - Pelvic fin
   2. The size of scissors on the photograph is 4.6
      The length of fish on the photograph is 13.6 };
      Mg = Image length
               Actual length
      Actual length of fish is 13.6 X 12.5  = 36.96 cm;
                                            4.6
   3.    
      1. Yawing - Dorsal fin;
      2. Pitching - Pectoral fin; Pelvic fin;
   4.          
      1. R - gill rakers
         S - gill bar
         T - gill filaments
         
         
      2. r - sharp/numerous/pointed/arranged closely in a row to trap solids that can damage the filaments;
         S - rigid/firm to hold gill filaments in place;
         T -  numerous to increase surface area for gaseous exchange/thin to reduce the distance for gaseous exchange/vascularized to transport respiratory gases away from the respiratory surface moist to dissolve oxygen for diffusion;
2.          
   1. Leaf D - class dicotyledonae;
      Reason - network of veins/presence of petiole;
      Leaf E - class monocotyledonae;
      Reason - parallel venation/presence of leaf sheath;
   2. Broad and flat to offer a large surface area for photosynthesis;
      Thin to reduce distance over which carbon IV oxide diffuses to reach the mesophyll cells;
      Rich supply of veins to transport water to photosynthetic cells;
      Presence of chlorophyll to absorb light for photosynthesis;
   3.      
      1. U - xylem;
         V - phloem;
         W - cambium;
      2.      
          

         Cross section of F	Cross section of G
         No pith Vascular bundles scattered Vascular bundles numerous Cambium absent Cortex absent Small vascular bundles	pith present; vascular bundles in a ring; vascular bundles few; cambium present; cortex present; large vascular bundles;

             (Total = 15 marks)
3.      
   

   PROCEDURE	OBSERVATION	CONCLUSION
   Iodine solution/solution J (added to the food sample drop by drop while shaking)	Blue black colour formed;	Starch present in food sample;
   Benedict's solution/ solution K added to the food sample in test tube in equal amounts. The test tube is then placed in a hot water bath	Solution changes colour to green,yellow and  then orange/brown	More reducing sugar present in food sample
   Biuret's reagent/solution L added to the food sample drop by drop while shak ing;	Colour of reagent retained	Protein absent in the food sample;

   Award marks for correct procedure, observation and conclusion only.
   (9 marks)