BIOLOGY PAPER 3 - KCSE 2019 STAREHE PRE MOCK EXAMINATION (WITH MARKING SCHEME)

1. You are provided with solution W. Using the provided reagents; carry out possible food tests to identify food substances present in solution. (14mks)
   

   Food substance	Procedure	Observation	Conclusion

2. Examine the photograph which shows parts of the urogenital system of a female rat and answer the questions that follow. The organ marked 1 is the stomach.
   
   
   1.  
      1. Name the organ marked 2              (1mk)
      2. State two functions of the organ       (2mks)
      3. What is the functional unit of the organ in (a)(i) above    (1mk)
   2.  
      1. Identify and name each of the organs marked 3 and 4     (2mks)
      2. State two functions of the part marked 4            (2mks)
   3.  
      1. Identify the organs marked 5            (2mks)
      2. Explain two functions of the organ named in c (i) above.  (2mks)
   4. The organ marked 6 is the large intestine. State three function of the large intestine. (3mks)
3. You are provided with seven specimens of plants. They are labeled D1, D2, D3, D4, D5, D6, and D7.
   The dichotomous key
   a) Leaves needle like ………………………………………………………………..go to 2
   b) Leaves broad ………………………………………………………………….….. go to3
   a) Leaves arranged in clusters on stem……………………………….………….. Pinnacea
   b) Leaves not arranged in clusters on stem …………………………………….…..Araucariaceae
   a) Leaves compound…………………………………………………..………….. go to 4
   b) Leaves simple…………………………………………………….…………… go to 7
   a) Leaflets pointed at the end …………………………………....……………….go to 5
   b) Leaflets rounded at the end…………………………………….………………go to 6
   a) Leaflets attached to many small stalks that join the main one ……………...….Mimosaceae
   b) Leaflets attached to one stalk ………………………………….………………Rosaceae
   a) Leaflets attached to many small stalks that join the main one……………...… Bignonaceae
   b) Leaflets attached to one stalk ………………………………….………………Compositae
   a) Leaves green ………………………………………………..………………….go to 8
   b) Leaves purple ……………………………………………….……………….. go to 9
   a) Leaves parallel veined ………………………………………..……..………..Graminae
   b) Leaves net veined ………………………………………………….….……. Geranaceae
   a) Leaves parallel veined ……………………………………………..……….…Commelinaceae
   b) Leaves net veined ………………………………………………………..…….Euphorbiaceae
   
   
   
   1. Use the dichotomous key to identify the taxonomics group of each of the seven specimens in the photographs provided. (7mks)
      

      Specimen	Steps followed	Identity
      D1 D2 D3 D4 D5 D6 D7

   2.  
      1. Suggest the possible habitat that specimen D4 is adapted to     (1mk)
      2. Name one observable feature that adopts D4 to the habitat you have mentioned in (b) (i) above (1mk)
      3. Give a reason for your answer in (b) (i) above      (1mk)
      4. State the importance of the structure labeled S in specimen D4        (1mk)

MARKING SCHEME

1.  
   

   Food substance	Procedure	Observation	Conclusion
   Starch	To solution W add (2 drops of) iodine solution	Brown/ yellow colour persist/remains Acc. No colour change observed	Starch absent
   Reducing sugars	To solution W add Benedict’s solution and heat/boil /warm	Colour /brown changes to blue to green to yellow to orange Acc. Final colour. Rej: red colour	Reducing sugars present
   Ascorbic Acid	To DCPIP, add the food solution dropwise, while shaking.	Blue colorof the DCPIP rataines	Ascorbic Acid absent
   proteins	To solution W add sodium hydroxide then copper (II) sulphate Rej: heat	Blue color of copper (II) sulphate retained	proteins absent

    
2.  
   1.  
      1. Kidney;
      2. Osmoregulation;
      3. Excretion;
      4. Nephrone;
   2.  
      1. 3-Funnel
         4-Ovary
      2. Site for production of ova/ female gametes/secondary oosytes;
         Secretion of hormones ;
         Uterus;
   3.  
      1. Site for implantation;
         Nourishment and development of foetus;
      2. Site for absorption of water;
         Site for absorption of vitamins and mineral salts;
         Propulsion of food down the alimentary canal;(any two points)
3. 
   
   1. specimens                   steps followed                        identity
      D1                               lb,3a,4b,6a                              bignonagae
      D2                               lb,3b,7b,9a                              commelinaceae
      D3                               la,2a                                        pinaceae
      D4                               lb,3a,4a,5a                              mimasaeeae
      D5                               lb,3b,7a,8b                             graminaceae
      D6                               lb,3b,7a,8a                              graminaceae
      D7                               lb,3a,4b,6b                              compositae
   2.  
      • Semi-arid /dry/desert/arid             (1mk)
      • Small reduced needle-like leaves/presence of thorns/spikes             (1mk)
      • To conserve water/reduced transpiration rate/reduced water loss (1mk)
      • Thorns/spikes provide protectors against injury by browsers/herbivores (1mk)