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

1. You are provided with specimen A and B
   1. Name the sub-division to which the specimen belong (1mk)
   2. Name the class to which the specimens belong (2mks)
      A
      B
   3. State three observable differences between the leaves of specimen A and B (3mks)
      

      Leaves A	Leaves B

   4. The diagram below show the cross-sections of stems obtained from specimens A and B
      
      
      1. Match the stem cross-sections with the specimens (2mks).
      2. Outline three differences between the two stems (3mks)
   5. Suggest the agent of pollination of the flowers of specimen A (1mk)
      

      Specimen A1	Specimen B1

   6. Give reason for your answer        (1mk)
2. You are provided with photographs of specimens labeled K (gills) and L (lungs). Examine them and answer the questions that follow.
   1. Name the class of organisms from where the specimens were obtained (2mks)
      

      Specimen	Class
      K
      L

   2. Label all the parts of specimen K on the photograph (3mks)
      I
      II
      III
   3. State the functions of each of the parts you have labeled in (b) above (3mks)
   4. State three ways in which the part labeled L is adapted to its functions (6mks)
      
   5. State the functional relationship between specimens K and L (1mk)

1. You are provided with:

• 1ml Olive oil
• K₁ (Concentrated sodium hydrogen carbonate solution)
• K₂
• Irish potato
• Test tube
• Iodine solution
  Label two test tubes X and Y. Into each test tube; put 2cm³ of water and 8 drops of Olive oil. To the test tube labeled X, add 8 drops of Liquid K₁. Shake both test tubes and allow the contents to stand for 2 minutes
  1.  
     1. Record your observation in: (2mks)
        Test tube X
        Test tube Y
     2. Name the process that has taken place in test tube X                                                       (1mk)
     3. Stage the significance of the process named in (a) (i) above in digestion             (1mk)
     4. Name the:
        1. Digestive juice in human beings that has the same effect on oil as liquid K₁ (1mk)
        2. Region of alimentary canal where the juice is secreted (1mk)
  2. Label two test tubes E and F. place 2cm³ of liquid K₂ into each. Add a drop of iodine solution into each test tube
     1. Record your observations (1mk)
     2. Suggest the identity of liquid K₂ (1mks)
     3. Cut out a cube whose sides are 1cm from the irish potato provided. Crush the cube to   obtain a paste and place the paste in the test tube labeled E. Leave the set up for at least 30minutes
        Record your observations                                                                                           (2mks)
     4. Account for the results in (b) (iii) above (2mks)

MARKING SCHEME

1. You are provided with specimen A and B
   1. Name the sub-division to which the specimens belong (1mk)
      Angiospermae/Angiospermaphyta
   2. Name the class to which the specimens belong                                                             (2mks)
      Dicotyledonae
      B - Monocotyledonae
   3. State three observable differences between the leaves of specimen A and B (3mks)
      

      Leaves A	Leaves B
      Network veined	Parallel veined
      Has a petiole	Has a sheath
      Broad lamina/leaf blade	Narrow lamina / leaf blade

   4. The diagram below show the cross-sections of stems obtained from specimens A and B
      1. Match the stem cross-section with the specimen (2mks)
         A-A₁
         B-B₁
      2. Outline three differences between the two stems (3mks)
         

         Specimen A1	Specimen B1
         Vascular bundles arranged in a ring	Vascular bundles scattered in the stem
         Has a distinct cortex and pith	Pith and cortex absent
         Vascular cambium present	Vascular cambium absent

      3. Suggest the agent of pollination of the flowers of specimen A (1mk)
         Insect
         Give reason for your answer                                                                                             (1mk)
         Brightly coloured petals to attract insects
2. You are provided with photographs of specimens labeled K (gills) and L (lungs). Examine them and answer the questions that follow.
   1. Name the class of organisms from where the specimens were obtained (2mks)
      

      Specimen	Class
      K	Pisces
      L	Mammalia

   2. Label all the parts of specimen K on the photograph (3mks)
      Gill bar
      Gill rakers
      Gill filaments
   3. State the functions of each of the parts you have labeled in (b) above (3mks)
      Gill bar            -           Supports the gill filament
      Gill filaments  -           Form the site of gaseous exchange
      Gill rankers     -           Protect the delicate gill filaments from damage by solid particles
   4. State three ways in which the part labeled L is adapted to its functions (6mks)
      Made of spongy elastic tissue that expands to accommodate a large volume of air
      Made up of numerous alveoli to provide a large surface area for gaseous exchange
      Supplied with numerous blood capillaries to maintain a high concentrated gradient for quick transportation of gases
   5. State the functional relationship between specimens K and L (1mk)
      Both are gaseous exchange organs in the organisms where they are found
      
      
3. You are provided with:
   • 1ml Olive oil
   • K₁ (Concentrated sodium hydrogen carbonate solution)
   • K₂ (1% starch solution)
   • Irish potato
   • Test tube
   • Iodine solution
     Label two test tube s X and Y. Into each test tube; put 2cm³ of water and 8 drops of Olive oil. To the test tube labeled X, add 8 drops of Liquid K₁. Shake both test tubes and allow the contents to stand for 2 minutes
     1.  
        1. Record your observation in: (2mks)
           Test tube X
           Liquid becomes cloudy/turbid, suspension formed/oil broken up into small droplets which are dispersed throughout the liquid. The oil becomes emulsified.
           Test tube Y
           Oil floats on the water/two separate /immiscible layers are formed
        2. Name the process that has taken place in test tube X                                                       (1mk)
           Emulsification
        3. Stage the significance of the process named in (a) (i) above in digestion             (1mk)
           Increases surface area for action of lipase enzyme
        4. Name the:
           1. Digestive juice in human beings that has the same effect on oil as liquid K₁ (1mk)
              Bile
           2. Region of alimentary canal where the juice is secreted (1mk)
              Duodenum.
              rej small intestines
     2. Label two test tubes E and F. place 2cm³ of liquid K₂ into each. Add a drop of iodine solution into each test tube
        1. Record your observations (1mk)
           Iodine solution changes from brown to blue-black
        2. Suggest the identity of liquid K₂ (1mks)
           Starch solution
        3. Cut out a cube whose sides are 1cm from the irish potato provided. Crush the cube to   obtain a paste and place the paste in the test tube labeled E. Leave the set up for at least 30minutes
           Record your observations    (2mks)
           Content of F remain unchanged/blue black colour in E disappears/fades/change to pale/light yellow/light/light brown/orange
        4. Account for the results in (b) (iii) above                                                                     (2mks)
           Enzyme /amylase in potato breaks down starch/converts/hydrolyse/changes/digest starch into maltose/reducing sugars/simple sugars that do not give a blue black colour with iodine.