Biology Paper 3 Questions and Answers - Butere Mock Exams 2021

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QUESTIONS

  1. Study photographs shown below then answer the questions.
    1
    1. State the type of evolution represented by structures Q1, R1 and S1. (1mk)
    2. Explain the type of evolution identified in (a) above. (1mk)
    3. Give the evolution term used to describe structures:
      1. Q1, R1 and S1 (1mk)
      2. A1, B1 and C1 (1mk)
    4. What type of evolution is illustrated by the limbs A1, B1 and C1? (1mk)
    5.        
      1. Name class for each Q, R and S.
        Q ………………………………………………………… (1mk)
        R ………………………………………………………… (1mk)
        S ………………………………………………………… (1mk)
      2. Give two observable reasons for your answer for class S. (2mks)
    6.      
      1. Suggest the diet of animals B and R.
        B……………………………………………………… (1mk)
        R……………………………………………………… (1mk)
      2. How is beak of animal B adapted to its function? (1mk)
    7. How are animals A, B and C adapted for thermoregulation? (1mk)
  2. You are provided with Iodine solution, starch suspension and visking tubing.
    • Wet the visking tubing in running water to soften it and make it easy to open. Tie one end of the tubing tightly.
    • Using a dropper, put starch suspension into the tubing until about three-quarters full.
    • Tie the open end of the tubing tightly.
    • Ensure that there is no leakage at both ends of the tubing.
    • Clean outer surface of the visking tubing over running water to remove all traces of starch Suspension.
    • Place the visking tubing containing starch suspension into the beaker with iodine solution and leave the set up undisturbed for about 30minutes.
    • Remove the tubing from the beaker and observe.
      1. Record your observation in a table by indicating the colour of the solution at the beginning on at the end of the experiment. (4mks)
          Starch solution inside tubing Iodine solution in the beaker
        Start experiment    
        End of experiment    
      2. Account for the observations. (6mks)
      3. Explain the modifications you could have made to realise faster results in the above experiment. (2mks)
      4. State the importance of the process under investigation in the above experiment in both plants and animals as far as reproduction is concerned. (2mks)
  3. You are provided with a photograph of a flower of a higher plant.
    2
    1. With reasons, state the class of kingdom plantae from which the specimen in the diagram was obtained.
      Class (lmk)
      ……………………
      Reasons (2mks)
      …………………
    2. Name the parts labeled A, E, and F. (3mks)
      A: ……………………………………………………………………………..
      E: ……………………………………………………………………………..
      F: ……………………………………………………………………………..
    3. State how the specimen shown in the photograph is adapted to its mode of pollination. (2mks)
    4. Label the structure in the photograph which protects the flower before it blooms. (1mk)
    5. Which letter in the photograph represents structure where the male gametes are produced. (lmk)
    6. Calculate the image magnification of the leaf from point X to Y if its actual length was 2cm. show your working. (2mks)

BIOLOGY CONFIDENTIAL

  1. Each student should be provided with the following:
  2. 10cm visking tubing
  3. 50cm3 Iodine solution
  4. 20cm3 starch suspension
  5. 100ml beaker
  6. 30cm sewing thread
  7. A dropper
  8. Distilled water.


MARKING SCHEME

  1.        
    1. Convergent evolution;
    2. Different structures with different embryonic origins/ ancestry modified to perform similar functions;
    3.        
      1. Analogous structures;
      2. Homologous structures;
    4. Divergent evolution/ adaptive radiation;
    5.      
      1. Q - Insecta; R - Aves; S – Mammalia;
      2. Has pinnae; Has fur covering body;
    6.      
      1. Flesh; R - Nectar from flowers;
      2. Strong, curved and sharp; to rip flesh from bones;
    7. Their bodies are covered with feathers for insulation / that insulate the body against heat loss.
  2.        

    1.   Starch solution inside tubing Iodine solution in the beaker
      Start experiment White;  Brown (colour of iodine); 
      End of experiment Blue –black;  Brown (colour of iodine); 
    2. The visking tubing is semi-permeable/ has tiny pores; iodine molecules are small; thus move through tubing wall by diffusion/ diffused through the tubing wall; and reacted with the starch (solution) forming blue-black compound/ colour; starch molecules are big; hence could not pass through the membrane pores into the beaker;
    3. Use a shorter visking tubing so as to increase surface area to volume ratio; warm the water to raise thekinet ic energy of iodine/ diffusing molecules;
    4. Insect pollinators are attracted by flower scent which reach them by diffusion; in animals like bees/ dogs/ cattle, the females release chemicals/ pheromones which diffuse attracting the males; acc. Any other relevant example of animals
  3.      
    1. Class - Dicotyledonae (lmk)
      Reasons
      • Floral parts in fives /multiples of five/five stigma/five petals/five sepals;
      • Leaf has (compact) petiole;
      • Leaf broad; with network venation;
        Mark 1st two
    2. A – Stigma;
      E- Filament;
      F- Petal;
    3. Large /conspicuous/ brightly colored petals-to attract insect/ birds/ pollinators;
    4. The sepals; Rj if label not in the photograph;
    5. C;
    6. Magnification = Length of leaf in the photograph from X to Y
                                                      Actual length
      = 3.3cm;
         1.1cm
      =X3;

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