Biology Paper 3 Questions and Answers - Mang'u Mock 2020 Exam

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BIOLOGY
PAPER 3
TIME: 2¼ HOURS.

Instructions to candidates

  • Answer all the questions
  • You are required to spend the first 15 minutes of the 1/4 hours allowed for this paper reading the whole paper carefully before commencing your work 
  1. You are provided with 20% glucose solution about 2.0grams of substance labeled J and solution labeled K place 20cm3 of glucose solution in a boiling tube. To the boiling tube add 2.0g of substance. Tightly fit a rubber stopper carrying a delivery tube to the boiling tube. Place the boiling tube in a water bath maintained at 350 to 40°C. Place the delivery tube into a test tube containing 1.0cm of solution K. Allow the set up to stand for twenty minutes.
    1. Record your observations (2mks)
    2. What conclusion would you draw for your observations in (a) above? (2mks)
    3.    
      1. Name the biological process that took place in the boiling tube(2mks)
      2. Explain the process you have named in c(i)(2mks)
    4. Suggest the identity of J (1 mk)
    5.    
      1. Suggest a reason why the temperature range in this experiment was maintained between 35° and 40° (2mks)
      2. With reasons, suggest the expected results if the experiment was performed at (4mks)
        0°C
        Reason
        100°C
        Reasons
  2. Examine the seedling below and use them to answer the questions that follow
    p3q2
    1. Name the parts labeled C, D, E and state their importance for the seedling. 
      C(1mk)
      Importance
      D:(1mk)
      Importance
      E: (1mk)
      Importance
    2. The R series of seedlings form swellings on the roots later in its life.
      1. What is the name of the swellings our ten (1mk)
      2. Name the organisms that would be found in the swellings (1mnk)
      3. Explain the relationship that exists between the named organisms and the plant. (2mks)
    3.    
      1. State the types of germination exhibited by R series of the seedlings (1mk)
      2. Give a reason for your answer in c) (i) above. (1mk)
    4. State any two external factors necessary for germination (2mks)
  3. Below is a photograph obtained from the pelvic region of a human being, and showing some bone of the vertebral column. Examine it
    p3q3
    1. Name the bones labeled 1, 2 and 3 on the photograph (3mks)
    2.    
      1. Name the type of joint formed at the proximal end bone 3 as it articulates with the adjacent bone (1mk)
      2. Give an observable feature on bone 3 for your answer in (b) (i) above (1mk)
    3.     
      1. Name the part labeled Q:(1mk)
      2. Give TWO functions of the part named in c (i) above (2mks)
    4. Indicate on the above diagram the position of pubis symphysis (1mk)
    5. Using observable features only, state how bone l as adapted to its functions (4mks)

MARKING SCHEME

  1.    
    1. Record your observations.
      • Bubbling/effervescence/ fizzing gas formed
      • White precipitate in solution K.

    2. What conclusion would you draw for your observation in (a) above?
      • Gas produced is carbon (IV) oxide;
      • Solution K is lime water/ calcium hydroxide

    3.    
      1. Name the biological process that took place in the boiling tube
        • Anaerobic respiration/ fermentation

      2. Explain the process you have named in c (i)
        • Glucose is broken down by enzymes (in yeast);
        • Giving out Carbon (TV) oxide/ ethanol and energy.

      3. Suggest the identity of J.
        • Yeast:

    4.    
      1. Suggest a reason why the temperature range in this experiment was maintained between 35° and40°.
        • It's the optimum temperature range for enzymatic reactions.

      2. With reasons, suggest the expected results if the experiment was performed at
        • 0ºC.
          • No reaction/ slow reaction
          • No. CO, produced
          • less CO

        • Reason
          • at this temperature, enzymes are inactive

        • 100°C
          • No reaction/ reaction stopped/
          • no CO, produced
          • rej. no change;

        • Reason
          • Enzymes are denatured/ yeast cells killed
          • rej. Yeast cells denatured.

  2.      
    1. Name the parts labeled C, D, E and state their importance for the seedling 
      • C:
      • Hypocotyl - protects the plumule/ shoot vip/ opens path for cotyledons to pass through the soil -
      • D-Cotyledons/ Seed leaves -
      • Photosynthesis; storage of food
      • E-Coleoptile/ plumule Sheath-Protects delicate tip/first leaves/ foliage leaves

       

    2.             

      1. What is the name of the swellings .
        • Root nodules

      2. Name the organisms that would be found in the swellings -
        • Rhizobium bacteria;

      3. Explain the relationship that exists between the named organisms and the plant
        • Symbic tic relationships were the bacteria get protection and nutrient while the points get nitrates fixed by bacteria.

    3.            
      1. State the types of germination exhibited by R series of the seedlings
        • Epigeal

      2. Give a reason for your answer in c (1) above
        • Cotyledons are brought out of the ground

    4. State any two external factors necessary for germination
      • Water
      • Oxygen
      • Optimum temperature

  3.           
    1. Name the bones labeled 1, 2, and 3 on the photograph
      • -Tlium - 
      • Pubis -
      • Femur 

    2.       .   
      1. Name type of joint found at the proximal end bone 3 as it articulates with the adjacent bone
        • Ball and socket

      2. Give an observable feature on bone 3 for your answer in (b) (i) above
        • Ball like head/Rounded head;
    3.            
      1. Name the part labeled Q.
        • Lumbar vertebra;
        • rej. vertebrae

      2. Give two functions of the part named above
        • Attachment of abdominal muscles
        • Supports the animals weight

    4. Indicate on the above diagram the position of pub symphysis
      • Pubis Bynphysis

    5. Using observable features only, state how bone I is adapted to its functions
      • Broad/ wide to provide large surface area for muscle attachment Has broad sacral facet; that attaches it to the terrace process of first sacral vertebrae;

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