WASSCE FOR PRIVATE CANDIDATES 2019 FIRST SERIES PAPER3

DETAILED COMMENTS ON EACH QUESTION


Question 4


. The diagrams below illustrate parasites of farm animals. Study them and answer the questions that follow.



  1. Identify the parasites labelled I and II.
  2. (2 mark)


  3. Mention three external features of the parasite labelled I.
  4. (3 mark)



  5. Name the part of the body of the host where the parasite labelled II is found.

    (1 mark)


    1. State four adaptive features of the parasite labelled II on its host.
    2. (4 mark)


    3. List two intermediate hosts of the parasite labelled II.
    4. (2mark)


  6. State three effects of the parasite labelled I on its host.
  7. (3 mark)


Observation

 

  1. Many candidates could identify the tapeworm but were unable to identify the louse.

  2. Candidates were not specific in naming the part of the host where the tapeworm is found.

  3. Many candidates wrote ‘intestine’ instead of the ‘small intestine’.


  4. However, many candidates were able to state the adaptive features of tapeworm on its host.

The expected answers include:


  1. Identification of the Parasites
  2. I -Louse


    II -Tapeworm (Taenia solium)


  3. External features of the parasite labelled I (Louse)

  4. - Head


    - Thorax

    - Three pairs/six legs with sharp claws


    - Segmented abdomen


    - A pair of antennae


    - A pair of compound eyes


    - Mouthparts for biting and sucking


  5. Part of the body of the host where the parasite labelled II (Tapeworm) is found

  6. - Small intestine


    1. Adaptive features of the parasite labelled II (Tapeworm) on its host).

    2. - Possesses four suckers with which it attaches itself to the walls of the intestine of its host


      - Possesses two rows of hooks with which it fixes itself into the intestine for a firm grip

      - The whole body is covered with cuticle which prevents it from being digested by the digestive enzymes of its host


      - Has the ability to absorb products of digestion with its entire body since it has

      no digestive system of its own


      -Its excessive length increases surface area for absorption


      - Produces many proglottides full of eggs


      - Rostellum forms part of appendages for attachment


    3. Intermediate hosts of the parasite labelled II (Tapeworm),


      -Cattle


      - Pigs


  7. Effects of the parasite labelled I (Louse) on its host
  8. - The host becomes restless due to skin irritation


    - Loss of appetite n


    - Loss of weight n


    - Reduction in livestock productionn


    -Causes loss of hairs or feathersn


    -Injuries caused may serve as source of secondary infectionn


    -It sucks blood of host leading to anaemian


    -eventually leads to death