Observation

(a) Many candidates could identify the tapeworm but were unable to identify the louse .

(b) Candidates were not specific in naming the part of the host where the tapeworm is found. Many candidates wrote ‘intestine’ instead of the ‘small intestine’.

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

The expected answers include:
4.   (a)(i) Identification of the Parasites
I - seed

II - seed
     

(b)  External features of the parasite labelled I (Louse)

- Head

- Thorax

- Three pairs/six legs with sharp claws

- Segmented abdomen

- A pair of Antennae

- A pair of compound eyes

- Mouthparts of biting and sucking

                                             

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

- Small Intestine

(d)(i) Adaptive features of the parasite labelled II (Tapeworm) on its host

- 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

(ii) Intermediate hosts of the parasite labelled II (Tapeworm)

- Cattle

- Pigs

(e)  Effects of the parasite labelled I (Louse) on its host

- The host becomes restless due to skin irritation

- Loss of appetite

- Loss of weight

- Reduction in livestock production

- Causes loss of hairs or feathers

- Injuries caused may serve as source of secondary infection

- It sucks blood of host leading to anaemia

- It eventually leads to death