The diagrams below illustrate parasites of farm animals Study them and answer the questions that follow. a) Identify the parasites labelled I and II. b) Men...

Answer Details

(a) Identification of the parasites

• I: Louse (an ecto-parasite)
• II: Tapeworm (an endo-parasite)

(b) Three external features of parasite I (Louse)

1. A distinct head, thorax and segmented abdomen.
2. Three pairs (six) of legs bearing sharp claws for clinging to the host.
3. A pair of antennae, a pair of compound eyes and biting-and-sucking mouthparts.

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

It is found in the small intestine of the host.

(c)(i) Four adaptive features of parasite II (Tapeworm) on its host

1. It possesses four suckers with which it attaches itself to the wall of the host's intestine.
2. It possesses two rows of hooks (rostellum) with which it fixes itself firmly in the intestine.
3. Its whole body is covered with a resistant cuticle that prevents it from being digested by the host's enzymes.
4. It has no digestive system of its own and absorbs digested food over its entire body, its great length providing a large surface area for absorption.

(c)(ii) Two intermediate hosts of parasite II (Tapeworm)

1. Cattle
2. Pigs

(d) Three effects of parasite I (Louse) on its host

1. It causes skin irritation, making the host restless, and leads to loss of hair or feathers.
2. It sucks the host's blood, leading to anaemia, loss of appetite and loss of weight.
3. The injuries it causes serve as sites for secondary infection, reducing livestock production and, in severe cases, causing death.

(e) Three effects of parasite II (Tapeworm) on its host

1. It robs the host of digested food, causing loss of weight, weakness and reduced production.
2. When present in large numbers it may block the intestine.
3. It releases toxins that make the host unthrifty and unproductive.