THE TAPEWORM

Taenia solium : pork tapeworm Location: the adult lives in the small intestine

of humans clings to the gut wall by:

hooks suckers

New segments:are produced at the neck

Older segments:are pushed to the back

and grow larger

A person can have only one tapeworm living inside the intestines.

Body form: flat about 1000 segments or proglottids

Proglottid: may contain up to

50000 eggs

The largest proglottids are about: 2 cm long 1.5 cm wide

Fig 2. Internal structure of proglottids.

The tapeworm is hermaphrodite.

The tapeworm is an endoparasite:• lives and gets its nutrients from inside its

host, causing it harm

Harm caused to host: gut blockageabdominal painbody weight loss

Benefit gained by parasite: food supplysheltersteady environment

The tapeworm has two hosts:Human:

primary host (parasite is in its

ADULT form)

Pig: intermediate or secondary host

(parasite is not in adult form – bladderworm in pig muscle)

Fig. 3 The life cycle of Taenia solium

9 Adaptations to a parasitic mode of life

1. Hooks and suckers allow it to hold on tightly to the wall of the intestine.

2. Its flat body gives it a large surface area to absorb food.

3. It has no need of a mouth or gut as it absorbs already digested food.

9 Adaptations to a parasitic mode of life

4. It produces chemicals which neutralise the digestive juices of the host.

5. It produces large numbers of eggs to increase chances of survival.

Adult tapeworm

9 Adaptations to a parasitic mode of life

6. It has a vector to carry it from one human to another.

9 Adaptations to a parasitic mode of life

7. It respires anaerobically as there is lack of oxygen within the intestines.

8. The tapeworm has both male and female sex

organs (is hermaphrodite) and can fertilise itself. This is because only one tapeworm can be present within the intestines,

9. It lacks sensory organs such as eyes as it does

not need them.

How to get rid of tapeworms

1. Health officers inspect meat before it is sold.

2. Proper sewage disposal is important to prevent tapeworms from spreading.

3. Cooking meat thoroughly destroys the tapeworm bladders.

4. An infected person can take medicine to cause the tapeworm to let go of the intestine wall. The tapeworm is then flushed out with the faeces.

Question: MAY 2004

1a) Distinguish between the terms parasite and saprophyte. (4)

Parasite gets its nutrients from a living host, causing it harm but not necessarily killing it.Saprophyte gets its nutrients by breaking down dead and decaying material.

Question: MAY 2004

b) Give one named example of a parasite and one named example of a saprophyte. (2)

Parasite: tapewormSaprophyte: bacteria / fungus

Question: MAY 2004

c) Explain how the parasite you mention in (b) is adapted to its mode of life. (6)

Question: No. 2

a) Why would a parasite be at an advantage if it could produce large numbers of eggs? (2)

More chance that some survive and infect a host so that the parasite can continue its life cycle.

Question: No. 2

b) Explain fully the meaning of the term ‘endoparasite’. (3)

An endoparasite lives inside its host to get its nutrients. The host is harmed.

Question: MAY 20103) Explain ONE benefit of each of the following

features in the parasitic mode of life of a parasite living in the gut of its host: (3)

i) body surface covered with microvilli: Large surface area to absorb nutrients.

ii) long and thin body: Long body increases the surface area to absorb nutrients and a thin body makes diffusion pathway short.

Question: MAY 2010iii) body wall has active transport systems:

To allow upatke of ions, glucose and amino acids against a concentration gradient.

Tapeworm cysts in a human brain

THE END