Component 3.3 - Parasites

Question 1

What is the pork tapeworm’s primary and secondary host?

Answer 1

Primary host: human

Secondary host: pig (a larval form)

Question 2

How is the anterior end of the pork tapeworm adapted for survival?

Answer 2

It is made of muscle carrying suckers and hooks, attaching it strongly to the duodenum wall.

Question 3

How does the tapeworm prevent itself from being killed by the host’s immune response?

Answer 3

1) It has a thick cuticle

2) It can make enzyme inhibitors, preventing the host’s enzymes digesting it.

Question 4

How is the pork tapeworm adapted to obtaining nutrients?

Answer 4

1) It has a large surface area to volume ratio so digested food is absorbed over the whole body surface
2) It has a short diffusion pathway so the tapeworm can obtain nutrients quickly
3) It lacks digestive system due to it feeding through its cuticle

Question 5

How does the pork tapeworm increase its chance of transmission and fertilisation?

Answer 5

1) Tapeworm is a hermaphrodite, contains both male and female reproductive organs so can self-fertilise
2) Produces a large number of eggs (with resistant shells) that pass out in faeces

Question 6

Describe features of a headlouse?

Answer 6

Wingless insects, cannot fly, they have legs poorly adapted to jumping - transferred by direct contact

If removed from the human, on which they live, they die.

Question 7

How does the headlouse feed?

Answer 7

By sucking blood from the scalp of the host

Question 7

How are humans infected by the pork tapeworm?

Answer 7

When they eat undercooked pork containing live larval forms

Question 8

How is the headlouse adapted to survival?

Answer 8

1) It has claws to hold onto hairs

2) Lays eggs which are glued to base hairs