Lesson 2 - Parasites

Question 1

Describe some features of the tapeworm

Answer 1

• Ribbon-like and up to 10 metres long
• Has a scolex (head) made of muscle with suckers and hooks
• Body is a series of linear sections
• Primary host is human and secondary is pig

Question 2

Describe life cycle of a tapeworm

Answer 2

• Livestock consumes vegetation containing eggs
• Larvae grow from eggs
• Larvae grow into larvae cysts in
pig
• Human consumes undercooked pork and becomes infected

Question 3

What are some potential problems faced by tapeworms?

Answer 3

• No digestive system
• Gut is in constant motion
• Extreme pH
• High offspring mortality
• Difficult for egg find new host
• Digestive enzymes

Question 4

How is tapeworm adapted against its problems?

Answer 4

• Suckers and hooks to attach to gut wall
• Has thick cuticle and produces inhibitory enzymes on surface
• Produce large number of eggs each having resistant shells
• Body is long and flat so big SA:V
so diffusion of host’s digested molecules is sufficient for survival

Question 5

Describe the life cycle of a head louse

Answer 5

• Lice egg laid on hair shaft
• Young lice born and moults 3 times across 10 days
• Male and larger female reproduce
• 2 day after mating, female starts laying eggs and lays 4-8 eggs for next 16 days and then dies

Question 6

How are head lice adapted for life?

Answer 6

• Has claws to grip onto hair
• Claws can be shaped to more efficiently grip different types of hair
• Suck blood from host