SYMBIOSIS U3

Question 1

State the definition of symbiosis, naming the 2 types

Answer 1

Symbiosis is the co-evolved intimate relationships between members of two different species.

The types of symbiotic relationship are parasitism and mutualism.

Question 2

Describe a parasitic relationship and explain how parasites are transmitted

Answer 2

A parasite will benefit in terms of energy or nutrients, where its host is harmed by the loss of these resources.

Parasites often have a limited metabolism and cannot survive out of contact with the host. Parasites are transmitted to new hosts through:

Direct contact – fleas and lice
Resistant stages – larvae, pupae and eggs that can survive adverse conditions.
Vectors – mosquitoes transferring the protozoa that causes malaria to humans.
Some parasitic life cycles involve intermediate (secondary) hosts to allow them to complete their lifecycle.

Example
Worms larvae forming cysts in slugs which are then eaten and infect weasels, stoats and shrews.

Question 3

State the meaning of the term ‘mutualism’

Answer 3

Mutualism is when both partner species benefit in an interdependent relationship.

Example
Bacteria living in the digestive system of cows, helping cows digest all of the plant material they eat.