U3.5 Symbiosis

Question 1

Define symbiosis.

Answer 1

An intimate relationship between two members of different species.

Question 2

What is symbiosis the result of?

Answer 2

A partnership over time resulting co-evolution.

Question 3

Describe the relationship between parasite and host.

Answer 3

A parasite benefits in terms of energy or nutrients whereas its host is harmed by the loss of these resources.

Question 4

Describe the metabolism of a parasite.

Answer 4

Limited metabolism and cannot survive out of contact with a host e.g. tapeworm has no gut.

Question 5

How may parasites be transmitted to new hosts?

Answer 5

• Direct contact (e.g. head lice),
• Resistant stages (e.g. larvae and pupae of cat fleas),
• Vectors (e.g. culex mosqitoes are used by plasmodium)

Question 6

What do some parasitic lifecycles involve?

Answer 6

Intermediate (secondary) hosts to allow them to complete their lifecycle e.g. humans are the intermediate hosts for plasmodium where gamete release occurs, but fertilisation happens in the mosquito.

Question 7

What is mutalism?

Answer 7

A form of symbiosis where each mutualistic partner benefit in the interdependent relationship e.g. coral polyps and zooxanthellae algae.