3.5 Symbiosis Flashcards
describe ‘symbiosis’
Symbiosis is a term used to describe relationships between members of two different species that are in direct contact.
The two categories of symbiosis are parasitism and mutualism.
Symbiotic relationships are the result of coevolution.
describe ‘coevolution’
coevolution occurs when the genetic changes of one species provides the selection pressure for the other, so the adaptation in one species results in the counter-adaptation in the second
describe ‘parasitic relationships’
In parasitic relationships, the parasite benefits by getting nutrients or energy from the host, and the host is harmed by a loss of the nutrients and energy.
Some parasites have evolved to have a limited metabolism, where they are unable to digest larger molecules (such as starch or proteins), or synthesise essential metabolic building blocks (such as amino acids). In these cases, they must get the nutrients/molecules required from their host organism and are unable to survive without contact from the host.
why might a parasite need to be able to move from one host to another?
just in case one host dies or is predated upon
describe ‘methods of parasite transmission — direct contact, resistant stages and vectors’
Direct Contact
- the parasite is passed on directly from individual to individual
- e.g. head lice, rabies and avian flu
Resistant Stages
- the parasite produces relatively inactive stages (e.g. cysts and eggs) that are resistant to environmental conditions
- e.g. flat worms, round worms and toxoplasmosis
Vectors
- when an organism transfers the parasite from one host to another
- e.g. malaria
describe ‘mutualistic relationships’
both partner species benefit from the interdependent relationship
name an example of a mutualistic relationship
- clownfish cleaning the anemone that it lives in which protect is from predators
- egrets cleaning ticks and other parasites from buffalo as a food source
