Parasitism & Mutualism (Edexcel GCSE Combined Science) : Revision Note

Parasitism & Mutualism

• The survival of some organisms in a community is dependent on other species within the same community

  • This is known as interdependence

• Two examples of interactions that can create interdependence within a community include:

  • Parasitism (parasitic relationships)

  • Mutualism (mutualistic relationships)

Parasitic relationships

• Parasites are organisms that are adapted to live very closely with another species, known as the host (or the host species)

  • The parasite lives either in or on the body of the host species

• The parasite gains resources (i.e. what it needs in order to survive) from the host

  • This can include, food, shelter and a suitable location to reproduce (where offspring can feed and grow)

• However, the host doesn't get any benefits from this relationship

  • In fact, parasites often harm the host in some way

• An example of a parasitic relationship is fleas being a parasite to mammals (e.g. dogs)

  • The fleas feed on the host's blood but don't provide anything to the host in return

Mutualistic relationships

• A mutualism is a type of relationship between two species within a community, where both organisms benefit in some way

• For example, bees and many species of flowering plants have a mutualistic relationship

  • Bees gain nectar (i.e. food to provide them with energy) from flowers

  • When bees visit flowers, pollen is transferred to their bodies

  • As bees visit multiple different flowers, they spread the pollen to these flowers, pollinating them

  • In this way, the flowers gain help in reproducing