Question

Toxoplasmosis is a disease caused by the microscopic parasite Toxoplasma gondii.

The parasite usually infects mice, affecting their nervous system and causing them to
take unusual risks (such as running out in the open, and coming unusually close to
animals which may eat them). Scientists believe this is actually a way for the parasite
to reach its primary host – cats. When a cat catches and eats an infected mouse, the
Toxoplasma gondii enters its digestive system and steals nutrients from the cat.
Humans can become infected by Toxoplasma gondii through contact with cat feces.
Scientists now believe that Toxoplasmosis in humans can cause substantial changes
in mood and behavior, and may even be linked to certain types of depression. It is
estimated that 30-65% of people worldwide may be infected with Toxoplasma gondii.
a) (10 Points) From the story above, identify at least two different symbiotic
relationships involved in Toxoplasma gondii transmission and explain each.

Answer 1

The parasite and the mouse because the parasite feeds off the mouse; and the mouse and the cat because the mouse died to feed the cat but the cat also has now infected itself with the parasite.