The diagram shows the life cycle of a pathogenic protozoan.

(i) Name the parasitic stage that is being transferred from host 'X' to host 'Y'.

(ii) Write the changes the parasite undergoes in the liver.

(iii) Write the changes the parasite undergoes when it enters the RBC.

(iv)a) Trace the changes the parasite undergoes when the host 'X' takes its blood meal from infected host 'Y'.

or

b) At which stage during the life cycle of the pathogen does the host 'Y' experience the symptoms of the disease? Name the disease and the toxic substance responsible for these symptoms.