Question

what is the function of haemoglobin present in red blood cells?

Answer 1

Hemoglobin in the blood carries oxygen from the lungs or gills to the rest of the body (i.e. the tissues). There it releases the oxygen to permit aerobic respiration to provide energy to power the functions of the organism in the process called metabolism.

Answer 2

haemoglobin is protein inside RBC.
it carries oxygen.