How are the modes of reproduction different in unicellular and multicellular organisms?

Explanation

a) Most of the unicellular organisms (such as protozoa and bacteria) reproduce by the asexual process of 'fission'. In this process, mere cell devision leads to the creation of new individuals.
b) In simple multicellular organisms, reproduction occurs by asexual methods such as budding, spore formation, fragmentation and regeneration, etc. But in complex multicellular organisms, reproduction takes place by sexual methods involving gametes (sex cells) from two parents- a male and a female.