(a) What is fragmentation in organisms? Name a multicellular organism which reproduces by this method.

(b) What is regeneration in an organism? Describe regeneration in Planaria with the help of a suitable diagram.

(a) Fragmentation is a mode of asexual reproduction. Fragmentation is the process in certain multi-cellular organisms with relatively simple body organisation, the body of the organism simply breaks up into smaller pieces upon maturation and these pieces or fragments grow into new individuals. Example: Spirogyra.

(b) Regeneration: Regeneration involves the capacity of an organism to give rise to an entire individual from a cut portion. This type of regeneration occurs in Planaria. When Planaria gets cut unintentionally, the cut fragments give rise to a new individual. Regeneration is carried out by specialised cells. These cells proliferate and make large numbers of cells. From this mass of cells, different cells undergo changes to become various cell types and tissues. The figure shows regeneration in planaria: