Asexual reproduction involves a single parent to produce offspring without the formation of gametes. It occurs by the following ways: Fission, Budding, Fragmentation, Spore formation and Regeneration. In one of the methods like regeneration, Planaria A is cut horizontally into three pieces – L, M and N and Planaria B is cut vertically into two equal halves – O and P. (a) Which of the cut pieces of the two Planaria could regenerate to form a complete organism? (b) Give an example of another organism which follows the same mode of reproduction as Planaria. (c) What is the meaning of ‘development’ in regeneration? OR (c) Differentiate between regeneration and fragmentation.
Step-by-step explanation of the concept of regeneration in Planaria and comparison with fragmentation:
Step 1: Understanding regeneration in Planaria (a) All cut pieces (L, M, N from Planaria A and O, P from Planaria B) are capable of regenerating into a complete organism. - This is possible because Planaria has a high regenerative ability. - It contains specialized stem cells called neoblasts that help in regenerating missing body parts.
Step 2: Other organisms that show regeneration (b) Another example of an organism that can regenerate is the Hydra. - Like Planaria, Hydra can also regenerate its entire body from small cut pieces. - This is also due to the presence of regenerative cells.
Step 3: Process involved in regeneration (c) Regeneration is a biological development process that involves: - Proliferation: Growth and division of cells. - Differentiation: Cells become specialized to perform specific functions. - Organization: Specialized cells arrange themselves to restore the structure and functionality of the organism.
Step 4: Comparing Regeneration and Fragmentation
Regeneration
Fragmentation
A cut or damaged part of an organism regenerates into a complete organism.
The body breaks into fragments, and each grows into a new individual.
It involves specialized cells (e.g., neoblasts).
It does not require specialized cells.
Example: Planaria
Example: Spirogyra
Final Note: Regeneration is different from fragmentation. Regeneration involves complex cell specialization and organization, while fragmentation is a simple process where each fragment grows independently into a new organism.
