Question

Among the vertebrates, which organism exhibits the maximum power of regeneration?
A. Dog
B. Lizard
C. Pigeon
D. Man

Answer 1

Hint:-Regeneration is defined as the phenomena carried out by organisms to replace missing or damaged tissues and body parts. This regeneration can be caused by cells arising from a pool of resident stem cells (self-renewing cells) or from dedifferentiated cells (reversal of differentiation of cell type to generate new cells) or from trans differentiated cells (change of cell state/type).

Complete answer:
The capacity and power of regeneration vary among different organisms, different organs/tissue parts within an organism, and different ages of the organ and organism. Invertebrates have the capability to renew their entire body from a small portion of cells, making them essentially immortal. This type of regeneration is known as restorative regeneration. Vertebrates, on the other hand, have a lower power of regeneration, owing to a number of reasons such as complexity of body organization, gene type, age, and developmental stage. Mammals, especially, only have the ability to renew certain damaged parts/tissues, called reparative regeneration.
Among vertebrates, Pisces like fish can regenerate fins, amphibians like salamanders and reptiles like lizards can regenerate tails and limbs, aves like birds can regenerate beaks and mammals like man and dog can regenerate (repair) skin, kidney, liver, etc. Therefore, from the options given in the question, A. Dog and D. Man are mammals which have the least power of regeneration, C. Pigeon has higher power than the mammals but still lower than option B. Lizard, making B the correct answer.
Thus, the right option is B.

Note:- The two mechanisms of regeneration are morphallaxis (restorative) and epimorphosis (reparative) of which the latter is employed by vertebrates.