Question

A Planaria worm is cut horizontally in the middle into two halves P and Q such that the part P contains the whole head of the worm. Another Planaria worm is cut vertically into two halves R and s in such a way that both the cut pieces R and S contain half head each. Which of the cut pieces of the two Planaria worms could regenerate to form the complete respective worms?
(a) only P
(b) only R and S
(c) P, R and S
(d) P, Q, R and S

Answer 1

Answer:

D) P,Q,R and S

Explanation:

How many times we cut them into pieces it grows as a new complete respective worms.

Answer 2

All the cut pieces of Planaria could regenerate to form complete worms - P, Q, R, S (option - d)

• Planaria belongs to the phylum Platyhelminthes (free-living) and shows the property of regeneration.
• When the body of Planaria is cut through any plane or in any number of parts, each cut piece is capable of regenerating or producing the whole worm.
• The callus at the cut site grows outward when leading to the formation of regenerating bud or Blastula.
• Stem cells called neoblasts are distributed all over the body of Planaria which are capable of dividing and forming organs in adult worms.
• Regeneration at a particular location takes place by the mobilization of these cells.