Question

Auxetic growth is characterized by
A) Increase in cell number
B) Growth without increase in cell number
C) Both increase in cell number and cell growth
D) Expansion in transverse direction

Answer 1

Hint: Growth occurs due to enlargement of cells. It occurs in nematodes, rotifers, and tunicates. Different kinds of growth are present and they are auxetic growth, multiplicative growth, accretionary growth, and appositional growth.

Complete Answer:
- Auxetic growth was observed in certain tissues of higher animals, such as muscles, as well as in certain organisms, such as tunicates, nematodes, and rotifers.
- Without any cell division, an auxetic substance will tend to increase cell growth in plant physiology. Auxins are auxetic hormones from plants.

Now, let us find the solution from the options-
- Instead of increasing the number of cells, Auxetic growth or Auxesis refers to the growth of tissue from an increase in cell size i.e., by increasing intracellular mass and volume.
- Growth occurs in some organisms as a result of an increase in the size of their cells.
- The number of cells remains the same.
- Because of the expansion of its cells, the body grows in size.

Thus, the correct answer is option (B) Growth without increase in cell number.

Note: In auxetic growth, the body grows due to enlargement of cells not by increasing cell number. In multiplicative growth, growth occurs due to increase in cell numbers, e.g., embryo. In accretionary growth, cell division power is lost in post embryonic development. Reserve cells present at some locations, divide, and new cells are produced to substitute the worm out cells, eg. Stratum malpighi. Appositional growth involves the addition of new layers to the layers previously created. E.g., cell wall