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NCERT Solutions for Class 9th Science Chapter 3 .2.3 Intercalary meristem; characteristics of meristematic tissue — In-text Questions

Book page 313 Updated on2026-09-08

Q1.
What do you think happens to the growth of the plant if the tip of a young stem is cut?
Answer

The stem stops growing in length, but the plant does not stop growing — new branches come out from the nodes (Fig. 3.5).

Read it as two separate meristems being affected differently:

  • The shoot apical meristem is at the tip. Cut it off and there is nothing left to add cells to the top, so height stops increasing.
  • The intercalary meristem, at the base of the internode just above the node, is untouched. It goes on dividing, so lateral buds at the nodes sprout into new branches.
Why gardeners use this: when a hedge is trimmed, every cut shoot loses its apex and pushes out several side branches instead of one long one. Many branches close together is exactly what makes a hedge look bushy. Grass behaves the same way after mowing or grazing (Fig. 3.6): its intercalary meristem sits low down at the nodes, below the level of a grazing animal's mouth, so the blade regrows from the base.
Try This: pinch off the growing tip of a tulsi or coriander plant at home and watch for a week. You will get a shorter, bushier plant with more leaves — the same trick, called pinching or pruning.
Q2.
Why do you think that the cell of meristematic tissues lack vacuoles?
Answer

Because a large vacuole would take up the space and the resources that a rapidly dividing cell needs for dividing.

  • A big central vacuole is mostly water; it pushes the cytoplasm into a thin layer against the wall. A meristematic cell instead keeps its cytoplasm dense and full of organelles — ribosomes, mitochondria, ER — because it must constantly build new proteins, new membranes and new cell walls.
  • Division needs energy. The mitochondria supplying that energy must sit in cytoplasm, not be squeezed out by a vacuole.
  • A vacuole makes a cell large. Meristematic cells stay small, so the nucleus is large relative to the cytoplasm and can control the cell easily through repeated divisions.
Why it happens: a vacuole is a storage and support structure — useful in a permanent cell that has finished dividing and now stores food or keeps the cell turgid. Vacuoles therefore appear later, when a meristematic cell differentiates into parenchyma. Being vacuole-free is not an accident; it is part of the same package as thin walls, dense cytoplasm, a large nucleus and no intercellular space — all of it built for continuous, rapid division.
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