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NCERT Solutions for Class 8th Science Chapter 2 In-text Questions — Variation in shape and structure of cells

Book page 13 Updated on2026-09-19

Q1.
Do different animal cells also vary in their shape and structure?
Answer

Yes. Even within one animal — even within one human body — cells differ widely in shape, size and structure.

  • A muscle cell is shaped like a spindle — thick in the middle and tapering at both ends (Fig. 2.6a).
  • A nerve cell is very long and has branches (Fig. 2.6b).
  • Cheek cells, which you saw in Activity 2.3, are thin and flat and polygon-shaped.
  • Some cells are round; others are long and thin.

The number of cells also varies from organism to organism — from a single cell in a bacterium or Amoeba to countless cells in a tree or a human being.

Why they vary: because they do different jobs. The unique shape, size and structure of a cell help it carry out its own specific function — a point the next two questions take further.
Q2.
The muscle cell and the nerve cell of a human are shown in Fig. 2.6a and (b). What are the similarities and differences you see in them?
(a) Muscle cell(b) Nerve cell
Fig. 2.6: Different types of cells in humans.
Answer

Both are animal cells built on the same plan; they differ almost entirely in shape.

Muscle cell (Fig. 2.6a)Nerve cell (Fig. 2.6b)
Basic partsCell membrane, cytoplasm, nucleusCell membrane, cytoplasm, nucleus
Cell wall / chloroplastAbsent (it is an animal cell)Absent (it is an animal cell)
ShapeSpindle-shaped — thick in the middle, pointed at both endsVery long, with many branches at the ends
PropertyThin and flexible, so it can shorten and lengthenElongated and branched, so it can reach far
FunctionContracts and relaxes to produce movementCarries messages from one part of the body to another
Tip: the nerve cell is also called a neuron. Its branches are what let one cell touch many others, so a message can spread quickly through the body.
Q3.
Why do cells look so different from each other? Does the shape and structure of a cell relate to its function?
Answer

Yes — a cell's shape and structure are directly related to the work it has to do. The unique shape, size and structure of cells help them carry out their specific functions.

CellIts shapeThe function that shape makes possible
Inner cheek cellThin and flatForms a smooth protective lining on the inner surface of the cheek
Nerve cell (neuron)Elongated and branchedReaches different parts of the body and passes on messages quickly
Muscle cell of the food pipeThin, flexible, spindle-shapedContracts and relaxes in a wave-like manner, pushing food down to the stomach
Onion peel cellNearly rectangular, with a cell wallPacks compactly to make a firm protective layer
Certain plant cellsLong and tube-likeJoin end to end to form tubes that carry water throughout the plant
Why it happens: a shape is useful only for a particular kind of job. A message has to travel a long distance, so the cell that carries it is drawn out into a long thread with branches at the ends. A lining must cover an area without gaps, so its cells are flat and broad. A cell that has to pull must be able to shorten, so it is slender and flexible. Change the shape and the cell could no longer do its work — which is why cells that do the same job look alike wherever you find them.
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