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NCERT Solutions for Class 9th Science Chapter 2 In-text Question — The Cell Interior

Book page 15 Updated on2026-09-19

Q1.

Which of the cells given in Fig. 2.10 fall under the categories of prokayotic and eukaryotic cells?

Appendage for locomotionCytoplasmNucleoid (Genetic material)RibosomeCell wall(a)VacuoleChloroplastGolgi bodyCell wallRibosomeCell membraneNucleusNucleolusEndoplasmic reticulumMitochondriaCytoplasm(b)NucleusNucleolusEndoplasmic reticulumMitochondriaCell membraneLysosomeVacuoleGolgi bodyRibosomeCytoplasm(c)
Fig. 2.10 — (a) a typical bacterial cell, (b) a typical plant cell, and (c) a typical animal cell.
Answer

The bacterial cell (Fig. 2.10a) is prokaryotic. The plant cell (Fig. 2.10b) and the animal cell (Fig. 2.10c) are eukaryotic.

pro = primitive, karyon = nucleus → prokaryotic = primitive nucleus
eu = true, karyon = nucleus → eukaryotic = true nucleus

What you can actually see in the figure that settles it:

  • Fig. 2.10a shows a nucleoid — genetic material lying naked in the cytoplasm — with ribosomes scattered around and an appendage for locomotion. There is no nuclear membrane and no organelle bounded by its own membrane.
  • Fig. 2.10b and 2.10c both show a nucleus with a nucleolus inside a nuclear membrane, together with mitochondria, endoplasmic reticulum, Golgi body, lysosome and vacuole — every one of them membrane-bound.
CharacteristicProkaryotic cellEukaryotic cell
Diameter of a typical cell1 to 10 µm10 to 100 µm
Membrane-bound nucleusAbsentPresent
Membrane-bound organellesAbsentPresent
Number of cells in an organismUsually unicellularCan be unicellular or multicellular
Why it happens: internal membranes are what make a eukaryotic cell possible. They divide the cell into rooms, so incompatible reactions can run side by side at the same time — digestive enzymes stay sealed in lysosomes instead of dissolving the cell, energy release is confined to mitochondria, protein processing to the ER and Golgi. A prokaryote has one open compartment, so all its chemistry must share a single space; that is one reason it stays small. The size figures follow from the same logic: 1–10 µm against 10–100 µm is a tenfold difference in length, which is a thousandfold difference in volume.
Note on Table 2.2: the book's first row reads “Primitive nucleus — Present in prokaryotic, Absent in eukaryotic”. Read it as “primitive nucleus (nucleoid)”, which is indeed present only in prokaryotic cells; the last two rows then correctly say that a membrane-bound nucleus is present only in eukaryotic cells.
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