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Biology · Grades 5–8

Cells and their components

Match structures to functions without implying every cell is identical.

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Learn the idea

Cell

Cells are basic structural and functional units of living organisms.

Membrane

A cell membrane helps regulate exchange with the surroundings.

Nucleus

A typical eukaryotic nucleus contains most of the cell’s DNA; prokaryotes lack a membrane-bound nucleus.

Organelles

Mitochondria, chloroplasts and vacuoles have different roles and are not found in the same form in every cell.

Worked examples

Which structure forms a selective boundary around a cell?

The membrane regulates exchange with the surroundings.

Cell membrane.

Which organelle is a site of photosynthesis in many plant cells?

Chloroplasts contain photosynthetic machinery.

Chloroplast.

Check your understanding

  1. Do all cells have a membrane-bound nucleus?

    1. Only all bacteria do.
    2. No; prokaryotic cells do not.
    3. Yes, without exceptions.

  2. A model tissue has 5 equal rows of 6 cells. How many cells are modeled?

  3. Why is a cell drawing a model rather than a literal picture of every cell?

Answers and marking notes

Answers and marking notes
  1. No; prokaryotic cells do not.

    A membrane-bound nucleus is a eukaryotic feature.

  2. 30

    5 × 6 = 30.

  3. Cell types differ, and diagrams simplify scale, shape and contents.

    State a relevant limitation.

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.