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Tamil Nadu (TNBSE)Class 6 Science★ 6-10 marks in the TN Class 6 Term 2 exam through book-back MCQs, fill-ups and short answers

The Cell

Samacheer Kalvi (TN State Board) Class 6 Science — Term 2 Chapter 5, The Cell. The cell as the basic unit of life, Robert Hooke and the microscope (Micrographia, 1665), the parts of a cell (cell membrane, cytoplasm, nucleus), prokaryotic and eukaryotic cells, and the difference between plant and animal cells, with the actual book-back questions, common mistakes and quick revision.

⏱ 14 min readEasy difficulty✓ Free · NCERT-aligned

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Study Guide

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Key points, glossary and the questions most likely to show up.

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By the end of this chapter you'll be able to…

1State that the cell is the basic unit of life
2Recall Robert Hooke and Micrographia
3Name the parts of a cell
4Differentiate prokaryotic and eukaryotic cells
5Differentiate plant and animal cells

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Why this chapter matters

The Cell introduces the basic unit of all life and the microscope that revealed it. Robert Hooke, the nucleus and the prokaryotic/eukaryotic difference are directly tested book-back content in the TN Class 6 Term 2 exam.

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A 5-minute refresher here will save you 30 minutes of confusion below.

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Chapter 4 — The World of Plants

Living things.

The Cell — Class 6 Science (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 6 Science, Term 2 — Chapter 5. The building block of all living things.

1. About this chapter

This chapter covers the discovery of the cell, the microscope, the parts of a cell, prokaryotic and eukaryotic cells, and the plant vs animal cell.

2. Discovery and size of the cell

The cell is the basic unit of life. Its size is measured in micrometres (µm).
Robert Hooke improved the microscope and built a compound microscope; he published a book called Micrographia in 1665, in which he first used the word "cell."

3. Parts of a cell

A cell has three main parts: the cell membrane (outer covering), the cytoplasm (jelly-like fluid), and the nucleus.
The nucleus is the "control centre" of a eukaryotic cell.

4. Types of cells

Prokaryotic cells have no true (distinct) nucleus — e.g. bacteria.
Eukaryotic cells have a true, distinct nucleus — plant and animal cells.
A cell that has both a cell wall and a distinct nucleus is a plant cell (a plant cell has a cell wall, a large vacuole and chloroplasts; an animal cell has none of these).

5. Worked examples

Example 1. Who first used the word "cell"? Robert Hooke (in Micrographia, 1665).

Example 2. What is the control centre of a eukaryotic cell? The nucleus.

Example 3. In what unit is the size of a cell measured? The micrometre (µm).

6. Book-back questions (Samacheer Kalvi)

I. Choose the correct answer

The unit used to express the size of a cell is the — (a) metre / (b) micrometre. Ans: (b) micrometre.
The control centre of a eukaryotic cell is the — (a) nucleus / (b) cytoplasm. Ans: (a) nucleus.
A cell with a cell wall and a distinct nucleus is a — (a) bacterial cell / (b) plant cell. Ans: (b) plant cell.

II. Fill in the blanks 4. The word "cell" was first used by Robert Hooke. 5. Robert Hooke published the book Micrographia in 1665. 6. A cell that has no true nucleus is a prokaryotic cell.

III. Answer briefly 7. What is a cell? — The basic unit of life. 8. Differentiate prokaryotic and eukaryotic cells. — A prokaryotic cell has no distinct nucleus (bacteria); a eukaryotic cell has a true nucleus (plants, animals). 9. Give one difference between a plant cell and an animal cell. — A plant cell has a cell wall and chloroplasts; an animal cell does not.

7. Common mistakes

Mistake: Saying bacteria have a distinct nucleus. Fix: Bacteria are prokaryotic — they have no distinct nucleus.
Mistake: Calling the cytoplasm the control centre. Fix: The nucleus is the control centre.
Mistake: Measuring cell size in millimetres. Fix: Cell size is measured in micrometres (µm).

8. Quick revision

Term 2 · Ch 5 · the cell.
Cell = basic unit of life; size in micrometres; Robert Hooke first used "cell" (Micrographia, 1665).
Parts: cell membrane, cytoplasm, nucleus (the control centre).
Prokaryotic (no distinct nucleus: bacteria) vs eukaryotic (true nucleus); plant cell has a cell wall + chloroplasts, animal cell does not.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Cell

basic unit of life; size in micrometres

Seen under a microscope.

Discovery

Robert Hooke; Micrographia (1665); coined 'cell'

Compound microscope.

Parts

cell membrane, cytoplasm, nucleus (control centre)

Three main parts.

Cell types

prokaryotic (no distinct nucleus) vs eukaryotic (true nucleus)

Bacteria vs plant/animal.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Saying bacteria have a distinct nucleus

✓ Bacteria are prokaryotic — they have no distinct nucleus.

WATCH OUT

✗ Calling the cytoplasm the control centre

✓ The nucleus is the control centre.

WATCH OUT

✗ Measuring cell size in millimetres

✓ Cell size is measured in micrometres (µm).

NCERT exercises (with solutions)

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Choose the correct answer

Book-back MCQs on the micrometre, the nucleus and the plant cell.

Questions

Fill in the blanks

Robert Hooke, Micrographia and prokaryotic cells.

Questions

Answer briefly

Definition, cell types and plant vs animal cell.

Questions

Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· MCQ

The unit used to express the size of a cell is the ____.

▶ Show solution

micrometre (µm).

Q2EASY· MCQ

The control centre of a eukaryotic cell is the ____.

▶ Show solution

nucleus.

Q3EASY· Fill in the blanks

The word 'cell' was first used by ____.

▶ Show solution

Robert Hooke.

Q4EASY· MCQ

A cell with a cell wall and a distinct nucleus is a ____.

▶ Show solution

plant cell.

Q5MEDIUM· Answer briefly

Differentiate prokaryotic and eukaryotic cells.

▶ Show solution

A prokaryotic cell has no true (distinct) nucleus, as in bacteria, while a eukaryotic cell has a true, distinct nucleus, as in plant and animal cells.

Q6EASY· Answer briefly

Give one difference between a plant cell and an animal cell.

▶ Show solution

A plant cell has a cell wall and chloroplasts, while an animal cell does not.

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Term 2 Chapter 5 of Samacheer Kalvi Class 6 Science.
•The cell is the basic unit of life; its size is measured in micrometres.
•Robert Hooke built a compound microscope and first used the word 'cell' in Micrographia (1665).
•A cell has a cell membrane, cytoplasm and a nucleus (the control centre).
•Prokaryotic cells (bacteria) have no distinct nucleus; eukaryotic cells have a true nucleus.
•A plant cell has a cell wall and chloroplasts; an animal cell does not.

Tamil Nadu (TNBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 6-10 marks across book-back MCQ, fill-ups and short answers

Question type	Marks each	Typical count	What it tests
MCQ / Fill	1	4-6	Cell size, nucleus, Hooke
Short Answer	2	1-2	Cell types; plant vs animal

Prep strategy

Remember Robert Hooke and Micrographia (1665)
Name the nucleus as the control centre
Separate prokaryotic and eukaryotic cells
List plant-only parts

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Biology

Cells are the foundation of all life science.

Medicine

Studying cells helps understand disease.

Microscopy

The microscope reveals the unseen living world.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

Quote Robert Hooke and Micrographia (1665)
Name the nucleus as the control centre
Use micrometre for cell size
Separate prokaryotic and eukaryotic cells

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

Draw and label the parts of a generalised cell.
Explain why the microscope was essential to discovering cells.

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

TN Class 6 Term 2 ExamHigh

NMMS / Foundation ScienceMedium

School unit testsHigh

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Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

Because every living thing is made of one or more cells, and a cell is the smallest part that can carry out all the activities of life, so all life is built from cells.

A prokaryotic cell, like a bacterium, has no membrane-bound (distinct) nucleus, while a eukaryotic cell, like a plant or animal cell, has a true nucleus enclosed in a membrane.

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