medium importancemedium difficulty5 min

Cell Growth and Division

Cell growth and division describe how a cell increases in size, prepares its contents, and divides to form new cells.

In one line: Cells divide to stay small enough to work well.

Understand it

A cell cannot simply grow indefinitely because its surface area does not keep up with its volume. A very large cell faces difficulty in exchange of materials and control. Therefore, cells grow, copy their genetic material, prepare for division, and then divide to support growth, repair, and replacement.

Example

A wound heals because nearby cells divide and replace damaged cells.

Rule to remember

As cell size increases, volume increases faster than surface area, making exchange of materials less efficient.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

During body growth, one fertilised egg divides repeatedly to form many cells, and those cells later specialise for different tissues.

Method you can reuse

State the problem of excessive cell size, mention exchange and control difficulty, then explain that division restores efficient cell size and increases cell number.

Sketch it in your answer

Show a simple cell cycle flow: growth, DNA copying, preparation, and division into two cells.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why does a cell divide instead of growing endlessly?

Think first, then show answer

A cell divides instead of growing endlessly because a very large cell cannot exchange materials efficiently or control all its activities properly.

Common wrong answer

Writing that a cell divides only when it becomes old is incomplete because division also supports growth and repair.

Don't mix this up

Students often think cell division happens only for reproduction, but it is also needed for growth and repair in multicellular organisms.

Exam tip

When asked why cells divide, mention surface-area-to-volume limitation and the need for growth or repair.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Questions may ask why division is needed for growth, repair, replacement of worn-out cells, or maintaining cell size.

1
Enough for 1 mark
Cell growth and division describe how a cell increases in size, prepares its contents, and divides to form new cells.
2
Add for 2 marks
Example: A wound heals because nearby cells divide and replace damaged cells.
3
Add for 3 marks
A cell cannot simply grow indefinitely because its surface area does not keep up with its volume.

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