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Cell as a Building Block
- All living things are made of cells.
- Cells build a body like bricks build a house.
- Cells are the building blocks of life.
- Amoeba is a one-celled organism.
Example 1 — A Human Being
- Our nose, skin, muscles and bones look very different.
- But all of them are made of tiny cells.
- A human body has trillions of cells working together.
Example 2 — An Amoeba
- Amoeba is one of the simplest living things.
- Its whole body is just one single cell.
- That one cell does all the work needed to stay alive.
Important Points
- "Structural unit" = builds the body; "functional unit" = does the work.
- A single Amoeba cell still does every life process on its own.
- Exam tip: the cell is both the structural and functional unit of life.
Definition — Cell (Basic Unit of Life)
The smallest unit of life which has a definite structure and does a special job.
Objective Type Questions Q2(a) - Page 34 Lakhmir Singh
Question
Fill in the blank: The smallest unit of life is a ______.
Show answer
Cell.
Explanation
- Every living body is made of cells.
- The cell is the smallest unit of life.
Multiple Choice Questions Q8 - Page 36 Lakhmir Singh
Question
A large spherical organelle present in all cells: (a) protoplasm (b) ribosome (c) mitochondria (d) nucleus
Show answer
(d) nucleus.
Explanation
- The nucleus is the large, round organelle.
- It is present in all cells.
