Cell as Basic Unit of Life MCQs Quiz | Class 9
Test your understanding of Class IX Science (Code 086), Unit II: Organization in the Living World. This quiz focuses on the topic “Cell as Basic Unit of Life”, covering concepts such as the cell as a structural unit, variety in cells, and the cell as a functional unit. Complete the 10 MCQs below to evaluate your knowledge and download the PDF answer sheet for revision.
Overview: Cell as the Fundamental Unit
The cell is defined as the fundamental structural and functional unit of all living organisms. It was first discovered by Robert Hooke in 1665 using a primitive microscope. Later, Leeuwenhoek discovered free-living cells in pond water. The invention of the electron microscope revealed the complex structure of the cell and its various organelles.
Key Milestones in Cell Biology
| Scientist | Discovery/Contribution |
|---|---|
| Robert Hooke (1665) | Discovered cells in cork slices. |
| Leeuwenhoek (1674) | Discovered free-living cells in pond water. |
| Robert Brown (1831) | Discovered the nucleus. |
| Purkinje (1839) | Coined the term ‘Protoplasm’. |
| Schleiden & Schwann (1838-39) | Proposed the Cell Theory. |
| Virchow (1855) | Expanded Cell Theory: “Omnis cellula-e cellula”. |
Variety in Cells
Cells vary greatly in number, shape, and size depending on the function they perform.
- Number: Organisms can be Unicellular (Amoeba, Chlamydomonas, Paramecium) or Multicellular (Fungi, Plants, Animals).
- Shape: Shapes are related to specific functions. For example, nerve cells are long to conduct impulses, while Amoeba has an irregular shape to move and engulf food via pseudopodia.
- Size: Cells vary from microscopic bacteria to large eggs (like the ostrich egg).
Cell as a Functional Unit
Every living cell has the capacity to perform certain basic functions that characterize living forms. In multicellular organisms, there is a “division of labour” where specific tissues perform specific tasks (e.g., heart pumps blood, stomach digests food). Even within a single cell, there is a division of labour, as specific organelles perform specific functions like making new material, clearing waste, or generating energy.
Practice Questions
- What is the chemical substance of the cell wall in plants?
- Name the smallest cell in the human body.
- Why are viruses an exception to the cell theory?
- What is the function of the nerve cell’s long structure?
- Define “division of labour” in the context of a single cell.
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