📙 Biology | Chapter 1: Cell – The Unit of Life
EasyMyLearning

🎯 In this chapter, you’ll learn:

  • Cell and Cell Theory
  • Structure of Cell
  • Prokaryotic and Eukaryotic Cell
  • Cell Division

🧬 Topic 1: Cell and Cell Theory

Active Recall

1. What is the basic unit of life in all living organisms?

  • a) Tissue
  • b) Organ
  • c) Cell
  • d) Organ System

Answer: c) Cell – The cell is the basic structural and functional unit of life.

2. Which of the following statement is NOT a part of cell theory?

  • a) All living organisms are made up of cells.
  • b) Cells are the basic structural and functional units of life.
  • c) All cells arise from pre-existing cells.
  • d) Cells can spontaneously generate from non-living matter.

Answer: d) Cells can spontaneously generate from non-living matter – According to cell theory, new cells arise only from pre-existing cells.

🧬 What is a Cell?

Definition:

A cell is the basic structural, functional, and biological unit of all living organisms. It is the smallest part of the body capable of performing all life activities such as nutrition, respiration, and reproduction.

Flow Concept

Cell→Tissue→Organ→Organ System→Organism

Key Points

  • All living things are made up of cells, the smallest and most basic units of life.
  • A cell can live and perform all necessary tasks independently.
  • It is called the structural, functional, and biological unit of life.
  • A cell performs all vital functions of life such as nutrition, respiration, and excretion.
  • The discovery of the cell was possible due to the invention of the microscope.

🧑‍🔬 Contributions of Scientists

Scientist Contribution Year
Robert Hooke First observed and named cells in cork (dead cells). He discovered dead cells while observing a thin slice of cork under a microscope and called them “cells” because they looked like small rooms or compartments. 1665
Anton van Leeuwenhoek First observed living cells, including bacteria, protozoa, and sperm cells. He called them “animalcules.” 1674
Matthias Schleiden Proposed that plants are made of cells. 1838
Theodor Schwann Proposed that animals are made of cells. 1839
Rudolf Virchow Stated that new cells arise from pre‑existing cells. 1858

🔬 Cell Theory

Proposed by: Matthias Schleiden and Theodor Schwann (1839)

Modified by: Rudolf Virchow (1858)

Main Postulates

  • All living things are made up of one or more cells.
  • The cell is the basic unit of structure and function in all living things.
  • New cells arise from pre‑existing cells.

Remember: Cells arise from pre‑existing cells. This idea completed the cell theory and became the foundation of modern biology.

📦 Fact Box

Cell theory forms the foundation of modern biology.

Every cell works like a tiny living factory — performing all the functions needed to keep an organism alive.

⚙️ Functions of a Cell

  • Nutrition: The cell takes in food and nutrients necessary for energy and growth.
  • Respiration: The process of breaking down food to release energy in the form of ATP.
  • Excretion: Removal of metabolic waste and toxic substances produced within the cell.
  • Transport: Movement of materials (like water, ions, and nutrients) inside the cell and between organelles.
  • Reproduction: The cell divides to form new cells, ensuring growth, repair, and continuity of life.

🧠 MCQs – Topic 1: Cell and Cell Theory

Click on Below button to practice MCQs Set of Cell and Cell Theory.

Practice Set: Cell and Cell Theory
⬇