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SS1: BIOLOGY - 1ST TERM

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  1. Introduction to Biology | Week 1
    7 Topics
    |
    2 Quizzes
  2. Recognizing Living Things | Week 2
    3 Topics
    |
    1 Quiz
  3. Organisation of Life | Week 3
    3 Topics
    |
    2 Quizzes
  4. Classification of Living Organisms | Week 4
    6 Topics
    |
    2 Quizzes
  5. Kingdom Prokaryotae / Monera & Kingdom Protista | Week 5
    4 Topics
    |
    3 Quizzes
  6. Kingdom Fungi & Kingdom Plantae | Week 6
    10 Topics
    |
    2 Quizzes
  7. Kingdom Animalia I | Week 7
    7 Topics
    |
    1 Quiz
  8. Kingdom Animalia II | Week 8
    6 Topics
    |
    2 Quizzes
  9. The Cell | Week 9
    4 Topics
    |
    1 Quiz
  10. The Cell Structure and Functions | Week 10
    5 Topics
    |
    1 Quiz
  11. The Cell and its Environment | Week 11
    5 Topics
    |
    1 Quiz
  12. Nutrition in Plants | Week 12
    5 Topics
    |
    1 Quiz
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Lesson 9, Topic 3
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Cell Theory

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Topic Content:

  • Contributions to the Cell Theory (History of cells)
  • Cell Theory

Contributions to the Cell Theory (History of cells):

(i) Robert Hooke (An English Botanist) 1665:

In a 1665 publication called Micrographia, Robert Hooke coined the term “cell” for the box-like structures he observed when viewing cork tissue through a lens.

(ii) Felix Dujardin (French Biologist) 1835:

  • He discovered that cells are made up of living substances which he named protoplasm.

(iii) Matthias Schleiden (German Botanist) 1838:

  • He revealed that the bodies of plants are made up of cells. He defined the cell as the basic unit of plant structure.

(iv) Theodore Schwann 1839 – (German Zoologist):

  • All animals’ bodies are composed of cells. He defined the cell as the basic unit of animal structure.
  • The discoveries of Schleiden and Schwann led to the formulation of cell theory.

(v) Rudolf Virchow (German Biologist) 1855:

  • He concluded in his research that all cells only arise from pre-existing cells. This led to bio-genesis.
  • The biologist also realized that cells are not only the structural but also the functional unit of life of living organisms.

The Cell theory states that:

i. The cell is the fundamental unit of structure and function in living things.

ii. All organisms are made up of one or more cells.

iii. All cells arise from pre-existing cells through cellular division.

The expanded version of cell theory can also include;

  • Cells carry genetic material passed to daughter cells during cellular division.
  • All cells are essentially the same in chemical composition.
  • Energy flow (metabolism and biochemistry) occurs within cells.