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SS1: BIOLOGY - 1ST TERM
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Introduction to Biology | Week 17 Topics|2 Quizzes
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Recognizing Living Things | Week 23 Topics|1 Quiz
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Organisation of Life | Week 33 Topics|2 Quizzes
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Classification of Living Organisms | Week 46 Topics|2 Quizzes
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Kingdom Prokaryotae / Monera & Kingdom Protista | Week 54 Topics|3 Quizzes
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Kingdom Fungi & Kingdom Plantae | Week 610 Topics|2 Quizzes
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Kingdom Animalia I | Week 77 Topics|1 Quiz
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Kingdom Animalia II | Week 86 Topics|2 Quizzes
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The Cell | Week 94 Topics|1 Quiz
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The Cell Structure and Functions | Week 105 Topics|1 Quiz
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The Cell and its Environment | Week 115 Topics|1 Quiz
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Nutrition in Plants | Week 125 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.
- EnergyEnergy is the ability to do work. Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy. Units of Energy: The SI unit... More flow (metabolismMetabolism is the sum of the chemical reactions that take place within each cell of a living organism and that provide energy for vital processes and for synthesizing new organic material.... More and biochemistry) occurs within cells.