SS1: BIOLOGY - 1ST TERM
Introduction to Biology | Week 16 Topics|1 Quiz
Recognizing Living Things | Week 23 Topics|1 Quiz
Organisation of Life | Week 33 Topics
Classification of Living Organisms | Week 47 Topics|1 Quiz
Kingdom Prokaryotae / Monera & Kingdom Protista | Week 53 Topics|3 Quizzes
Kingdom Fungi & Kingdom Plantae | Week 69 Topics|2 Quizzes
Kingdom Animalia I | Week 76 Topics|1 Quiz
Kingdom Animalia II | Week 85 Topics|1 Quiz
The Cell | Week 93 Topics|1 Quiz
The Cell Structure and Functions | Week 104 Topics|1 Quiz
The Cell and its Environment | Week 114 Topics|1 Quiz
Nutrition in Plants | Week 124 Topics|1 Quiz
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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) Rudulf 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 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.