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Questions and Answers
Who is credited with discovering the nucleus of a cell?
Who is credited with discovering the nucleus of a cell?
What is the fundamental structural and functional unit of all living organisms?
What is the fundamental structural and functional unit of all living organisms?
Which scientist first saw and described a live cell?
Which scientist first saw and described a live cell?
Who reported that cells had a thin outer layer known today as the 'plasma membrane'?
Who reported that cells had a thin outer layer known today as the 'plasma membrane'?
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What characteristic ensures independent living for unicellular organisms?
What characteristic ensures independent living for unicellular organisms?
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What did Rudolf Virchow contribute to the cell theory?
What did Rudolf Virchow contribute to the cell theory?
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What is the main arena of cellular activities in both plant and animal cells?
What is the main arena of cellular activities in both plant and animal cells?
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Which type of cells contain membrane-bound organelles like endoplasmic reticulum and golgi complex?
Which type of cells contain membrane-bound organelles like endoplasmic reticulum and golgi complex?
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What is the function of ribosomes within a cell?
What is the function of ribosomes within a cell?
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Which organelle found in animal cells helps in cell division?
Which organelle found in animal cells helps in cell division?
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Study Notes
Characteristics of Living Organisms
- The presence of cells is the basic unit of life that distinguishes living organisms from non-living things.
- All organisms, whether unicellular or multicellular, are composed of cells.
Unicellular Organisms
- Unicellular organisms are capable of independent existence and performing essential functions of life.
- Anything less than a complete cell structure does not ensure independent living.
Cell Theory
- In 1838, Matthias Schleiden observed that all plants are composed of different kinds of cells that form tissues.
- Theodore Schwann, in 1839, studied animal cells and reported that cells have a thin outer layer called the plasma membrane.
- Schwann proposed that bodies of animals and plants are composed of cells and products of cells.
- Rudolf Virchow, in 1855, explained that cells divide and new cells are formed from pre-existing cells (Omnis cellula-e cellula).
- The cell theory states that all living organisms are composed of cells and products of cells, and all cells arise from pre-existing cells.
Cell Structure
- Plant cells have a distinct cell wall as their outer boundary and a cell membrane just within it.
- Animal cells have an outer membrane as the delimiting structure of the cell.
- Cells have a dense membrane-bound structure called the nucleus, which contains chromosomes and genetic material (DNA).
- Cells have a semi-fluid matrix called cytoplasm, which is the main arena of cellular activities.
- Eukaryotic cells have membrane-bound organelles like the endoplasmic reticulum (ER), golgi complex, lysosomes, mitochondria, microbodies, and vacuoles.
- Prokaryotic cells lack membrane-bound organelles.
- Ribosomes are non-membrane bound organelles found in all cells.
- Cells differ greatly in size, shape, and activities.
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Description
Test your knowledge about the basic unit of life - the cell. This quiz covers topics such as unicellular and multicellular organisms, cell structure, and cell functions.
