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Questions and Answers
What is the function of cell organelles in a cell?
What is the function of cell organelles in a cell?
What is the basic unit of life that consists of organelles?
What is the basic unit of life that consists of organelles?
What is the process by which substances move across the cell membrane?
What is the process by which substances move across the cell membrane?
Why do substances move from a region of high concentration to a region of low concentration?
Why do substances move from a region of high concentration to a region of low concentration?
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What is the term used to describe the cell membrane's ability to control what enters and leaves the cell?
What is the term used to describe the cell membrane's ability to control what enters and leaves the cell?
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What happens to the substance when it accumulates in high concentrations inside the cell?
What happens to the substance when it accumulates in high concentrations inside the cell?
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What is the term used to describe the organization of cells into different components, each with a specific function?
What is the term used to describe the organization of cells into different components, each with a specific function?
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What is the function of all cells, regardless of their function or organism they are found in?
What is the function of all cells, regardless of their function or organism they are found in?
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What is the primary function of the cell membrane's flexibility?
What is the primary function of the cell membrane's flexibility?
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What is the direction of water movement during osmosis in a hypotonic environment?
What is the direction of water movement during osmosis in a hypotonic environment?
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Why do plant, fungi, and bacterial cells not burst in hypotonic media?
Why do plant, fungi, and bacterial cells not burst in hypotonic media?
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What is the process by which Amoeba acquires its food?
What is the process by which Amoeba acquires its food?
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What is the term for the movement of water into a cell through a selectively permeable membrane?
What is the term for the movement of water into a cell through a selectively permeable membrane?
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What is the function of the electron microscope in understanding the structure of the plasma membrane?
What is the function of the electron microscope in understanding the structure of the plasma membrane?
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What is the result of osmosis in a cell placed in a hypotonic environment?
What is the result of osmosis in a cell placed in a hypotonic environment?
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What is the direction of water movement in a living cell, compared to a dead cell?
What is the direction of water movement in a living cell, compared to a dead cell?
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Who discovered the nucleus in the cell?
Who discovered the nucleus in the cell?
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What is the term coined by Purkinje in 1839?
What is the term coined by Purkinje in 1839?
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Who are the two biologists who presented the cell theory?
Who are the two biologists who presented the cell theory?
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What was observed by Leeuwenhoek in 1674?
What was observed by Leeuwenhoek in 1674?
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What was made possible by the discovery of the electron microscope in 1940?
What was made possible by the discovery of the electron microscope in 1940?
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Who expanded the cell theory by suggesting that all cells arise from pre-existing cells?
Who expanded the cell theory by suggesting that all cells arise from pre-existing cells?
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What is depicted in the picture shown?
What is depicted in the picture shown?
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What was observed by Robert Hooke with the help of a primitive microscope?
What was observed by Robert Hooke with the help of a primitive microscope?
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Study Notes
Cell Structure and Function
- The cell membrane is selectively permeable, allowing certain substances to pass through while restricting others.
- The cell membrane allows substances like carbon dioxide and oxygen to move across it through diffusion.
- Water can cross the cell membrane in both directions, but in a process called osmosis, more water leaves the cell than enters it, causing the cell to shrink.
Cellular Organelles and Division of Labour
- Each cell has specific components called organelles, which perform special functions.
- Examples of organelles include ones that make new material, clear waste, and perform other functions.
- All cells have the same organelles, regardless of their function or the organism they are found in.
Cell Membrane Flexibility
- The flexibility of the cell membrane enables the cell to engulf food and other materials from its external environment through a process called endocytosis.
- Amoeba acquires its food through endocytosis.
Osmosis and Cell Size
- Osmosis is a special case of diffusion through a selectively permeable membrane.
- Living cells can absorb water by osmosis, but dead cells cannot.
- Cell walls in plants, fungi, and bacteria allow cells to withstand very dilute external media without bursting.
Cell Discovery and Theory
- Antonie van Leeuwenhoek discovered free living cells in pond water in 1674 using a primitive microscope.
- Robert Brown discovered the nucleus in 1831.
- The cell theory, which states that all plants and animals are composed of cells and that the cell is the basic unit of life, was presented by Schleiden (1838) and Schwann (1839).
- The cell theory was further expanded by Virchow (1855) by suggesting that all cells arise from pre-existing cells.
Electron Microscope and Cell Structure
- The discovery of the electron microscope in 1940 allowed for the observation and understanding of the complex structure of the cell and its various organelles.
- The structure of the plasma membrane can only be observed through an electron microscope.
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Description
Learn about the cell membrane's selective permeability, how substances pass through it, and the role of osmosis in cell function.
