Cells
Cell Structure and Function
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All living organisms are composed of basic building blocks known as cells.
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Cells can be categorised into prokaryotic cells (like bacteria) and eukaryotic cells (like plant and animal cells).
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A typical eukaryotic cell comprises a nucleus which controls cell activities and contains the genetic material, DNA.
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Cells also contain cytoplasm - a gel-like substance where most of the cell's metabolism occurs.
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The cell membrane surrounds the cell providing a barrier between the internal cell environment and the outside world.
Specialised Cells
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Some cells become specialised for specific functions. For example, sperm cells in males are specialised for reproduction.
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Specialisation in plant cells could lead to forms such as root hair cells or xylem cells.
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Stem cells have the potential to turn into any type of cell that the body needs.
Microscopy
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Microscopes are essential tools in biology, allowing us to observe cells and their components, which are too small to see with the naked eye.
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Light microscopes are commonly used in schools and can magnify objects up to about 2000 times.
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Electron microscopes can magnify objects up to about 2 million times, providing a high-resolution image of the cell's ultrastructure.
Diffusion
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Diffusion is a process by which molecules move from an area of high concentration to an area of low concentration.
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It's a crucial process in biology, enabling nutrients and waste materials to enter and leave cells.
Osmosis
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Osmosis is a specific type of diffusion involving the movement of water molecules across a partially permeable membrane.
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It's important for the movement of water into and out of cells in plants and animals, impacting cell turgidity and therefore shape and function.
Active Transport
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Active transport is the process by which substances move against a concentration gradient, from a low-concentration area to a high-concentration one.
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It requires energy from the cell and is important for processes like nutrient uptake in plant roots.