AS Biology OCR Unit 1 , OCR, AS, Biology, Keywords

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Biology ­ Unit 1
Key Words
Magnification ­ the degree to which the size of the image is larger than the object itself
Resolution ­ the degree to which it is possible to distinguish between two objects that are very close together
Micrometre ­ equal to one millionth (10^-6) of a metre
Nanometre ­ is one thousandth (10^-3) of a micrometre. It is one thousand millionth of a metre (10^-9)
Staining ­ refers to any process that helps to reveal or distinguish different features. In light microscopes fluorescent
dyes used to stain, in electron microscopes they use metal particles or metal salts.
Cytoskeleton ­ refers to the network of protein fibres found within cells that gives structure and shape to the cell
Organelle ­ to the particular structure of a cell that has a specialised function, some membrane bound some not.
Phospholipid ­ bilayer is the basic structural component of plasma membranes. It consists of two layers or phospholipid
molecules. Proteins are embedded in this layer.
Fluid Mosaic ­ refers to the model of cell membrane structure. The lipid molecules give fluidity and proteins in the
membrane give it a mosaic appearance
Cell Signalling ­ cells communicate with one another by signals. Cytokines are an example of cell signals
Diffusion ­ the movement of molecules from a region of high concentration to a region of lower concentration down a
concentration gradient.
Active Transport ­ refers to the movement of molecules or ions across membranes, which uses ATP to drive protein
`pumps' within the membrane
Solute- solid that dissolves in liquid.
Solvent- liquid that dissolves solids
Solution- liquid containing dissolved solids.
Cell Cycle ­ describes the events that take place as one parent cell divides to produce two new daughter cells which
then grow to full size.
Mitosis - refers to the process of nuclear division where two genetically identical nuclei are formed from one parent
cell nucleus
Clones ­ genetically identical cells or organisms derived from one parent
Differentiation ­ refers to the changes occurring in cells of a multicellular organism so that each different type of cell
becomes specialised to perform a specific function
Tissue ­ a collection of similar cells that carry out a specific function
Organ ­ a collection of tissues that work together to carry out a specific function
Exchange Surfaces ­ a specialised area that is adapted to make it easier for molecules to cross from one side to the
Gaseous Exchange ­ the movement of gases by diffusion between an organism and its environment across a barrier
e.g. the alveolus wall.

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Inspiration (or inhalation) and Expiration (or exhalation) are the terms used to describe breathing in and out.
Transport ­ the movement of oxygen, nutrients, hormones and water and heat around the body.
Heart ­ a muscular pump that creates pressure to propel blood through the arteries and around the body.
Cardiac Cycle ­ the sequence of events in one heartbeat.
Sinoatrial Node ­ the heart's pacemaker.…read more


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