Biology - Cells

• Active transport


  The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient) with the use of energy from respiration
• Adult stem cell


  A type of stem cell that can form many type of cells
• Agar jelly


  A substance placed in petri dishes which is used to culture microorganisms
• Cell differentiation


  The process when a cell becomes specialised to its function
• Cell membrane


  A partially permeable barrier that surrounds the cell
• Cell wall


  An outer layer made of cellulose that strengthens plant cells
• Chloroplast


  An organelle which is the site of photosynthesis
• Chromosome


  DNA structures that are found in the nucleus which are made up of genes
• Concentration gradient


  The difference in concentration between two areas
• Diffusion


  The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration
• Embryonic stem cell


  A type of stem cell that can differentiate into most types of human cells
• Eukaryotic cell


  A type of cell found in plants and animals that contains a nucleus
• Magnification


  How much bigger an image appears compared to the original object
• Meristematic cells


  A type of stem cell that can differentiate into any type of plant cell
• Mitochondria


  An organelle which is the site of respiration
• Mitosis


  A type of cell division which produces two genetically identical daughter cells from one parent
• Nucleus


  An organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell
• Organelle


  A specialised structure found inside a cell
• Osmosis


  The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• Plasmid


  Loop of DNA found in the cytoplasm of prokaryotic cells
• Prokaryotic cell


  A type of cell found in bacteria that does not contain a nucleus
• Resolution


  How much detail can be seen.
• Specialised cells


  Cells that are adapted to perform a specific function
• Stem cell


  An undifferentiated cell that can divide to produce many specialised cells of the same type
• Surface area


  The amount of contact an object has with its surroundings
• Surface area to volume ratio (SAV)


  The ratio of the surface area of an object compared with the amount of volume it occupies
• The cell cycle


  A series of stages preparing the cell for division
• Therapeutic cloning


  Producing an embryo that has the same genes as a patient
• Vacuole


  An organelle that stores cell sap
• All living things are made of cells, which can either be prokaryotic or eukaryotic
• Structures in eukaryotic animal and plant cells


  • Cell membrane
  • Cytoplasm
  • Nucleus containing DNA
• Structures in prokaryotic bacterial cells


  • Cell wall
  • Cell membrane
  • Cytoplasm
  • Single circular strand of DNA
  • Plasmids
• Organelles


  • Structures in a cell that have different functions
• Orders of magnitude


  A way to understand how much bigger or smaller one object is compared to another, using powers of 10
• Prefixes used to show multiples of units

  • Centi (0.01)
  • Milli (0.001)
  • Micro (0.000,001)
  • Nano (0.000, 000, 001)
• Specialised animal cells


  • Sperm cell
  • Nerve cell
• Sperm cell


  • Streamlined head and long tail to aid swimming
  • Many mitochondria to supply energy for movement
  • Acrosome with digestive enzymes to break down egg cell membrane
• Nerve cell


  • Long axon to transmit signals over long distances
  • Many branched dendrites to form connections with other nerve cells
  • Many mitochondria to supply energy for neurotransmitter release
• In mature animals, cell division mostly only happens to repair or replace damaged cells
• In plants, many types of cells retain the ability to differentiate throughout life