AQA GCSE Biology Key Terms questions and answers

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 types of cells. Agar jelly A substance placed in petri dishes which is used to culture microorganisms on. Cell differentiation The process where 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. Chromosomes 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 cell. 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 Loops 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 The ability to distinguish two different points in a specimen. 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 environment. Surface area to volume ratio (SA:V) The size of the object compared with the amount of area where it contacts its environment.