Biology GCSE Dictionary

Active site The site where the reactants bind to the enzyme.
Active transport The movement of substances against a concentration gradient using energy.
Adaptations Special features which make an organism particularly well suited to its habitat.
Alleles Different versions of a particular gene.
Antigens The unique proteins on the surface of a cell, that are recognised by the immune system as ‘self’ or ‘non-self’.
Biogas Gas made through the action of microorganisms on the remains of living organisms.
Cell membrane The membrane around a cell which controls what moves in and out of the cell.
Central nervous system (CNS) The central nervous system is made up of the brain and spinal cord where information is processed.
Chlorophyll The green pigment contained in the chloroplast that absorbs sunlight.
Chloroplasts The organelles where photosynthesis takes place.
Chromosomes Thread-like structures made of DNA that carry the genetic information found in the nucleus of a cell.
Clones Offspring produced by asexual reproduction which are genetically identical to their parent organism.
Concentration gradient The gradient between an area where a substance is at a high concentration and an area where it the substance is at a low concentration.
Cytoplasm The water-based gel where the organelles of all living cells are suspended.
Decomposers Microorganisms that break down waste products and dead matter.
Denatured Enzymes that are denatured have unfolded protein structures and can no longer catalyse a reaction.
Diffusion The net movement of particles of a gas or a solute from an area of high concentration to an area of low concentration (along or down a concentration gradient).
DNA Deoxyribose nucleic acid, the material that makes up chromosomes.
Ecosystem The total of the animals and plants living in an area, along with things which affect them such as the soil and the weather.
Enzyme Protein molecules which function as biological catalysts. They change the rate of chemical reactions without being affected themselves at the end of the reaction.
Evolution The slow change in living organisms over long periods of time as those best fitted to survive breed successfully.
Gene A short section of DNA carrying genetic information (codes fora single protein or characteristic).
Genetic engineering / genetic modification A modern technique for changing the genetic information of a cell.
Hemoglobin The red pigment which carries oxygen around the body, found in red blood cells.
Homeostasis The maintenance of constant internal body conditions such as temperature and blood pH.
Hormones Chemical messages secreted by special glands and carried around the body in the blood, e.g. insulin and adrenaline.
Limiting factors Factors which limit the rate of a reaction, e.g. light intensity for photosynthesis.
Meiosis A two-stage process of cell division which halves the chromosome number of the daughter cells. It is involved in making the gametes for sexual reproduction.
Menstrual cycle The reproductive cycle in women regulated by hormones.
Metabolic rate The rate at which all the reactions of your body take place, particularly cellular respiration.
Microorganism Bacteria, viruses and other small organisms which can only be seen using a microscope.
Mitochondria Organelles responsible for aerobic cellular respiration in cells.
Mitosis Asexual cell division where two genetically identical daughter cells are formed.
Mutation Any change in the genetic material of an organism.
Natural selection The process by which evolution takes place. Organisms produce more offspring than the environment can support so only those which are most suited to their environment will survive to breed and pass on their useful characteristics.
Neurones Basic cells of the nervous system that carry minute electrical impulses around the body.
Nucleus (of a cell) An organelle found in many living cells that contain the genetic information.
Organelles Membrane-bound structures in a cell which carry out particular functions.
Osmosis The passive movement of water from an area of high concentration (of water) to an area of low concentration (of water) along a concentration gradient.
Partially permeable Allowing only particular substances to pass through.
Pathogens Microorganisms which can cause disease in humans and other organisms.
Photosynthesis The process by which plants produce their own food using carbon dioxide, water and light energy.
Respiration The process by which food molecules are broken down to release energy for living cells.
Ribosomes The site of protein synthesis in a cell, found in the cytoplasm.
Specialised Adapted for a particular biological function.
Stem cells Undifferentiated cells that have the potential to form a wide variety of different cell types.
Stomata Openings in the leaves of plants that allow gases to enter and leave the leaf. They are opened and closed by the guard cells.
Synapses The gaps between neurones where the transmission of information is passed chemically rather than electrically.
Transpiration The loss of water vapour from the leaves of plants through the stomata when they are opened to facilitate gas exchange for photosynthesis.
Villi The finger-like projections from the lining of the small intestines which increases the surface area for the absorption of nutrients into the blood.
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