Biology Paper 1 key words

• aerobic respiration

  an exothermic reaction in which glucose is broken down using oxygen to produce carbon dioxide and water and release energy for the cells
• anaerobic respiration

  an exothermic reaction in which glucose is broken down in the absence of oxygen to produce lactic acid in animals and ethanol and carbon dioxide in plants and yeast. A small amount of energy is transferred for the cells
• exothermic reaction


  a reaction that transfers energy to the environment
• glycogen

  carbohydrate store in animals
• lactic acid

  the end product of anaerobic respiration in animal cells
• oxygen debt

  the extra oxygen that must be taken into the body after exercise has stopped to complete the aerobic respiration of lactic acid
• active transport

  the movement of substances from a dilute solution to a more concentrated solution against a concentration gradient, requiring energy from respiration
• algae

  simple aquatic organisms (protista) that make their own food by photosynthesis
• alveoli

  tiny air sacs in the lungs that increase the surface area for gaseous exchange
• bacteria

  single-celled prokaryotic organisms
• cell membrane

  the membrane around the contents of a cell that controls what moves in and out of the cell
• cell wall

  the rigid structure around plant and algal cells. It is made of cellulose and strengthens the cell
• cellulose

  the complex carbohydrate that makes up plant and algal cell walls and gives them strength
• chlorophyll

  the green pigment contained in the chloroplasts
• chloroplasts

  the organelles in which photosynthesis takes place
• cytoplasm

  the water-based gel in which the organelles of all living cells are suspended and most of the chemical reactions of life take place
• diffusion

  the spreading out of the particles of any substance in a solution, or particles in a gas, resulting in a net movement of particles from an area of higher concentration to an area of lower concentration down a concentration gradient
• eukaryotic cells

  cells from eukaryotes that have a cell membrane, cytoplasm, and genetic material enclosed in a nucleus
• mitochondria

  the site of aerobic cellular respiration in a cell
• nucleus

  organelle found in many living cells containing the genetic information surrounded by the nuclear membrane
• osmosis

  the diffusion of water through a partially permeable membrane from a dilute solution (which has a high concentration of water) to a concentrated solution (with a low concentration of water|) down a concentration gradient
• partially permeable membrane


  a membrane that allows only certain substances to pass through
• permanent vacuole

  space in the cytoplasm filled with cell sap
• phloem

  the living transport tissue in plants that carries dissolved food (sugars) around the plant
• plasmolysis

  the state of plant cells when so much water is lost from the cell by osmosis that the vacuole and cytoplasm shrink and the cell membrane pulls away from the cell wall
• prokaryotic cells

  from prokaryotic organisms have a cytoplasm surrounded by a cell membrane, and a cell wall that does not contain cellulose. The genetic material is a DNA loop that is free in the cytoplasm and not enclosed by a nucleus. Sometimes there are one or more small rings of DNA called plasmids
• resolving power


  a measure of the ability to distinguish between two separate points that are very close together
• ribosomes

  the site of protein synthesis in a cell
• sperm

  the male sex cells or gametes that carry the genetic material from the male parent
• stomata

  openings in the leaves of plants, particularly on the underside and opened and closed by guard cells, allowing gases to enter and leave the leaf
• ventilated

  movement of air or water into and out of the gas exchange organ, for example lungs or gills
• xylem

  the non-living transport tissue in plants that transports water from the roots to the leaves and shoots
• clinical trials


  test potential new drugs on healthy and patient volunteers
• placebo

  a medicine that does not contain the active drug being tested, used in clinical trials of new medicines
• preclinical testing


  is carried out on a potential new medicine in a laboratory using cells, tissues, and live animals
• vaccine

  dead or inactive pathogenic material used in vaccination to develop immunity to a disease in a healthy person
• benign tumours

  growths of abnormal cells that are contained in one area, usually within a membrane, and do not invade other tissues
• cancer

  the common name for a malignant tumour, formed as a result of changes in cells that lead to uncontrolled growth and division
• carcinogens

  agents that cause cancer or significantly increase the risk of developing cancer
• correlation

  an apparent link or relationship between two factors