GCSE Combined Science Biology key terms and definitions
51 Biology terms with their meanings, in alphabetical order. Each comes from a Yumio Biology lesson, and links to the topic where it is taught.
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- Acrosome
- The part at the head of a sperm cell that holds enzymes to break into the egg. Cell structure and specialised cells
- Alveoli
- Tiny air sacs at the ends of the airways in the lungs where gas exchange happens. Exchange surfaces and gas exchange in the lungs
- Anomalous result
- A result that does not fit the pattern of the other results. Required practicals and working scientifically in biology
- Bipedal
- Walking on two legs. Evidence for human evolution
- BMI
- Body mass index: mass in kg divided by height in m squared. Maths skills for biology
- Cardiac output
- The volume of blood pumped by the heart each minute: stroke volume × heart rate. Maths skills for biology
- Cilia
- Tiny hair-like projections on some cells that sweep mucus along. Cell structure and specialised cells
- Clomifene
- A fertility drug that stimulates the release of FSH and LH so that eggs mature and are released. Puberty, the menstrual cycle and contraception
- Control variable
- A variable you keep the same to make the test fair. Required practicals and working scientifically in biology
- Correlation
- A link between two variables. It does not prove that one causes the other. Maths skills for biology
- Crop rotation
- Growing a different crop in a field each year, including a legume. Parasites, mutualism and the nitrogen cycle
- Dependent variable
- The variable you measure. Required practicals and working scientifically in biology
- Differentiation
- The process by which a cell becomes specialised for a particular job. Growth, differentiation and percentile charts
- Diploid
- Having two sets of chromosomes, as in a body cell. Chromosomes, mitosis and the cell cycle
- Dry mass
- The mass of an organism after all the water has been removed. Growth, differentiation and percentile charts
- Elongation
- A plant cell getting longer as it takes in water. Growth, differentiation and percentile charts
- Exchange surface
- A surface where substances pass between an organism and its surroundings. Exchange surfaces and gas exchange in the lungs
- Fossil
- The preserved remains or traces of an organism that lived long ago. Evidence for human evolution
- Growth
- An increase in size or mass, from more cells or bigger cells. Growth, differentiation and percentile charts
- Haploid
- Having one set of chromosomes, as in a gamete. Sexual and asexual reproduction and meiosis
- Hominin
- A member of the human family tree, including our ancestors who walked upright. Evidence for human evolution
- Independent variable
- The variable you change in an investigation. Required practicals and working scientifically in biology
- Interdependence
- When species in a community depend on each other for food, shelter, pollination and other needs. Parasites, mutualism and the nitrogen cycle
- Interphase
- The stage of the cell cycle in which the cell grows and copies its DNA. Chromosomes, mitosis and the cell cycle
- Legume
- A plant such as clover, peas or beans, with nitrogen-fixing bacteria in its root nodules. Parasites, mutualism and the nitrogen cycle
- Ligase
- An enzyme that joins pieces of DNA together. Selective breeding and genetic engineering
- Magnification
- How many times bigger an image is than the real object: image size ÷ real size. Required practicals and working scientifically in biology
- Mean
- The total of the values divided by the number of values. Maths skills for biology
- Median
- The middle value when the values are put in order. Maths skills for biology
- Meristem
- A region at the tip of a root or shoot where plant cells divide by mitosis. Growth, differentiation and percentile charts
- Mutualism
- A relationship in which both organisms benefit. Parasites, mutualism and the nitrogen cycle
- Nitrogen-fixing bacteria
- Bacteria that turn nitrogen gas into nitrogen compounds such as nitrates. Parasites, mutualism and the nitrogen cycle
- Optimum
- The condition, such as temperature or pH, at which an enzyme works best. Required practicals and working scientifically in biology
- Organ
- A group of different tissues that work together to do a job. The digestive system and food tests
- Organ system
- A group of organs that work together, such as the digestive system. The digestive system and food tests
- Parasitism
- A relationship in which a parasite lives on or in a host and harms it. Parasites, mutualism and the nitrogen cycle
- Pedigree
- A family tree showing how an inherited characteristic is passed on. Inheritance: genetic crosses, sex and inherited disorders
- Percentage cover
- The percentage of the quadrat area covered by a plant species. Fieldwork: quadrats, transects and population estimates
- Percentile
- The percentage of a group that have a lower value. The 50th percentile is the middle. Growth, differentiation and percentile charts
- Population
- All of the organisms of one species living in an area. Fieldwork: quadrats, transects and population estimates
- Quadrat
- A square frame of known area used to sample organisms in a habitat. Fieldwork: quadrats, transects and population estimates
- Radioactive decay
- The breakdown of unstable atoms at a steady rate, used to date rocks. Evidence for human evolution
- Random sample
- A sample chosen so that every part of the area has an equal chance of being picked. Fieldwork: quadrats, transects and population estimates
- Restriction enzyme
- An enzyme that cuts DNA at a specific sequence, leaving sticky ends. Selective breeding and genetic engineering
- Standard form
- A number written as A × 10ⁿ, where A is between 1 and 10. Maths skills for biology
- Stone tool
- A tool made from stone by early humans. Evidence for human evolution
- Surface area to volume ratio
- The surface area of an object divided by its volume. Exchange surfaces and gas exchange in the lungs
- Tissue
- A group of similar cells with the same job. The digestive system and food tests
- Transect
- A line or belt across a habitat along which organisms are recorded. Fieldwork: quadrats, transects and population estimates
- Ventilation
- Moving air in and out of the lungs by breathing. Exchange surfaces and gas exchange in the lungs
- Villi
- Finger-like projections in the small intestine that increase surface area for absorption. Exchange surfaces and gas exchange in the lungs
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