Cambridge IGCSE Combined Science glossary
78 key terms from the Cambridge IGCSE Combined Science notes, A to Z. Each definition links to the note that teaches it.
A
- Absorption
- The movement of nutrients from the intestines into the blood.Revise it: Organs of the digestive system
- Accuracy
- A measurement is accurate if it is close to the true value.Revise it: Errors, uncertainty and the language of measurement
- Active immunity Supplement
- Defence against a pathogen by antibody production in the body.Revise it: Antigens, antibodies and active immunity
- Active site Supplement
- The region of the enzyme where the substrate fits. Its shape is complementary to the substrate.Revise it: How enzymes work
- Active transport Supplement
- The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration.Revise it: Active transport
- Aerobic respiration
- the chemical reactions in cells that use oxygen to break down nutrient molecules to release energyRevise it: Aerobic respiration
- Alveoli
- Tiny air sacs at the ends of the bronchioles where gas exchange takes place.Revise it: The breathing system
- Anomalous result
- A result that does not fit the pattern of the other results.Revise it: Evaluating experiments: errors, anomalies and improvements
- Anomaly
- A value that is outside the general pattern of the results: very high or very low compared with the others.Revise it: Errors, uncertainty and the language of measurement
- Assimilation
- Uptake and use of nutrients by cells.Revise it: Organs of the digestive system
B
- Balanced diet
- A diet that contains all the nutrients in the correct proportions and gives the right amount of energy for the person.Revise it: A balanced diet and the main nutrients
- Biodiversity
- The number of different species that live in an area.Revise it: Biodiversity and habitat destruction
C
- Carnivore
- An animal that gets its energy by eating other animals.Revise it: Producers, consumers and decomposers
- Catalyst
- A substance that increases the rate of a chemical reaction and is not changed by the reaction.Revise it: Enzymes as biological catalysts
- Cell
- The basic unit of living things; cells are the building blocks of all organisms.Revise it: Cells, tissues, organs and organ systems
- Cervix
- A ring of muscle at the opening of the uterus.Revise it: The male and female reproductive systems
- Chemical digestion
- The breakdown of large insoluble molecules into small soluble molecules.Revise it: Chemical digestion and digestive enzymes
- Chlorophyll
- a green pigment found in chloroplasts that transfers energy from light into energy in chemicals, for the synthesis of carbohydratesRevise it: Photosynthesis and chlorophyll
- Circulatory system
- A system of blood vessels with a pump and valves to ensure one-way flow of blood.Revise it: The circulatory system
- Community
- All of the populations of different species in an ecosystem.Revise it: Populations, communities and ecosystems
- Consumer
- An organism that gets its energy by feeding on other organisms.Revise it: Producers, consumers and decomposers
- Control experiment
- A set-up that is identical except that the factor being tested is missing or inactive, for example boiled enzyme or no plant. It shows that any change is caused by the factor being tested.Revise it: Planning an investigation: variables, controls, range and repeats
- Controlled (constant) variables
- Other variables that could affect the dependent variable, so they are kept the same in every test.Revise it: Planning an investigation: variables, controls, range and repeats
- Coronary heart disease Supplement
- Blockage of the coronary arteries by fatty deposits, reducing blood flow to the heart muscle.Revise it: Coronary heart disease
D
- Decomposer
- An organism that gets its energy from dead or waste organic material.Revise it: Producers, consumers and decomposers
- Denaturation
- A permanent change in the shape of an enzyme's active site, so the substrate no longer fits and the enzyme no longer works.Revise it: Investigating temperature and pH
- Dependent variable
- The variable that is observed or measured in a scientific experiment. It may change based on changes made to the independent variable.Revise it: Planning an investigation: variables, controls, range and repeats
- Diffusion
- The net movement of particles from a region of their higher concentration to a region of their lower concentration (i.e. down a concentration gradient), as a result of their random movement.Revise it: Diffusion
- Digestion
- The breakdown of food.Revise it: Organs of the digestive system
- Drug
- Any substance taken into the body that modifies or affects chemical reactions in the body.Revise it: Drugs and antibiotics
E
- Ecosystem
- A unit containing the community of organisms and their environment, interacting together.Revise it: Populations, communities and ecosystems
- Egestion
- The removal of undigested food from the body as faeces.Revise it: Organs of the digestive system
- Enzyme
- A protein that functions as a biological catalyst.Revise it: Enzymes as biological catalysts
- Enzyme-substrate complex Supplement
- The temporary structure formed when the substrate is bound to the active site.Revise it: How enzymes work
- Excretion
- the removal of the waste products of metabolism and substances in excess of requirementsRevise it: The seven characteristics of living organisms
F
- Fertilisation (in plants)
- The fusion of a pollen nucleus with a nucleus in an ovule.Revise it: Pollination and fertilisation
- Flaccid cell Supplement
- A plant cell that has lost water and turgor pressure, so it is soft.Revise it: Turgor, flaccid cells and plasmolysis
- Food chain
- Shows the transfer of energy from one organism to the next, beginning with a producer.Revise it: Food chains and food webs
- Food web
- A network of interconnected food chains.Revise it: Food chains and food webs
G
- Growth
- a permanent increase in size and dry massRevise it: The seven characteristics of living organisms
H
- Herbivore
- An animal that gets its energy by eating plants.Revise it: Producers, consumers and decomposers
I
- Independent variable
- The variable that is changed in a scientific experiment by the scientist. Changing an independent variable may cause a change in the dependent variable.Revise it: Planning an investigation: variables, controls, range and repeats
- Ingestion
- The taking of substances, e.g. food and drink, into the body.Revise it: Organs of the digestive system
- Interpolation
- Reading a value from a graph between the plotted points.Revise it: Drawing graphs and charts the Cambridge way
M
- Measurement error
- The difference between a measured value and the true value of a quantity.Revise it: Errors, uncertainty and the language of measurement
- Movement
- an action by an organism or part of an organism causing a change of position or placeRevise it: The seven characteristics of living organisms
- MRSA Supplement
- A bacterium that is resistant to many antibiotics.Revise it: Limiting antibiotic resistance
N
- Nutrition
- the taking in of materials for energy, growth and developmentRevise it: The seven characteristics of living organisms
O
- Organ
- A structure made up of a group of tissues, working together to perform specific functions.Revise it: Cells, tissues, organs and organ systems
- Organ system
- A group of organs with related functions, working together to perform body functions.Revise it: Cells, tissues, organs and organ systems
- Organism
- A whole living thing. It may be a single cell (e.g. a bacterium) or many cells organised into tissues, organs and organ systems that work together.Revise it: Cells, tissues, organs and organ systems
- Osmosis Supplement
- The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane.Revise it: Water potential
- Osmosis using water potential Supplement
- The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane.Revise it: Water potential
P
- Pathogen
- A disease-causing organism.Revise it: Pathogens and how they are transmitted
- Photosynthesis
- the process by which plants synthesise carbohydrates from raw materials using energy from lightRevise it: Photosynthesis and chlorophyll
- Physical digestion
- The breakdown of food into smaller pieces without chemical change to the food molecules.Revise it: Physical digestion and teeth
- Plasmid
- A small ring of extra DNA found in bacterial cells.Revise it: Bacterial cells
- Plasmolysis Supplement
- The cell membrane and cytoplasm pulling away from the cell wall after water leaves the cell by osmosis.Revise it: Turgor, flaccid cells and plasmolysis
- Pollination
- The transfer of pollen grains from an anther to a stigma.Revise it: Pollination and fertilisation
- Population
- A group of organisms of one species, living in the same area, at the same time.Revise it: Populations, communities and ecosystems
- Precision
- How close the measured values of a quantity are to each other.Revise it: Errors, uncertainty and the language of measurement
- Producer
- An organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis.Revise it: Producers, consumers and decomposers
R
- Range
- The maximum and minimum values of the independent or dependent variable.Revise it: Errors, uncertainty and the language of measurement
- Repeatability
- A measurement is repeatable if the same or a similar result is obtained when it is repeated under the same conditions, by the same method, in the same experiment.Revise it: Errors, uncertainty and the language of measurement
- Repeats
- Doing the same test again, so that anomalous results can be spotted and a mean calculated.Revise it: Evaluating experiments: errors, anomalies and improvements
- Replicates
- Several identical set-ups tested at the same time, such as five seeds in each dish.Revise it: Evaluating experiments: errors, anomalies and improvements
- Reproducibility
- A measurement is reproducible if the same or a similar result is obtained under different conditions, by a different method or in a different experiment.Revise it: Errors, uncertainty and the language of measurement
- Reproduction
- the processes that make more of the same kind of organismRevise it: The seven characteristics of living organisms
- Respiration
- the chemical reactions in cells that break down nutrient molecules and release energy for metabolismRevise it: The seven characteristics of living organisms
S
- Seed bank Supplement
- A store of seeds of rare plants, kept so plants can be grown if wild populations are lost.Revise it: Endangered species and how to conserve them
- Sensitivity
- the ability to detect and respond to changes in the internal or external environmentRevise it: The seven characteristics of living organisms
- Source of error
- Something in the method or apparatus that makes the measured values differ from the true values.Revise it: Evaluating experiments: errors, anomalies and improvements
T
- Tissue
- A group of cells with similar structures, working together to perform a shared function.Revise it: Cells, tissues, organs and organ systems
- Transmissible disease
- A disease in which the pathogen can be passed from one host to another.Revise it: Pathogens and how they are transmitted
- Transpiration
- The loss of water vapour from leaves.Revise it: Transpiration
- True value
- The value that would be obtained in an ideal measurement.Revise it: Errors, uncertainty and the language of measurement
- Turgid cell Supplement
- A plant cell full of water, with the cell contents pressing on the cell wall (turgor pressure).Revise it: Turgor, flaccid cells and plasmolysis
V
- Validity
- An experiment is valid if it tests what it says it will test: a fair test in which only the independent and dependent variables change and the controlled variables are kept constant.Revise it: Errors, uncertainty and the language of measurement
Test yourself on these terms with the Cambridge IGCSE Combined Science flashcards, or tick them off on the specification checklist.