Biology (school) glossary
87 key terms from Biology (school), A to Z. Each is explained in one plain sentence and links to its free lesson.
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A
- Active transportMoving materials, enzymes and energy
- Moving substances against a concentration gradient, from low to high concentration, using energy from respiration.
- AdaptationVariation and evolution
- A feature of an organism that helps it survive in its habitat.
- Aerobic respirationMoving materials, enzymes and energy
- Releasing energy from glucose using oxygen.
- Air pollutionHumans and the environment
- Harmful gases and particles in the air, such as sulfur dioxide that causes acid rain or smoke particles that damage lungs.
- AlleleGenes and inheritance
- A different version of the same gene.
- AlveoliThe human body
- Tiny air sacs in the lungs where oxygen enters the blood and carbon dioxide leaves it.
- Anaerobic respirationMoving materials, enzymes and energy
- Releasing energy from glucose without oxygen.
- AntibioticHealth and disease
- A medicine that kills bacteria or stops them growing.
- Antibiotic resistanceHealth and disease
- When bacteria evolve so that an antibiotic no longer kills them.
- AntibodyHealth and disease
- A protein made by white blood cells that locks onto a particular pathogen and helps destroy it.
B
- BiodiversityHumans and the environment
- The variety of different living things in an area.
- BiomassEcosystems and food chains
- The mass of living material.
- Biotic and abiotic factorsEcosystems and food chains
- Biotic factors are living things that affect a community, like predators.
- BloodThe human body
- A liquid tissue that carries oxygen, food, waste and heat.
C
- Carbon cycleEcosystems and food chains
- How carbon moves between the air, living things and the ground.
- CellCells
- The smallest unit of life.
- Cell membraneCells
- A thin skin around the cell.
- Cell wallCells
- A stiff outer layer made of cellulose found in plant cells.
- ChloroplastCells
- A green part of plant cells that contains chlorophyll and carries out photosynthesis.
- ChromosomeGenes and inheritance
- A long, coiled strand of DNA containing many genes.
- ClassificationVariation and evolution
- Sorting living things into groups based on their features.
- Communicable diseaseHealth and disease
- A disease that can pass from one person or animal to another.
- CompetitionEcosystems and food chains
- When living things use the same limited resources, like food, light, water or mates.
- ConservationHumans and the environment
- Protecting and managing living things and habitats so they are not lost.
- ConsumerEcosystems and food chains
- An organism that gets energy by eating other organisms.
- Coronary heart diseaseThe human body
- A disease where the heart's own blood vessels get clogged with fatty deposits, so the heart muscle gets too little oxygen.
- CytoplasmCells
- The jelly-like liquid that fills a cell.
D
- DecomposerEcosystems and food chains
- A microorganism, mostly bacteria and fungi, that breaks down dead plants and animals and returns nutrients to the soil.
- DeforestationHumans and the environment
- The clearing of large areas of forest, often to make farmland or sell timber.
- DenaturingMoving materials, enzymes and energy
- When heat or the wrong pH changes the shape of an enzyme so it can no longer work.
- DiffusionMoving materials, enzymes and energy
- The spreading out of particles from where there are lots of them to where there are fewer.
- Digestive systemThe human body
- The organs that break food into small molecules the blood can carry around the body.
- DNAGenes and inheritance
- A long molecule shaped like a twisted ladder that carries the instructions for building and running a living thing.
- Dominant and recessive allelesGenes and inheritance
- A dominant allele shows up even if you have only one copy.
- Double circulationThe human body
- Blood passes through the heart twice on each full trip: once to the lungs and once to the body.
E
- EcosystemEcosystems and food chains
- All the living things in an area together with their non-living surroundings, such as soil, water and weather.
- EnzymeMoving materials, enzymes and energy
- A protein that speeds up a chemical reaction without being used up.
- EutrophicationHumans and the environment
- When fertiliser runs into water, algae grow too fast, then die and use up the oxygen so fish suffocate.
- EvolutionVariation and evolution
- The slow change of a species over many generations as natural selection favours helpful features.
- ExtinctionVariation and evolution
- When no living members of a species remain anywhere on Earth.
F
- Food securityHumans and the environment
- Having enough safe, nutritious food to feed everyone.
- Food webEcosystems and food chains
- A diagram of many food chains joined together, showing who eats whom in an ecosystem.
- FossilVariation and evolution
- The preserved remains or traces of a living thing from long ago, often found in rock.
G
- GeneGenes and inheritance
- A short section of DNA that holds the instructions for making one protein.
- Genetic engineeringVariation and evolution
- Moving a gene from one organism into another to give it a new feature.
- Genotype and phenotypeGenes and inheritance
- Genotype is the alleles an organism has.
- Global warmingHumans and the environment
- The rise in Earth's average temperature caused by extra greenhouse gases from human activity.
- Greenhouse effectHumans and the environment
- Gases like carbon dioxide and methane trap heat in the air, keeping Earth warm enough for life.
H
- HabitatEcosystems and food chains
- The place where an organism lives.
- Herd immunityHealth and disease
- When enough people are vaccinated that a disease cannot spread easily, which protects even those who are not vaccinated.
- HomeostasisThe human body
- Keeping conditions inside the body steady, such as temperature and blood sugar.
- HormoneThe human body
- A chemical messenger made in a gland and carried by the blood to a target organ.
I
- Immune systemHealth and disease
- The body's defence against pathogens, based mostly on white blood cells.
- Inherited disorderGenes and inheritance
- A condition caused by faulty alleles passed from parents to children.
L
- Limiting factorMoving materials, enzymes and energy
- The thing in shortest supply that stops a process from going any faster, such as light, carbon dioxide or temperature.
M
- MagnificationCells
- How many times bigger an image looks than the real object.
- MeiosisGenes and inheritance
- Cell division that makes four different sex cells, each with half the usual number of chromosomes.
- MitochondriaCells
- Tiny parts of a cell where energy is released from food.
- MitosisGenes and inheritance
- Cell division that makes two identical cells.
- MutationVariation and evolution
- A random change in the DNA of a gene.
N
- Natural selectionVariation and evolution
- Individuals with features that suit their environment survive and breed more, passing those features on.
- Negative feedbackThe human body
- A control system where a change triggers a response that reverses the change and brings the body back to normal.
- Non-communicable diseaseHealth and disease
- An illness that is not caused by a pathogen and cannot be passed on, such as heart disease or most cancers.
- NucleusCells
- The control centre of a cell.
O
- Organ systemThe human body
- A group of organs that work together to do a big job.
- OsmosisMoving materials, enzymes and energy
- The movement of water through a partially permeable membrane from a dilute solution to a more concentrated one.
P
- PathogenHealth and disease
- A microorganism that causes disease.
- Peat bogHumans and the environment
- A wet habitat where dead plants build up slowly and store carbon for thousands of years.
- PhotosynthesisMoving materials, enzymes and energy
- The process where plants use light energy to make glucose from carbon dioxide and water, releasing oxygen.
- ProducerEcosystems and food chains
- An organism that makes its own food, usually by photosynthesis.
- Punnett squareGenes and inheritance
- A grid that shows all the possible combinations of alleles from two parents and how likely each is.
R
- Reflex arcThe human body
- A fast, automatic response to a stimulus that does not need conscious thought.
- RibosomeCells
- A tiny part of a cell that builds proteins by joining small building blocks together.
S
- Selective breedingVariation and evolution
- Humans choosing parents with useful features and breeding them to produce better offspring over generations.
- Sex chromosomesGenes and inheritance
- The pair of chromosomes that decides whether a person is female (XX) or male (XY).
- Specialised cellCells
- A cell with a shape and parts that suit one particular job.
- SpeciationVariation and evolution
- The formation of a new species when two populations become so different they can no longer breed together.
- Stem cellCells
- An unspecialised cell that can divide and turn into many different types of cell.
- StomataMoving materials, enzymes and energy
- Tiny holes on the underside of leaves that let gases in and out.
- Sustainable developmentHumans and the environment
- Meeting today's needs without using up resources that future people will need.
T
- TranspirationMoving materials, enzymes and energy
- The loss of water vapour from leaves.
V
- VaccinationHealth and disease
- Giving a harmless form of a pathogen so the body learns to make antibodies before meeting the real thing.
- VacuoleCells
- A fluid-filled space in a plant cell.
- VariationVariation and evolution
- The differences between individuals of the same species.
- VectorHealth and disease
- An animal that carries a pathogen from one host to another without usually being harmed itself.
- VilliThe human body
- Tiny finger-like folds lining the small intestine.
W
- Water cycleEcosystems and food chains
- The constant movement of water between the sea, air and land by evaporation, condensation and precipitation.