Glossary of biology

This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices.

A

• Abiotic factor – A non-living chemical or physical factor in an ecosystem.
• Active transport – The movement of molecules across a membrane requiring energy.
• Aerobic respiration – The process of producing cellular energy with oxygen.
• Allele – A variant form of a gene.
• Autotroph – An organism that produces its own food through photosynthesis or chemosynthesis.

B

• Biodiversity – The variety of life in a particular habitat or ecosystem.
• Biotic factor – A living component of an ecosystem.
• Biosphere – The global ecological system integrating all living beings and their environments.
• Bacteria – Single-celled microorganisms that exist in various environments.

C

• Cell – The basic structural and functional unit of life.
• Chloroplast – The organelle in plant cells where photosynthesis occurs.
• Chromosome – A structure containing genetic information in the form of DNA.
• Codon – A sequence of three nucleotides in DNA or RNA that corresponds to a specific amino acid.
• Cytoplasm – The fluid inside a cell that contains organelles.

D

• DNA – The molecule that carries genetic instructions for growth, development, and reproduction.
• Diffusion – The movement of molecules from high to low concentration.
• Decomposer – An organism that breaks down dead material and recycles nutrients.

E

• Ecosystem – A community of interacting organisms and their physical environment.
• Endoplasmic reticulum – A network of membranes within cells that aids in protein and lipid synthesis.
• Enzyme – A protein that speeds up chemical reactions in living organisms.
• Evolution – The process by which organisms change over generations through genetic variation and natural selection.

F

• Facilitated diffusion – The passive movement of molecules across a membrane via transport proteins.
• Food chain – A series of organisms each dependent on the next as a source of food.
• Fossil – The preserved remains or traces of ancient organisms.

G

• Gene – A segment of DNA that encodes a specific trait.
• Genotype – The genetic makeup of an organism.
• Golgi apparatus – An organelle responsible for modifying and packaging proteins.
• Ground tissue – Plant tissue involved in photosynthesis, storage, and support.

H

• Habitat – The natural environment where an organism lives.
• Haploid – A cell containing a single set of unpaired chromosomes.
• Homeostasis – The process of maintaining a stable internal environment.
• Hormone – A chemical messenger produced in the body.

I

• Immune system – The body's defense mechanism against infections.
• Inorganic molecule – A molecule that does not contain carbon-hydrogen bonds.
• Insulin – A hormone that regulates blood sugar levels.

J

• Juvenile stage – An early developmental stage before reaching maturity.

K

• Karyotype – The number and appearance of chromosomes in a cell.
• Keystone species – A species that has a disproportionately large effect on its environment.

L

• Lactic acid fermentation – A metabolic process in which glucose is converted into lactic acid.
• Lipid – A type of organic molecule that includes fats, oils, and waxes.
• Lysosome – An organelle that contains digestive enzymes.

M

• Meiosis – A type of cell division that reduces the chromosome number by half.
• Mitochondrion – The powerhouse of the cell, responsible for energy production.
• Mutation – A change in the genetic sequence.

N

• Natural selection – The process by which organisms better adapted to their environment survive and reproduce.
• Neuron – A nerve cell that transmits signals in the body.
• Nucleus – The control center of a cell that contains genetic material.

O

• Organelle – A specialized subunit within a cell with a specific function.
• Osmosis – The diffusion of water across a semi-permeable membrane.

P

• Parasite – An organism that lives on or inside another organism.
• Pathogen – A microorganism that causes disease.
• Photosynthesis – The process by which plants convert sunlight into energy.
• Plasma membrane – The outer layer of a cell that controls substance exchange.
• Protein – A molecule made of amino acids essential for cellular function.

Q

• Quorum sensing – A bacterial communication process that coordinates behavior.
• Quadrat – A sampling tool in ecology to study species distribution.

R

• Recessive trait – A trait expressed only when two recessive alleles are present.
• Ribosome – An organelle that synthesizes proteins.

S

• Speciation – The formation of new species over time.
• Symbiosis – A close interaction between two different species.
• Synapse – The connection between two neurons.

T

• Taxonomy – The classification system for living organisms.
• Trophic level – The position of an organism in a food chain.
• Turgor pressure – The pressure within a plant cell due to water uptake.

U

• Ultrastructure – The fine detail of cell components seen under an electron microscope.
• Unicellular – An organism consisting of a single cell.

V

• Vacuole – A storage organelle in plant cells.
• Variation – Differences in traits among individuals of a population.

W

• Water cycle – The movement of water through the biosphere.
• White blood cell – An immune cell that fights infections.

X

• Xylem – The plant tissue responsible for water transport.

Y

• Yeast – A unicellular fungus that ferments sugars.

Z

• Zygote – A fertilized cell formed by the fusion of gametes.
• Zooplankton – Microscopic animals that drift in aquatic environments.

See also

• Index of biology articles
• Outline of biology
• Glossaries of sub-disciplines and related fields:
  • Glossary of botany
  • Glossary of ecology
  • Glossary of entomology
  • Glossary of environmental science
  • Glossary of genetics
  • Glossary of ichthyology
  • Glossary of ornithology
  • Glossary of scientific naming
  • Glossary of speciation
  • Glossary of virology