Biology Terms: Essential Terminology Study Set

A curated set of the biology terms that show up most often in school and university exams, written in plain English. Read it straight through, or copy any section into the Flashcard Generator to turn it into a revision deck.

Cell biology

Almost every biology syllabus opens here, and later topics (respiration, genetics, immunity) assume you already know these words cold.

Cell membrane
The phospholipid bilayer surrounding a cell; it is selectively permeable, controlling what enters and leaves.
Cytoplasm
The jelly-like fluid filling a cell, where most metabolic reactions take place.
Nucleus
The organelle housing the cell's DNA; it directs protein synthesis and cell division.
Mitochondrion
The site of aerobic respiration, producing ATP — the cell's usable energy currency.
Ribosome
The structure where amino acids are joined into proteins during translation.
Chloroplast
A plant-cell organelle containing chlorophyll, where photosynthesis occurs.
Osmosis
The movement of water across a partially permeable membrane from high to low water potential.
Diffusion
The net movement of particles from high to low concentration; passive, requiring no energy.
Active transport
Movement of substances against a concentration gradient using ATP and carrier proteins.
Mitosis
Cell division producing two genetically identical daughter cells; used for growth and repair.
Meiosis
Cell division producing four genetically distinct gametes, each with half the chromosome number.

Genetics and inheritance

Genetics questions are usually vocabulary questions in disguise — most marks are lost by confusing gene with allele, or genotype with phenotype.

Gene
A section of DNA coding for a particular protein or characteristic.
Allele
A different version of the same gene, e.g. the alleles for brown and blue eyes.
Genotype
The combination of alleles an organism carries for a trait.
Phenotype
The observable characteristics produced by the genotype and the environment.
Homozygous
Carrying two identical alleles for a gene (BB or bb).
Heterozygous
Carrying two different alleles for a gene (Bb).
Dominant allele
An allele expressed in the phenotype even when only one copy is present.
Recessive allele
An allele expressed only when two copies are present.
Mutation
A change in the DNA base sequence; it may be neutral, harmful or beneficial.
Punnett square
A grid used to predict the probability of offspring genotypes from a cross.

Human physiology

Homeostasis
Maintaining a stable internal environment — temperature, blood glucose, water balance.
Enzyme
A biological catalyst that speeds up reactions; it has an active site specific to its substrate.
Denaturation
Loss of an enzyme's three-dimensional shape (and function) due to heat or extreme pH.
Alveoli
Tiny air sacs in the lungs providing a large, moist surface for gas exchange.
Haemoglobin
The protein in red blood cells that binds and transports oxygen.
Antibody
A protein produced by lymphocytes that binds to a specific antigen on a pathogen.
Hormone
A chemical messenger secreted by a gland and carried in the blood to a target organ.
Neurone
A nerve cell that transmits electrical impulses; sensory, relay or motor.

Ecology and evolution

Ecosystem
A community of organisms interacting with each other and their physical environment.
Producer
An organism, usually a plant, that makes its own food by photosynthesis.
Trophic level
A feeding position in a food chain, e.g. producer, primary consumer.
Biodiversity
The variety of species within an ecosystem or on Earth as a whole.
Natural selection
The process by which organisms better adapted to their environment survive and reproduce more.
Adaptation
A feature that increases an organism's chance of survival in its habitat.
Carbon cycle
The movement of carbon between the atmosphere, organisms, oceans and rocks.

How to revise biology terminology

Definitions reward active recall far more than re-reading. Cover the right-hand column, say the definition out loud, then check. Terms you miss twice belong in a flashcard deck reviewed the next day, then three days later, then a week later. Exam answers also reward precision: say 'partially permeable membrane', not 'special wall', because mark schemes credit exact terminology.

Frequently asked questions

How many biology terms should I learn for an exam?

Most school-level papers draw on 150–250 core terms. The set on this page covers the highest-frequency ones; add your syllabus-specific vocabulary on top.

What's the difference between a gene and an allele?

A gene is a stretch of DNA coding for a characteristic. An allele is one particular version of that gene — you inherit one allele from each parent.

Can I turn this list into flashcards?

Yes. Copy any section into the Flashcard Generator to build a deck you can shuffle and export as a PDF.

Is this study set free?

Yes, completely free, with no sign-up needed.

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