GCSE Biology

Overview

For parents: AQA writes your child's Biology course and exams. AQA writes the specifications and exams for most GCSE subjects taught in English state schools. If your school uses AQA, every topic, paper and mark scheme follows AQA's specification.

Topics

Biology key terms

Original definitions for core course vocabulary, informed by the references below. Not an official or exhaustive board-specific glossary.

40 of 40 terms

Cell

The smallest structural and functional unit of a living organism.

Cells and biological molecules

Nucleus

A membrane-bound cell structure containing chromosomes that carry genetic information and help control cell activities.

Cells and biological molecules

Cell membrane

A selectively permeable boundary that controls the movement of substances into and out of a cell.

Cells and biological molecules

Mitochondrion

An organelle where most stages of aerobic respiration occur in eukaryotic cells.

Cells and biological molecules

Chloroplast

An organelle containing chlorophyll in which photosynthesis takes place.

Cells and biological molecules

Diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration, resulting from random motion.

Cells and biological molecules

Osmosis

The net movement of water molecules through a partially permeable membrane from higher water potential to lower water potential.

Cells and biological molecules

Active transport

The movement of substances across a membrane against their concentration gradient, using energy supplied by respiration.

Cells and biological molecules

Enzyme

A protein that acts as a biological catalyst by increasing reaction rate without being used up.

Cells and biological molecules

Denaturation

A change in a protein's three-dimensional shape that can prevent it functioning, such as loss of an enzyme's active-site shape.

Cells and biological molecules

Photosynthesis

The process in which light energy is used to make carbohydrates from carbon dioxide and water, releasing oxygen.

Nutrition, transport and respiration

Chlorophyll

A green pigment that absorbs light energy for photosynthesis.

Nutrition, transport and respiration

Limiting factor

A factor whose availability restricts the rate of a process when other factors are adequate.

Nutrition, transport and respiration

Digestion

The breakdown of large, insoluble food molecules into small, soluble molecules that can be absorbed.

Nutrition, transport and respiration

Absorption

The movement of digested nutrients through the wall of the intestine into the blood or lymph.

Nutrition, transport and respiration

Assimilation

The uptake and use of absorbed nutrients by cells to make substances they need.

Nutrition, transport and respiration

Transpiration

The loss of water vapour from a plant, mainly by evaporation from leaf cells followed by diffusion through stomata.

Nutrition, transport and respiration

Xylem

Plant tissue that transports water and mineral ions and provides mechanical support.

Nutrition, transport and respiration

Phloem

Plant tissue that transports sucrose and amino acids between sources and sinks by translocation.

Nutrition, transport and respiration

Aerobic respiration

Chemical reactions in cells that release usable energy from glucose using oxygen, producing carbon dioxide and water.

Nutrition, transport and respiration

Homeostasis

The maintenance of internal conditions within suitable limits despite internal or external changes.

Coordination and reproduction

Negative feedback

A control mechanism in which a deviation from a normal level triggers responses that oppose the deviation.

Coordination and reproduction

Hormone

A chemical messenger secreted by an endocrine gland and transported in the blood to target cells.

Coordination and reproduction

Reflex action

A rapid, automatic response to a stimulus that does not require conscious decision-making.

Coordination and reproduction

Synapse

A junction between neurones, or between a neurone and an effector, across which a signal is usually transmitted chemically.

Coordination and reproduction

Tropism

A directional growth response of a plant part towards or away from a stimulus.

Coordination and reproduction

Sexual reproduction

Reproduction involving fusion of gamete nuclei to form a zygote, producing genetically varied offspring.

Coordination and reproduction

Asexual reproduction

Reproduction from one parent without fusion of gamete nuclei, usually producing genetically identical offspring.

Coordination and reproduction

Fertilisation

The fusion of male and female gamete nuclei to form the nucleus of a zygote.

Coordination and reproduction

Meiosis

Cell division that halves the chromosome number and produces genetically different haploid cells from a diploid cell.

Coordination and reproduction

Gene

A length of DNA that provides the instructions for producing a functional product, usually a protein.

Inheritance and ecology

Allele

One of the alternative versions of a gene at the same position on homologous chromosomes.

Inheritance and ecology

Genotype

The alleles an organism possesses, either for a particular gene or more generally.

Inheritance and ecology

Phenotype

The observable characteristics of an organism resulting from its genotype and its environment.

Inheritance and ecology

Mutation

A change in the DNA sequence that can create a new allele.

Inheritance and ecology

Natural selection

The process in which individuals with advantageous inherited characteristics leave more offspring, making those characteristics more common over generations.

Inheritance and ecology

Population

All organisms of one species living in a defined area at a particular time.

Inheritance and ecology

Community

All the populations of different species living and interacting in an area.

Inheritance and ecology

Ecosystem

A community of organisms together with its non-living environment and the interactions between them.

Inheritance and ecology

Biodiversity

The variety of living organisms in an area, often assessed using species richness and relative abundance.

Inheritance and ecology

Exams

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Revision

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Practice

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• ✓ Marking with feedback and a model answer

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Resources

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