Edexcel International GCSE (9-1) Biology - Key Vocabulary

Comprehensive practice flashcards defining core vocabulary terms from the Edexcel International GCSE (9-1) Biology syllabus, covering cell biology, physiology, ecology, genetics, and biotechnology.

Homeostasis

The maintenance of a relatively constant conditions in the internal environment of the body.

Osmoregulation

The maintenance of the water and salt content of the internal environment of an organism.

Enzyme

A protein that acts as a biological catalyst, speeding up metabolic reactions without being consumed in the process.

Active site

The specific area on the surface of an enzyme where the substrate attaches and the reaction takes place.

Active transport

The movement of substances against a concentration gradient across a cell membrane, using energy released from respiration.

Osmosis

The net diffusion of water molecules across a partially permeable membrane from a solution with a higher water potential to a solution with a lower water potential.

Stem cell

An undifferentiated cell that has the ability to divide multiple times by mitosis and differentiate into specialised cell types.

Saprotrophic nutrition

A mode of nutrition where an organism feeds on dead organic matter by secreting extracellular enzymes and absorbing the dissolved nutrients.

Pathogen

A disease-causing organism, such as certain bacteria, viruses, fungi, or protoctists.

Peristalsis

Waves of muscular contraction produced by circular and longitudinal muscle layers that squeeze food along the alimentary canal.

Bile

A green alkaline liquid made in the liver and stored in the gall bladder that neutralises stomach acid and emulsifies lipids into tiny droplets.

Double circulatory system

A circulatory system where blood travels through the heart twice during each complete circuit of the body, divided into the pulmonary and systemic circulations.

Phagocytosis

The process by which a white blood cell engulfs and digests pathogenic microorganisms using pseudopodia and digestive enzymes.

Reflex action

A rapid, automatic, and involuntary response to a stimulus that does not require conscious initiation by the brain.

Synapse

A microscopic gap between two neurones across which chemical neurotransmitters diffuse to transmit electrical signals.

Accommodation

The changes that take place in the shape of the lens within the eye to focus light from objects situated at different distances onto the retina.

Ultrafiltration

The process occurring under high pressure in the Bowman's capsule where water and small molecules are separated from the blood, leaving blood cells and large proteins behind.

Transpiration

The evaporation of water from the surface of a plant, primarily through the stomata of the leaves.

Phototropism

The directional growth response of a plant shoot or root in response to a unidirectional light stimulus.

Auxin

A plant growth substance produced at the tip of shoots that diffuses downwards and causes cell elongation on the shaded side during phototropism.

Pollination

The transfer of pollen grains from an anther of a flower stamen to a receptive stigma.

Biodiversity

The amount of biological variation shown by species in an ecosystem, combining species richness and the relative abundance of each species.

Eutrophication

The enrichment of water by excess mineral ions, such as nitrates or phosphates, leading to an algal bloom, oxygen depletion, and death of aerobic aquatic organisms.

Mitosis

A type of nuclear cell division that produces two genetically identical diploid daughter cells used for growth, tissue repair, cloning, and asexual reproduction.

Meiosis

A reduction division involving two rounds of division that produces four genetically different haploid gametes containing half the original chromosome number.

Allele

An alternative form of a specific gene that codes for different expressions of an inherited characteristic.

Natural selection

The mechanism of evolution whereby organisms best adapted to environmental selection pressures are more likely to survive, reproduce, and pass on their alleles.

Selective breeding

The artificial selection and cross-breeding by humans of individual animals or plants displaying desirable characteristics over successive generations.

Micropropagation

An in vitro plant tissue culture technique where small plant explants are grown on sterile agar medium containing nutrients and plant hormones to produce large clones.

Transgenic organism

An organism that has had genetic material transferred into its genome from a different species.

Restriction enzyme

An enzyme used in genetic engineering to cut DNA molecules at specific recognition base sequences, often producing sticky or blunt ends.

DNA ligase

An enzyme used in genetic engineering to join together the cut ends of DNA strands and recombinant plasmids.

Vector

A biological vehicle, such as a bacterial plasmid or a bacteriophage, used to transfer foreign recombinant DNA into a recipient host cell.