GCSE Biology (8461) Specification Key Vocabulary

Comprehensive vocabulary flashcards defining core biological terms, structures, and processes from the AQA GCSE Biology (8461) specification.

Eukaryotic Cells

Plant and animal cells that contain a cell membrane, cytoplasm, and genetic material enclosed in a nucleus.

Prokaryotic Cells

Much smaller bacterial cells with cytoplasm and a cell membrane surrounded by a cell wall, whose genetic material is a single DNA loop not enclosed in a nucleus, often with small rings of DNA called plasmids.

Plasmids

Small rings of DNA found in prokaryotic (bacterial) cells.

Cell Differentiation

The process by which an unspecialised cell acquires different sub-cellular structures to enable it to carry out a specific function, becoming a specialised cell.

Stem Cell

An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

Therapeutic Cloning

A process where an embryo is produced with the same genes as the patient, so stem cells harvested from it are not rejected by the patient's body.

Diffusion

The spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.

Osmosis

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

Active Transport

The movement of substances from a more dilute solution to a more concentrated solution (against a concentration gradient), which requires energy from respiration.

Tissue

A group of cells with a similar structure and function.

Organ

An aggregation of tissues performing specific functions.

Organ System

A group of organs that work together to perform specific functions and form organisms.

Enzymes

Biological catalysts that speed up specific reactions in living organisms due to the unique shape of their active site.

Bile

An alkaline substance made in the liver and stored in the gall bladder that neutralises hydrochloric acid from the stomach and emulsifies fats into small droplets to increase surface area for lipase action.

Pacemaker

A group of cells located in the right atrium that monitors and controls the natural resting heart rate.

Stents

Mechanical devices inserted into coronary arteries to keep them open, ensuring blood and oxygen flow to heart muscle.

Statins

Drugs widely used to reduce blood cholesterol levels, thereby slowing down the rate of fatty material deposit in coronary arteries.

Benign Tumours

Growths of abnormal cells that are contained in one area, usually within a membrane, and do not invade other parts of the body.

Malignant Tumours

Cancers consisting of abnormal cells that invade neighbouring tissues and spread to different parts of the body via the blood to form secondary tumours.

Transpiration

The movement of water and dissolved mineral ions from roots to stems and leaves via lignin-strengthened xylem vessels, driven by evaporation from the leaves.

Translocation

The movement of dissolved sugars from the leaves to the rest of the plant for immediate use or storage through elongated phloem tubes.

Pathogens

Microorganisms—such as viruses, bacteria, protists, or fungi—that infect plants or animals and cause infectious communicable disease.

Vaccination

The introduction of small quantities of dead or inactive forms of a pathogen into the body to stimulate white blood cells to produce specific antibodies.

Antibiotics

Medicines, such as penicillin, that help to cure bacterial disease by killing infective bacteria inside the body without damaging host cells.

Monoclonal Antibodies

Antibodies produced from a single clone of cells that are specific to one binding site on one protein antigen, targeting a specific chemical or cell in the body.

Hybridoma Cell

A hybrid cell created by combining a mouse lymphocyte with a tumour cell, retaining the ability to divide rapidly and produce specific antibodies.

Chlorosis

A plant condition causing yellow leaves due to magnesium deficiency, as magnesium ions are needed to produce chlorophyll.

Photosynthesis

An endothermic reaction in which energy is transferred from the environment to chloroplasts by light, converting carbon dioxide and water into glucose and oxygen.

Aerobic Respiration

An exothermic reaction continuously occurring in living cells that transfers energy by breaking down glucose using oxygen, yielding carbon dioxide and water.

Anaerobic Respiration

Cellular respiration occurring without oxygen that yields much less energy than aerobic respiration due to the incomplete oxidation of glucose.

Oxygen Debt

The amount of extra oxygen the body needs after vigorous exercise to react with accumulated lactic acid in the liver and remove it from cells.

Metabolism

The sum of all the chemical reactions occurring in a cell or the body.

Homeostasis

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.

Central Nervous System (CNS)

The brain and spinal cord, which receive impulses from sensory receptors and coordinate responses in effectors (muscles and glands).

Accommodation

The process of changing the shape of the eye lens to focus clearly on near or distant objects.

Myopia

Short sightedness; an eye defect in which light rays focus in front of the retina rather than directly on it.

Hyperopia

Long sightedness; an eye defect in which light rays focus behind the retina.

Vasodilation

The widening of blood vessels supplying the skin capillaries when body temperature is high, transferring energy from the skin to the environment.

Vasoconstriction

The narrowing of blood vessels supplying the skin capillaries when body temperature is low, reducing heat transfer to the environment.

Pituitary Gland

The 'master gland' located in the brain that secretes several hormones into the blood to stimulate other endocrine glands.

Insulin

A hormone produced by the pancreas when blood glucose is high that causes glucose to move from the blood into cells, and into liver/muscle cells for storage as glycogen.

Glucagon

A hormone produced by the pancreas when blood glucose is low that causes stored glycogen in the liver to be converted into glucose and released back into the blood.

Antidiuretic Hormone (ADH)

A hormone released by the pituitary gland when the blood is too concentrated, which increases kidney tubule permeability so more water is reabsorbed into the blood.

Ovulation

The release of a mature egg from an ovary, occurring approximately every 28 days during the human menstrual cycle.

Auxin

A plant hormone that controls growth in plant shoots and roots by creating unequal growth rates in response to light (phototropism) and gravity (gravitropism).

Gene

A small section of DNA on a chromosome that codes for a particular sequence of amino acids to make a specific protein.

Genome

The entire genetic material of an organism.

Allele

A different form or variant of a particular gene.

Dominant Allele

An allele that is always expressed in the phenotype, even if only one copy is present.

Recessive Allele

An allele that is only expressed in the phenotype if two copies are present (with no dominant allele present).

Homozygous

Having two identical alleles present for a particular gene or trait.

Heterozygous

Having two different alleles present for a particular gene or trait.

Genotype

The combination of alleles an organism carries for a specific trait.

Phenotype

The physical characteristics and features expressed by an organism as a result of its genotype interacting with the environment.

Selective Breeding

The artificial selection process by which humans breed plants and animals for particular desired genetic characteristics over multiple generations.

Genetic Engineering

A process that involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.

Speciation

The formation of new species when two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring.

Fossils

The preserved 'remains' or traces of organisms from millions of years ago found preserved in rocks.

Extinction

The permanent loss of a species when there are no remaining individuals alive anywhere.

Three-Domain System

A biological classification system developed by Carl Woese that divides all organisms into Archaea, Bacteria, and Eukaryota based on chemical analysis.

Ecosystem

The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.

Interdependence

The mutual dependence within a community where each species relies on other species for food, shelter, pollination, and seed dispersal.

Abiotic Factors

Non-living physical or chemical factors that affect an ecosystem, such as light intensity, temperature, moisture levels, and soil pH.

Biotic Factors

Living factors that affect a community, including food availability, new predators, new pathogens, and competition between species.

Extremophiles

Organisms that live in environments with extreme conditions, such as very high temperature, pressure, or high salt concentrations.

Biodiversity

The variety of all the different species of organisms on Earth or within an ecosystem.

Apex Predators

Carnivores situated at the top of the food chain that have no natural predators.

Food Security

Having sufficient and reliable access to enough food to feed a population.

Mycoprotein

A protein-rich food source suitable for vegetarians produced by culturing the fungus Fusarium under aerobic conditions using glucose syrup.