OCR GCSE Biology A key terms

A new tumour formed elsewhere in the body after malignant cells spread from the original tumour.

A collection in which seeds from many plant varieties or species are kept under controlled conditions to conserve genetic material.

An environmental factor that affects which individuals survive and reproduce.

The process in which humans choose organisms with desirable inherited characteristics to reproduce, then repeat this selection over many generations.

A weedkiller that kills certain plants while leaving others relatively unharmed.

A nerve cell that carries impulses from a receptor towards the central nervous system.

A specialised cell or group of cells that detects a stimulus, such as light, pressure or a change in temperature.

The muscular wall separating the left and right sides of the heart and preventing oxygenated and deoxygenated blood from mixing.

A chromosome involved in determining an individual's chromosomal sex; in humans these are called X and Y.

An infection transmitted mainly through sexual contact.

Reproduction in which two gametes fuse, combining genetic material to produce an offspring with a new combination of genes.

Rapid, involuntary contractions of skeletal muscles that increase energy transfer from respiration.

A focusing defect in which distant objects appear blurred because light is brought to a focus in front of the retina.

A perforated end wall between neighbouring sieve tube elements through which phloem sap can pass.

A living phloem cell specialised for conducting dissolved organic substances and joined end to end with other sieve tube elements.

Inheritance in which one gene is chiefly responsible for the feature being considered.

A part of a plant where transported sugar is used or stored.

Any body cell other than a cell involved in producing offspring. A genetic change to a somatic cell is not inherited by the patient's children.

A part of a plant that supplies sugar for transport in the phloem.

A cell with structures and features that enable it to carry out a particular function.

The formation of a new species as populations become sufficiently different that they can no longer interbreed to produce fertile offspring.

A group of similar organisms that can reproduce with one another to produce fertile offspring.

A piece of material being examined, such as a thin sample of plant or animal tissue.

A community in which populations and environmental factors are sufficiently balanced for population sizes to remain fairly constant over time.

A coloured chemical used to increase contrast or make particular biological structures easier to see.

A chemical test in which iodine solution changes from orange-brown to blue-black when starch is present.

A medicine that lowers the concentration of cholesterol in the blood, reducing the risk of coronary heart disease.