Edexcel GCSE Biology key terms

A visible change in a plant caused by a problem, such as leaf spots, wilting or stunted growth.

A junction between two neurones where a chemical neurotransmitter carries the signal across a small gap.

The building of larger molecules from smaller molecules.

The circulation carrying blood from the left side of the heart around the body and back to the right side.

Treatment directed at a particular molecular feature of cancer cells rather than acting equally on all cells.

A cell, tissue or organ that responds to a particular hormone because it has the appropriate receptors.

The temperature increase, calculated as final temperature minus initial temperature.

The region that becomes coloured when the target substance, such as hCG, has been detected.

The control of internal body temperature within a suitable range.

An endocrine gland in the neck that produces thyroxine when stimulated by TSH.

A hormone made by the thyroid gland that helps control the body's metabolic rate.

Growing cells or small pieces of tissue outside an organism in a suitable nutrient medium.

How harmful or poisonous a substance is, including the unwanted effects it may cause.

The process in which RNA polymerase uses DNA to make a complementary mRNA strand.

The conversion of one form of energy or information into another; in the retina, light is converted into electrical signals.

A line laid across a habitat along which organisms and environmental conditions are sampled.

The proportion of energy or biomass at one trophic level that is transferred to the next trophic level, expressed as a percentage.

An organism containing genetic material introduced from a different species by genetic engineering.

The stage of protein synthesis in which the sequence of bases in mRNA determines the sequence of amino acids joined into a polypeptide at a ribosome.

The movement of dissolved sugars, especially sucrose, through a plant's phloem from places where they are available to places where they are used or stored.

An electron microscope that forms an image from electrons transmitted through a very thin specimen, revealing internal detail.

The loss of water vapour from a plant, mainly through pores in its leaves.

The continuous movement of water from the roots, through the xylem and out of the leaves by transpiration.

A medical procedure in which cells or tissue are transferred into a patient to replace damaged or diseased material.

Movement of substances between an organism and its environment, or between different parts of an organism.

A system that moves substances between exchange surfaces and cells elsewhere in a multicellular organism.

Thyrotropin-releasing hormone, which is produced by the hypothalamus and stimulates the pituitary gland to release TSH.