Biology key terms

In plant growth, the stage in which new cells produced by mitosis increase in length, before they differentiate to form tissues.

An early stage in the development of a multicellular organism.

A stem cell found in an early embryo that can differentiate into most types of human cell.

Testing an embryo’s genetic material to find out whether particular alleles or genetic conditions are present.

An animal-cloning method in which cells of an early embryo are separated and the resulting identical embryos are transferred into host mothers.

The breaking of large fat droplets into smaller droplets, increasing their total surface area.

A cloudy mixture of tiny droplets of one liquid dispersed through another liquid.

A species at serious risk of becoming extinct.

A gland that secretes hormones into the blood rather than through a duct.

A system of glands that release hormones directly into the bloodstream to coordinate body processes.

A process that takes in energy from its surroundings.

A reaction in which energy is transferred from the surroundings to the reacting system.

The point at which the chosen measurable change shows that a reaction has finished or reached a specified stage.

The stage at which the measured reaction is judged to be complete; here, it is the first sample in which iodine detects no starch.

The balance between energy taken in through food and drink and energy used by the body.

Energy content expressed for each unit of mass, commonly in joules per gram.

The surroundings and conditions that affect an organism, including factors such as diet, light, temperature, water and exercise.

A non-living cause of a plant problem, such as drought, unsuitable growing conditions or mineral deficiency.

A long-term alteration in environmental conditions, including changes in temperature and rainfall patterns.

A gradual change in an environmental condition across a habitat, such as the change from deep shade to open ground.

Variation caused by differences in the conditions in which organisms develop or live.

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

The ability of an enzyme to catalyse only a particular reaction because only a substrate with a complementary shape can bind to its active site.

A temporary association formed when a substrate is bound to an enzyme’s active site.

The study of the occurrence, distribution and possible causes of health conditions in populations.

The outer tissue covering a plant organ, providing protection.

The outer layer of the skin, which forms a protective barrier and contains temperature receptors.