Edexcel GCSE Biology key terms

A characteristic, behaviour or exposure associated with an increased probability of developing a disease.

An enzyme that binds to DNA and builds a complementary mRNA copy during transcription.

A retinal photoreceptor that is very sensitive to dim light but does not provide colour vision.

A specialised cell on the surface of a plant root with a long projection that increases its surface area for absorbing water and mineral ions.

A preparation containing a growth-promoting hormone that encourages a plant cutting to develop roots.

A part of a larger population that is counted or measured to provide information about the whole population.

Safe disposal and treatment of human waste so that it does not contaminate water or food.

The relationship between a represented or measured distance and the corresponding actual distance.

A measured line on an image or drawing that represents a stated real distance in the specimen.

An electron microscope that scans a specimen's surface and uses scattered electrons to reveal its surface form.

The faster and larger specific immune response that occurs when the same antigen is encountered again.

A factor that makes organisms with some inherited characteristics more likely to survive and reproduce than others.

Choosing organisms with desired inherited characteristics as parents and repeating this over generations so those characteristics become more common.

A membrane that allows some substances to pass through but prevents others from passing through freely.

The return of useful substances from the filtrate in a nephron to the blood.

The ability of a medicine to affect a microorganism more than the host because it targets structures or processes that differ between their cells.

A weedkiller that kills particular types of plant while leaving others relatively unaffected.

A neurone that carries an electrical impulse from a receptor towards the central nervous system.

An organ or cell that detects a stimulus and converts information about it into an electrical signal in the nervous system.

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

One of the pair of chromosomes involved in determining chromosomal sex; in the usual human genetic model these are X and Y.

Inheritance in which a gene responsible for a characteristic is located on a sex chromosome, usually the X chromosome in the GCSE examples studied.

An infection that can be passed between people through sexual contact.

Reproduction in which gametes fuse at fertilisation to produce an offspring with genetic material from two parents.

Rapid, involuntary contractions of skeletal muscles that increase heat production.

A focusing defect in which distant objects appear blurred because their light is focused in front of the retina.

A perforated end wall between phloem sieve-tube cells that allows dissolved substances to pass through.