Edexcel GCSE Biology key terms

The process of taking and plotting repeated measurements to identify a pattern over time.

One of a pair of specialised cells that controls the opening and closing of a stoma.

Cells beside a stoma that change shape to open or close the pore.

A protein in red blood cells that binds oxygen in the lungs and releases it to body tissues.

A serious illness involving fever and bleeding.

A cell containing one set of chromosomes, which is half the chromosome number of a diploid cell.

Human chorionic gonadotropin, a hormone that can be detected in urine during pregnancy.

A state of complete physical, mental and social well-being, not merely the absence of disease or infirmity.

A muscular organ that pumps blood through the lungs and around the body.

The number of times the heart beats in one minute, usually measured in beats per minute (bpm).

A bacterium that can infect the stomach lining and cause stomach ulcers.

Having only one copy of a gene rather than a pair, as human males do for most genes on the X chromosome.

Indirect protection produced when a large proportion of a population is immune, making transmission less likely and helping to protect people who are not immune.

Mendel’s name for a discrete unit of inheritance passed from a parent to its offspring, rather than permanently blending with another unit.

Having two different alleles for a gene, such as $Dd$.

Human immunodeficiency virus; a virus that damages the immune system.

The maintenance of a stable internal environment despite internal or external changes.

A member of the human evolutionary lineage; in this lesson, the term refers to humans and their extinct relatives.

Body structures in different species that share an underlying pattern because they were inherited from a common ancestor.

Having two identical alleles for a gene, such as $DD$ or $dd$.

A contraceptive that changes hormone levels to interfere with processes needed for pregnancy, such as ovulation.

A chemical messenger produced by a gland and carried in the blood to target cells or organs.

An organism in or on which a parasite lives and from which the parasite obtains resources.

A living cell used by a virus to produce its genetic material and proteins.

The organism in or on which another organism or pathogen lives; during a human infection, the patient is the host organism.

A cell formed by fusing an antibody-producing lymphocyte with a myeloma cell; it can divide while producing antibodies.

A weak bond that forms between complementary bases on opposite DNA strands.