Biology key terms

A plant-cell structure containing chlorophyll where photosynthesis takes place.

The yellowing of normally green plant tissue because too little chlorophyll is present.

A bacterial disease that causes diarrhoea.

The main closed loop of DNA in a bacterium, carrying most of its genetic information and lying free in the cytoplasm.

A structure made from a long DNA molecule that carries many genes.

Tiny hair-like structures on specialised cells that move mucus towards the throat.

A ring of tissue around the lens containing muscles that alter tension in the suspensory ligaments.

A muscle around the lens that helps change its shape for focusing.

A ring of muscles around the lens that helps change its shape for focusing.

A cell forming part of a sheet that lines a surface or body structure and bears moving cilia.

The organ system in which the heart pumps blood through blood vessels to transport substances around the body.

Severe scarring of the liver that usually cannot be reversed.

The organisation of organisms into groups according to shared characteristics and relationships.

A circular region around an antibiotic disc in which there is no visible bacterial growth.

A long-term change in climate patterns, including temperature and rainfall.

Testing a potential medicine in human volunteers or patients.

Testing of a potential drug using healthy volunteers and patients.

A fertility drug that stimulates the pituitary gland to release more follicle-stimulating hormone and luteinising hormone.

A group of genetically identical cells produced from one parent cell by cell division.

The part of DNA in a gene whose base sequence is used to produce a complementary mRNA strand.

The inheritance pattern in which both alleles in a heterozygous genotype are fully expressed in the phenotype.

A set of three bases in mRNA that codes for a particular amino acid.

A large number written before a chemical formula to show how many molecules or formula units take part.

The simultaneous infection of an individual by two or more pathogens.

A tube in the kidney through which fluid passes as it becomes urine; water can be reabsorbed from it into the blood.

A colour vision deficiency in which a person cannot distinguish certain colours in the usual way because one or more types of cone do not respond normally.

Burning a substance, such as wood or a fossil fuel, which releases carbon dioxide into the atmosphere.