OCR GCSE Biology A key terms

A U-shaped section of kidney tubule that descends into the medulla and rises again.

The space inside a blood vessel through which blood flows.

A hormone released by the pituitary gland whose surge triggers ovulation and stimulates formation of the corpus luteum.

A white blood cell that can produce antibodies or antitoxins.

The bursting of a cell when its membrane ruptures, for example after too much water enters by osmosis.

The number of times larger an image appears than the real object.

A cancerous tumour whose cells can invade surrounding tissues and spread to other parts of the body.

The repeated movement of a material between living organisms and the non-living environment.

A region at the base of the brain that controls involuntary activities such as breathing and heart rate.

Cell division that reduces the chromosome number by half to produce genetically different haploid cells.

A long-lived lymphocyte formed after exposure to an antigen that enables a faster immune response if the same antigen is encountered again.

The curved surface of a liquid in a container, used when reading its volume.

The recurring sequence in which an egg matures and may be released, while the lining of the uterus builds up and is later shed if pregnancy does not occur.

The breakdown and loss of the uterine lining at the beginning of a menstrual cycle.

A region of plant tissue containing unspecialised cells that divide and differentiate to produce new growth.

All the chemical reactions taking place in the cells of an organism.

An organism too small to be seen clearly without a microscope; bacteria and some fungi are examples.

A thin piece of glass that holds a specimen for viewing under a microscope.

Electrically charged particles dissolved in soil water that plants require for healthy growth, such as nitrate and magnesium ions.

A sub-cellular structure containing enzymes for aerobic respiration.

A type of nuclear division in which copied chromosomes are separated to produce two genetically identical nuclei.

The study of evolutionary relationships using biological molecules, particularly comparisons of DNA sequences.

The repeated collection of information to check whether conditions or populations are changing and whether a conservation scheme is working.

Identical antibodies made by cells cloned from one selected antibody-producing cell; they bind to the same target.

An identical antibody made as part of a group of antibodies that all bind the same specific antigen.

A small molecular unit that can join to other units to form a polymer.

A nerve cell that carries impulses from the central nervous system to an effector.

Messenger RNA: a molecule that carries a copy of a gene's nucleotide sequence from the nucleus to a ribosome.