37 of the Biology glossary’s terms, each with the part of the syllabus where you first meet it.
An organism that needs oxygen gas to survive because it can obtain enough energy only by aerobic respiration, for example Mycobacterium tuberculosis.
An organism that cannot survive in the presence of oxygen gas and respires only anaerobically, for example Clostridium botulinum.
An organism or agent that can reproduce only inside the living cells of a host, using the host cell's metabolism; all viruses are obligate intracellular parasites.
The decrease in the pH of seawater caused by absorption of atmospheric carbon dioxide, which forms carbonic acid and reduces the concentration of carbonate ions available for calcification.
The main female sex hormone, a steroid made mainly in the ovaries; being non-polar, it diffuses through plasma membranes to receptors inside target cells.
A short section of DNA built discontinuously on the lagging strand during replication, each starting from its own RNA primer.
An animal that feeds on both plants and animals, such as Homo sapiens.
A mutated form of a proto-oncogene whose product is permanently active or overproduced, stimulating uncontrolled cell division.
The production of egg cells in the ovary; its divisions are unequal, so one cell keeps most of the cytoplasm and the others form small polar bodies.
A system that exchanges both energy and matter with its surroundings; natural ecosystems are open systems.
A group of genes in a prokaryote that are transcribed together as one mRNA from a single promoter, under the control of one operator.
An infection by a pathogen that rarely causes disease in a healthy person but does so when the immune system is weakened, as in AIDS.
The value of a factor, such as temperature or pH, at which the rate of an enzyme-catalysed reaction is highest.
A structure made of two or more different tissues that work together to perform one or more functions, such as the heart or the brain.
A group of organs that work together to perform a major function in the body, such as the circulatory system or the nervous system.
A discrete subunit of a cell that has a distinct structure and is adapted to perform one or more specific functions, for example the nucleus, ribosomes, vesicles and the plasma membrane.
A compound containing carbon atoms covalently bonded to other atoms, usually including hydrogen, of the kind made by living organisms; carbon dioxide and carbonates are not usually counted as organic.
A specific base sequence at which DNA replication begins; prokaryotes usually have one per chromosome, eukaryotes many.
An instrument that displays changes in voltage against time; used to record resting and action potentials from electrodes inside and outside a neuron.
The total concentration of all solute particles (molecules and ions) in a solution, measured in osmoles or milliosmoles per litre (mOsm/L); osmolality is measured per kilogram of water.
A receptor cell in the hypothalamus that detects the osmotic concentration of the blood and causes ADH secretion to change.
The control of the osmotic concentration (water and solute content) of the blood and other body fluids; in mammals, mainly by the kidneys.
The net movement of water across a partially permeable membrane from a region of lower solute concentration to a region of higher solute concentration.
A value that lies unusually far from the rest of the data; in a box-and-whisker plot, more than 1.5 × IQR above the upper quartile or below the lower quartile.
The part of the menstrual cycle that takes place in the ovary: development of a follicle, ovulation, and formation and breakdown of the corpus luteum.
One of the two female gonads, containing follicles in which eggs develop; it releases eggs at ovulation and secretes oestradiol and progesterone.
Harvesting a species by hunting, fishing, logging or collecting faster than its population can replace the individuals removed.
The production by organisms of more offspring than the environment can support, so that many die before they reproduce.
The tube that collects the egg released from the ovary and carries it to the uterus; the usual site of fertilisation. Also called the fallopian tube.
The release of an egg (secondary oocyte) from a mature follicle in the ovary, triggered by a surge in LH.
The structure inside the ovary of a flower that contains the female gamete (egg cell) and develops into a seed after fertilisation.
The large, non-motile female gamete, with a haploid nucleus and cytoplasm containing nutrient stores and organelles for the early embryo.
The four-carbon compound of the Krebs cycle that accepts an acetyl group to form citrate and is regenerated at the end of each turn.
The loss of electrons from a substance, often by the removal of hydrogen (dehydrogenation) or the addition of oxygen; it releases energy from the substance oxidised.
The synthesis of ATP in mitochondria using energy released by the oxidation of reduced NAD and reduced FAD in the electron transport chain, through chemiosmosis.
A graph of the percentage saturation of haemoglobin with oxygen against the partial pressure of oxygen; it is S-shaped because of cooperative binding.
A hormone secreted by the posterior pituitary that stimulates contraction of the muscle of the uterus during childbirth; its secretion increases by positive feedback.