BGCSE BSSE Biology 1428 key terms

A thin flexible layer surrounding a cell that controls which substances enter and leave, keeping the cell contents separate from the surroundings.

The large structure inside most cells that holds the genetic material and controls the cell's activities.

A small structure in the cytoplasm where aerobic respiration takes place, releasing energy from glucose for the cell's activities.

A green structure found in plant cells that contains chlorophyll and carries out photosynthesis.

The net movement of particles from a region of higher concentration to a region of lower concentration, caused by random motion of the particles.

The movement of water molecules through a partially permeable membrane from a dilute solution to a more concentrated solution.

The movement of substances across a membrane from low to high concentration, using energy released by respiration.

A protein that speeds up a chemical reaction in living things without being used up, acting on one specific substrate.

The loss of an enzyme's shape and therefore its function, usually caused by high temperature or extremes of pH.

The substance that an enzyme acts on, fitting into the enzyme's active site to form a product.

A biological molecule made of carbon, hydrogen and oxygen, used mainly as an energy source; sugars and starch are examples.

A biological molecule built from amino acids, used for growth, repair and making enzymes and other body substances.

A fat or oil molecule made of fatty acids and glycerol, used for long-term energy storage and insulation.

The breakdown of large insoluble food molecules into smaller soluble ones that can be absorbed into the blood.

A finger-like fold of the small intestine wall that increases surface area for absorbing digested food into the blood.

Wave-like contractions of the muscles in the gut wall that push food along the digestive system.

The release of energy from glucose using oxygen, producing carbon dioxide and water inside cells.

The release of energy from glucose without oxygen, producing less energy and forming lactic acid in muscles or ethanol in yeast.

A tiny air sac in the lungs where oxygen enters the blood and carbon dioxide leaves it, giving a very large surface area.

A blood vessel that carries blood away from the heart under high pressure; it has thick muscular walls and a narrow lumen.

A very narrow blood vessel with thin walls, where substances are exchanged between the blood and body tissues.

The control of conditions inside the body, such as temperature and water content, so they stay close to ideal values.

The control of water and dissolved salts in the body, carried out mainly by the kidneys adjusting the amount of urine produced.

A control mechanism in which a change is detected and a response reverses that change, bringing the body back to its set value.

A rapid automatic response to a stimulus that does not involve conscious thought, protecting the body from harm.

The small gap between two neurones across which a chemical messenger diffuses to pass a nerve impulse along.

A chemical produced by a gland and carried in the blood, which alters the activity of a target organ.

A type of cell division that produces gametes with half the normal number of chromosomes, creating genetic variation.

Cell division that produces two genetically identical daughter cells, used for growth and repair of body tissues.

One of the different forms of a gene that can occupy the same position on a chromosome and give different features.

A version of a gene that shows its effect in the phenotype even when only one copy is present.

A version of a gene that only shows its effect in the phenotype when two copies are present and no dominant allele is.

A diagram showing the direction of energy transfer from one organism to the next, starting with a producer.

An organism that makes its own food by photosynthesis, forming the first level of a food chain.

An organism such as a bacterium or fungus that breaks down dead material and returns nutrients to the soil.

The process by which organisms best suited to their environment survive and pass on their alleles, changing populations over generations.

A feature of an organism that helps it survive and reproduce in its particular habitat.

A microorganism that causes disease, such as some bacteria, viruses, fungi or protoctists.

A protein made by white blood cells that binds to a specific pathogen or its toxin and helps destroy it.