Scio NSZ Biology key terms

A thin, flexible barrier of lipids and proteins that surrounds every cell and controls which substances enter or leave it.

A specialised structure inside a cell, such as a nucleus or mitochondrion, that carries out a particular job for the cell.

An organelle in which aerobic respiration takes place, releasing energy from glucose and producing ATP for the cell's activities.

A green organelle found in plant cells that contains chlorophyll and is the site where photosynthesis takes place.

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

The movement of water across a partially permeable membrane from a dilute solution to a more concentrated one, down a water potential gradient.

A protein that speeds up a specific chemical reaction in living things by lowering the activation energy needed, without being used up itself.

The small region of an enzyme molecule where the substrate binds and the reaction is catalysed, shaped to fit that substrate specifically.

Loss of a protein's functional shape caused by high temperature or extreme pH, which permanently destroys the activity of enzymes.

The release of energy from glucose using oxygen, producing carbon dioxide and water and yielding a large amount of ATP.

Release of energy from glucose without oxygen, producing small amounts of ATP and, in animals, lactic acid.

The process by which green plants use light energy to convert carbon dioxide and water into glucose and oxygen inside chloroplasts.

The green pigment in chloroplasts that absorbs light energy for photosynthesis and gives plant leaves their colour.

The loss of water vapour from plant leaves through stomata, which pulls water up the stem in the xylem.

Plant tissue made of dead, hollow cells that transports water and dissolved minerals upward from the roots to the leaves.

Living plant tissue that transports sugars made in the leaves to other parts of the plant, including roots and growing regions.

A small pore in the surface of a leaf, surrounded by guard cells, through which gases and water vapour pass.

A section of DNA that carries the instructions for making a particular protein or trait and can be passed to offspring.

One of the alternative versions of a gene, which may give different forms of the same characteristic, such as brown or blue eye colour.

A thread-like structure of DNA and protein found in the nucleus, carrying genes; humans have 46 in most body cells.

The combination of alleles an organism carries for a particular gene, for example homozygous dominant or heterozygous.

The observable characteristics of an organism, produced by its genotype interacting with the environment.

Cell division that produces gametes with half the normal chromosome number, creating genetic variation through independent assortment and crossing over.

Cell division that produces two genetically identical daughter cells, used for growth, repair and asexual reproduction.

A change in the base sequence of DNA, which may alter a protein and can be inherited if it occurs in gametes.

The process by which individuals with inherited features better suited to their environment survive and reproduce more, so those features become commoner.

An inherited feature of an organism that improves its chance of surviving and reproducing in its particular habitat.

A group of organisms with similar characteristics that can breed together to produce fertile offspring.

A sequence showing the transfer of energy from one organism to the next, beginning with a producer and ending with a top predator.

An organism, usually a green plant or alga, that makes its own food by photosynthesis and so starts every food chain.

An organism such as a bacterium or fungus that breaks down dead material and waste, recycling nutrients back into the soil.

A community of living organisms together with the non-living parts of their environment, such as soil, water and climate, interacting as a unit.

All the individuals of one species living in the same area at the same time.

The maintenance of a stable internal environment, such as constant body temperature and blood glucose, despite changes outside the body.

A chemical messenger produced by an endocrine gland and carried in the blood to act on a specific target organ.

A control mechanism in which a change away from normal triggers a response that reverses the change and restores the normal level.

A nerve cell specialised to carry electrical impulses rapidly between parts of the body.

The tiny gap between two neurons or between a neuron and a muscle, across which a chemical signal diffuses to pass the impulse on.

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