NCEA Level 3 Biology key terms

The extent to which an investigation measures what it claims to measure, achieved by controlling variables so that only the manipulated factor affects the measured outcome.

The consistency of results when an investigation is repeated, improved by taking repeated measurements, using adequate sample sizes and standardising the method.

The factor deliberately changed or selected by the investigator between trials, such as temperature, light intensity or substrate type.

The factor measured in an investigation, which is expected to respond to changes in the independent variable, for example enzyme activity or rate of oxygen uptake.

A comparison group treated identically except that the manipulated factor is absent or held at a standard level, allowing the effect of that factor to be isolated.

The number of individuals or replicates measured in an investigation; larger samples reduce the influence of chance variation and make conclusions more trustworthy.

A selection method in which every member of a population has an equal chance of being chosen, reducing bias in estimates of population characteristics.

A square frame of known area placed in a habitat to sample the organisms within it, used to estimate population density or percentage cover.

A line or belt laid across a habitat along which organisms are recorded, revealing how species distribution changes with an environmental gradient.

A non-living feature of an environment, such as light intensity, temperature, pH, salinity or moisture, that influences the distribution and survival of organisms.

A living influence on an organism, including competition, predation, disease and mutualism, which shapes population size and community structure.

A real-world problem with a scientific dimension that also involves social, economic, cultural or ethical values, so decisions require weighing evidence against competing perspectives.

A systematic distortion in evidence, data interpretation or reporting that favours a particular position, often arising from funding sources, sampling method or selective use of results.

A structured judgement of the likelihood and severity of harm from an action or technology, weighed against its potential benefits.

The idea that when evidence suggests serious or irreversible harm is possible, lack of full certainty should not delay proportionate action to prevent it.

Evaluation of research by independent experts before publication, intended to check methods, interpretation and claims before evidence is widely cited.

A directional growth response of a plant towards or away from a one-sided stimulus, such as phototropism to light or gravitropism to gravity.

A plant hormone, chiefly indoleacetic acid, that promotes cell elongation and redistributes in response to light or gravity, producing curvature during growth.

Suppression of lateral bud growth by auxin produced in the shoot tip, giving a plant a dominant main stem.

A non-directional plant movement triggered by a stimulus, such as the closing of leaflets or the folding of petals, independent of the direction of the stimulus.

An internal cycle of roughly 24 hours that controls behaviours such as sleep, activity or leaf movement, and can be reset by environmental cues like light.

Oriented and non-oriented movement responses of animals: a taxis is directional movement towards or away from a stimulus, while a kinesis is a change in activity rate.

A simple form of learning in which an animal reduces its response to a repeated stimulus that proves harmless, conserving energy and attention.

Maintenance of a relatively stable internal environment within narrow limits despite external fluctuations, achieved through coordinated control systems.

A control mechanism in which a deviation from the normal level triggers a response that counteracts the deviation, restoring the internal condition towards its set value.

The target value around which a regulated internal variable, such as core temperature or blood glucose concentration, is held by control mechanisms.

Control of body temperature through mechanisms such as sweating, vasodilation, shivering and vasoconstriction, balancing heat gain and heat loss.

Control of water and solute balance in body fluids, involving the kidneys and hormones such as ADH to keep osmotic concentration within a workable range.

The formation of new species when populations become reproductively isolated and diverge genetically until they can no longer interbreed successfully.

Any barrier preventing members of different populations from producing fertile offspring, including geographical separation, timing differences, behavioural mismatch or hybrid inviability.

Speciation that occurs when a physical barrier divides a population, stopping gene flow so the separated groups diverge through mutation, drift and differing selection.

Speciation arising without geographic separation, often through polyploidy, habitat shifts or assortative mating within a single area.

Differential survival and reproduction of individuals whose inherited variations make them better suited to current environmental conditions, changing allele frequencies over generations.

The proportion of a particular allele among all copies of a gene in a population, which shifts as selection, drift, mutation and migration act.

Random change in allele frequencies between generations, especially pronounced in small populations, occurring independently of selection.

A member of the evolutionary lineage leading to modern humans after the split from the chimpanzee lineage, identified from fossils by features such as bipedalism.

Habitual upright walking on two legs, indicated in fossils by features such as a forward-placed foramen magnum, bowl-shaped pelvis and valgus knee.

The opening at the base of the skull through which the spinal cord passes; its more forward position in hominins reflects an upright posture.

The internal volume of the braincase, used as an estimate of brain size and a key trend in hominin fossil comparison.

DNA formed by joining fragments from different sources, the basis of genetic engineering techniques that insert a gene of interest into a vector.

A small circular DNA molecule used to carry a foreign gene into a host cell, typically engineered with a marker gene and restriction sites.

A bacterial enzyme that cuts DNA at specific recognition sequences, producing fragments with sticky or blunt ends used in gene cloning.

The introduction of genetic material into an organism, whether by natural means such as bacterial conjugation or by artificial techniques such as transformation and microinjection.

An organism containing a gene from another species that has been deliberately introduced and is usually inherited by its offspring.

A gene-editing system in which a guide RNA directs the Cas9 nuclease to cut a target DNA sequence, allowing genes to be disrupted or altered.