The smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane

The acceleration of an object moving in a circle at a constant speed. Centripetal acceleration always acts towards the centre of the circle

When fission neutrons cause further fission, so more fission neutrons are released. This goes on to produce further fission.

Consortium of Local Education Authorities for the Provision of Science Services

http://science.cleapss.org.uk

Climate change refers to the variation in the Earth's global climate or in regional climates over time. It describes changes in the atmosphere over time scales ranging from decades to millions of years. These changes may come from processes within the Earth, or be caused by human activities

A confounding variable is one that may, in addition to the variable independent variable, affect the outcome of the investigation. Confounding variables must be kept constant or the investigation will not be a fair test. Confounding variables are sometimes referred to as control variables.

In a closed system, the momentum before a collision/event is equal to the total momentum after the collision/event.

A force that acts at the point of contact between two objects

Continuous variables can have values (called a quantity) that can be given a magnitude either by counting (as in the case of the number of cars) or by measurement (eg electrical current, speed etc).

A control experiment is one that is set up to eliminate certain possibilities. In a well designed investigation, the independent variable is changed and all confounding variables are kept constant. The possibilityexists, however, that something else other than the independent variable might have produced the results that were obtained. A control experiment is one that is designed to eliminate this possibility

A control group is one that is treated in exactly the same way as the experimental group except for the factor that is being investigated. This allows scientists to make a comparison. It ensures that the data that are collected are valid because any differences between the results for the experimental group and those for the control group will be due to a single independent variable.

A control variable is one which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored.

A lens that makes light rays near and parallel to the principal axis converge to a point, known as the principal focus

A correlation shows that there is a relationship between two variables, however, it might not be a causal one

Crotalus atrox, the western diamondback rattlesnake, is a venomous rattlesnake species found in the United States and Mexico. It is likely responsible for the majority of snakebite fatalities in northern Mexico and the second-greatest number in the U.S., after C. adamanteus.

Defeat device means a device which measures, senses, or responds to operating variables (e.g., engine speed, temperature, intake pressure or any other parameter) for the purpose of activating, modulating, delaying or deactivating the operation of any component or the function of the emission control system such that the effectiveness of the emission control system is reduced under conditions encountered during normal operation, unless the use of such a device is substantially included in the applied emission certification test procedures.      

Source: Resolution MEPC.176(58), amendments to the Annex of the Protocol of 1978 relating to the International Convention for the Prevention of Pollution from Ships (Revised MARPOL Annex VI), 10 October 2008, International Maritime Organization

The changes of forested areas to non-forest land use such as arable land, urban use, logged area or wasteland.

The dependent variable is the variable of which the value is measured for each and every change in the independent variable.

The dependent variable is the variable of which the value is measured for each and every change in the independent variable.

An area that receives an average annual precipitation of less than 250 mm (9.8 in) or an area in which more water is lost than falls as precipitation

a large burrowing land tortoise (Gopherus agassizii) of arid regions of the southwestern United States and adjacent Mexico

The degradation of land in arid, semi arid and dry sub-humid areas resulting from various climatic variations, but primarily from human activities

A wide variety of teaching techniques and lesson adaptations that educators use to instruct a diverse group of students, with diverse learning needs, in the same course, classroom, or learning environment

 Variables that can only take on a finite number of values 

An impairment of the normal state of the living animal or plant body or one of its parts that interrupts or modifies the performance of the vital functions,

Total distance moved by an object along a particular direction.

deoxyribonucleic acid, a self-replicating material which is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

A trial, usually used in the context of medicine, when assessing the effects of a new drug or treatment on humans. Neither the patients nor the scientists concerned know which treatment a particular individual is receiving until after completion of the trial. This helps to avoid bias and increase the validity of the trial.