Biology - Key words

Question 1

Accuracy *

Answer 1

A measurement result is considered accurate if it is judged to be close to the true value

Question 2

Calibration

Answer 2

Marking a scale on a measuring instrument
Involved establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied.
For example, placing a thermometer in melting ice to see whether it reads as zero

Question 3

Measurement error *

Answer 3

The difference between a measured value and the true value.

Question 4

Anomalies *

Answer 4

These are values in a set of results which are judged not to be part of the variation caused by random uncertainty

Question 5

Data *

Answer 5

Information, either qualitative or quantitative, that has been collected.

Question 6

Random Error

Answer 6

These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next.
Present when any measurement is made, and cannot be corrected.
The effect can be reduced by making more measurements and calculating a new mean

Question 7

Systematic error

Answer 7

These cause readings to differ from the true value by a consistent amount each time a measurement is made.
Sources of systematic error can include the environment, methods of observation or instruments used.
Cannot be dealt with by simple repeats. If suspected, the data collection should be repeated using a different technique or a different set of equipment, and the results compared

Question 8

Zero error

Answer 8

Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero, eg the needle on an ammeter failing to return to zero when no current flows. May result in a systematic uncertainty

Question 9

Evidence

Answer 9

Data which has been shown to be valid

Question 10

Fair test *

Answer 10

One in which only the independent variable has been allowed to affect the dependent variable.

Question 11

Hypothesis *

Answer 11

A proposal intended to explain certain facts or observations.

Question 12

Intervals

Answer 12

The quantity between readings, eg a set of 11 readings equally spaced over a distance of 1 metre would give an interval of 10 centimetres.

Question 13

Precision

Answer 13

Precise measurements are ones in which there is very little spread about the mean value.
Depends only on the extent of random errors – it gives no indication of how close results are to the true value.

Question 14

Prediction

Answer 14

A prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.

Question 15

Range

Answer 15

The maximum and minimum values of the independent or dependent variables; important in ensuring that any pattern is detected.
For example a range of distances may be quoted as either: ‘From 10 cm to 50 cm’ or ‘From 50 cm to 10 cm

Question 16

Repeatable

Answer 16

A measurement is repeatable if the original experimenter repeats the investigation using same method and equipment and obtains the same results. Previously known as reliable

Question 17

Reproducible

Answer 17

A measurement is reproducible if the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained. Previously known as reliable.

Question 18

Resolution

Answer 18

Resolution
This is the smallest change in the quantity being measured (input) of a measuring instrument gives a perceptible change in the reading.

Question 19

Independent variable *

Answer 19

Variable for which values are changed or selected by the investigator

Question 20

Sketch graph

Answer 20

A line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables.
It will not have any points plotted and although the axes should be labelled they may not be scaled.

Question 21

True value

Answer 21

The value that would be obtained in an ideal measurement

Question 22

Uncertainty

Answer 22

The interval within which the true value can be expected to lie.
Whenever a measurement is made, there will always be some uncertainty or doubt about the result obtained.
Can be expressed in terms of spread of values obtained.

Question 23

Validity

Answer 23

Suitability of the investigative procedure to answer the question being asked. For example, an investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants would not be a valid procedure if the temperature of the reactants was not controlled.

Question 24

Valid conclusion

Answer 24

A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning.

Question 25

Variables

Answer 25

Physical, chemical or biological quantities or characteristics

Question 26

Categoric values

Answer 26

Have values that are labels, eg names of plants or types of material

Question 27

Continuous variable

Answer 27

Can have values (called a quantity) that can be given a magnitude either by counting (as in the case of the number of shrimp) or by measurement (eg light intensity, flow rate etc). Previously known as discrete variable

Question 28

Control variable *

Answer 28

One which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant

Question 29

Dependent variable *

Answer 29

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