CCEA Life and Health Sciences AS 1 Experimental Techniques overview quiz quiz

By an internally assessed portfolio of practical work moderated by CCEA

By a single terminal written examination at the end of the course

By a spoken viva with an external examiner about practical methods

By a multiple-choice screening test taken online under supervision

The quantity that is measured in response to the change

The factor that is deliberately changed by the investigator

A factor that is kept constant to keep the test fair

The average calculated from several repeat readings

Changing only the independent variable while holding the controls constant

Using the most expensive apparatus available in the laboratory

Taking as many repeat readings as the time allows

Drawing a smooth curve of best fit through every data point

How close a reading is to the true accepted value of the quantity

The smallest change in a quantity that the instrument can display

The total range of values the instrument is able to measure

The number of times a reading is repeated before averaging

0.25 per cent

2.5 per cent

1.25 per cent

5.0 per cent

It shifts every reading by the same amount in the same direction

It cannot be reduced by any change to the method

It is always caused by an uncalibrated instrument

It causes scatter around the trend and is reduced by repeating and averaging

Because the offset is the same in every reading, so averaging keeps it

Because systematic errors only occur in biological investigations

Because repeats increase the percentage uncertainty of the reading

Because a systematic error is the same as an anomalous result

Reliability is controlling variables; validity is repeating readings

Reliability is consistent repeats; validity is measuring the intended thing

Reliability and validity mean exactly the same thing

Reliability is the cost of apparatus; validity is its resolution

Axes left unlabelled to save space on the grid

A scale that uses less than half of the available grid

Labelled axes with units and a line or curve of best fit

Every point joined dot-to-dot with short straight segments

The number of repeats divided by the range of the readings

The time taken multiplied by the volume of gas collected

The resolution of the apparatus divided by the reading

The change in the measured quantity divided by the time taken

It should be excluded, with a reason, so it does not distort the mean

It should be doubled to balance the other readings

It should be included so the data set is complete

It should replace the closest reading to the trend line

Be more careful when taking the readings next time

Use a gas syringe of finer resolution to lower the percentage uncertainty

Take fewer readings so the graph is less cluttered

Change the hypothesis so it matches the results obtained

A list of every other student in the practical class

A photograph of the student wearing a laboratory coat

A risk assessment giving each hazard, its risk and a control measure

A copy of the textbook chapter the experiment is based on

Increasing it, because larger readings are harder to take

Removing it entirely, because large readings have no uncertainty

Leaving it unchanged, because it depends only on resolution

Decreasing it, because the fixed absolute uncertainty is a smaller fraction