Draw the table & headings

Many full marks; some recorded minutes & seconds instead of seconds only; headings often lacked detail (e.g., “test-tubes” too vague).

State a valid conclusion

Vast majority produced a suitable conclusion from the data.

Identify the independent variable

Generally answered well: glucose concentration identified correctly.

Identify one control variable

Most cited temperature/volume of yeast but needed specificity; “yeast” alone insufficient.

Why stir the yeast suspension?

No glucose present at this step; stirring was for even distribution of yeast cells (not to ensure reaction).

Two improvements to the method

Many struggled to give two valid improvements; repeating at each concentration was commonly identified.

Make 5.0 cm?3; of 0.25% glucose

Some described correctly; others couldn’t determine the dilution or make the specified volume.

Test for reducing sugars

Well learned; a few omitted the need for high temperature.

Apparatus for collecting gas

Gas syringe correct; some gave measuring cylinder without qualifying displacement/over-water method.

Identify an anomalous result

Identify point not fitting trend or lying off line of best fit.

Mean with an anomaly present

Exclude the anomaly; some incorrectly divided by three rather than two.

Compare results at different temperatures

Demanding; better answers supported statements by manipulating figures. Comparisons ? explanations.

Draw a suitable graph with a key

Issues included unsuitable scales/units, incorrect lines of best fit, and extrapolation beyond data.

Estimate value & show working on graph

To gain both marks, candidates had to estimate and show working clearly on the graph.

Hydrogen carbonate indicator colour change

Very few correctly identified the colour change when CO? was bubbled through the indicator.

Standard biological drawing

Sharp pencil, clear continuous lines, no shading. Draw single cell X (many drew too many); include shape and details (cell wall, extensions).

Calculate actual length (3 s.f.)

Attempted well; common error was not using three significant figures. Show working for partial credit.

Plan, variables & safety (NaCl on plant tissue)

Many strong plans; most named ?2 control variables; dependent variable trickier. Marks for measuring length/mass before & after submersion and comparing with final. Safety: knife away from body/on flat surface; gloves only if allergy risk.