Biology (0610) Paper 6 Notes

IGCSE Biology (0610)
Paper 6 Alternative to practical

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(1) The humidity did not change during the investigation.

State two other variables that should be kept constant during the investigation.

Describe how each variable could be kept constant.

- temperature: keep in the same room/put into an environmental chamber

- idea of no air currents/wind/draughts: keep all windows and doors closed

- (sun) light (intensity): use a light source at a fixed source/same light source

- leaf surface area: use leaves of same size/surface area

(2) How would you improve the experiment [exercise and breathing rate environment]

- To improve experiment of exercise, increase exercise time, do different levels of intensity, cross out anomalies, controls

- Control: same intensity/time of exercise, temperature, clothing, diet of person

When describing about exercise, mention what heart does, like more oxygen is required so heart beats faster

(3) Making comparisons (e.g. seeds)

- When making comparisons, comment of shape/outline (is it smooth? Are there projections?), symmetry (regular/irregular),…

(4) Describe how you could safely test a sample (of any food) for reducing sugar

- Benedict’s reagent / solution / test;

- heat / boil; NOT warm/burn

- safety feature: goggles / water bath / tongs;

- correct colour change: blue to green / yellow / orange /red;

(5) A student carried out the emulsion test on a sample of yolk and it gave a positive result. State what the student would observe.

- cloudy / white solid / milky / white (emulsion);

(6) Describing graphs. Refer to these points:

- general increase from… to…

- are increases or decreases smooth

- figures with years/time/…

- general decrease from… to…

- peak/maximum at…

(7) Suggest why a sample of ten seedlings is better than a sample of only three seedlings

- (more) reliable/you are able identify anomalies 

(8) How could you carry out an experiment to determine whether temperature affects water uptake of shoots with leaves

Three of:

1 idea of at least three temperatures tested

2 suitable range of temperatures

3 control variable (eg light / wind / height or volume of water / humidity)

4 method of measuring rate of water uptake

5 Repeat for reliability

(9) [experiment on enzyme… and gas being released] Suggest how you could improve the method that they followed

- repeat and calculate mean

- exclude anomalies from mean calculation

- collect the gas and measure the volume

(10) The students were given a hypothesis that said

“the activity of catalase increases with increasing temperature”.

Describe an investigation to test this hypothesis.

- give a range of at least 4 temperatures;

- describe how temperature would be changed / water-bath;

- describe the use of a controlled equilibration time to reach temperature;

- control stated as: an inert cube / boiled cube or same volume of water as hydrogen peroxide;

- appropriate description of how volume of gas will be measured / bubbles counted;

- appropriate statement regarding time

- surface area of potato controlled

- another controlled variable stated, e.g. pH / same potato

- repeat and calculate mean

(11) A student criticised the results by saying that the loss in mass does not allow for a fair comparison between leaves. Suggest a more appropriate calculation and explain why it gives a fairer comparison.

- percentage change in mass = (change in mass ÷ starting mass) × 100

- different original mass would affect result/to take into account the starting mass

(12) [experiment with yeast] Example of description and explanation: describing solutions A and B

 (a) description

 1 number of bubbles in a minute increases with time 

 2 A released bubbles, more/faster (than B) 

 3 (colour change) from red to, yellow/yellow pink with time 

 4 A changed colour faster (than B) 

 5 A formed foam, more/ faster (than B

 6 suitable comparative data quote at a stated time

 (b) explanation

 7 releasing gas by respiration 

 8 gas released carbon dioxide 

 9 carbon dioxide is acidic 

 10 causes hydrogen carbonate indicator solution to change from red to yellow 

 11 A is respiring aerobically/B is respiring anaerobically 

 12 (the rate of) gas released in anaerobic respiration is slower

(13) Why was the solution covered with oil [experiment with yeast, glucose]

- to exclude air or oxygen

(14) Why was the temperature made warmer

- warm temperature speeds up enzyme/yeast activity

(15) How was the rate of respiration of yeast determined?

- bubble production/ colour change of hydrogen carbonate/ foam production 

- divided by time 

For rate, you need to write ‘divided by (unit) time’

(16) Describe a control experiment [for investigation with enzymes]

- idea of replacing the peroxide with water/ leaf with paper/using a boiled leaf 

- reference to keeping the rest of the experiment unchanged/describe the same experimental conditions