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Edexcel IGCSE Biology 2.39 respiration products practical

Practise respiration practicals by calculating gas-production rates, explaining apparatus choices and evaluating reliability from controls and repeats.

Syllabus
First assessment 2019
Course
Biology 4BI1

Exam points

  • Calculate CO2 production or bubble movement rates from table values and time.
  • Explain why soda lime or KOH lets a respirometer measure oxygen uptake.
  • Evaluate seed or animal investigations using controls, repeats, anomalies and variables.

2.39 Respiration products practical question 1

[Maximum number: 8]

Wheat seeds contain stores of a large insoluble molecule.
This molecule is digested by amylase as the seeds germinate.

Question (a)

(a)

A student investigates the oxygen absorbed by germinating seeds at different temperatures.

The diagram shows some of the student's apparatus.

Figure for Question (a) — Edexcel IGCSE Biology
[ 6 ]

Question (i)

(i)

Suggest why the student opens the tap after obtaining one set of results.

[ 2 ]

Question (ii)

(ii)

What is the function of the soda lime?

A

it absorbs carbon dioxide

B

it absorbs oxygen

C

it releases carbon dioxide

D

it releases oxygen

[ 1 ]

Question (iii)

(iii)

The student measures the distance moved by the coloured liquid and converts this to volume of oxygen absorbed.

The volume of oxygen absorbed can be calculated using the formula
volume =π×=\pi \times radius 2×^{2} \times distance
Calculate the volume of oxygen absorbed when the coloured liquid moves a distance of 6.0 mm.
[diameter of tube =1.0 mm=1.0 \mathrm{~mm} ]
volume = cm3\mathrm{cm}^{3}

[ 3 ]

Question (b)

(b)

The graph shows the results of the student's investigation.

Figure for Question (b) — Edexcel IGCSE Biology
[ 2 ]

Question (i)

(i)

Calculate the percentage increase in the rate of oxygen absorption at 22∘C22^{\circ} \mathrm{C} compared to the rate of oxygen absorption at 12∘C12^{\circ} \mathrm{C}.

[ 2 ]
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