Edexcel IGCSE Biology F Respiration Questions

Use respiration evidence across plant, animal and practical contexts: balance equations, calculate gas-use rates and explain anaerobic recovery.

Exam points

Write or balance aerobic and anaerobic respiration equations using correct products.
Calculate oxygen use or carbon dioxide production from tables, time, mass or ppm data.
Evaluate respirometer or seed investigations using controls, repeats and variables.

Covered syllabus points

2.34 Respiration and ATP 2.35 ATP provides energy for cells 2.36 Aerobic and anaerobic respiration 2.37 Aerobic respiration equations 2.38 Anaerobic respiration equations 2.39 Respiration products practical

[Maximum number: 5]

Aerobic respiration uses oxygen and produces ATP.

(a)

Complete the word equation for aerobic respiration.
oxygen + ......⟶ ......+ ......+ ATP

[ 2 ]

(b)

A scientist investigates the rates of aerobic respiration of some animals.

The scientist calculates the rate of respiration per gram of each animal.
The results are shown in the table.

Table for Question (b) — Edexcel IGCSE Biology

Explain why a mouse uses more oxygen per gram than a human.

[ 3 ]

[Maximum number: 2]

A scientist investigates the effect of exercise on breathing rate.
She measures the breathing rate in breaths per minute of two people, P and Q , every 5 minutes for 30 minutes.

This is her method.
- measure their breathing rate every 5 minutes while they exercise for 20 minutes
- measure their breathing rate every 5 minutes for a further 10 minutes while they recover from the exercise

The table shows her results.

Table for Question 2 — Edexcel IGCSE Biology

Explain why the breathing rates of persons P and Q remain high for five minutes after they have finished exercising.

[Maximum number: 10]

Respiration is the process that provides energy for cells.
Respiration can be aerobic or anaerobic.

(a)

Give the word equation for anaerobic respiration in plants.

[ 2 ]

(b)

A scientist uses a gas sensor to investigate the carbon dioxide produced by a sample of dry seeds, and the carbon dioxide produced by a sample of respiring seeds.

The sensor measures the concentration of carbon dioxide in parts per million (ppm) in the air surrounding the seeds.

The scientist measures the initial and final concentration of carbon dioxide for dry seeds, for respiring seeds and for air with no seeds.

The table shows the scientist's results.

[ 8 ]

(i)

Give one biotic variable the scientist should keep constant in this investigation.

[ 1 ]

(ii)

Calculate the rate, in ppm per s, of $\mathrm{CO}_{2}$ production for the respiring seeds.
rate = ppm per s

[ 2 ]

calculation method not marking points

1108-564=544

$544 \div 180$

= 3.0

full marks for correct answer allow 1 mark for 544 or ÷ 180

allow 544 from table

allow 3 or 3.02 or 3.022

allow from table

(iii)

Comment on the scientist's method and results.

[ 5 ]

An answer that makes reference to five of the following

1. high $\mathrm{CO}_{2}$ / most change (in $\mathrm{CO}_{2}$ ) produced in respiring seeds /eq

2. low $\mathrm{CO}_{2}$ / less change (in $\mathrm{CO}_{2}$ ) / produced in dry seeds / eq

3. no change (in $\mathrm{CO}_{2}$ ) normal air / eq

4. as dry seeds are not respiring / respiring very slowly / eq

5. enzymes are not active / less active / (in dry seeds) eq

6. no water for chemical / metabolic reactions / hydrolysis (in dry seeds) / eq

7. experiment not repeated / not reliable / eq

8. only done for short period / 3 minutes / eq

9. temperature not controlled / not stated / eq

10. could be aerobic or anaerobic / eq

slightly higher change in $\mathrm{CO}_{2}$ than no seeds

ignore respiration

[Maximum number: 3]

Aerobic respiration uses oxygen and produces ATP.

A scientist investigates the rates of aerobic respiration of some animals.

The scientist calculates the rate of respiration per gram of each animal.
The results are shown in the table.

Table for Question 4 — Edexcel IGCSE Biology

Explain why a mouse uses more oxygen per gram than a human.

[Maximum number: 2]

Aerobic respiration uses oxygen and produces ATP.

Complete the word equation for aerobic respiration.
oxygen + ......⟶ ......+ ......+ ATP

[Maximum number: 2]

Respiration is the process that provides energy for cells.
Respiration can be aerobic or anaerobic.

Give the word equation for anaerobic respiration in plants.

[Maximum number: 8]

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

(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 ]

(i)

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

[ 2 ]

(ii)

What is the function of the soda lime?

it absorbs carbon dioxide

it absorbs oxygen

it releases carbon dioxide

it releases oxygen

[ 1 ]

(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 $=\pi \times$ radius $^{2} \times$ distance

Calculate the volume of oxygen absorbed when the coloured liquid moves a distance of 6.0 mm.
[diameter of tube $=1.0 \mathrm{~mm}$ ]
volume = $\mathrm{cm}^{3}$

[ 3 ]

multiply by length

- determine volume

- correct answer

0.0047(13) /

$4.7(13) \times 10^{-3}(3)$

Award full marks for correct
numerical answer without
working
$3.142 \times 0.05 \times 0.05=$
0.007855
$\times 0.6=0.0047(13) /$ $4.7(13) \times 10^{-3}$
Allow one mark for
$\times 6.0 / \times 0.6 \mathrm{in}$ working
Allow two marks for
4.7 / 47 / 0.47 in working
Allow three marks for
$4.7 \mathrm{~mm}^{3}$

(b)

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

Figure for Question (b) — Edexcel IGCSE Biology

[ 2 ]

(i)

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

[ 2 ]

oxygen absorbed at 22 and 12

- calculation of percentage increase

Award full marks for correct numerical answer without working

rate at $22=1.6 \div 20=0.08$ and rate at $12=0.8 \div 20=0.04$

percentage increase = $(0.08-0.04) \div 0.04 \times 100$ = 100(\%)

Or

$(1.6-0.8) \div 0.8 \times 100$ = 100(\%)

One mark for 0.08 and 0.04 or 1.6 and 0.8 in working

All question bank results loaded

Covered syllabus points

Question 1

Question (a)

Question (b)

Question 2

Question 3

Question (a)

Question (b)

Question (i)

Question (ii)

Question (iii)

Question 4

Question 5

Question 6

Question 7

Question (a)

Question (i)

Question (ii)

Question (iii)

Question (b)

Question (i)