C4.2 Transfers of energy and matter questions for IB Biology
43 questions on Transfers of energy and matter, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.
- IB Biology
- Part of C Interaction and interdependence
- SL and HL
Questions by paper and level
SL and HL questions are for students at either level. HL only questions cover what only HL students study.
| Paper | SL and HL | HL only | All |
|---|---|---|---|
| Paper 1A | 20 | 0 | 20 |
| Paper 1B | 5 | 0 | 5 |
| Paper 2 | 18 | 0 | 18 |
| Every paper | 43 | 0 | 43 |
Counted on
Questions to try
Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.
A sealed glass jar containing soil, moss, water and small invertebrates has been kept on a sunny windowsill for several years. Which can enter and leave the jar?
Students investigated gas exchange in a small aquatic community. Boiling tubes were each filled with 20 cm3 of hydrogencarbonate indicator solution at pH 8.3 and sealed with a bung. The tubes contained either no organisms, a 5 cm shoot of pondweed (Elodea canadensis), two pond snails (Lymnaea stagnalis), or both the pondweed and the snails. Five tubes of each type were placed under a lamp and five were placed in darkness, all at 20 °C. After six hours the pH of the indicator in each tube was measured with a pH probe. A rise in pH shows a decrease in dissolved carbon dioxide and a fall in pH shows an increase.
Contents of tube | Mean final pH in light (± SD) | Mean final pH in dark (± SD) |
|---|---|---|
indicator only | 8.3 ± 0.1 | 8.3 ± 0.1 |
pondweed | 8.9 ± 0.1 | 7.9 ± 0.1 |
snails | 7.6 ± 0.2 | 7.6 ± 0.1 |
pondweed and snails | 8.6 ± 0.2 | 7.4 ± 0.1 |
- (a)
State two variables, other than temperature, that should have been kept constant in this investigation.
2 marks
- (b)
Explain the purpose of the tubes containing indicator only.
1 mark
- (c)
Explain the difference between the results for the tubes containing pondweed only in the light and in the dark.
2 marks
- (d)
Deduce, with a reason, whether the community in the tubes containing pondweed and snails acted as a carbon sink or a carbon source in the light and in the dark.
2 marks
- (e)
Outline how the pondweed and the snails in the same tube depend on each other for gases.
2 marks
- (f)
The sealed tubes are closed systems. State what can enter and leave a closed system.
1 mark
Organisms obtain energy and carbon compounds in a wide variety of ways.
- (a)
Describe mixotrophic nutrition in protists, with reference to Euglena.
4 marks
- (b)
Outline the role of saprotrophs in ecosystems.
4 marks
- (c)
Explain the transfer of energy through a food chain, and why food chains rarely have more than four or five trophic levels.
7 marks
Which community is sustained mainly by a source of energy other than sunlight?
Students measured the energy budget of caterpillars of the large white butterfly (Pieris brassicae) feeding on cabbage (Brassica oleracea) leaves. Ten caterpillars were each kept in a separate container with a weighed cabbage leaf for three days. The dry mass of leaf eaten, the dry mass of faeces (frass) produced and the increase in dry mass of each caterpillar were found. The initial dry mass of the caterpillars was estimated by drying a second sample of ten similar caterpillars. The energy content of each material was measured by burning dried samples in a calorimeter.
Material | Mean dry mass per caterpillar / g | Energy content / kJ g-1 | Mean energy per caterpillar / kJ |
|---|---|---|---|
leaf eaten | 0.240 | 18.0 | 4.32 |
frass produced | 0.130 | 15.0 | 1.95 |
increase in caterpillar mass | 0.040 | 22.0 | 0.88 |
- (a)
Calculate the mean energy per caterpillar that was released in cell respiration during the three days. Show your working.
2 marks
- (b)
Calculate the percentage of the energy in the leaf eaten that was converted into caterpillar biomass.
1 mark
- (c)
Explain why dry mass rather than fresh mass was measured.
2 marks
- (d)
Suggest why the initial dry mass was estimated from a second sample of caterpillars rather than measured on the caterpillars that were fed.
1 mark
- (e)
Outline what happens to the energy in the frass after it has been produced.
2 marks
Energy is transformed and transferred in ecosystems.
- (a)
Outline how light energy is absorbed and transformed into chemical energy in photosynthesis.
4 marks
- (b)
Explain how a hypothesis about the effect of a limiting factor on the rate of photosynthesis can be tested experimentally.
7 marks
- (c)
Outline how both autotrophs and heterotrophs release energy from carbon compounds, and why this energy is eventually lost from ecosystems as heat.
4 marks
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More questions in Interaction and interdependence
- C1.1Enzymes and metabolism
- C1.2Cell respiration
- C1.3Photosynthesis
- C2.1Chemical signallingHL only
- C2.2Neural signalling
- C3.1Integration of body systems
- C3.2Defence against disease
- C4.1Populations and communities
- C4.2Transfers of energy and matterThis page
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