C1.3 Photosynthesis questions for IB Biology
42 questions on Photosynthesis, 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 | 9 | 11 | 20 |
| Paper 1B | 3 | 3 | 6 |
| Paper 2 | 9 | 7 | 16 |
| Every paper | 21 | 21 | 42 |
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.
Photosynthesis supplies most of the chemical energy used by organisms in an ecosystem. In what form is this energy stored by a photosynthesizing plant?
Chloroplasts were isolated from spinach (Spinacia oleracea) leaves in a cold isotonic buffer. Half of the suspension was used as intact chloroplasts. The other half was placed in distilled water for one minute and then returned to the isotonic buffer, which broke the outer double membrane (envelope) but left the thylakoids intact. Each preparation was kept in light or dark. In separate tubes, two rates were measured: the rate of reduction of DCPIP, a blue dye that accepts electrons from the light-dependent reactions, and the rate of carbon dioxide fixation, measured with radioactive hydrogencarbonate. Values are means of four replicates ± standard deviation.
Preparation | Condition | Rate of DCPIP reduction / μmol mg-1 chlorophyll h-1 | Rate of CO2 fixation / μmol mg-1 chlorophyll h-1 |
|---|---|---|---|
Intact | light | 21 ± 3 | 84 ± 7 |
Intact | dark | 1 ± 1 | 2 ± 1 |
Broken envelope | light | 63 ± 5 | 4 ± 2 |
Broken envelope | dark | 1 ± 1 | 1 ± 1 |
- (a)
Explain how placing the chloroplasts in distilled water broke their envelope.
2 marks
- (b)
Calculate the percentage decrease in the rate of CO2 fixation in light when the envelope was broken.
1 mark
- (c)
State the purpose of the tubes kept in the dark.
1 mark
- (d)
Explain why chloroplasts with broken envelopes fixed almost no carbon dioxide.
2 marks
- (e)
Suggest reasons for the higher rate of DCPIP reduction by chloroplasts with broken envelopes.
2 marks
- (f)
Evaluate the claim that these results show the light-dependent reactions occur in the thylakoids and carbon fixation occurs in the stroma.
2 marks
Organisms are adapted to the ecological niches that they occupy.
- (a)
Explain how natural selection could lead to adaptations in prey species that help them to resist predation.
7 marks
- (b)
Outline the differences between obligate anaerobes, facultative anaerobes and obligate aerobes, with reference to cell respiration.
4 marks
- (c)
Outline photosynthesis as a mode of nutrition, including the groups of organisms that use it.
4 marks
During photosynthesis, carbon dioxide is converted to glucose. What is the source of the hydrogen in the glucose?
Students ground spinach (Spinacia oleracea) leaves with propanone to extract the photosynthetic pigments. A small, concentrated spot of the extract was placed on a pencil line (the origin) 1.5 cm from the bottom of a thin-layer chromatography (TLC) plate. The plate was stood in a tank containing a shallow layer of solvent, below the origin, and removed when the solvent front was 84 mm above the origin. The table shows the spots that were seen.
Spot | Colour | Distance moved from origin / mm | Rf |
|---|---|---|---|
1 | orange-yellow | 79 | 0.94 |
2 | yellow | 48 | |
3 | blue-green | 36 | 0.43 |
4 | yellow-green | 25 | 0.30 |
- (a)
Calculate the Rf value of spot 2.
1 mark
- (b)
Identify the pigments in spots 1 and 3.
2 marks
- (c)
Explain why the origin line was drawn in pencil rather than in ink.
1 mark
- (d)
Suggest why the solvent level in the tank had to be below the origin.
1 mark
- (e)
Suggest reasons for the pigments moving different distances up the plate.
2 marks
Both plants and animals have surfaces specialised for exchanging gases with their environment.
- (a)
Outline the properties of gas-exchange surfaces.
4 marks
- (b)
Compare and contrast gas exchange in the lungs of a mammal and in the leaves of a dicotyledonous plant.
7 marks
- (c)
Outline the conversion of carbon dioxide into glucose in photosynthesis.
4 marks
Practice all 42 in Augment
Free with an account. Every question has its markscheme, and Augment keeps the ones you got wrong so you can come back to them.
More questions in Interaction and interdependence
- C1.1Enzymes and metabolism
- C1.2Cell respiration
- C1.3PhotosynthesisThis page
- 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 matter
Check your answers in Augment
A free account opens all 42 questions on Photosynthesis with their markschemes, and keeps a record of what you have marked.