Practise chloroplast adaptations, pigment spectra, light-dependent reactions and the Calvin cycle while analysing chromatography, limiting factors and rate investigations.
Chloroplasts carry out photosynthesis.
Fig. 1.1 shows some structural features of a chloroplast and some processes that occur within it.
Fig. 1.1
Identify the structures labelled A in Fig. 1.1.
Explain how the structure and appearance of the granum, and the components labelled A, relate to their function.
Explain why pathway C is described as a cycle.
Environmental conditions such as light intensity affect plant physiology.
Use the letter X to identify a point on the sketch graph in Fig. 8.1 where light intensity is acting as a limiting factor on the rate of photosynthesis.
Fig. 8.1
An experiment investigated how light intensity affected gene expression in kale, Brassica oleracea sabellica.
- Two groups of kale plants were grown, with one group in high light intensity and one group in low light intensity. All other conditions were standardised.
- After the same period of time, messenger RNA (mRNA) was extracted from each group of kale plants.
- The mRNA was used to produce cDNA.
- The cDNA was hybridised with probes for 89621 kale genes on a microarray.
- The microarrays showed which genes were switched on (expressed) in each set of conditions.
The results showed that expression of 18\% of the genes was affected by light intensity.
- 14 % of the genes were switched on only in high light intensity.
- 4 % were switched on only in low light intensity.
Suggest why more genes were switched on only in plants growing in high light intensity compared to fewer genes that were switched on only in plants growing in low light intensity.
Photosynthesis is the energy transfer process that occurs in chloroplasts.
Fig. 5.1 shows some biochemical events that occur in a chloroplast during the light-dependent stage of photosynthesis. Photosystems I and II (PSI and PSII) and some associated proteins of the thylakoid membrane are shown.
Fig. 5.1
A and B are areas of the chloroplast. Name areas A and B.
A
B
The group of proteins labelled C, PSI and the protein labelled E are involved in a specific biochemical process during the light-dependent stage of photosynthesis.
Name this specific biochemical process and the protein labelled E.
process
E
Product D is used during the Calvin cycle.
Identify product D and describe its specific role in the Calvin cycle.
The rate at which plants use photosynthesis to transfer light energy into chemical energy that is stored in plant biomass can be measured in megajoules per square metre per year .
Fig. 5.2 compares the rates of energy transfer for different ecosystems.
Limiting factors affect the rate of photosynthesis.
Describe and suggest how the results for tropical forest, temperate forest and snow forest in Fig. 5.2 show the effect of limiting factors on photosynthesis.
Suggest reasons why grasslands and desert have a lower rate of energy transfer by photosynthesis than forests.
A student investigated the effect of temperature on the rate of photosynthesis at two different light intensities. The rate of photosynthesis was determined by measuring the rate of oxygen production of the plant.
Fig. 7.1 shows the result of the investigation.
rate of oxygen production
Fig. 7.1
With reference to Fig. 7.1, describe and explain the results of the investigation for the plant in low light intensity.
With reference to Fig. 7.1, describe and explain the results of the investigation for the plant in high light intensity above .
Describe the process that produces oxygen during non-cyclic photophosphorylation.