13.1 Photosynthesis as an energy transfer process
13.2 Investigation of limiting factors
13.3 Adaptations for photosynthesis
13.2 Investigation of limiting factors
13.3 Adaptations for photosynthesis
Photosynthesis is the energy transfer process that is the basis of much of life on Earth. It provides the basis of most food chains providing energy directly or indirectly for all other organisms. In eukaryotes, the process occurs within chloroplasts. Candidates use their knowledge of plant cells and leaf structure from the section on Cell structure while studying photosynthesis. Various environmental factors influence the rate at which photosynthesis occurs.
Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and unfamiliar contexts.
Learning outcomes
Candidates should be able to:
13.1 Photosynthesis as an energy transfer process
Light energy absorbed by chloroplast pigments in the light dependent stage of photosynthesis is used to drive reactions of the light independent stage that produce complex organic compounds.
Chromatography is used to identify chloroplast pigments and was also used to identify the intermediates in the Calvin cycle.
a) explain that energy transferred as ATP and reduced NADP from the light dependent stage is used during the light independent stage (Calvin cycle) of photosynthesis to produce complex organic molecules
b) state the sites of the light dependent and the light independent stages in the chloroplast
c) describe the role of chloroplast pigments (chlorophyll a, chlorophyll b, carotene and xanthophyll) in light absorption in the grana
d) interpret absorption and action spectra of chloroplast pigments e) use chromatography to separate and identify chloroplast pigments and carry out an investigation to compare the
chloroplast pigments in different plants (reference should be made to Rf values in identification)
f) describe the light dependent stage as the photoactivation of chlorophyll resulting in the photolysis of water and the transfer of energy to ATP and reduced NADP (cyclic and non-cyclic photophosphorylation should be described in outline only)
g) outline the three main stages of the Calvin cycle:
• fixation of carbon dioxide by combination with ribulose bisphosphate (RuBP), a 5C compound, to yield two molecules of GP (PGA), a 3C compound
• the reduction of GP to triose phosphate (TP) involving ATP and reduced NADP
• the regeneration of ribulose bisphosphate (RuBP) using ATP
h) describe, in outline, the conversion of Calvin cycle intermediates to carbohydrates, lipids and amino acids and their uses in the plant cell
13.2 Investigation of limiting factors
Environmental factors influence the rate of photosynthesis. Investigating these shows how they can
be managed in protected environments used in crop production.
a) explain the term limiting factor in relation to photosynthesis
b) explain the effects of changes in light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis
c) explain how an understanding of limiting factors is used to increase crop yields in protected environments, such as glasshouses
d) carry out an investigation to determine the effect of light intensity or light wavelength on the rate of photosynthesis using a redox indicator (e.g. DCPIP) and a suspension of chloroplasts (the Hill reaction)
e) carry out investigations on the effects of light intensity, carbon dioxide and temperature on the rate of photosynthesis using whole plants, e.g. aquatic plants such as Elodea and Cabomba
13.3 Adaptations for photosynthesis
All the stages of photosynthesis occur in the chloroplast. Some tropical crops have C4 metabolism and adaptations to maximise carbon dioxide fixation.
a) describe the relationship between structure and function in the chloroplast using diagrams and electron micrographs
b) explain how the anatomy and physiology of the leaves of C4 plants, such as maize or sorghum, are adapted for high rates of carbon fixation at high temperatures in terms of:
• the spatial separation of initial carbon fixation from the light dependent stage (biochemical details of the C4 pathway are required in outline only)
• the high optimum temperatures of the enzymes involved
Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and unfamiliar contexts.
Learning outcomes
Candidates should be able to:
13.1 Photosynthesis as an energy transfer process
Light energy absorbed by chloroplast pigments in the light dependent stage of photosynthesis is used to drive reactions of the light independent stage that produce complex organic compounds.
Chromatography is used to identify chloroplast pigments and was also used to identify the intermediates in the Calvin cycle.
a) explain that energy transferred as ATP and reduced NADP from the light dependent stage is used during the light independent stage (Calvin cycle) of photosynthesis to produce complex organic molecules
b) state the sites of the light dependent and the light independent stages in the chloroplast
c) describe the role of chloroplast pigments (chlorophyll a, chlorophyll b, carotene and xanthophyll) in light absorption in the grana
d) interpret absorption and action spectra of chloroplast pigments e) use chromatography to separate and identify chloroplast pigments and carry out an investigation to compare the
chloroplast pigments in different plants (reference should be made to Rf values in identification)
f) describe the light dependent stage as the photoactivation of chlorophyll resulting in the photolysis of water and the transfer of energy to ATP and reduced NADP (cyclic and non-cyclic photophosphorylation should be described in outline only)
g) outline the three main stages of the Calvin cycle:
• fixation of carbon dioxide by combination with ribulose bisphosphate (RuBP), a 5C compound, to yield two molecules of GP (PGA), a 3C compound
• the reduction of GP to triose phosphate (TP) involving ATP and reduced NADP
• the regeneration of ribulose bisphosphate (RuBP) using ATP
h) describe, in outline, the conversion of Calvin cycle intermediates to carbohydrates, lipids and amino acids and their uses in the plant cell
13.2 Investigation of limiting factors
Environmental factors influence the rate of photosynthesis. Investigating these shows how they can
be managed in protected environments used in crop production.
a) explain the term limiting factor in relation to photosynthesis
b) explain the effects of changes in light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis
c) explain how an understanding of limiting factors is used to increase crop yields in protected environments, such as glasshouses
d) carry out an investigation to determine the effect of light intensity or light wavelength on the rate of photosynthesis using a redox indicator (e.g. DCPIP) and a suspension of chloroplasts (the Hill reaction)
e) carry out investigations on the effects of light intensity, carbon dioxide and temperature on the rate of photosynthesis using whole plants, e.g. aquatic plants such as Elodea and Cabomba
13.3 Adaptations for photosynthesis
All the stages of photosynthesis occur in the chloroplast. Some tropical crops have C4 metabolism and adaptations to maximise carbon dioxide fixation.
a) describe the relationship between structure and function in the chloroplast using diagrams and electron micrographs
b) explain how the anatomy and physiology of the leaves of C4 plants, such as maize or sorghum, are adapted for high rates of carbon fixation at high temperatures in terms of:
• the spatial separation of initial carbon fixation from the light dependent stage (biochemical details of the C4 pathway are required in outline only)
• the high optimum temperatures of the enzymes involved
No comments:
Post a Comment