A-Level Biology AQA 7402

The light-dependent reaction in such detail as to show that:

• chlorophyll absorbs light, leading to photoionisation of chlorophyll
• some of the energy from electrons released during photoionisation is conserved in the production of ATP and reduced NADP
• the production of ATP involves electron transfer associated with the transfer of electrons down the electron transfer chain and passage of protons across chloroplast membranes and is catalysed by ATP synthase embedded in these membranes (chemiosomotic theory)
• photolysis of water produces protons, electrons and oxygen.

The light-independent reaction uses reduced NADP from the light-dependent reaction to form a simple sugar. The hydrolysis of ATP, also from the light-dependent reaction, provides the additional energy for this reaction.

The light-independent reaction in such detail as to show that:

• carbon dioxide reacts with ribulose bisphosphate (RuBP) to form two molecules of glycerate 3-phosphate (GP). This reaction is catalysed by the enzyme rubisco
• ATP and reduced NADP from the light-dependent reaction are used to reduce GP to triose phosphate
• some of the triose phosphate is used to regenerate RuBP in the Calvin cycle
• some of the triose phosphate is converted to useful organic substances.

Students should be able to:

• identify environmental factors that limit the rate of photosynthesis
• evaluate data relating to common agricultural practices used to overcome the effect of these limiting factors.

Required practical 7

Use of chromatography to investigate the pigments isolated from leaves of different plants, eg, leaves from shade-tolerant and shade-intolerant plants or leaves of different colours.

Required practical 8

Investigation into the effect of a named factor on the rate of dehydrogenase activity in extracts of chloroplasts.