Questions and Answers

Describe and carry out investigations using redox indicators, including DCPIP and methylene blue, and a suspension of chloroplasts to determine the effects of light intensity and light wavelength on the rate of photosynthesis

Explain the effects of changes in light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis

Explain that during photophosphorylation: • energetic electrons release energy as they pass through the electron transport chain (details of carriers are not expected) • the released energy is used to transfer protons across the thylakoid membrane • protons return to the stroma from the thylakoid space by facilitated diffusion through ATP synthase, providing energy for ATP synthesis (details of ATP synthase are not expected)

Explain that in non-cyclic photophosphorylation: • photosystem I (PSI) and photosystem II (PSII) are both involved • photoactivation of chlorophyll occurs • the oxygen-evolving complex catalyses the photolysis of water • ATP and reduced NADP are synthesised

Explain that in cyclic photophosphorylation: • only photosystem I (PSI) is involved • photoactivation of chlorophyll occurs • ATP is synthesised

State that cyclic photophosphorylation and non-cyclic photophosphorylation occur during the light-dependent stage of photosynthesis

Describe and use chromatography to separate and identify chloroplast pigments (reference should be made to Rf values in identification of chloroplast pigments)

Interpret absorption spectra of chloroplast pigments and action spectra for photosynthesis

Describe the role of chloroplast pigments (chlorophyll a, chlorophyll b, carotene and xanthophyll) in light absorption in thylakoids

State that within a chloroplast, the thylakoids (thylakoid membranes and thylakoid spaces), which occur in stacks called grana, are the site of the light-dependent stage and the stroma is the site of the light-independent stage