Fixing one carbon atom into sugar takes at least eight photons and stores per mole of .

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Problem

Fixing one carbon atom into sugar takes at least eight photons and stores

478\,\mathrm{kJ}

per mole of

\mathrm{CH_2O}

. ((a)) Find the energy of a mole of photons at

600\,\mathrm{nm}

, and the efficiency of the photochemical step for light of that wavelength. ((b)) A

\mathrm{C_4}

crop is capped at

6.0

per cent of incident sunlight. On a site with a year-round mean of

180\,\mathrm{W\,m^{-2}}

, find the largest dry-matter yield this allows, in tonnes per hectare per year, at

16\,\mathrm{MJ\,kg^{-1}}

. ((c)) The crop actually yields

20\,\mathrm{t\,ha^{-1}\,yr^{-1}}

. What fraction of its ceiling is that?

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