(a(i))[3]
Explain why carbon dioxide enrichment is used in many glasshouses to raise crop plant yield.
(a(ii))[1]
Suggest a way in which the carbon dioxide concentration in a glasshouse may be increased.
(a(iii))[2]
Outline how carbon dioxide from a glasshouse gets into leaves.
(b(i))[2]
Calculate the percentage rise in energy used by the metal halide lamp compared with the fluorescent lamp. Give your answer to two significant figures.
(b(ii))[1]
State which type of lamp gives the greatest light intensity output per unit of electrical energy used.
(b(iii))[3]
Explain the possible consequences of excessive heat for plants in a glasshouse.