Most sugars synthesised by plants are used as respiratory substrates; the rest are used to make other biological molecules forming plant biomass
Plants use most of the sugar they make as fuel for respiration. They convert the remaining sugar into other molecules, which build up the plant's body.
Real World
An oak tree uses most of its daily glucose output for respiration to fuel active transport in root cells, but channels the remainder into cellulose — which is why mature oaks can weigh over 10 tonnes.
Exam Focus
Distinguish 'respiratory substrate' (fuel broken down for ATP) from 'biomass' (structural molecules retained in the organism).
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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