Introduction

Try sitting beneath a tree after dark and you may notice the air feels a little harder to breathe - at night, with no sunlight to drive photosynthesis, plants only take in oxygen and give out carbon dioxide, so CO2 tends to build up in the still air around them. This continuous release of CO2 is what we call respiration, and importantly it isn't just a night-time phenomenon - it goes on during the day as well, running alongside photosynthesis rather than instead of it. At its core, respiration is the breakdown of food substrates to release usable energy. This chapter follows that process as it happens inside a plant cell, examining exactly how respiration proceeds at the cellular level.