大象传媒

When plants respire, they use oxygen in the air producing carbon dioxide and water. But in the light, plants photosynthesise. This clip investigates the gas exchange and respiration of plants in the dark which means no photosynthesis can take place. A tube is used to pass pure oxygen into a bell jar. From the bell jar, another tube passes the outlet gas through a bi-carbonate indicator which by morning has turned yellow indicating that the plant produced carbon dioxide without any light. The experiment proves that plants respire at night as well as during the day and looks at why plants need to respire - to release energy to help them grow, move, reproduce, take up minerals and produce specialised cells.