Question

why is photorespiration harmful to photosynthesis

Answer 1

Photorespiration refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP
causing some of the energy produced by photosynthesis to be wasted.

Answer 2

Visible light is the basic energetic driver of plant biomass production through photosynthesis. The constantly fluctuating availability of lightand other environmental factors means thatthe photosynthetic apparatus must be able to operate in adynamic fashion appropriate to the prevailing conditions. Dynamic regulationis achieved throughan array of homeostatic control mechanismsthat both respond to and influence cellular energy andreductant status. In addition, light availability and quality are continuously monitored by plants through photoreceptors. Outside the laboratory growth room, it is within the context of complex changes in energy and signalling status that plants must regulate pathways to deal with biotic challenges, and this can be influenced by changes in the highly energetic photosynthetic pathways and in the turnover of thephotosynthetic machinery. Because of this, defence responses are neither simple nor easily predictable, but rather conditioned by the nutritional and signalling status of the plant cell. This review discusses recent data and emergingconcepts of how recognized defence pathways interact with and are influenced by light-dependent processes. Particular emphasis is placed on the potential roles of the chloroplast, photorespiration, and photoreceptor-associated pathways in regulating the outcome of interactions between plants andpathogenic organisms.