Year: 2019
Type: article
Abstract: The effect of addition of herbicides or insecticide to the rate of photosynthesis or respiration in spinach leaf discs was studied. Spinach leaf discs floated in an illuminated bicarbonate solution as they photosynthesized and generated oxygen and sank in the dark as they respired and consumed oxygen. The rates of photosynthesis and respiration were calculated from the time for 50% of the leaf discs to float or to sink respectively. The ratio of the photosynthesis rate to the respiration rate (P/R) in the presence of different herbicides was calculated and compared against the control. It was found that a P/R rate < control was indicative of the herbicide disrupting electron transfer in Photosystem II or I upstream of the Calvin cycle, whereas a P/R > control was indicative of redox disruption in the mitochondrial electron transfer chain, the shikimate pathway or at sites downstream of the Calvin cycle. The magnitude of the P/R ratio to the control can potentially accurately determine the site of action of a particular herbicide on photoautotrophic organisms.
Source: Journal of High School Science
DOI: 10.64336/001c.7518
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2951851037