Beet Photosynthesis Lab Report

Photosynthesis is a crucial energy conversion process that occurs in the chloroplasts of eukaryotic cells. The rate of photosynthetic activity holds importance in environmental, horticultural and agricultural situations. (Boardman, N.K. 1977). Pigments in the chloroplasts thylakoid membrane absorb the electromagnetic radiation from a light source and release an electron into the electron transport chain. DCPIP’s chemical ability to favourably accept electrons, and undergo a colour change from blue to clear when reduced, (Trebst, A. 2007) was utilised to measure the photosynthetic activity in silver beet chloroplasts.
The rate of DCPIP reduction was measured at varying distances from the light source. Assays with a spectrophotometer were performed to find and compare the absorbance, and hence quantitative effects of light intensity on the chloroplasts. The aim was to determine how the quantity of light affects the rate of photosynthetic activity in silver beet (beta vulgaris) chloroplasts. The greatest rate of photosynthetic activity is expected to occur at the point of highest light intensity, that is the point closest to the light source, as the photons
The lower rates of photosynthetic activity in this experiment corresponded to less of a colour change in the chloroplast DCPIP solution. Therefore suggesting low rates are due to a decreased rate of electron flow through the electron transport chain (Boardman, N.K. 1977). The relatively constant rate of the negative control, from which light was eliminated, displays DCPIP did not reduce, thus inferring that it did not undergo the process of photosynthesis. The absorbance readings of DCPIP replicates remained reasonably constant across the varied distances after 8 minutes of light exposure, indicating that photosynthetic activity did not occur. This eliminated the possibility of the DCPIP itself affecting the experimental