Investigate The Effect Of Bicarbonate Concentration On The Rate Of Photosynthesis In Asystasia Leaves
Background information Photosynthesis is the process by which autotrophic organisms use light energy to convert carbon dioxide into sugars as their form of nutrition. Plants, algae and many species of bacteria carry out photosynthesis.
Photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product: light energy captured by chlorophyll 6 CO2 + 6 H2O C6H12O6 + 6 O2
This is a simplified equation of the two types of chemical reactions that occur in chloroplasts. They are the light dependent and light independent reactions. During the day, the limiting factor for photosynthesis is usually the amount of carbon dioxide and this is what will be investigated in this experiment. The rate of photosynthesis can be measured by measuring the rate of oxygen produced.
The leaf discs are extracted from the same area as much as possible to minimise inaccuracies caused by differences in chlorophyll density in different areas of the leaf. They are prepared for the experiment by subjecting them to a low-pressure environment so that air will come out of the leaf discs, causing them to sink. In this way, the time taken for them to float back up is measured, because a faster time means that the rate of photosynthesis is faster, so oxygen is produced faster in the leaf and this lowers the density of the leaf disc, causing it to float.
The time taken for the first three leaf discs to float up is measured so that if one leaf disc is a special case and a result significantly different from the others, it will not affect the results so much. In other words, an anomaly will not have that great an impact on the results.
Aim To investigate the effect of carbon dioxide concentration on the rate of photosynthesis in leaves
Hypothesis The greater the concentration of carbon dioxide, the faster the rate of photosynthesis