To investigate the effect of carbon dioxide concentration on the rate of photosynthesis

Objective
To investigate the effect of carbon dioxide concentration on the rate of photosynthesis

Introduction
Photosynthesis is a process that is essential for every living organism. Organic substances, such as glucose, are made from carbon dioxide and water by light energy from the sun. The light energy is absorbed by chlorophyll and converted to chemical energy. During the process, oxygen is released as a by-product.

The rate of photosynthesis is affected by a few of factors, including light intensity, temperature, availability of water and carbon dioxide concentration.

The purpose of this experiment was to study about how the variation of carbon dioxide concentration would affect the rate of photosynthesis. This set-up was chosen rather than just counting the number of bubbles as it was more accurate. The errors of missing the bubbles and the difference of the sizes of the bubbles can be eliminated. Also, boiling tube was used instead of beaker to hold the Hydrilla plant because of the smaller surface area which can provide a more obvious change in the liquid level. To obtain the results more quickly, 200-watt bench lamp can be used to provide a higher light intensity.

Investigate The Effect Of Bicarbonate Concentration On The Rate Of Photosynthesis In Asystasia Leaves
Lucas T.

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

Variables Independent...
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