Photosynthesis Coursework

Essay by sarahakagilly March 2004

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Photosynthesis is how plants get their food. The reason why plants have leaves, roots or being green is all linked to photosynthesis. In photosynthesis, a plant takes carbon dioxide from the air and water from the soil and uses the light from sunlight to turn them into food. Photosynthesis occurs only in the presence of light, and takes place in the chloroplasts of green plant cells. Photosynthesis can be defined as the production of simple sugars from carbon dioxide and water causing the release of sugar and oxygen.

The first food they make is glucose but that can be changed into other food types. Oxygen is also produced in photosynthesis, plants don't really need oxygen so they give it out as a waste product but saves a little to use for respiration (releasing energy from food). The sunlight is absorbed by green pigment called chlorophyll.

Much of the glucose is turned into other substances such as starch.

Starch is insoluble and so can be stored in the leaf without affecting water movement into and out of cells by osmosis.

The fact that all plants need light in order to photosynthesis has been proven several times in experiments, and so it is possible to say that without light, the plant would die. The reason that light intensity does affect the rate of photosynthesis is because as light, and therefore energy, falls on the chloroplasts in a leaf, it is trapped by the chlorophyll, which then makes the energy available for chemical reactions in the plant. So as the amount of sunlight, or in this case the light bulb, falls on the plant, more energy is absorbed, so more energy is available for the chemical reactions, and so more photosynthesis takes place in a given time.

The word equation for photosynthesis...