Photosynthesis: It will cover the basics of this process, the word equation, what is needed for photosynthesis                                         and more.

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  • Created by: Anna Fox
  • Created on: 27-11-11 14:58



Green plants absorb light energy using chlorophyl in their leaves. They use it to react with carbon dioxide and water to make a sugar called glucose. The glucose is then used in respiration, or can be converted into a starch, or can be stored. Oxygen is produced as a by-product.                                                                         ^^^ This process is called PHOTOSYNTHESIS!

For photosynthesis to take place they need the following factors of: Teperature, Light intensity, carbon dioxide and concentration!

Plus: Plants need mineral ions, such as nitrate and magnesium for a healthy growth, as some plant suffer from poor growth conditions where mineral ions are dificent.

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Photosynthesis is the chemical change  which happens in the leaves of green plants. It is the first step in towards making food- not just for plants but ultimatly every animal on the planet!                                                                                    During this reaction carbon dioxide and water are conveted in to making glucose and oxygen. This reaction requires light energy which is absorbed by a green substance called chlorophyll.

Here is the word equation for photosynthesis:                                                                                                  Carbon dioxide+Water(+Light energy)---> Glucose+Oxygen

Plants absorb water through their roots, and carbon dioxide through their leaves. Some glucose is used for respiration, while some is converted into insoluable starch for storage. The stored starch can later be turned back into Glucose in respiration.

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Factors liminating phtosynthesis

Three factors can limit the speed of phtosynthesis: Light intensity, temperature and carbon dioxide concentration.

1. Without enough light intensity, a plant cannot photosynthesise very quickly, even though there may be plenty of carbon dioxide and water. increasing the light intensity will increase the speed of photosynthesis.

2. Sometimes photosynthesis is limited by the carbon dioxide concentration in the air. Even if there is plenty of light, a plant cannot photosynthesise if there is not enough carbon dioxide.

3. If it gets to cold the rate of phtosynthesis will decrease, also plants cannot photosynthesise if it gets to hot.

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Plants and minerals

Plants need a number of elements to stay alive. The most important are: Carbon, hydrogen and oxygen. Plants get hydrogen and oxygen from the water in the soil, and carbon and oxygen from carbon dioxide and oxygen from the atomsphere.

Water and carbon dioxide are used to synthesise food during photosynthesis. Oxygen is used to release energy from food during respiration.

In addition to these three elements plants also need minerals for healthy growth. These are absorbed through the roots as mineral ions are dissolved in the soil water. The two most important mineral ions needed for plants are: Nitrate ( for making amino acids, which are needed to make proteins.) And magnesium ( for making chlorophyll.

If plants do not get enough minerals its growth will be poor. It will suffer form difficiency syptoms: deficent in nitrate ( it will suffer from stunted growth) deficient in magnesium ( its leaves will turn yellow)

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