Hello Readers, here we are posting some study notes on Biology. we hope that the below given post will be helpful to you all in he upcoming exams..- "photo" = light
- "synthesis" = putting together
Plants take in carbon dioxide from the air and water from the soil; put them together (in the presence of light energy and chlorophyll) to produce sugar (glucose) and oxygen.
Chlorophyll is the green pigment found in plants. Both chlorophyll and light energy need to be present for photosynthesis to take place, but they are not used up in the process.
Thus, the process of photosynthesis can be represented as follows:
| carbon dioxide + water | chlorophyll →→→→→→→→ light energy | sugar (glucose) + oxygen |
The chemical equation for this process is:
6CO2 + 12H2O + light → C6H12O6 + 6O2 + 6H2O
6 molecules of carbon dioxide (6CO2) and 12 molecules of water (12H2O) are consumed in the process, while glucose (C6H12O6), six molecules of oxygen (6O2), and six molecules of water (6H2O) are produced.
Carbon dioxide is obtained through tiny pores in plant leaves called stomata. Oxygen is also released through the stomata. Water is obtained by the plant through the roots and delivered to the leaves through vascular plant tissue systems.
Sunlight is absorbed by Chlorophyll, a green pigment located in plant cell structures called chloroplasts . Chloroplasts are the sites of photosynthesis. Chloroplasts contain several structures, each having specific functions:
Some of the sugar produced during photosynthesis is used by the plant for its life processes (such as growing and reproducing); the excess is converted mainly to starch and stored in various plant parts which may be used as food by animals and humans.
Oxygen produced during photosynthesis replenishes the oxygen that was used up by living things during respiration ... mouseover the above picture for more information on respiration.
This cycle of photosynthesis and respiration maintains the balance of carbon dioxide and oxygen on earth.
- Outer and inner membranes: protective coverings that keep chloroplast structures enclosed.
- Stroma: dense fluid within the chloroplast. Site of conversion of carbon dioxide to sugar.
- Thylakoid: flattened sac-like membrane structures. Site of conversion of light energy to chemical energy.
- Grana: dense layered stacks of thylakoid sacs. Sites of conversion of light energy to chemical energy.
- Chlorophyll: a green pigment within the chloroplast. Absorbs light energy.
| Photosynthesis | Respiration |
| Occurs in the presence of light (and chlorophyll in plant cells) | Occurs at all times in cells |
| Requires energy (light) to make sugar (glucose) | Releases energy from sugar |
| Complex substances (sugar) are formed from simpler ones. | Complex substances (sugar) are broken down into simpler ones. |
| Carbon dioxide and water are the raw materials. | Carbon dioxide and water are the waste products. |
| Oxygen is given out. | Oxygen is taken in. |
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