B8 - Photosynthesis Flashcards
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Whats the balanced equation for photosynthesis ?
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6CO2 + 6H2O → C6H12O6 + 6O2
the arrow is the reaction with light
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Where does photosynthesis happen?
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Photosynthesis occurs in the chloroplasts of plant cells.
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What is Photosynthesis
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The endothermic reaction that transfers light energy to
chemical potential energy. CO² and H²O are converted into more complex molecules (glucose) that can be used for food.
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what factors affect the rate of photosynthesis?
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- Temperature : chemical reactions speed up as the temperature increases. However, as photosynthesis is controlled by enzymes, too high a temperature prevents photosynthesis
- Carbon dioxide concentration: the higher the concentration of CO² , the more is available for photosynthesis, so the rate of photosynthesis increases
- Light intensity :as the equation shows, photosynthesis requires light energy. So, the higher the light intensity, the higher the rate of photosynthesis.
- Amount of chlorophyll: more chlorophyll means more light can be absorbed. Some leaves have pale parts, as you may have seen, due to a lack of chlorophyll. The rate of photosynthesis is much lower in the pale parts compared to the green parts.
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what is the equation for light intensity
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light intensity =1/ (distance from source)²
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What is the word equation fror photosynthesis
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carbon dioxide + water → glucose + oxygen
the arrow is the reaction with light
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What is a limiting factor ?
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A limiting factor is substance that will run out first.
(once this is finished a reaction can no longer take place)
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Chlorophyll
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the green pigment in leaves that absorbs light for photosynthesis. Chlorophyll is found in chloroplasts.
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Why do plants do photosyntesis?
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The glucose produced in photosynthesis can be:
- Used in respiration in the cells of the plant
- Converted into starch for storage. Starch is good for storage as it is insoluble, so it doesn’t affect the osmosis occurring in the plant, unlike glucose.
- Used to produce fats or lipids for storage. This is particularly
- Used to produce cellulose, which is a component of the cell wall.
- Used to produce amino acids, whichare used to synthesise proteins (in the ribosomes). To produce amino acids, plants also require nitrates from the soil.
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How do you test for starch ?
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Starch turns iodine a blue black colour
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How do you test for Glucose ?
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Glucose turns Benedict’s solution orange-red when heated with it
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