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5 Cards in this Set
- Front
- Back
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There are three limiting factors that control the rate of photosynthesis. What is the first one?
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Not enough light slows down the rate of photosynthesis. Light provides the energy needed for photosynthesis. 1. If the light is raised, the rate of photosynthesis will increase, but only up to a certain point. 2. Beyond that, it won't make any difference because it'll be either the temperature or the CO2 level which is now the limiting factor. |
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There are three limiting factors that control the rate of photosynthesis. What is the second one?
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Too little carbon dioxide also slows it down. CO2 is one of the raw materials needed for photosynthesis . 1. As with light intensity, the amount of CO2 will only increase the rate of photosynthesis up to a point. 2. As long as light and CO2 are in plentiful supply then the limiting factor would be temperature. |
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There are three limiting factors that control the rate of photosynthesis. What is the third one?
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The temperature needs to be right. Photosynthesis works best when it's warm but not too hot. 1. If the temperature is too high, the plants enzymes will be denatured, so the rate rapidly decreases. 2. This happens at about 45 degrees Celsius. 3. Usually though, if the temperature is the limiting factor it's because it is too low and things need warming up a bit. |
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Where does oxygen produced in photosynthesis come from?
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Scientists have realised that plants release oxygen during photosynthesis, but they didn't know whether the oxygen came from oxygen or carbon dioxide (both of which contain oxygen atoms). It comes from water. |
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How did the scientists find out where oxygen came from?
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A scientist supplied plants with water containing an isotope of oxygen called oxygen 18. The carbon dioxide the plants received contained ordinary oxygen 16. It was found that when plants photosynthesised, they released oxygen 18. This shows that the oxygen came from the water that was supplied to the plant, not the carbon dioxide.
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