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Photosynthesis

Photosynthesis

Common Mistakes

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  1. Need help remembering the difference between a heterotroph and an autotroph? It helps to learn the roots of these words. "Troph" means feed, auto mean "self," and hetero means "different." Therefore, autotrophs are self-feeders, meaning that they can produce all the carbohydrates they need to survive.
      
  2. Remember that the chloroplast has three membranes. Count 'em: 1, 2, and 3. Two membranes surround the organelle, and the third surrounds the thylakoid inside. When we think about photosynthesis, it is the thylakoid membrane we discuss most. This location is where the light reactions occur. When it comes to chloroplasts, the beauty is on the inside.
      
  3. How to tell chlorophyll and chloroplast apart. Chlorophyll is the light-absorbing, green pigment that is found within the chloroplast; the chloroplast is the whole organelle that plants use to conduct photosynthesis.
      
  4. Do not confuse stomata, or the openings in leaves where gases enter the leaf, with stroma, which is the inner matrix of the chloroplast. Remember that the root word for stom means "mouth." The word stomach also relates to the word mouth. Think about a stomach or your mouth as an opening, like in a plant's stomata.
      
  5. Oxidizing and reducing agents messing you up? An oxidizing agent is not itself oxidized; it is doing the oxidizing. After it oxidizes another molecule, the poor molecule it stole an electron from is referred to as oxidized. However, the poor molecule is actually the reducing agent because he reduces the oxidizing agent, which is then referred to as reduced.
     
    Oxidizing agent → oxidizes → gains an electron → is reduced.
    Reducing agent → reduces → loses an electron → is oxidized.
      
  6. Equilibrium. What about it? Remember, the cell is all about equality. You might not be too happy if someone randomly gave your little brother $100 and only gave you $10, right? In the same way, the difference in proton concentration between the lumen and the stroma breaks the rule of equality. The result? The protons create a gradient, rushing into the stroma in search of equality. What good-hearted little subatomic particles. The cell then uses these protons to generate ATP and NADPH, which keeps the proton gradient a-goin'. A constant battle for equilibrium.
      
  7. The light-independent reactions are sometimes called the dark reactions. This might help you remember that they do not need light. However, the term is misleading because light-independent reactions do not need to happen at night. They can happen any old time, light or not. Light reactions, however, absolutely, positively need light to work.

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