匿名
匿名 發問於 科學及數學生物學 · 1 十年前

photosynthesis

請問light reaction中

H ions and NADP combine ge過程係點樣??

正確的equation應該係點write?

advanced level write邊個先o岩?

Also,ATP ge energy for what?

NADPH有energy嗎?

更新:

無equation?

本書都有~只係唔知邊個o岩...

你講的是不是out of syllabus的...

果隻enzyme未聽過..

唔該講返d syl. ge野..

2 個解答

評分
  • 匿名
    1 十年前
    最愛解答

    Photosynthesis uses the energy of light to make the sugar, glucose. A simple general equation for photosynthesis follows.

    6 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O

    carbon dioxide + water + light energy → glucose + oxygen + water

    Photosynthesis occurs in two stages. In the first phase light-dependent reactions or photosynthetic reactions (also called the Light reactions) capture the energy of light and use it to make high-energy molecules. During the second phase, the light-independent reactions (also called the Calvin-Benson Cycle, and formerly known as the Dark Reactions) use the high-energy molecules to capture carbon dioxide (CO2) and make the precursors of glucose.

    In the light-dependent reactions the pigment chlorophyll absorbs light and loses an electron that travels down an electron transport chain producing the high energy molecules NADPH and ATP. The chlorophyll molecule regains its electron by taking one from a water molecule through a process called photolysis, that releases oxygen gas as a byproduct.

    In the Light-independent or dark reactions the enzyme RuBisCO captures CO2 from the atmosphere and in a complex process called the Calvin-Benson cycle releases 3-carbon sugars which are later combined to form glucose.

    Photosynthesis may simply be defined as the conversion of light energy into chemical energy by living organisms. It is affected by its surroundings and the rate of photosynthesis is affected by the concentration of carbon dioxide, light intensity and the temperature.

    [edit] In plants

    Most plants are photoautotrophs, which means that they are able to synthesize food directly from inorganic compounds using light energy -for example the sun, instead of eating other organisms or relying on nutrients derived from them. This is distinct from chemoautotrophs that do not depend on light energy, but use energy from inorganic compounds.

    The energy for photosynthesis ultimately comes from absorbed photons and involves a reducing agent, which is water in the case of plants, releasing oxygen as a waste product. The light energy is converted to chemical energy (known as light-dependent reactions), in the form of ATP and NADPH, which is used for synthetic reactions in photoautotrophs. Most notably plants use the chemical energy to fix carbon dioxide into carbohydrates and other organic compounds through light-independent reactions. The overall equation for carbon fixation (sometimes referred to as carbon reduction) in green plants is

    n CO2 + 2n H2O + ATP + NADPH → (CH2O)n + n H2O + n O2,

    Where n is defined according to the structure of the resulting carbohydrate.

    More specifically, carbon fixation produces an intermediate product, which is then converted to the final hexose carbohydrate products. These carbohydrate products are then variously used to form other organic compounds, such as the building material cellulose, as precursors for lipid and amino acid biosynthesis or as a fuel in cellular respiration. The latter not only occurs in plants, but also in animals when the energy from plants get passed through a food chain. Organisms dependent on photosynthetic and chemosynthetic organisms are called heterotrophs. In general outline, cellular respiration is the opposite of photosynthesis: glucose and other compounds are oxidised to produce carbon dioxide, water, and chemical energy. However, both processes actually take place through a different sequence of reactions and in different cellular compartments

  • 匿名
    1 十年前

    在photosystem I 的最後

    當兩粒電子到了eletron transport chain的末端

    有個enzyme叫ferredoxin會將d electron 送比NADP+

    NADP就會同一個proton合成

    NADPH

    冇equation的

    唔通寫

    2e- + NADP + H+ -------> NADPH...?

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