PHOTOSYNTHESIS

因為畢業多年啦, 希望我冇記錯啦:
有光的時候, 植物會用大部份細胞做photosynthesis 但同時亦會做repiration; 但因為做light reaction的細胞較多, 所以只會放出氧, 而夜間因為無光所以只會做 respiration 同 photosynthesis 的 dark reaction.
至於呢個 Light reaction 同 Dark reaction的問題, 其實兩個都係光合作用的過程, 只不過一個要光同一個唔使光, 細胞面先利用光將將葉綠素分解等到足夠的二氧化炭才做過程。
因為晚間唔會有光, 所以當被電解的葉綠素用完便不可再做dark reaction, 那麼只會做到respiration. 而光源是其中一個影響 respiration 同 photosynthesis 的 源頭, 所以做實驗時要用光
唔係再睇下面段文字我諗會好少少:
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 carbohydrates.
In the light reactions one molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytin, which passes the electron to a quinone molecule, allowing the start of a flow of electrons down an electron transport chain that leads to the ultimate reduction of NADP into NADPH. In addition, it serves to create a proton gradient across the chloroplast membrane; its dissipation is used by ATP Synthase for the concomitant synthesis of ATP. The chlorophyll molecule regains the lost electron by taking one from a water molecule through a process called photolysis, that releases oxygen gas as a waste product.
In the Light-independent or dark reactions the enzyme RuBisCO captures CO2 from the atmosphere and in a process that requires the newly formed NADPH, called the Calvin-Benson cycle releases three-carbon sugars which are later combined to form sucrose and starch.
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, the intensity of light, and the temperature.

light reaction in photosynthesis require light (i.e. only happen in day time)
dark reaction don't require light (i.e. can happen in day time or at night), but require product from light reaction to act as raw material in dark reaction
respiration can happen in day time or at night(i.e. happen all the time)
係day time,係可以同時有photosynthesis(light reaction and dark reaction)同respiration
係night,係可以同時有dark reaction of photosynthesis同respiration (但一定要day time時做左light reaction,出左ADP同NADPH2 先可以做dark reaction)

photosynthesis唔要oxygen,oxygen係light reaction of photosynthesis的by-product
but respiration(happen all the time) require oxygen

係day time,係咪可以同時有hotosynthesis同respiration ga?????
係night,係咪可以同時有hotosynthesis同respiration ga?????/

2句都岩
但係咁樣
photosynthesis 同 respiration
無論幾時都係同時進行中

因為day light 有陽光吸既light 就自然多啦
咁因為佢吸既 野多 釋放出既carbon dioxide 就自然多
但因為係夜晚 光少好多 吸得少d 釋放出既carbon dioxide 就自然會少d
(有時會無 因為直情係無光 無得放carbon dioxide)

就係因為咁樣 day light 既 carbon dioxide 會多過夜晚
同時佢又做既respiration 會釋放出oxygen
所以daylight 係釋放carbon dioxide 而night 就釋放oxygen 啦

2007-07-17 19:24:24 補充：
daylight 係 carbon dioxide 釋放得多過oxygen (唔好唔記得光合作用係要吸oxygen!)light 就oxygen釋放得多過carbon dioxide