I have noticed a lot of discussions about photosynthesis, pearl, fixation of carbon by plants … So, I decided to try to write a text about photosynthesis in a form that is not very scientific but to explain the process so we can all understand about what is it about?
First, to clarify an essential thing. Photosynthesis is a term that defines, in fact, two clear processes that take place in the plant photosynthetic organ, the leaf. Although they are linked and ensure the continuity of the process.
So, we have PHOTO and SYNTHESIS.
PHOTO is the phase in which light is captured by chlorophyll pigments and in which light energy is converted into chemical energy. SYNTHESIS is the phase in which chemical energy is used to synthesize the plant’s own substances from a precursor, glucose. Let’s take them together …
We have a planted aquarium with different plants, with different requirements and rhythm of different growth. Some are planted in the substrate, others are caught by wood or stone, others are floating. The light turns on. Suddenly, the aquarium looks amazing, bright. Under certain conditions, after a while, small bubbles of oxygen, like glowing pearls, are gathered beneath the leaves and eventually rising to the surface of the water. Pearl, a phenomenon desired by all owners of planted aquariums although not necessarily or beneficial to plants.
What is happening? In the structure of leaves there is a formation called chlorophyll pigment. An “invention” of nature or a gift from God, which allows us to breathe the air that surrounds us. The chlorophyll is of two types, A and B. Each one is dedicated to the absorption of a range of different light spectrum, except in the green field. Ups! That’s why chlorophyll appears to be green, because this light-colored spectrum is reflected by chlorophyll. Otherwise, the light is absorbed and used in the PHOTO phase. Whether it is the red or yellow field, or the blue one, the two types of chlorophyll can use them. Radiation light contains photons. A rudimentary statement, but … you understand what I mean. This photon flux reaches the surface of the leaf and is absorbed by it. Here comes the first element of the photosynthetic process: water. That is H2O. That is, two molecules of hydrogen and one of oxygen (according to the valences of the two elements, obviously). Does the plant need oxygen? Does he need carbon? At this stage, no. At this point the plant needs the most important chemical element, without which no biosynthesis can be initiated: hydrogen. The unique and essential phenomenon is that photons activate electrons that separate water into components, oxygen and hydrogen. Each molecule of water releases an O and two H. Cool! Plants make water electrolysis! Awesome! However, the plant does not need so much oxygen. What to do with it? Give him the door out! On the underside of the leaves there are some formations called stomata (from the Greek “stoma”, everyone knows it). They have the appearance of two kidney-shaped formations, joining, defining and delimiting an orifice between them. Stoma! It is basically a kind of cheek-anal organ of the plant. It feeds there, eliminates there, breathes there. OK, not necessarily in this order. So, the leaf is filled with a “waste” resulting from the decomposition of water, oxygen. And if it’s waste, it will eliminate it. In extreme conditions, pearl. Here is a bracket: pearl is not a sign of plant decomposition! That’s called streaming. But, please, some still believe in stories.So, the leaf removes excess oxygen and remains with the hydrogen. Well, here I apologize, but I must be a bit more … scientific! Hydrogen, for the plant, is like hydrogen for Hindenburg: a source of energy. But how to use this source. Well, we have two substances that can combine with hydrogen and thus activate. These are ADP and NADP. Basically, they are the storage of the energy needed for the Synthesis phase, that of the carbon fixation and the synthesis of the self-substances. By adding hydrogen to them, we get ATP and NADPH. Scientists have also found a term for this: phosphorylation! The process is repetitive, so once they do their job, they return to their original form and take a portion of hydrogen.And with that, the PHOTO phase is over. It is what is called the light-dependent or Phase Hill phase. Her role is to capture an existing energy in the form of a radiation and transform it into another form of energy, the chemical energy the plant can use. Obviously, the process is continuous throughout the lighting. But to understand, we treat it separately. SYNTHESIS This is the most spectacular. Here we find out why it is useful to add CO2 to water and what is the most important chemical element on which plants depend. In this phase carbon dioxide is captured by the plant and converted to organic self-type structures. Attention: Carbon in CO2, not carbon in the beautiful story of liquid carbon (glutaraldehyde). He, he! There is a classification of plants according to the number of carbon atoms used for the synthesis of the primary organic substance. Depending on this, they are C3 plants and C4 plants. That is, plants that use 3 carbon atoms or 4 atoms in the primary biosynthesis process. OK, there are also CAM-type plants that can fix carbon in the form of a malt compound, without being dependent on light, but it’s not our case. There are various varieties of juices such as aloe. However, it is worth mentioning that such plants are welcome in our bedrooms. They do air purification during the night.So there comes the basic element of any organic system, carbon. It’s just about oxygen. Most plants are C3 type. So here comes Calvin’s Cycle. With the energy pumped by the PHOTO phase, the carbon is separated from the oxygen and introduced into a biosynthesis cycle. The plant produces the substance that is the precursor to the rest of the self-glucose: That is C6H12O6. It’s just a small problem here. Carbon dioxide is written as … CO2. If C remains O2. I hope now I understand the circuses why, even after the light is extinguished, the plants still pearls and why we do not have to stop the addition of CO2 once the light goes out (details in private, SMS). The Calvin cycle begins. Carbon passes through several successive phases and is incorporated into glucose. That is 2 x C3! Interesting, right? The plant produces a brick, which then, in the dark or light phase, “builds” the rest of the substances. Including pigments with which, under the stress of light, the plants look red or yellow. Here again I cannot help! Fertilizer manufacturers! Red from certain minerals does not cause but supports pigmentation. And with that, all done! We have everything we need to grow and differentiate plant organs and to support them healthy and beautiful. There would still be a topic: Optimal fertilization of plants. But this … in the next episode! REQUIRED REQUIREMENTS Biosynthesis does not depend only on the elements mentioned above. The important in the process are iron, manganese and potassium. We do not detail here that we are entering other areas. But one thing should be known: nutrients such as iron and manganese also occur in the physiology of plant tissue, not only in its structure. So, when you see a sign of deficiency in this element, that is a sign of the dysfunction of the plant tissue in physiological, not structural sense. Notice to fertilizer producers, when they give “professional” explanations to their group colleagues. NOTE: Colleagues with deeper knowledge of biology and chemistry, apologize for profane terms. This text is intended to explain a very complex phenomenon in accessible terms. For those who want very precise details, they are always at their disposal. An article written by my friend Silviu Man