What do you remember about photosynthesis we learned together in those years? Do you remember what photosynthesis is? Remember what it does? Today, let's review photosynthesis!
Photosynthesis what is photosynthesis: photosynthesis refers to the process that green plants use light energy to convert carbon dioxide and water into energy storing organic matter and release oxygen through chloroplasts. The important significance of photosynthesis is to transform inorganic matter into organic matter, transform and store solar energy, and make the content of oxygen and carbon dioxide in the atmosphere relatively stable. In short, photosynthesis is the fundamental source of survival, prosperity and development of almost all living things on the earth.
The place of photosynthesis and photosynthetic pigment leaf are the main organs of photosynthesis, chloroplast is the important organelle of photosynthesis. Photosynthetic pigments are distributed on the thylakoid membrane of chloroplast, and there are many enzymes needed for photosynthesis in thylakoid membrane and stroma.
There are three kinds of pigments in chloroplasts: 1) chlorophyll, mainly chlorophyll a and chlorophyll B. Most of chlorophyll a and all of chlorophyll b have the function of collecting light energy, and a few of chlorophyll a molecules in different states have the function of converting light energy into electric energy. 2) Carotenoids, including carotene and lutein. Besides the function of collecting light energy, they also have the function of preventing light from damaging chlorophyll. ③ Phycobilidin is the main pigment for photosynthesis of algae.
The total reaction formula of photosynthesis is summarized as follows:
CO2＋H2O（CH2O）＋O2
1. Photoreaction stage
It is a photochemical reaction caused by light, which is carried out on the thylakoid of chloroplast, including two steps: 1. The absorption, transmission and conversion of light energy are completed through the primary reaction. This process converts light energy into electricity. 2. The conversion of electric energy into active chemical energy is completed by electronic transmission and photophosphorylation. As a result, the active chemical energy converted from electrical energy is stored in ATP and NADPH2.
2. Dark reaction stage
It is a chemical reaction catalyzed by a number of enzymes, which does not need light and is carried out in the stroma of chloroplast. Dark reaction is a process in which active chemical energy changes into stable chemical energy, which is completed by carbon assimilation. The pathways of carbon assimilation are Calvin cycle (C3 pathway), C4 pathway and Crassulaceae acid metabolism (CAM). Calvin cycle is the main form of carbon assimilation, which can be roughly divided into three stages: 1. Carboxylation stage (CO2 fixation). 2. Restore stage. 3. Update stage. According to the different initial photosynthetic products of carbon assimilation, higher plants are divided into C3 plants and C4 plants.
The influence of external conditions on Photosynthesis in the process of photosynthesis mainly includes light intensity, carbon dioxide concentration, temperature and water content.