Which of these equations best summarizes photosynthesis?

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Which of these equations best summarizes photosynthesis?

When it comes to photosynthesis, Which of these equations best summarizes photosynthesis?

1. C₆H₁₂O₆ + 6O₂ → 6 CO₂ + 12H₂O
2. C₆H₁₂O₆ + 6O₂ → 6 CO₂ + 6H₂O + Energy
3. 6 CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
4. H₂O → 2H+ + 1/2 O₂ + 2e-
5. 6CO₂ + 6O₂ → C₆H₁₂O₆ + 6H₂O

Photosynthesis

The process by which green plants use light energy from the sun to assimilate CO2 and H2O, make organic matter, and release oxygen is called photosynthesis.

Photosynthesis is a relatively complex process. The organic matter produced by photosynthesis is mainly carbohydrates and releases energy.

In 1957, Emerson observed that when Chlorella Vulgaris was irradiated with far-red light supplemented with a little light of a slightly shorter wavelength, such as 650 nm, the quantum yield was higher than the sum of these two wavelengths of light alone.

This phenomenon of adding a shorter wavelength of light in addition to long-wave red light to promote photosynthetic efficiency is known as the dual-light gain effect or Emerson enhancement effect.

It was later learned that this is because photosynthesis requires the synergistic action of two photochemical reactions.

In the late 1990s, significant progress was made in the study of the dynamic structure and reaction mechanism of enzymes catalyzing photosynthetic phosphorylation of photosynthesis and oxidative phosphorylation of respiration.

Photosynthesis consists of a light reaction phase and a dark reaction phase.

The photoreaction phase is characterized by the light-driven transfer of electrons released from the oxidation of water molecules to NADP+ for its reduction to NADPH via an electron transfer system similar to the mitochondrial respiratory electron transfer chain.

The dark phase is the assimilation of carbon using light reactions to generate NADPH and ATP to reduce gaseous CO2 to sugar. Since this stage is essentially not directly dependent on light, but only on the availability of NADPH and ATP, it is called the dark reaction stage.

Therefore, the equation that best summarizes photosynthesis is:

6 CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.

CO2 assimilation

CO2 assimilation is an important aspect of the photosynthesis process. Carbon assimilation is the conversion of CO2 into organic substances such as sugars through and by a series of CO2 assimilation processes driven by.

There are three biochemical pathways for CO2 fixation in higher plants: the Calvin cycle, the C4 pathway, and the saprophytic acid metabolic pathway.

Among them, the Calvin cycle is the most basic pathway. It is also the only pathway that has the ability to synthesize products such as starch. The other two pathways are not common. In particular, the phenolic acid metabolic pathway can only play a role in fixing and running CO2, and cannot form products such as starch.

Photosynthetic rate

Photosynthetic rate is usually defined as the amount of carbon dioxide absorbed or oxygen released per unit of leaf area per unit of time. It can also be expressed as the amount of dry matter accumulated per unit of leaf area per unit of time.

Within a certain range, the higher the chlorophyll content, the stronger the photosynthesis. In the case of a leaf, for example, the photosynthetic rate is low in the youngest leaves. As the leaf grows, the photosynthetic rate intensifies and reaches a peak, and then the rate decreases as the leaf ages.

The photosynthetic rate of a crop varies from one reproductive period to another. The photosynthetic rate is generally strongest during the nutritional growth period and decreases at the end of growth. In rice, for example, the photosynthetic rate is faster during the tiller bloom and decreases when the rice spike is near maturity.

However, from a population perspective, the photosynthetic amount of a population is not only determined by the photosynthetic rate per unit leaf area but is also largely influenced by the total leaf area and population structure.

Photosynthesis is a photochemical reaction, so the photosynthetic rate increases or decreases with the increase or decrease of light intensity in the cupboard. In the dark, photosynthesis stops, while respiration releases CO2.

As light increases, the photosynthetic rate gradually increases and approaches the respiratory rate, and finally, the photosynthetic rate and respiratory rate reach a dynamic equilibrium.

The light intensity of the same leaf at the same time, when the CO2 absorbed during photosynthesis is equal to the CO2 released during photorespiration and respiration, is called the light compensation point.

At the light compensation point, plants form and consume organic matter in equal amounts and cannot accumulate dry matter. In contrast, dry matter is consumed in the evening. Therefore, the minimum light intensity required by plants must be higher than the light compensation point for normal plant growth from the whole day.

Organisms capable of photosynthesis

C3 plants

Plants that fix CO2 through the C3 pathway are called C3 plants. The starch they obtain from photosynthesis is stored in the chloroplasts because this is the site of the Calvin cycle.

C4 plants

Plants that fix CO2 through the C4 pathway are called C4 plants. They are mainly those plants that live in arid tropical regions.

Algae and bacteria

Eukaryotic algae, such as red algae, green algae, and brown algae, have chloroplasts like higher plants and are also capable of oxygen-producing photosynthesis. Light is absorbed by chlorophyll, and many algae have other different pigments in their chloroplasts that give them their different colors.

Bacteria that carry out photosynthesis do not have chloroplasts but are carried out directly by the cells themselves.

Cyanobacteria, which are prokaryotes, also contain chlorophyll and perform oxygen-producing photosynthesis in the same way as chloroplasts.

In fact, it is widely believed that chloroplasts evolved from cyanobacteria. Other photosynthetic bacteria have a variety of pigments called bacteriochlorophylls of mesophyll. However, they do not oxidize water to produce oxygen but use other substances, such as hydrogen sulfide, sulfur, or hydrogen, as electron donors.

CAM plants

If C4 plants are spatially staggered between CO2 fixation and the Calvin cycle, then crassulacean acid metabolism, CAM, is temporally staggered between the two. The plants that exercise this pathway are those with inflated fleshy leaves, such as bromeliads. These plants open their stomata at night to absorb CO2, which is also fixed by the Hatch-Slake pathway. In the morning the stomata are closed to avoid excessive water loss.

At the same time, the Calvin cycle starts in the leaf flesh cells. The CO2 fixation efficiency of these plants is also high.

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