The light reactions of photosynthesis use _____ and produce _____.

Here is the answer and explanation to the question: The light reactions of photosynthesis use _ and produce _.

This is a biology question, we post it here as a biology practice for MCAT practice tests.

The light reactions of photosynthesis use _ and produce _.

When the plant is photosynthesizing, what do the light reactions of photosynthesis use? And produce what? In another way, the question is: True or false? the light-dependent reactions of photosynthesis use water and produce oxygen.

1. water, NADPH
2. carbon dioxide, sugar
3. carbon dioxide, oxygen
4. NADPH, oxygen
5. NADPH, NADP+

Photosynthesis

Photosynthesis is a process in which green plants absorb light energy and synthesize carbon dioxide and water into energy-rich organic matter, while releasing oxygen, and consists of two main stages: light and dark reactions.

The process of Photosynthesis involves light absorption, electron transfer, photosynthetic phosphorylation, carbon assimilation and other important reaction steps. It is important to realize the energy conversion in nature and maintain the carbon-oxygen balance in the atmosphere.

The meaning of Photosynthesis

1. Conversion of solar energy into chemical energy

When plants assimilate inorganic carbons, they convert solar energy into chemical energy, which is stored in the organic compounds they form.

Each year, photosynthesis assimilates about 10 times more solar energy than is required by humans. The chemical energy stored in organic matter is more important as a source of energy for human nutrition and activities, in addition to being used by the plants themselves and all heterotrophs.

Thus it can be said that photosynthesis provides the main source of energy today. Green plants are a giant energy conversion station.

2. Maintaining the carbon-oxygen balance in the atmosphere

The ability of the atmosphere to regularly maintain an oxygen content of 21% is largely dependent on photosynthesis.

Photosynthesis provides the conditions for aerobic respiration on the one hand. On the other hand, as oxygen accumulates, an ozone (O3) layer gradually forms in the surface layer of the atmosphere.

The ozone layer absorbs the strong ultraviolet radiation from sunlight that is harmful to living organisms. Although photosynthesis by plants removes a large amount of CO2 from the atmosphere. However, the concentration of CO2 in the atmosphere is still increasing, mainly due to urbanization and industrialization.

3. Turning inorganic substances into organic substances

The scale of organic matter production by plants through photosynthesis is enormous. It is estimated that plants can absorb CO2 to synthesize approximately organic matter each year.

40% of the carbon assimilated by autotrophic plants on Earth is assimilated by phytoplankton, and the remaining 60% is assimilated by terrestrial plants.

The food, oil, fiber, wood, sugar, fruits, etc. that humans need are all derived from photosynthesis. Without photosynthesis, human beings would not have food and various daily necessities. In other words, without photosynthesis, there would be no human survival and development.

Reaction phase of Photosynthesis

Light reaction of photosynthesis

The Light reaction 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.

Another result of electron transfer is that protons in the matrix are pumped into the vesicle-like lumen and the transmembrane proton gradient formed drives ADP phosphorylation to generate ATP.

Light reaction phase of photosynthesis formula:

Dark reaction phase

The dark phase of the reaction uses the light reaction to generate NADPH and ATP for carbon assimilation and the reduction of gaseous carbon dioxide 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 phase.

Dark reaction phase of photosynthesis formula

Correct Answer

Below is the correct answer of the question: The light reactions of photosynthesis use _ and produce _.

The light reactions of photosynthesis use water and produce NADPH.

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