How do photosynthesis work

The wavelength — distance between waves — determines energy level. Some of those wavelengths are visible to us as the colors we see. If a molecule, such as chlorophyll, has the right shape, it can absorb the energy from some wavelengths of light. Chlorophyll can absorb light we see as blue and red. Green is the wavelength plants reflect, not the color they absorb. While light travels as a wave, it also can be a particle called a photon.

Photons have no mass. They do, however, have a small amount of light energy. When a photon of light from the sun bounces into a leaf, its energy excites a chlorophyll molecule. That photon starts a process that splits a molecule of water. The oxygen atom that splits off from the water instantly bonds with another, creating a molecule of oxygen, or O 2.

Both of these allow a cell to store energy. Notice that the light reaction makes no sugar. This is where sugar is made. But the light reaction does produce something we use: oxygen. All the oxygen we breathe is the result of this step in photosynthesis, carried out by plants and algae which are not plants the world over.

The next step takes the energy from the light reaction and applies it to a process called the Calvin cycle. The cycle is named for Melvin Calvin, the man who discovered it. The Calvin cycle is sometimes also called the dark reaction because none of its steps require light. But it still happens during the day. This is the space inside the chloroplast but outside the thylakoid membranes.

National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.

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These primary producers form the base of an ecosystem and fuel the next trophic levels. Without this process, life on Earth as we know it would not be possible. We depend on plants for oxygen production and food. Learn more about this vital process with these classroom resources. Chlorophyll is a pigment that gives plants their green color, and it helps plants create their own food through photosynthesis.

What does a plant leaf have to do with the solar energy panels on the White House? Producers convert water, carbon dioxide, minerals, and sunlight into the organic molecules that are the foundation of all life on Earth.

Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Image Green Tree Leaves The plant leaves are green because that color is the part of sunlight reflected by a pigment in the leaves called chlorophyll. Photograph courtesy of Shutterstock. During the Calvin Cycle, the following steps take place:.

Embedded within the thylakoid membrane are two light-capturing systems: photosystem I and photosystem II comprised of multiple antenna-like proteins which is where the plant's leaves change light energy into chemical energy. Photosystem I provides a supply of low-energy electron carriers while the other delivers the energized molecules where they need to go. Chlorophyll is the light-absorbing pigment, inside the leaves of plants and trees, that begins the photosynthesis process.

As an organic pigment within the chloroplast thylakoid, chlorophyll only absorbs energy within a narrow band of the electromagnetic spectrum produced by the sun within the wavelength range of nanometers nm to nm. Called the photosynthetically active radiation band, green sits in the middle of the visible light spectrum separating the lower energy, but longer wavelength reds, yellows and oranges from the high energy, shorter wavelength, blues, indigoes and violets.

As chlorophylls absorb a single photon or distinct packet of light energy, it causes these molecules to become excited. Once the plant molecule becomes excited, the rest of the steps in the process involve getting that excited molecule into the energy transport system via the energy carrier called nicotinamide adenine dinucleotide phosphate or NADPH, for delivery to the second stage of photosynthesis, the Dark Reaction phase or the Calvin Cycle. After entering the electron transport chain , the process extracts hydrogen ions from the water taken in and delivers it to the inside of the thylakoid, where these hydrogen ions build up.

The ions pass across a semi-porous membrane from the stromal side to the thylakoid lumen, losing some of the energy in the process, as they move through the proteins existing between the two photosystems. The hydrogen ions gather in the thylakoid lumen where they wait for re-energization before participating in the process that makes Adenosine triphosphate or ATP, the energy currency of the cell.

The antenna proteins in photosystem 1 absorb another photon, relaying it to the PS1 reaction center called P This is where the plant cell converts light energy into chemical energy. The chloroplast coordinates the two stages of photosynthesis to use light energy to make sugar. The thylakoids inside the chloroplast represent the sites of the light reactions, while the Calvin Cycle occurs in the stroma.

Cellular respiration, tied to the photosynthesis process, occurs within the plant cell as it takes in light energy, changes it to chemical energy and releases oxygen back into the atmosphere. Respiration occurs within the plant cell happens when the sugars produced during the photosynthetic process combines with oxygen to make energy for the cell, forming carbon dioxide and water as byproducts of respiration.

Cellular respiration occurs in all the plant's living cells, not only in the leaves, but also in the roots of the plant or tree. Since cellular respiration does not need light energy to occur, it can occur in either the day or night. But overwatering plants in soils with poor drainage causes a problem for cellular respiration, as inundated plants cannot take in enough oxygen through their roots and transform glucose to uphold the cell's metabolic processes.

If the plant receives too much water for too long, its roots can be deprived of oxygen, which can essentially stop cellular respiration and kill the plant. University of California Merced Professor Elliott Campbell and his team of researchers noted in an April article in "Nature," an international journal of science, that the photosynthesis process increased dramatically during the 20th century.

The research team discovered a global record of the photosynthetic process straddling two hundred years. This led them to conclude that the total of all plant photosynthesis on the planet grew by 30 percent during the years they researched. While the research did not specifically identify the cause of an uptick in the photosynthesis process globally, the team's computer models suggest several processes, when combined, that could result in such a large increase in global plant growth.

The models showed that the leading causes of increased photosynthesis includes increased carbon dioxide emissions in the atmosphere primarily due to human activities , longer growing seasons because of global warming due to these emissions and increased nitrogen pollution caused by mass agriculture and fossil fuel combustion. Human activities that led to these results have both positive and negative effects on the planet. Professor Campbell noted that while increased carbon dioxide emissions stimulate crop output, it also stimulates the growth of unwanted weeds and invasive species.

He noted that increased carbon dioxide emissions directly cause climate change leading to more flooding along coastal areas, extreme weather conditions and an increase in ocean acidification, all of which have compounding effects globally.