How fast does photosynthesis take place

The speed of photosynthesis changes depending on the environmental light intensity, carbon dioxide and water availability, temperature and the amount of chlorophyll present in an organism. All these factors change throughout the day so how fast photosynthesis occurs is continually variable. In addition to daily cycles, the rate of photosynthesis changes throughout the seasons. This is why in winter, when temperatures are cold, many species of trees shed their leaves to go into a dormant state as their photosynthetic processes are too inefficient to balance the energetic cost of maintaining their leaves.

On one end of the scale, photosynthesis cannot occur without sufficient quantities of light, carbon dioxide, water or heat. Therefore, as each of these factors' availability increases, the rate of photosynthesis also increases.

However, infinitely increasing each of these factors doesn't continually enhance the speed of photosynthesis. This is because there are thresholds of each factor that are eventually too high and stop cells from functioning efficiently.

Different organisms have different compensation points depending on their environmental adaptations. For example, shade-adapted plants have a lower compensation point for light intensity than plants suited to full-sun environments.

The palisade layer contains most of the chloroplast and principal region in which photosynthesis is carried out. The airy spongy layer is the region of storage and gas exchange.

The stomata regulate carbon dioxide and water balance. In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a chloroplast. For plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts have a double membrane envelope composed of an outer membrane and an inner membrane. Within the double membrane are stacked, disc-shaped structures called thylakoids.

Embedded in the thylakoid membrane is chlorophyll, a pigment that absorbs certain portions of the visible spectrum and captures energy from sunlight. Chlorophyll gives plants their green color and is responsible for the initial interaction between light and plant material, as well as numerous proteins that make up the electron transport chain.

The thylakoid membrane encloses an internal space called the thylakoid lumen. Structure of the Chloroplast : Photosynthesis takes place in chloroplasts, which have an outer membrane and an inner membrane. Stacks of thylakoids called grana form a third membrane layer. Light-dependent and light-independent reactions are two successive reactions that occur during photosynthesis. Just as the name implies, light-dependent reactions require sunlight. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and converted into stored chemical energy, in the form of the electron carrier molecule NADPH nicotinamide adenine dinucleotide phosphate and the energy currency molecule ATP adenosine triphosphate.

The light-dependent reactions take place in the thylakoid membranes in the granum stack of thylakoids , within the chloroplast. The two stages of photosynthesis : Photosynthesis takes place in two stages: light-dependent reactions and the Calvin cycle light-independent reactions.

The process that converts light energy into chemical energy takes place in a multi-protein complex called a photosystem. Each photosystem plays a key role in capturing the energy from sunlight by exciting electrons.

Photosystems consist of a light-harvesting complex and a reaction center. Pigments in the light-harvesting complex pass light energy to two special chlorophyll a molecules in the reaction center. The light excites an electron from the chlorophyll a pair, which passes to the primary electron acceptor. The excited electron must then be replaced. However, changing the color of light is not as easy as it seems. The green light has to pass through different phycobiliprotein molecules, which absorb light of one color and give out light of another color.

The color that is given out is then taken up by a second phycobiliprotein, which turns it into a third color. This process continues until the emitted light is red, which can finally be taken up by Chl.

For this whole process to take place, we have three different kinds of phycobiliprotein molecules arranged as a sort of a hat over the Chl molecule, as you can see in Figure 3. These three kinds of phycobiliproteins are:. The reason phycobiliproteins absorb light of different colors is that they contain chemical molecules called bilins inside them, which give them their bright colors.

These bilins are responsible for absorbing light of one color and emitting light of another color, thus causing a change in the color of light. Advanced instruments have let us analyze the arrangement of these molecules and proteins in the cyanobacteria. We know that phycobiliproteins are shaped like disks [ 3 ], and the disks are stacked on top of each other to form the hat-like structure. This assembly joins to the core, made of APC.

This entire structure is linked to Chl, which accepts the red light emitted by APC. The arrangement of the hat-like structure has been shown in Figure 3. The change in light color from green to red takes place through a process known as fluorescence. Let us see what fluorescence is. Imagine a transparent container filled with a pink-colored liquid that, when illuminated with a flashlight, shines a bright orange!

That is exactly what CPE does Figure 4. 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.