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Plants name in hausa to english.

Welcome to ‘Plants Name in Hausa,’ your comprehensive guide to discovering the rich and diverse world of flora through the lens of the Hausa language.

Plants name in Hausa

Explore the beauty of nature, one leaf at a time, as we provide you with the names of various plants , trees, and flowers in the Hausa language.

Whether you’re a botanist, a nature enthusiast, or simply curious about the Hausa language and its connection to the natural world, this resource is here to help you explore the green wonders of our planet. Join us on this educational journey as we bridge language and nature, one plant name at a time.

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ENCYCLOPEDIC ENTRY

Photosynthesis.

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.

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Learning materials, instructional links.

Photosynthesis (Google doc)

Most life on Earth depends on photosynthesis .The process is carried out by plants, algae, and some types of bacteria, which capture energy from sunlight to produce oxygen (O 2 ) and chemical energy stored in glucose (a sugar). Herbivores then obtain this energy by eating plants, and carnivores obtain it by eating herbivores.

The process

During photosynthesis, plants take in carbon dioxide (CO 2 ) and water (H 2 O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose. The plant then releases the oxygen back into the air, and stores energy within the glucose molecules.

Chlorophyll

Inside the plant cell are small organelles called chloroplasts , which store the energy of sunlight. Within the thylakoid membranes of the chloroplast is a light-absorbing pigment called chlorophyll , which is responsible for giving the plant its green color. During photosynthesis , chlorophyll absorbs energy from blue- and red-light waves, and reflects green-light waves, making the plant appear green.

Light-dependent Reactions vs. Light-independent Reactions

While there are many steps behind the process of photosynthesis, it can be broken down into two major stages: light-dependent reactions and light-independent reactions. The light-dependent reaction takes place within the thylakoid membrane and requires a steady stream of sunlight, hence the name light- dependent reaction. The chlorophyll absorbs energy from the light waves, which is converted into chemical energy in the form of the molecules ATP and NADPH . The light-independent stage, also known as the Calvin cycle , takes place in the stroma , the space between the thylakoid membranes and the chloroplast membranes, and does not require light, hence the name light- independent reaction. During this stage, energy from the ATP and NADPH molecules is used to assemble carbohydrate molecules, like glucose, from carbon dioxide.

C3 and C4 Photosynthesis

Not all forms of photosynthesis are created equal, however. There are different types of photosynthesis, including C3 photosynthesis and C4 photosynthesis. C3 photosynthesis is used by the majority of plants. It involves producing a three-carbon compound called 3-phosphoglyceric acid during the Calvin Cycle, which goes on to become glucose. C4 photosynthesis, on the other hand, produces a four-carbon intermediate compound, which splits into carbon dioxide and a three-carbon compound during the Calvin Cycle. A benefit of C4 photosynthesis is that by producing higher levels of carbon, it allows plants to thrive in environments without much light or water. The National Geographic Society is making this content available under a Creative Commons CC-BY-NC-SA license . The License excludes the National Geographic Logo (meaning the words National Geographic + the Yellow Border Logo) and any images that are included as part of each content piece. For clarity the Logo and images may not be removed, altered, or changed in any way.

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5.1 Overview of Photosynthesis

Learning objectives.

Summarize the process of photosynthesis
Explain the relevance of photosynthesis to other living things
Identify the reactants and products of photosynthesis
Describe the main structures involved in photosynthesis

All living organisms on earth consist of one or more cells. Each cell runs on the chemical energy found mainly in carbohydrate molecules (food), and the majority of these molecules are produced by one process: photosynthesis. Through photosynthesis, certain organisms convert solar energy (sunlight) into chemical energy, which is then used to build carbohydrate molecules. The energy used to hold these molecules together is released when an organism breaks down food. Cells then use this energy to perform work, such as cellular respiration.

Photosynthesis also results in the release of oxygen into the atmosphere. In short, to eat and breathe, humans depend almost entirely on the organisms that carry out photosynthesis.

Link to Learning

Click the following link to learn more about photosynthesis.

Solar Dependence and Food Production

Some organisms can carry out photosynthesis, whereas others cannot. An autotroph is an organism that can produce its own food. The Greek roots of the word autotroph mean “self” ( auto ) “feeder” ( troph ). Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae ( Figure 5.2 ). Oceanic algae contribute enormous quantities of food and oxygen to global food chains. Plants are also photoautotrophs , a type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. All organisms carrying out photosynthesis require sunlight.

Heterotrophs are organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms. The Greek roots of the word heterotroph mean “other” ( hetero ) “feeder” ( troph ), meaning that their food comes from other organisms. Even if the food organism is another animal, this food traces its origins back to autotrophs and the process of photosynthesis. Humans are heterotrophs, as are all animals. Heterotrophs depend on autotrophs, either directly or indirectly. Deer and wolves are heterotrophs. A deer obtains energy by eating plants. A wolf eating a deer obtains energy that originally came from the plants eaten by that deer. The energy in the plant came from photosynthesis, and therefore it is the only autotroph in this example ( Figure 5.3 ). Using this reasoning, all food eaten by humans also links back to autotrophs that carry out photosynthesis.

Everyday Connection

Photosynthesis at the grocery store.

Major grocery stores in the United States are organized into departments, such as dairy, meats, produce, bread, cereals, and so forth. Each aisle contains hundreds, if not thousands, of different products for customers to buy and consume ( Figure 5.4 ).

Although there is a large variety, each item links back to photosynthesis. Meats and dairy products link to photosynthesis because the animals were fed plant-based foods. The breads, cereals, and pastas come largely from grains, which are the seeds of photosynthetic plants. What about desserts and drinks? All of these products contain sugar—the basic carbohydrate molecule produced directly from photosynthesis. The photosynthesis connection applies to every meal and every food a person consumes.

Main Structures and Summary of Photosynthesis

Photosynthesis requires sunlight, carbon dioxide, and water as starting reactants ( Figure 5.5 ). After the process is complete, photosynthesis releases oxygen and produces carbohydrate molecules, most commonly glucose. These sugar molecules contain the energy that living things need to survive.

The complex reactions of photosynthesis can be summarized by the chemical equation shown in Figure 5.6 .

Although the equation looks simple, the many steps that take place during photosynthesis are actually quite complex, as in the way that the reaction summarizing cellular respiration represented many individual reactions. Before learning the details of how photoautotrophs turn sunlight into food, it is important to become familiar with the physical structures involved.

In plants, photosynthesis takes place primarily in leaves, which consist of many layers of cells and have differentiated top and bottom sides. The process of photosynthesis occurs not on the surface layers of the leaf, but rather in a middle layer called the mesophyll ( Figure 5.7 ). The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata .

In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a chloroplast . In plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts have a double (inner and outer) membrane. Within the chloroplast is a third membrane that forms stacked, disc-shaped structures called thylakoids . Embedded in the thylakoid membrane are molecules of chlorophyll , a pigment (a molecule that absorbs light) through which the entire process of photosynthesis begins. Chlorophyll is responsible for the green color of plants. The thylakoid membrane encloses an internal space called the thylakoid space. Other types of pigments are also involved in photosynthesis, but chlorophyll is by far the most important. As shown in Figure 5.7 , a stack of thylakoids is called a granum , and the space surrounding the granum is called stroma (not to be confused with stomata, the openings on the leaves).

Visual Connection

On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?

The Two Parts of Photosynthesis

Photosynthesis takes place in two stages: the light-dependent reactions and the Calvin cycle. In the light-dependent reactions , which take place at the thylakoid membrane, chlorophyll absorbs energy from sunlight and then converts it into chemical energy with the use of water. The light-dependent reactions release oxygen from the hydrolysis of water as a byproduct. In the Calvin cycle, which takes place in the stroma, the chemical energy derived from the light-dependent reactions drives both the capture of carbon in carbon dioxide molecules and the subsequent assembly of sugar molecules. The two reactions use carrier molecules to transport the energy from one to the other. The carriers that move energy from the light-dependent reactions to the Calvin cycle reactions can be thought of as “full” because they bring energy. After the energy is released, the “empty” energy carriers return to the light-dependent reactions to obtain more energy. The two-stage, two-location photosynthesis process was discovered by Joan Mary Anderson, whose continuing work over the subsequent decades provided much of our understanding of the process, the membranes, and the chemicals involved.

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English to Hausa

Plant names in Hausa and English

To learn Hausa language, common vocabulary is one of the important sections. Common Vocabulary contains common Hausa words that we can used in daily life. Plant are one part of common words used in day-to-day life conversations. If you are interested to learn Plant names in Hausa, this place will help you to learn all Plant names in English to Hausa language. Plant vocabulary words are used in daily life, so it is important to learn all Plant names in English to Hausa and play Hausa quiz and also play picture vocabulary, play some games so you get not bored. If you think too hard to learn Hausa language, then 1000 most common Hausa words will helps to learn Hausa language easily, they contain 2-letter words to 13-letter words. The below table gives the translation of Plant vocabulary words in Hausa.

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List of Plant names in Hausa

Here is the list of Plant in Hausa language and their pronunciation in English.

Plant names - Hausa

Top 1000 hausa words.

Here you learn top 1000 Hausa words, that is separated into sections to learn easily (Simple words, Easy words, Medium words, Hard Words, Advanced Words). These words are very important in daily life conversations, basic level words are very helpful for beginners. All words have Hausa meanings with transliteration.

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Here you learn top Hausa sentences, these sentences are very important in daily life conversations, and basic-level sentences are very helpful for beginners. All sentences have Hausa meanings with transliteration.

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what is the meaning of photosynthesis in hausa

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What is photosynthesis?

Photosynthesis is the process plants, algae and some bacteria use to turn sunlight, carbon dioxide and water into sugar and oxygen.

Photosynthetic processes
Photosynthesis equation
The carbon exchange
How do plants absorb sunlight?
Location of photosynthesis

Light-dependent reactions

The Calvin cycle

Types of photosynthesis

Additional resources.

Photosynthesis is the process used by plants, algae and some bacteria to turn sunlight into energy. The process chemically converts carbon dioxide (CO2) and water into food (sugars) and oxygen . The chemical reaction often relies on a pigment called chlorophyll, which gives plants their green color. Photosynthesis is also the reason our planet is blanketed in an oxygen-rich atmosphere.

Types of photosynthetic processes

There are two types of photosynthesis: oxygenic and anoxygenic. They both follow very similar principles, but the former is the most common and is seen in plants, algae and cyanobacteria.

During oxygenic photosynthesis, light energy transfers electrons from water (H2O) taken up by plant roots to CO2 to produce carbohydrates . In this transfer, the CO2 is "reduced," or receives electrons, and the water is "oxidized," or loses electrons. Oxygen is produced along with carbohydrates.

This process creates a balance on Earth, in which the carbon dioxide produced by breathing organisms as they consume oxygen in respiration is converted back into oxygen by plants, algae and bacteria.

Anoxygenic photosynthesis, meanwhile, uses electron donors that are not water and the process does not generate oxygen, according to "Anoxygenic Photosynthetic Bacteria" by LibreTexts . The process typically occurs in bacteria such as green sulfur bacteria and phototrophic purple bacteria.

The Photosynthesis equation

Though both types of photosynthesis are complex, multistep affairs, the overall process can be neatly summarized as a chemical equation.

The oxygenic photosynthesis equation is:

6CO2 + 12H2O + Light Energy → C6H12O6 + 6O2 + 6H2O

Here, six molecules of carbon dioxide (CO2) combine with 12 molecules of water (H2O) using light energy. The end result is the formation of a single carbohydrate molecule (C6H12O6, or glucose) along with six molecules each of oxygen and water.

Similarly, the various anoxygenic photosynthesis reactions can be represented as a single generalized formula:

CO2 + 2H2A + Light Energy → [CH2O] + 2A + H2O

The letter A in the equation is a variable, and H2A represents the potential electron donor. For example, "A" may represent sulfur in the electron donor hydrogen sulfide (H2S), according to medical and life sciences news site News Medical Life Sciences .

How is carbon dioxide and oxygen exchanged?

stomata are the gatekeepers of the leaf, allowing gas exchange between the leaf and surrounding air.

Plants absorb CO2 from the surrounding air and release water and oxygen via microscopic pores on their leaves called stomata.

When stomata open, they let in CO2; however, while open, the stomata release oxygen and let water vapor escape. Stomata close to prevent water loss, but that means the plant can no longer gain CO2 for photosynthesis. This tradeoff between CO2 gain and water loss is a particular problem for plants growing in hot, dry environments.

How do plants absorb sunlight for photosynthesis?

Plants contain special pigments that absorb the light energy needed for photosynthesis.

Chlorophyll is the primary pigment used for photosynthesis and gives plants their green color, according to science education site Nature Education . Chlorophyll absorbs red and blue light and reflects green light. Chlorophyll is a large molecule and takes a lot of resources to make; as such, it breaks down towards the end of the leaf's life, and most of the pigment's nitrogen (one of the building blocks of chlorophyll) is resorbed back into the plant, When leaves lose their chlorophyll in the fall, other leaf pigments such as carotenoids and anthocyanins begin to show. While carotenoids primarily absorb blue light and reflect yellow, anthocyanins absorb blue-green light and reflect red light, according to Harvard University's The Harvard Forest .

Pigment molecules are associated with proteins, which allow them the flexibility to move toward light and toward one another. A large collection of 100 to 5,000 pigment molecules constitutes an "antenna," according to an article by Wim Vermaas , a professor at Arizona State University. These structures effectively capture light energy from the sun, in the form of photons.

The situation is a little different for bacteria. While cyanobacteria contain chlorophyll, other bacteria, for example, purple bacteria and green sulfur bacteria, contain bacteriochlorophyll to absorb light for anoxygenic photosynthesis, according to " Microbiology for Dummies " (For Dummies, 2019).

Related: What if humans had photosynthetic skin?

Where in the plant does photosynthesis take place?

Plants need energy from sunlight for photosynthesis to occur.

Photosynthesis occurs in chloroplasts, a type of plastid (an organelle with a membrane) that contains chlorophyll and is primarily found in plant leaves.

Chloroplasts are similar to mitochondria , the energy powerhouses of cells, in that they have their own genome, or collection of genes, contained within circular DNA. These genes encode proteins that are essential to the organelle and to photosynthesis.

Inside chloroplasts are plate-shaped structures called thylakoids that are responsible for harvesting photons of light for photosynthesis, according to the biology terminology website Biology Online . The thylakoids are stacked on top of each other in columns known as grana. In between the grana is the stroma — a fluid containing enzymes, molecules and ions, where sugar formation takes place.

Ultimately, light energy must be transferred to a pigment-protein complex that can convert it to chemical energy, in the form of electrons. In plants, light energy is transferred to chlorophyll pigments. The conversion to chemical energy is accomplished when a chlorophyll pigment expels an electron, which can then move on to an appropriate recipient.

The pigments and proteins that convert light energy to chemical energy and begin the process of electron transfer are known as reaction centers.

When a photon of light hits the reaction center, a pigment molecule such as chlorophyll releases an electron.

The released electron escapes through a series of protein complexes linked together, known as an electron transport chain. As it moves through the chain, it generates the energy to produce ATP (adenosine triphosphate, a source of chemical energy for cells) and NADPH — both of which are required in the next stage of photosynthesis in the Calvin cycle. The "electron hole" in the original chlorophyll pigment is filled by taking an electron from water. This splitting of water molecules releases oxygen into the atmosphere.

Light-independent reactions: The Calvin cycle

Photosynthesis involves a process called the Calvin cycle to use energy stored from the light-dependent reactions to fix CO2 into sugars needed for plant growth.

The Calvin cycle is the three-step process that generates sugars for the plant, and is named after Melvin Calvin , the Nobel Prize -winning scientist who discovered it decades ago. The Calvin cycle uses the ATP and NADPH produced in chlorophyll to generate carbohydrates. It takes plate in the plant stroma, the inner space in chloroplasts.

In the first step of this cycle, called carbon fixation, an enzyme called RuBP carboxylase/oxygenase, also known as rubiso, helps incorporate CO2 into an organic molecule called 3-phosphoglyceric acid (3-PGA). In the process, it breaks off a phosphate group on six ATP molecules to convert them to ADP, releasing energy in the process, according to LibreTexts.

In the second step, 3-PGA is reduced, meaning it takes electrons from six NADPH molecules and produces two glyceraldehyde 3-phosphate (G3P) molecules.

One of these G3P molecules leaves the Calvin cycle to do other things in the plant. The remaining G3P molecules go into the third step, which is regenerating rubisco. In between these steps, the plant produces glucose, or sugar.

Three CO2 molecules are needed to produce six G3P molecules, and it takes six turns around the Calvin cycle to make one molecule of carbohydrate, according to educational website Khan Academy.

There are three main types of photosynthetic pathways: C3, C4 and CAM. They all produce sugars from CO2 using the Calvin cycle, but each pathway is slightly different.

The three main types of photosynthetic pathways are C3, C4 and CAM.

C3 photosynthesis

Most plants use C3 photosynthesis, according to the photosynthesis research project Realizing Increased Photosynthetic Efficiency (RIPE) . C3 plants include cereals (wheat and rice), cotton, potatoes and soybeans. This process is named for the three-carbon compound 3-PGA that it uses during the Calvin cycle.

C4 photosynthesis

Plants such as maize and sugarcane use C4 photosynthesis. This process uses a four-carbon compound intermediate (called oxaloacetate) which is converted to malate , according to Biology Online. Malate is then transported into the bundle sheath where it breaks down and releases CO2, which is then fixed by rubisco and made into sugars in the Calvin cycle (just like C3 photosynthesis). C4 plants are better adapted to hot, dry environments and can continue to fix carbon even when their stomata are closed (as they have a clever storage solution), according to Biology Online.

CAM photosynthesis

Crassulacean acid metabolism (CAM) is found in plants adapted to very hot and dry environments, such as cacti and pineapples, according to the Khan Academy. When stomata open to take in CO2, they risk losing water to the external environment. Because of this, plants in very arid and hot environments have adapted. One adaptation is CAM, whereby plants open stomata at night (when temperatures are lower and water loss is less of a risk). According to the Khan Academy, CO2 enters the plants via the stomata and is fixed into oxaloacetate and converted into malate or another organic acid (like in the C4 pathway). The CO2 is then available for light-dependent reactions in the daytime, and stomata close, reducing the risk of water loss.

Discover more facts about photosynthesis with the educational science website sciencing.com . Explore how leaf structure affects photosynthesis with The University of Arizona . Learn about the different ways photosynthesis can be measured with the educational science website Science & Plants for Schools .

This article was updated by Live Science managing editor Tia Ghose on Nov. 3, 2022.

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Daisy Dobrijevic joined Space.com in February 2022 as a reference writer having previously worked for our sister publication All About Space magazine as a staff writer. Before joining us, Daisy completed an editorial internship with the BBC Sky at Night Magazine and worked at the National Space Centre in Leicester, U.K., where she enjoyed communicating space science to the public. In 2021, Daisy completed a PhD in plant physiology and also holds a Master's in Environmental Science, she is currently based in Nottingham, U.K.

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Photosynthesis

Photosynthesis is a process by which phototrophs convert light energy into chemical energy, which is later used to fuel cellular activities. The chemical energy is stored in the form of sugars, which are created from water and carbon dioxide.

Table of Contents

What is Photosynthesis?
Site of photosynthesis

Photosynthesis definition states that the process exclusively takes place in the chloroplasts through photosynthetic pigments such as chlorophyll a, chlorophyll b, carotene and xanthophyll. All green plants and a few other autotrophic organisms utilize photosynthesis to synthesize nutrients by using carbon dioxide, water and sunlight. The by-product of the photosynthesis process is oxygen.Let us have a detailed look at the process, reaction and importance of photosynthesis.

What Is Photosynthesis in Biology?

The word “ photosynthesis ” is derived from the Greek words phōs (pronounced: “fos”) and σύνθεσις (pronounced: “synthesis “) Phōs means “light” and σύνθεσις means, “combining together.” This means “ combining together with the help of light .”

Photosynthesis also applies to other organisms besides green plants. These include several prokaryotes such as cyanobacteria, purple bacteria and green sulfur bacteria. These organisms exhibit photosynthesis just like green plants.The glucose produced during photosynthesis is then used to fuel various cellular activities. The by-product of this physio-chemical process is oxygen.

A visual representation of the photosynthesis reaction

Photosynthesis is also used by algae to convert solar energy into chemical energy. Oxygen is liberated as a by-product and light is considered as a major factor to complete the process of photosynthesis.
Photosynthesis occurs when plants use light energy to convert carbon dioxide and water into glucose and oxygen. Leaves contain microscopic cellular organelles known as chloroplasts.
Each chloroplast contains a green-coloured pigment called chlorophyll. Light energy is absorbed by chlorophyll molecules whereas carbon dioxide and oxygen enter through the tiny pores of stomata located in the epidermis of leaves.
Another by-product of photosynthesis is sugars such as glucose and fructose.
These sugars are then sent to the roots, stems, leaves, fruits, flowers and seeds. In other words, these sugars are used by the plants as an energy source, which helps them to grow. These sugar molecules then combine with each other to form more complex carbohydrates like cellulose and starch. The cellulose is considered as the structural material that is used in plant cell walls.

Where Does This Process Occur?

Chloroplasts are the sites of photosynthesis in plants and blue-green algae. All green parts of a plant, including the green stems, green leaves, and sepals – floral parts comprise of chloroplasts – green colour plastids. These cell organelles are present only in plant cells and are located within the mesophyll cells of leaves.

Also Read: Photosynthesis Early Experiments

Photosynthesis Equation

Photosynthesis reaction involves two reactants, carbon dioxide and water. These two reactants yield two products, namely, oxygen and glucose. Hence, the photosynthesis reaction is considered to be an endothermic reaction. Following is the photosynthesis formula:

Unlike plants, certain bacteria that perform photosynthesis do not produce oxygen as the by-product of photosynthesis. Such bacteria are called anoxygenic photosynthetic bacteria. The bacteria that do produce oxygen as a by-product of photosynthesis are called oxygenic photosynthetic bacteria.

Structure Of Chlorophyll

The structure of Chlorophyll consists of 4 nitrogen atoms that surround a magnesium atom. A hydrocarbon tail is also present. Pictured above is chlorophyll- f, which is more effective in near-infrared light than chlorophyll- a

Chlorophyll is a green pigment found in the chloroplasts of the plant cell and in the mesosomes of cyanobacteria. This green colour pigment plays a vital role in the process of photosynthesis by permitting plants to absorb energy from sunlight. Chlorophyll is a mixture of chlorophyll- a and chlorophyll- b .Besides green plants, other organisms that perform photosynthesis contain various other forms of chlorophyll such as chlorophyll- c1 , chlorophyll- c2 , chlorophyll- d and chlorophyll- f .

Process Of Photosynthesis

At the cellular level, the photosynthesis process takes place in cell organelles called chloroplasts. These organelles contain a green-coloured pigment called chlorophyll, which is responsible for the characteristic green colouration of the leaves.

As already stated, photosynthesis occurs in the leaves and the specialized cell organelles responsible for this process is called the chloroplast. Structurally, a leaf comprises a petiole, epidermis and a lamina. The lamina is used for absorption of sunlight and carbon dioxide during photosynthesis.

Structure of Chloroplast. Note the presence of the thylakoid

“Photosynthesis Steps:”

During the process of photosynthesis, carbon dioxide enters through the stomata, water is absorbed by the root hairs from the soil and is carried to the leaves through the xylem vessels. Chlorophyll absorbs the light energy from the sun to split water molecules into hydrogen and oxygen.
The hydrogen from water molecules and carbon dioxide absorbed from the air are used in the production of glucose. Furthermore, oxygen is liberated out into the atmosphere through the leaves as a waste product.
Glucose is a source of food for plants that provide energy for growth and development , while the rest is stored in the roots, leaves and fruits, for their later use.
Pigments are other fundamental cellular components of photosynthesis. They are the molecules that impart colour and they absorb light at some specific wavelength and reflect back the unabsorbed light. All green plants mainly contain chlorophyll a, chlorophyll b and carotenoids which are present in the thylakoids of chloroplasts. It is primarily used to capture light energy. Chlorophyll-a is the main pigment.

The process of photosynthesis occurs in two stages:

Light-dependent reaction or light reaction
Light independent reaction or dark reaction

Stages of Photosynthesis in Plants depicting the two phases – Light reaction and Dark reaction

Light Reaction of Photosynthesis (or) Light-dependent Reaction

Photosynthesis begins with the light reaction which is carried out only during the day in the presence of sunlight. In plants, the light-dependent reaction takes place in the thylakoid membranes of chloroplasts.
The Grana, membrane-bound sacs like structures present inside the thylakoid functions by gathering light and is called photosystems.
These photosystems have large complexes of pigment and proteins molecules present within the plant cells, which play the primary role during the process of light reactions of photosynthesis.
There are two types of photosystems: photosystem I and photosystem II.
Under the light-dependent reactions, the light energy is converted to ATP and NADPH, which are used in the second phase of photosynthesis.
During the light reactions, ATP and NADPH are generated by two electron-transport chains, water is used and oxygen is produced.

The chemical equation in the light reaction of photosynthesis can be reduced to:

2H 2 O + 2NADP+ + 3ADP + 3Pi → O 2 + 2NADPH + 3ATP

Dark Reaction of Photosynthesis (or) Light-independent Reaction

Dark reaction is also called carbon-fixing reaction.
It is a light-independent process in which sugar molecules are formed from the water and carbon dioxide molecules.
The dark reaction occurs in the stroma of the chloroplast where they utilize the NADPH and ATP products of the light reaction.
Plants capture the carbon dioxide from the atmosphere through stomata and proceed to the Calvin photosynthesis cycle.
In the Calvin cycle , the ATP and NADPH formed during light reaction drive the reaction and convert 6 molecules of carbon dioxide into one sugar molecule or glucose.

The chemical equation for the dark reaction can be reduced to:

3CO 2 + 6 NADPH + 5H 2 O + 9ATP → G3P + 2H+ + 6 NADP+ + 9 ADP + 8 Pi

* G3P – glyceraldehyde-3-phosphate

Calvin photosynthesis Cycle (Dark Reaction)

Also Read: Cyclic And Non-Cyclic Photophosphorylation

Importance of Photosynthesis

Photosynthesis is essential for the existence of all life on earth. It serves a crucial role in the food chain – the plants create their food using this process, thereby, forming the primary producers.
Photosynthesis is also responsible for the production of oxygen – which is needed by most organisms for their survival.

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11.1.1: Overview of Photosynthesis

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The energy that is harnessed from photosynthesis enters the ecosystems of our planet continuously and is transferred from one organism to another. Therefore, directly or indirectly, the process of photosynthesis provides most of the energy required by living things on earth. Photosynthesis also results in the release of oxygen into the atmosphere. In short, to eat and breathe, humans depend almost entirely on the organisms that carry out photosynthesis.

CONCEPT IN ACTION

Click the following link to learn more about photosynthesis.

Solar Dependence and Food Production

Some organisms can carry out photosynthesis, whereas others cannot. An autotroph is an organism that can produce its own food. The Greek roots of the word autotroph mean “self” ( auto ) “feeder” ( troph ). Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae (Figure \(\PageIndex{1}\)). Oceanic algae contribute enormous quantities of food and oxygen to global food chains. Plants are also photoautotrophs, a type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. All organisms carrying out photosynthesis require sunlight.

Photo a shows a green fern leaf. Photo b shows a pier protruding into a large body of still water; the water near the pier is colored green with visible algae. Photo c is a micrograph of cyanobacteria.

Heterotrophs are organisms incapable of photosynthesis that must therefore obtain energy and carbon from food by consuming other organisms. The Greek roots of the word heterotroph mean “other” ( hetero ) “feeder” ( troph ), meaning that their food comes from other organisms. Even if the food organism is another animal, this food traces its origins back to autotrophs and the process of photosynthesis. Humans are heterotrophs, as are all animals. Heterotrophs depend on autotrophs, either directly or indirectly. Deer and wolves are heterotrophs. A deer obtains energy by eating plants. A wolf eating a deer obtains energy that originally came from the plants eaten by that deer. The energy in the plant came from photosynthesis, and therefore it is the only autotroph in this example (Figure \(\PageIndex{2}\)). Using this reasoning, all food eaten by humans also links back to autotrophs that carry out photosynthesis.

This photo shows deer running through tall grass at the edge of a forest.

BIOLOGY IN ACTION: Photosynthesis at the Grocery Store

This photo shows people shopping in a grocery store

Main Structures and Summary of Photosynthesis

Photosynthesis requires sunlight, carbon dioxide, and water as starting reactants (Figure \(\PageIndex{4}\)). After the process is complete, photosynthesis releases oxygen and produces carbohydrate molecules, most commonly glucose. These sugar molecules contain the energy that living things need to survive.

This photo shows a tree. Arrows indicate that the tree uses carbon dioxide, water, and sunlight to make sugars and release oxygen.

The complex reactions of photosynthesis can be summarized by the chemical equation shown in Figure \(\PageIndex{5}\).

The photosynthesis equation is shown. According to this equation, six carbon dioxide molecules and six water molecules produce one sugar molecule and one oxygen molecule. The sugar molecule is made of 6 carbons, 12 hydrogens, and 6 oxygens. Sunlight is used as an energy source.

In plants, photosynthesis takes place primarily in leaves, which consist of many layers of cells and have differentiated top and bottom sides. The process of photosynthesis occurs not on the surface layers of the leaf, but rather in a middle layer called the mesophyll (Figure \(\PageIndex{6}\)). The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata.

In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a chloroplast. In plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts have a double (inner and outer) membrane. Within the chloroplast is a third membrane that forms stacked, disc-shaped structures called thylakoids. Embedded in the thylakoid membrane are molecules of chlorophyll, a pigment (a molecule that absorbs light) through which the entire process of photosynthesis begins. Chlorophyll is responsible for the green color of plants. The thylakoid membrane encloses an internal space called the thylakoid space. Other types of pigments are also involved in photosynthesis, but chlorophyll is by far the most important. As shown in Figure \(\PageIndex{6}\), a stack of thylakoids is called a granum, and the space surrounding the granum is called stroma (not to be confused with stomata, the openings on the leaves).

ART CONNECTION

The upper part of this illustration shows a leaf cross-section. In the cross-section, the mesophyll is sandwiched between an upper epidermis and a lower epidermis. The mesophyll has an upper part with rectangular cells aligned in a row, and a lower part with oval-shaped cells. An opening called a stomata exists in the lower epidermis. The middle part of this illustration shows a plant cell with a prominent central vacuole, a nucleus, ribosomes, mitochondria, and chloroplasts. The lower part of this illustration shows the chloroplast, which has pancake-like stacks of membranes inside.

On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?

The Two Parts of Photosynthesis

Photosynthesis takes place in two stages: the light-dependent reactions and the Calvin cycle. In the light-dependent reactions, which take place at the thylakoid membrane, chlorophyll absorbs energy from sunlight and then converts it into chemical energy with the use of water. The light-dependent reactions release oxygen from the hydrolysis of water as a byproduct. In the Calvin cycle, which takes place in the stroma, the chemical energy derived from the light-dependent reactions drives both the capture of carbon in carbon dioxide molecules and the subsequent assembly of sugar molecules. The two reactions use carrier molecules to transport the energy from one to the other. The carriers that move energy from the light-dependent reactions to the Calvin cycle reactions can be thought of as “full” because they bring energy. After the energy is released, the “empty” energy carriers return to the light-dependent reactions to obtain more energy.

The process of photosynthesis transformed life on earth. By harnessing energy from the sun, photosynthesis allowed living things to access enormous amounts of energy. Because of photosynthesis, living things gained access to sufficient energy, allowing them to evolve new structures and achieve the biodiversity that is evident today.

Only certain organisms, called autotrophs, can perform photosynthesis; they require the presence of chlorophyll, a specialized pigment that can absorb light and convert light energy into chemical energy. Photosynthesis uses carbon dioxide and water to assemble carbohydrate molecules (usually glucose) and releases oxygen into the air. Eukaryotic autotrophs, such as plants and algae, have organelles called chloroplasts in which photosynthesis takes place.

Art Connections

Figure \(\PageIndex{6}\): On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?

Levels of carbon dioxide (a reactant) will fall, and levels of oxygen (a product) will rise. As a result, the rate of photosynthesis will slow down.

Contributors and Attributions

Samantha Fowler (Clayton State University), Rebecca Roush (Sandhills Community College), James Wise (Hampton University). Original content by OpenStax (CC BY 4.0; Access for free at https://cnx.org/contents/b3c1e1d2-83...4-e119a8aafbdd ).

Photosynthesis

Photosynthesis n., plural: photosyntheses [ˌfŏʊ.ɾoʊ.ˈsɪn̪.θə.sɪs] Definition: the conversion of light energy into chemical energy by photolithorophs

Table of Contents

Photosynthesis is a physio-chemical process carried out by photo-auto-lithotrophs by converting light energy into chemical energy . Among the endless diversity of living organisms in the world, producers are a unique breed.

Unlike consumers ( herbivores , carnivores , omnivores , or decomposers ) that rely upon other living organisms for their nutritional requirements and nourishment, producers have been distinguished by their ability to synthesize their own food. This is the reason that we call producers “autotrophic or self-reliable” in nature while consumers of all the different categories are called “heterotrophic or dependent” in nature.

Now among producers, there are different categories of producers, i.e. different mechanisms via which they produce their own food.

Photo-auto-litho-trophs: Since these organisms tend to derive their nutrition by channeling the sun’s light energy, they are termed phototrophic in nature. Also, since they utilize inorganic carbon and translate it into organic carbon atoms, i.e. their means of deriving food becomes autotrophic. Additionally, since the source of electrons (electron donors) here are inorganic compounds, they are specified as lithotrophic . In totality, they can be called photo-auto-litho-trophic in nature. Example : Green plants are nature’s brilliant entities that come under this category. They carry out a photosynthesis cycle by taking in carbon dioxide and fixing it into carbohydrates (energy storage molecule). Some of them also give out oxygen gas that’s vital for the other life forms to survive in the earth’s atmosphere.
Chemo-auto-lithotrophs: Many of us might be unaware of the fact that there are some autotrophs that don’t utilize sunlight. Rather they derive their energy stored from a different energy source like oxidation of inorganic compounds.

The scope of today’s discussion is limited to photosynthesis and photoautotrophs. So, let’s get started and get to know the answers to these common questions: what is the photosynthesis process, what are the 3 stages of photosynthesis, what does photosynthesis produce, what is a byproduct of photosynthesis, what is the purpose of photosynthesis, is photosynthesis a chemical change, the various inputs and outputs of photosynthesis, which organisms perform photosynthesis , and many other more questions!!!

photolithotroph pioneer species features

What is Photosynthesis?

Photosynthesis definition: Photosynthesis is a physio-chemical process carried out by photo-auto-lithotrophs . In simpler language, photosynthesis is the process by which green plants convert light energy into ‘chemical energy’.

This energy transformation is only possible due to the presence of the miraculous pigment molecule chlorophyll in photosynthesis. The chemical energy as referred to before is the fixed carbon molecules generated during photosynthesis.

Green plants and algae have the ability to utilize carbon dioxide molecules and water and produce food (carbohydrates) for all life forms on Earth. There’s no doubt in the fact that life is impossible and unimaginable without green plants that photosynthesize and sustain the cycles of life.

Let’s give you a brief outline of the topic before we head forward.

Etymology: The photosynthesis process finds its origin in 2 Greek words, firsts one being “phōs (φῶς)” meaning ‘light’ and the second one being “sunthesis (σύνθεσις)” meaning ‘putting together’ . The process of photosynthesis aids the conversion of light energy to chemical energy in varied forms of carbohydrate molecules like sugar molecules and starches.
Organisms that perform photosynthesis: The organisms are called photo-auto-litho-trophs or simply photoautotrophs.
Atmospheric gas consumed: Photosynthesizing organisms utilize carbon dioxide in photosynthesis (CO 2 ).
Atmospheric gas released by “some” photosynthetic organisms (MIND IT-Not all): Some photosynthesizing organisms convert carbon dioxide and aid the process of producing oxygen gas (O2).
Examples of photosynthesizing organisms: Green plants, cyanobacteria (earlier termed as blue-green algae), and different types of algae that essentially carry out phytoplankton photosynthesis.
Why is photosynthesis important? The important function of photosynthesis: Food supply for the organisms on Earth, Oxygen supply for the survival of all organisms.
Site of photosynthesis: Leaves and green tissues. (So when asked where photosynthesis takes place, we can tell that it is this site.)
What are the reactants of photosynthesis: Carbon dioxide molecules + Water molecules + Light energy
Products of photosynthesis: Fixed carbon (carbohydrates) + Oxygen (some cases) + Water

Watch this vid about photosynthesis:

Biology Definition: Photosynthesis is the synthesis of complex organic material using carbon dioxide , water , inorganic salts , and light energy (from sunlight) captured by light-absorbing pigments , such as chlorophyll and other accessory pigments . Photosynthesis may basically be simplified via this equation: 6CO 2 +12H 2 O+energy=C 6 H 12 O 6 +6O 2 +6H 2 O, wherein carbon dioxide (CO 2 ), water (H 2 O), and light energy are utilized to synthesize an energy-rich carbohydrate like glucose (C 6 H 12 O 6 ). Other products are water and oxygen .

Photosynthesis occurs in plastids (e.g. chloroplasts ), which are membrane-bounded organelles containing photosynthetic pigments (e.g. chlorophyll ), within the cells of plants and algae .
In photosynthetic bacteria ( cyanobacteria ) that do not have membrane-bounded organelles, photosynthesis occurs in the thylakoid membranes in the cytoplasm .

Etymology: from the Greek photo-, “light”, and synthesis, “putting together” Related forms: photosynthetic (adjective) Compare: chemosynthesis See also: photoautotroph

Types of Photosynthesis

Plant photosynthesis and photosynthetic organisms can be classified under different categories on the basis of some characteristic features. They are:

Types of organisms that carry out photosynthesis on the basis of “cellular structure” Both prokaryotic and eukaryotic organisms carry out photosynthesis.
Photosynthetic prokaryotes: for example, cyanobacteria
Eukaryotic: for example, protists ( diatoms , dinoflagellates , Euglena) and green plants. In particular, algae photosynthesis can be observed in green algae , red algae , brown algae , & land plants, like bryophytes , pteridophytes, gymnosperms , and angiosperms .
Prokaryotic ONLY (anoxygenic photosynthetic bacteria, green sulfur bacteria and purple bacteria)

Cyanobacteria photosynthesis and nitrogen fixation diagram

Photosynthesis: a two-stage process

Photosynthesis is an example of a metabolic process with 2 stages. Both the stages need light (direct or indirect sunlight). Hence, the long-claimed notion of the 2 processes being ‘absolute LIGHT and DARK reactions’ isn’t apt.

Scientific studies have pointed out that even the 2nd stage of photosynthesis requires indirect sunlight. Therefore, rather than classifying the stages as light and dark photosynthesis reactions, we’ll like to classify the 2 stages as follows:

Photochemical Reaction Process: Light energy is converted to ATP ; photophosphorylation process (light-dependent reactions)
Through Calvin cycle: In oxygenic photosynthesis as well as anoxygenic photosynthesis
Through Non-Calvin cycle: Only is some anoxygenic photosynthesis

Evolution of Photosynthesis Process

It is postulated that the very first photosynthetic beings and photosynthesis evolved quite early down the evolutionary timescale of life.

It is also believed that the first photosynthetic beings would have initially resorted to other available reducing agents like hydrogen ions or hydrogen sulfide in contrast to the modern-day photosynthetic organisms that utilize water as the “prime and only sources of electrons”.

It is believed that cyanobacteria would have appeared on the surface of Earth much later than the first photosynthetic beings. Once appeared they must have saturated the Earth’s atmosphere with oxygen gas and led to its oxygenation. Only after the Earth was oxygenated, the more complex forms of life would have later evolved.

When we compare photosynthesis to other metabolic processes like respiration, we can clearly notice that these two processes are almost opposite to each other. But another point to note is that both the processes in synchrony sustain life on Earth.

You cannot separate respiration from photosynthesis or photosynthesis from respiration and expect life to run normally. It is not possible that way. Let’s try to compare and list some characteristic features of photosynthesis and cellular respiration processes.

Photosynthesis vs. Respiration

Photosynthesis: Anabolic process
Cellular respiration: Catabolic process By anabolic, we mean the photosynthesis process “utilizes energy to build biomolecules” like carbohydrates, starch, and sugars. These biomolecules are further utilized by both the plants and the organisms dependent on plants for their nutritional needs. On the other hand, respiration is a catabolic process. This energy is utilized to break down complex molecules to derive nutrition out of them.
Photosynthesis: In the chloroplasts of the eukaryotic phototrophic cells.
Respiration: Primarily in the mitochondria of the cell.
Photosynthesis: Carbon dioxide molecules + Water molecules + Light energy
Respiration: Glucose + Oxygen
Photosynthesis: Fixed carbon (carbohydrates) + Oxygen (some cases) + Water
Respiration: Carbon dioxide + Water +energy (ATP)
Photosynthesis: Endergonic and endothermic
Respiration: Exergonic and exothermic Just note that these terms endergonic and endothermic both convey the same meaning of “absorbing heat”. And the terms exergonic and exothermic also convey the same meaning of “releasing heat”. The only difference is that –gonics relates to “the relative change in the free energy of the system” while –thermic relates to “the relative change in enthalpy of the system”.
Photosynthesis: 6CO 2 + 6H 2 O → C6H 12 O 6 + 6O 2
Respiration: C 6 H 12 O 6 6 + 6O 2 → 6CO 2 + 6H 2 O

Photosynthetic Membranes and Organelles

When we begin the discussion on this topic, it’s important that we know that no photosynthesis is possible without the pigment molecules that absorb light. The absorption of sunlight is the most vital step of photosynthesis.

We should also note that the energy of photons is different for every light of different wavelengths. And the energy needed for the photosynthesis to be conducted is of “a very specific wavelength range”.

For the absorption of lights of desired wavelengths, phototrophs organize their pigment molecules in the form of reaction center proteins . These proteins are located in the membranes of the organisms. Let’s learn how these pigment molecules reside inside the organism and how they make the membranes photosynthetic in nature.

Prokaryotic photosynthetic organisms: These organisms have their pigment systems or photosystems located in the cell membranes or the thylakoid membranes in the cytosol itself. There are no special organelles called chloroplasts in the prokaryotes.

Eukaryotic photosynthetic organisms (like green plants): These organisms have their pigment systems or photosystems located in the thylakoids of the chloroplast membranes. Eukaryotes have specialized organelles called chloroplasts (chlorophyll-containing plastids) in their cells.

Photosynthetic Pigments

There are 2 types of photosynthetic pigments in the oxygenic photosynthesizing organisms . They are as follows:

Porphyrin-derivatives (Chlorophyll in plants and Phycobilin)

Carotenoids

Chlorophyll.

Chlorophyll is the green-colored pigment essential for photosynthesis. Let’s try to list its major characteristic features and roles of it.

Nature: Lipid
Location: Embedded in the thylakoid membrane
Types: 9 types as identified by Arnoff and Allen in 1966 (chlorophyll-a, b, c, d, e, bacteriochlorophyll a, b, chlorobium chlorophyll-650,666). Bacteriochlorophylls are present in the anoxygenic photosynthetic organisms.
Primary photosynthetic pigment: Chlorophyll-a
Presence: In all oxygenic photosynthetic organisms
Absorption range: Visible (blue and red) and IR (Infra-red)
Ion important for its biological functioning: Magnesium ion (Mg 2+ )
Structure: Chlorophyll-a, b, and d are “ chlorin ” derivatives; c is a “ porphyrin ” derivative.
Chlorophyll Tail: Oxygenic photosynthetic organisms have a “ phytol ” tail in their chlorophyll; anoxygenic photosynthetic organisms have a “ geranyl ” tail in their bacteriochlorophylls.
Main pigment for capturing and storing solar energy
Photochemical reaction (chlorophyll-a is present in the photochemical reaction center i.e. PCRC. Chlorophyll a, b, c, and d play a role in resonance energy transfer.)

Carotenoid is the photosynthetic pigment essential for working in conjunction with chlorophyll. Let’s try to list its major characteristic features and roles of it.

Nature: Lipid-soluble
Types: More than 150
Absorption range: 400-500nm
Forms: Carotene (simple hydrocarbon, for example, beta carotene) and xanthophyll (oxygenated hydrocarbon, for example, lutein)
In excitation and resonance energy transfer
Photo-protection (work as a free-radical scavenger as well as a quencher)

Phycobilins

Phycobilins aren’t present in all the oxygenic photosynthetic organisms. They have a tetrapyrrole structure (no need for magnesium ion).

Types: Phycoerythrobilin, Phycocyanobilins, Allophycocyanobilins When these pigment molecules combine with a water-soluble protein, they form the pigment-protein complex (phycobiliproteins, like phycoerythrin and phycocyanin).
Location: Since these phycobiliproteins are water-soluble, they can’t exist in the membranes like chlorophyll and carotenoids. Therefore, phycobilin pigments as their pigment-protein complex aggregate into clusters and adhere to the membrane. These clusters are called phycobilisomes .
Exceptional Note: These are the only pigments that are associated with protein molecules.
Role: Resonance energy transfer

Organelle for Photosynthesis

What is chloroplast? In eukaryotes, photosynthesis occurs in chloroplasts as they are the designated organelles for the photosynthesis process. There are nearly 10-100 chloroplasts in a typical plant cell .

Inside chloroplasts are the thylakoids; the very specific site for the light capturing. The structure of this very unique part of the chloroplasts is briefly discussed here.

Thylakoid is a membrane-bound compartment in the chloroplasts of eukaryotic organisms. They are also present as such in the cytosol of cyanobacteria (cyanobacteria don’t have chloroplasts but they have simply thylakoids).

These thylakoids are the “primary site of the 1st stage of photosynthesis. i.e. “photochemical reaction” or popularly called “light-dependent reactions of photosynthesis”. The main components of the thylakoid are membrane, lumen, and lamellae. The chlorophyll molecules are present inside these thylakoid membranes.

Light-dependent Reactions

The first stage of photosynthesis is popularly called “light-dependent reactions” . We choose to call this stage the “1st stage: PHOTOCHEMICAL REACTION STAGE”. It is also called the “thylakoid reaction stage” or “hill’s reaction” .

This stage is marked by 3 essential steps of photosynthesis: Oxidation of water , reduction of NADP + , and ATP formation . The site where these reactions occur is the lamellar part of the chloroplast. The units of light-dependent reactions are quantosomes .

Let’s discuss this stage under some subheadings:

Wavelengths of light involved and their absorption

The white light that reaches Earth has subparts of different wavelengths together constituting the visible spectrum (390-760nm). But the photosynthetic organisms specifically use a subpart called PAR ( P hotosynthetically A ctive R adiation).

PAR ranges from 400-760nm. Blue light is 470-500nm while red light is 660-760nm). The green light (500-580nm) is reflected back by the plants and this is the reason that plants appear green in color. Blue-green light is not used, only blue light is used.

Absorption spectrum and action spectrum

Absorption Spectrum: This is a pigment-specific entity or terminology. To find the absorption spectrum of a pigment, you need to plot “the amount of absorption of different wavelengths of light by that particular pigment” . The graph has the “wavelengths of light (in nanometers/nm)” on the X-axis and the “percentage of light absorption” on the Y-axis.

Action Spectrum: To find the action spectrum of a pigment, you need to plot the “effectiveness of the different wavelengths of light in stimulating photosynthesis process” . The graph has the “wavelengths of light (in nanometers/nm)” on the X-axis and the “rate of photosynthesis (measured as oxygen released)” on the Y-axis. When you superimpose the action spectrum of photosynthesis with the absorption spectrum of the specific pigment, you can find the contribution of each different wavelength in the photosynthesis rate, photosynthetic efficiency, and photosynthetic productivity.

IMPORTANT NOTE: The absorption spectrum is calculated for any of the many pigments involved in photosynthesis. Contrastingly, the action spectrum is calculated only for the photochemical reaction performing pigment i.e. chlorophyll-a present at the reaction center. We identify the progress of photochemical reactions as the “evolution of oxygen gas” that primarily happens at the reaction center where only chlorophyll-a is present. Since the action is directly correlated to the specific excitation of chlorophyll-a molecule, the action spectrum is scientifically calculated only for this chlorophyll-a.

Absorption spectrum of chlorophyll- a : 430 nm (blue), 660nm (red) {more absorbance at 660 nm)
Absorption spectrum of chlorophyll-b: 430 nm (blue), 660nm (red) {more absorbance at 430 nm)

What actually happens in the Light-dependent reaction

Let’s briefly describe what actually happens here.

1 photon is absorbed by 1 molecule of the chlorophyll (P680) and simultaneously 1 electron is lost here.
The electron flow of the photochemical reaction begins here.
The electron is transferred to D1/D2 protein, then to a modified form of chlorophyll and “pheophytin”.
After that, it’s transferred to plastoquinone A and then B.
Initiates an electron flow down an electron transport chain.
Ultimately aids the NADP reduction to NADPH.
Creation of a proton gradient across the chloroplast membrane.
Further on this proton gradient is exploited by the ATP synthase for the generation of ATP molecules.

Water photolysis

Now, if you are wondering how the first electron lost by the 1st chlorophyll is replenished to keep this cycle going, read on. The answer to this query is “photolysis of water molecules” . The chlorophyll molecule regains the lost electron when the “oxygen-evolving complex” in the thylakoid membrane carries out the photolysis of water. The chlorophyll molecule ultimately regains the electron it lost when a water molecule is split in a process called photolysis, which releases oxygen.

Many scientists had a doubt about the source of oxygen in photosynthesis. Some speculated the oxygen atom of the CO 2 gas is the source of oxygen post-photosynthesis. But it was the collective contribution of some 4 scientists that gave clarity on this topic.

C.B. Van Niel worked on purple photosynthetic bacteria ( Chromatium vinosum ) and found out that the source of oxygen is the oxidation of water molecules (‘indirect evidence’). While Ruben, Hassid, and Kamen carried out an isotopic study that gave ‘direct evidence’ of oxygen-evolving from H 2 O molecules and not CO 2 molecules.

Hydrolysis of 2 molecules of water leads to the evolution of 1 molecule of oxygen gas. The photosynthesis equation for light-dependent reactions (non-cyclic electron flow) or the chemical formula for photosynthesis:

2 H 2 O + 2 NADP+ + 3 ADP + 3 Pi + light → 2 NADPH + 2 H+ + 3 ATP + O 2

The photochemical reaction (or the light-dependent reactions) can be classified as:

Cyclic reaction: Only 1 photosystem ( PS1 ) is involved. (Photon excites P700 in PS1, electron reaches Fe-S, then Ferredoxin, then Plastoquinone and then Cyt b6f complex and then Plastocyanin). Since in the solo involvement of PS1 here, the electron flow becomes cyclic. And this phosphorylation process is called cyclic phosphorylation. It happens in the stroma lamellae when light beyond 680nm is available.
Non-cyclic reaction: Both photosystems (PS1 and PS2 ) are involved. (Photon excites P680 in PS2, the electron is lost and transferred to pheophytin, then sent on a roller coaster (Z-scheme). Within the z-scheme, the final redox reaction enables the reduction of NADP+ to NADPH. And the chemiosmotic potential generation via proton pumping proton across the membrane and into the thylakoid lumen ensures ATP synthesis.

Data Source: Akanksha Saxena of Biology Online

Light-Independent Reactions (Carbon-fixation Reaction)

Also called the carbon fixation process, the “light-independent reactions” is a misnomer as Science has now already proved that the second stage of photosynthesis isn’t really light-independent reactions. Though it doesn’t need direct light, indirect light is involved even in this process. We choose to label this stage of photosynthesis as the “2nd stage: CARBON-FIXATION REACTION STAGE ”, which is also called:

Calvin Cycle or “stromal reaction” as it manifests in the stroma part of the chloroplast
“C3 Cycle” or the “reductive pentose phosphate cycle”

Calvin cycle

The inputs for the Calvin cycle in most plants come from the previously occurred photochemical reaction. In this cycle, the carbon dioxide produced is fixed to a glucose molecule. To be very specific, the Calvin cycle directly doesn’t produce glucose, rather it produces glyceraldehydes-5-phosphate (G-3-P). Glucose is formed after these G-3-P molecules move into the cytosol from the chloroplast .

It consists of primarily 3 steps as follows:

Carboxylation: Acceptance of CO 2 by RuBP which is a 5-carbon compound and the CO2-acceptor). 2 molecules of 3-phosphoglycerate are generated as the result of the carboxylation process.
Reduction: Generation of 3C/4C/5C/6C/7C molecules.
Regeneration of RUBP: 3 molecules of RuBP are regenerated.

In totality, 3 molecules of CO 2 produce 1 molecule of G-3-P. This uses 9 ATPs and 6 NADPHs. And, 6 molecules of CO 2 produce 2 molecules of G-3-P which further produce 1 molecule of glucose. This uses 18ATPs and 12 NADPHs.

The main enzyme is RuBisCo . It’s a multi-enzyme complex with 8 large and 8 small subunits. The substrates for this enzyme are CO 2 , O 2 , and RuBP. An essential ion for the biological functioning of this enzyme: Mg 2+ . The role of RuBisCo is that it captures carbon dioxide gas from the atmosphere and utilizes the NADPH from the 1st stage (photochemical reaction/light-dependent reaction stage) to fix the CO 2 .

The equation of dark reaction of photosynthesis/light-independent reaction stage/2nd stage is: 3 CO 2 + 9 ATP + 6 NADPH + 6 H + → C 3 H 6 O 3 -phosphate + 9 ADP + 8 Pi + 6 NADP+ + 3 H 2 O

The simple carbon sugars formed via the C3 cycle are utilized by the biological systems to form complex organic compounds like cellulose, precursors for amino acids synthesis and thereby proteins, precursors for lipids, and the source of fuel for respiration.

Important Point To Note: It happens in all the photosynthetic organisms as the basic carbon-fixation step.

Carbon concentrating mechanisms

There are many carbon concentrating mechanisms to increase the carbon dioxide levels and the carbon fixation process like C4, CAM, etc.

Doesn’t happen in all photosynthetic organisms. Rather it happens in conjunction with the C3 cycle in some 4% of angiosperm families.
Most commonly angiosperm families that witness C4 cycle: Poaceae, Cyperaceae.
First explained by: Hatch and Slack (hence also called the Hatch and Slack cycle). They worked on the maize plant.
Role: Endow the ability to efficiently conduct photosynthesis in plants of the semi-arid regions by making them well adapted.
Mechanism: By separation of photosynthesis stages in 2 types of cells (mesophyll cells and bundle sheath cells). The light reaction is restricted to the mesophyll cells and the CO 2 fixation happens in the bundle sheath cells. This phenomenon is also termed as “chloroplast dimorphism” in C4 plants. The Kranz anatomy is visible here.
Why does the need arise in the first place? – In semi-arid regions or regions with very hot and dry environmental conditions, plants are forced to close their stomata in order to limit water loss. Under such harsh conditions, the intake of CO 2 decreases during the day as the stomata are forced closed. This might lead to no CO 2 intake and hence no CO 2 fixation (2nd stage of photosynthesis). But the 1st stage of photosynthesis keeps running as it doesn’t depend on stomata opening or closure. This means that a continuous oxygen evolution happens which can lead to oxygen saturation. As we know that RuBisCo enzymes use O 2 gas as substrate too, and this can lead to an increased rate of photorespiration by the oxygenase activity of RuBisCo. This further decreases the carbon fixation. This is a very big issue if not resolved. Hence, for situations like these, carbon concentrating mechanisms have evolved in some families of plants to concentrate and enrich the CO 2 concentration in the leaves of these plants under such conditions.
Important enzyme for CO 2 concentration: PEP carboxylase
CO 2 is first added to a three-carbon compound called phosphoenolpyruvate (PEP) in this cycle. This leads to the formation of a four-carbon (4C) molecule called oxaloacetic acid or malate. This step happens in the mesophyll cells of the leaves.
After that, these 4C compounds are transferred to the bundle sheath cells where the normal C3 cycle fixes them into glucose molecules.
This CO 2 concentrating mechanism works on the “principle of separating the RuBisCo enzyme from the O 2 -generating photochemical reactions” in order to reduce the rates of photorespiration and simultaneously increase the rates of CO 2 fixation.
This increases the photosynthetic capacity of the leaf/leaf photosynthesis.
When the high light and high-temperature conditions are dominant, C4 plants prove more photosynthetically efficient than C3 plants as they produce more sugar molecules in such conditions.
Examples of C4 plants: Many crop plants like wheat, maize, rice, sorghum, millet, and sugarcane.
Number of ATPs required: 12 (for C-enrichment) + 18 (for C-fixation)= 30 ATPS for 1 glucose production
Number of NADPH required: 18 NADPH for 1 glucose production
Some plants resort to another mechanism called the CAM cycle in conjunction with the C3 cycle to fix carbon dioxide.
Examples: xerophytes like cactus photosynthesis, and most succulents.
Around 16,000 species of plants utilize the CAM mechanism
Mechanism: Utilize PEP carboxylase to capture carbon dioxide. In contrast to the C4 cycle where there is a “spatial separation of the 2 processes of CO 2 reduction to PEP and PEP fixation to glucose”, CAM plants display a “temporal separation of the 2 listed processes”.

Land plants display different types of photosynthesis based on their requirements and environmental constraints. They are C3, C4 +C3, and CAM+ C3 types of photosynthesis.

Aquatic plants and algae display some extra features in the photosynthetic machinery. These features further refine and define the smooth functioning and efficiency of photosynthesis.

Example: Cyanobacteria photosynthesis – cyanobacteria have carboxysomes that help in enriching the concentration of carbon dioxide around the RuBisCO enzyme. This directly increases the photosynthetic rates. The distinguished and specially enabled enzyme in the carboxysomes is called “carbonic anhydrase”. The carbonic anhydrase possesses the ability to evolve and release CO 2 from the dissolved hydrocarbonate ions (HCO-). As soon as the CO 2 is released, RuBisCo takes care that it doesn’t go to waste.

Order and Kinetics

There are innumerable reactions and processes involved in the biological mechanism of photosynthesis. Besides the normal flow of photosynthesis, there are some plant-specific and condition-specific additional steps that further complicate the mechanism.

Since every biological mechanism has a lot of enzymes, factors, cofactors, substrates, and entities involved, photosynthesis is no different.

Let’s try to list some kinetics-specific pointers that may help.

As discussed in the overview and starting of this article, the early photosynthetic organisms must have been primarily “anoxygenic” in nature. These bacteria used some other source than water molecules as their primary electron donors. Even the geological evidence aligns with this fact as the early atmosphere of Earth was highly reducing in nature. Some speculated organisms of the early evolutionary phase are :

Green sulfur bacteria (Electron donor= hydrogen and sulfur)
Purple sulfur bacteria (Electron donor= hydrogen and sulfur)
Green nonsulfur bacteria (Electron donor= various amino and other organic acids)
Purple nonsulfur bacteria (Electron donor= variety of nonspecific organic molecules)

After this, some filamentous photosynthetic organisms are expected to have evolved. This is scaled to be an occurrence of some 3.4 billion years old timeline. It is around 2 million years ago that oxygenic photosynthesis is believed to have evolved.

The modern and more commonly known photosynthesis in plants and most of the photosynthetic prokaryotes= Oxygenic (Electron donor= Water molecules)

Symbiosis and the origin of chloroplasts

There are some animal groups that have the ability to form and establish symbiotic relationships with photosynthetic organisms. By establishing such a relationship, these organisms can directly rely upon their photosynthetic partner for energy and food requirements. Some examples of such animal groups are:

Sea anemones
Marine mollusks (example: Elysia viridis & Elysia chlorotica )
Fungi photosynthesis (Lichens)

When such symbiotic relationships are established, it’s sometimes observed that some genes of the plant cell’s nucleus get transferred to the animal cell . (Observed in some slugs).

Origin of Chloroplasts

Such symbiosis is popularly claimed to be the source of chloroplast evolution. As we notice many similarities between the photosynthetic bacteria and chloroplasts, the evolution of chloroplasts is often hinted to have occurred from these bacteria. Some of the common features between the 2 are:

Circular chromosome
Prokaryotic-type ribosome
A similar set of proteins in the photosynthetic reaction center

It is for all these commonalities the “ endosymbiotic theory ” had been proposed for the evolution of chloroplasts and mitochondria in the eukaryotic cells. According to the endosymbiotic theory, the early eukaryotic cells are believed to have acquired the photosynthetic bacteria by the process of endocytosis). Those early eukaryotic cells after acquiring the photosynthetic bacteria transformed to be self-sustainable and became the “first plant cells”. (Mitochondria photosynthesis is true, they are associated with respiration!)

Photosynthetic eukaryotic lineages

Photosynthetic eukaryotic lineages include:

Glaucophytes
Chlorophytes
Rhodophytes
Cryptophytes (some clades)
Haptophytes (some clades)
Dinoflagellates & chromerids
Euglenids—clade Excavata (unicellular)

Cyanobacteria and the evolution of photosynthesis

Almost all the prokaryotes carry out anoxygenic photosynthesis in contrast to cyanobacteria, which perform oxygenic photosynthesis. This ability to carry out oxygenic photosynthesis is speculated to have evolved at least 2450–2320 million years ago. The first photosynthetic cyanobacteria might not have been oxygenic as Earth’s atmosphere had no oxygen then.

This topic still requires more scientific study to bring out conclusive results. From the paleontological evidence, it is claimed that the 1st cyanobacteria evolved around 2000 Ma.

For the initial years of the Earth’s oxygen-rich environment (after the oxygen-evolving mechanism evolved), cyanobacteria are claimed to be the “principal primary producers of oxygen”. Even to date, cyanobacteria have been proven vital for marine ecosystems. They’re the primary producers of oxygen in oceans.

Cyanobacteria also fix nitrogen electrons fixation and play a role in biological nitrogen cycles.

Experimental History

We will list the long experimental history in deciphering the extensive photosynthesis process through the ages.

Discovery, Refinements, and Development of the concept

Find out the discovery, refinements, and development of photosynthesis as summarized in the table below:

C3 : C4 photosynthesis research

Several studies were conducted using isotopes of radioactive elements to identify the various aspects of the photosynthetic process. A number of organisms like Chlorella , Stellaria media, Cladophora, Spirogyra, Rhodopseudomonas , sulfur bacteria, green plants like maize, etc have been used to understand the photosynthesis process over the years. Gas exchange studies, isotopic studies, light spectrum studies, radioactive studies, plant anatomical and physiological studies, studies involving roles of carbon dioxide and water, etc have all together opened the gates for our deeper understanding of this topic.

The 3 main factors that directly affect the photosynthesis process are:

Light irradiance and wavelength
Carbon dioxide concentration

Temperature

Although there are many more corollary factors, these 3 are the most important ones.

Light intensity (irradiance), wavelength, and temperature

Light is an essential factor for photosynthesis. It directly affects the rate of it. There are 3 different parameters that we should look into:

Sciophytes : Grow under “diffuse” light. Example: Oxalis
Heliophytes: Grow under “direct: light. Example: Dalbergia
Light quality: PAR as previously discussed is the quality or the fraction of light energy that is ‘photosynthetically active’ in nature. It ranges from 400-700nm in wavelength.
Duration of light: This parameter doesn’t affect the rate of photosynthesis but affects the total photosynthetic output.

Carbon dioxide levels and photorespiration

Carbon dioxide concentration is the major factor in determining the rate of photosynthesis. There is no carbon-dioxide enriching system in C3 plants like the C4 plants. So, if you increase the concentration of CO 2 in the system, the photosynthetic rate of C3 plants will increase as the CO 2 concentration increases. On the other hand, the photosynthetic yield of the C4 plant won’t increase in such a scenario.

CO 2 Compensation Point: A stage in CO 2 concentration when there’s no absorption of CO 2 by the illuminated plant part.

Featuring… “The curious case of RuBisCO and PEP Carboxylase”

Imagine an equal concentration (50-50%) of the two isotopes of carbon, C-12 and C-13, in the form of 12CO 2 and 13CO 2 , made available to both C3 and C4 plants. Now, can you tell which isotope of the carbon will be fixed more or less by the two types of photosynthetic organisms? Can you guess if there would be a “preferable” isotope between the two? Do you think C3 plants will fix the 12CO 2 and 13CO 2 equally or unequally? Or do you think the 12CO 2 and 13CO 2 incorporation would have a biased ratio in any of the two (C3/C4 plants)????

The answer to this lies in the major carbon fixing enzyme involved.

C3 plants: Major C-fixing enzyme is RuBisCo and RuBisCo has a “discriminatory ability” to preferably fix 12CO 2 and not 13CO2. Hence, you will find more 12CO 2 fixed than 13CO 2 in the C3 plants.
C4 plants: Major C-fixing enzyme is not RuBisCo but PEP Carboxylase . PEP Carboxylase has “no discriminatory ability”. So, you’ll find an almost equal proportion of 12CO 2 and 13CO 2 getting fixed in C4 plants. So, in comparison to C3 plants, the chances of getting 13CO 2 fixed are more in C4 plants.

Choose the best answer.

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Rutherford, A.W., Faller, P. (Jan 2003). “Photosystem II: evolutionary perspectives”. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 358 (1429): 245–253. doi:10.1098/rstb.2002.1186. PMC 1693113. PMID 12594932.
Arnon, D.I., Whatley, F.R., Allen, M.B. (1954). “Photosynthesis by isolated chloroplasts. II. Photophosphorylation, the conversion of light into phosphate bond energy”. Journal of the American Chemical Society. 76 (24): 6324–6329. doi:10.1021/ja01653a025.
Ehrenberg, R. (2017-12-15). “The photosynthesis fix”. Knowable Magazine. Annual Reviews. doi:10.1146/knowable-121917-115502. Retrieved 2018-04-03.
El-Sharkawy, M.A., Hesketh, J.D. (1965). “Photosynthesis among species in relation to characteristics of leaf anatomy and CO 2 diffusion resistances”. Crop Sci. 5 (6): 517–521. doi:10.2135/cropsci1965.0011183x000500060010x.
Earl, H., Said Ennahli, S. (2004). “Estimating photosynthetic electron transport via chlorophyll fluorometry without Photosystem II light saturation”. Photosynthesis Research. 82 (2): 177–186. doi:10.1007/s11120-004-1454-3. PMID 16151873. S2CID 291238.

Last updated on July 15th, 2022

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Introduction

Plants carry out a form of photosynthesis called oxygenic photosynthesis . In oxygenic photosynthesis, water molecules are split to provide a source of electrons for the electron transport chain, and oxygen gas is released as a byproduct. Plants organize their photosynthetic pigments into two separate complexes called photosystems (photosystems I and II), and they use chlorophylls as their reaction center pigments.
Purple sulfur bacteria, in contrast, carry out anoxygenic photosynthesis , meaning that water is not used as an electron source and oxygen gas is not produced. Instead, these bacteria use hydrogen sulfide ( H 2 S ‍ ) as an electron source and produce elemental sulfur as a byproduct. In addition, purple sulfur bacteria have only one photosystem, and they use chlorophyll-like molecules called bacteriochlorophylls as reaction center pigments 1 , 2 , 3 ‍ .

Overview of the light-dependent reactions

Light absorption in PSII. When light is absorbed by one of the many pigments in photosystem II, energy is passed inward from pigment to pigment until it reaches the reaction center. There, energy is transferred to P680, boosting an electron to a high energy level. The high-energy electron is passed to an acceptor molecule and replaced with an electron from water. This splitting of water releases the O 2 ‍ we breathe.
ATP synthesis. The high-energy electron travels down an electron transport chain, losing energy as it goes. Some of the released energy drives pumping of H + ‍ ions from the stroma into the thylakoid interior, building a gradient. ( H + ‍ ions from the splitting of water also add to the gradient.) As H + ‍ ions flow down their gradient and into the stroma, they pass through ATP synthase, driving ATP production in a process known as chemiosmosis .
Light absorption in PSI. The electron arrives at photosystem I and joins the P700 special pair of chlorophylls in the reaction center. When light energy is absorbed by pigments and passed inward to the reaction center, the electron in P700 is boosted to a very high energy level and transferred to an acceptor molecule. The special pair's missing electron is replaced by a new electron from PSII (arriving via the electron transport chain).
NADPH formation. The high-energy electron travels down a short second leg of the electron transport chain. At the end of the chain, the electron is passed to NADP + ‍ (along with a second electron from the same pathway) to make NADPH.

What is a photosystem?

Photosystem i vs. photosystem ii.

Special pairs. The chlorophyll a special pairs of the two photosystems absorb different wavelengths of light. The PSII special pair absorbs best at 680 nm, while the PSI special absorbs best at 700 nm. Because of this, the special pairs are called P680 and P700 , respectively.
Primary acceptor . The special pair of each photosystem passes electrons to a different primary acceptor. The primary electron acceptor of PSII is pheophytin, an organic molecule that resembles chlorophyll, while the primary electron acceptor of PSI is a chlorophyll called A 0 ‍ 7 , 8 ‍ .
Source of electrons . Once an electron is lost, each photosystem is replenished by electrons from a different source. The PSII reaction center gets electrons from water, while the PSI reaction center is replenished by electrons that flow down an electron transport chain from PSII.

Photosystem II

Electron transport chains and photosystem i, some electrons flow cyclically, attribution:, works cited:.

Lodish, H., Berk, A., Zipursky, S. L., Matsudaira, P., Baltimore, D., and Darnell, J. (2000). Molecular analysis of photosystems. In Molecular cell biology (4th ed., section 16.4). New York, NY: W. H. Freeman. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK21484/ .
Boundless. (2015, July 21). Anoxygenic photosynthetic bacteria. In Boundless microbiology . Retrieved from https://www.boundless.com/microbiology/textbooks/boundless-microbiology-textbook/microbial-evolution-phylogeny-and-diversity-8/nonproteobacteria-gram-negative-bacteria-105/anoxygenic-photosynthetic-bacteria-551-7338/ .
Purple sulfur bacteria. (2015, July 16). Retrieved October 24, 2015 from Wikipedia: https://en.wikipedia.org/wiki/Purple_sulfur_bacteria .
Soda lake. (2015, September 26). Retrieved October 24, 2015 from Wikipedia: https://en.wikipedia.org/wiki/Soda_lake .
Gutierrez, R. Bio41 Week 7 Biochemistry Lectures 11 and 12. Bio41. 2009.
Berg, J. M., Tymoczko, J. L., and Stryer, L. (2002). Accessory pigments funnel energy into reaction centers. In Biochemistry (5th ed., section 19.5). New York, NY: W. H. Freeman. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK22604/ .
Pheophytin. (2015, February 11). Retrieved October 28, 2015 from Wikipedia: https://en.wikipedia.org/wiki/Pheophytin .
Photosystem I. (2016, June 25). Retrieved from Wikipedia on July 22, 2016: https://en.wikipedia.org/wiki/Photosystem_I .
Berg, J. M., Tymoczko, J. L., and Stryer, L. (2002). Two photosystems generate a proton gradient and NADPH in oxygenic photosynthesis. In Biochemistry (5th ed., section 19.3). New York, NY: W. H. Freeman. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK22538/#_A2681_ .
Joliot, P. and Johnson, G. N. (2011). Regulation of cyclic and linear electron flow in higher plants. PNAS, 108(32), 13317-13322. http://dx.doi.org/10.1073/pnas.1110189108 .
Johnson, Giles N. (2011). Physiology of PSI cyclic electron transport in higher plants. Biochimica et Biophysica Acta - Bioenergetics , 1807 (8), 906-911. http://dx.doi.org/doi:10.1016/j.bbabio.2010.11.009 .
Berg, J. M., Tymoczko, J. L., and Stryer, L. (2002). A proton gradient across the thylakoid membrane drives ATP synthesis. In Biochemistry (5th ed., section 19.4). New York, NY: W. H. Freeman. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK22519/ .
Takahashi, S., Milward, S. E., Fan, D.-Y., Chow, W. S., and Badger, M. R. (2008). How does cyclic electron flow alleviate photoinhibition in Arabidopsis? Plant Physiology , 149 (3), 1560-1567. http://dx.doi.org/10.1104/pp.108.134122 .

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HausaDictionary.com is an online bilingual dictionary that aims to offer the most useful and accurate Hausa to English or English to Hausa translations and definitions. This site contains a wide range of Hausa and English language materials and resources to help you learn Hausa or English. Pick up some basic terms and phrases here, expand your ...
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Photosynthesis
In chemical terms, photosynthesis is a light-energized oxidation-reduction process. (Oxidation refers to the removal of electrons from a molecule; reduction refers to the gain of electrons by a molecule.) In plant photosynthesis, the energy of light is used to drive the oxidation of water (H 2 O), producing oxygen gas (O 2 ), hydrogen ions (H ...
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Photosynthesis ( / ˌfoʊtəˈsɪnθəsɪs / FOH-tə-SINTH-ə-sis) [1] is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their activities.
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The process. During photosynthesis, plants take in carbon dioxide (CO 2) and water (H 2 O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose.
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Photosynthesis is powered by energy from sunlight. This energy is used to rearrange atoms in carbon dioxide and water to make oxygen and sugars. Carbon dioxide and water are inputs of photosynthesis. These inputs come from the environment. Oxygen and sugars are outputs of photosynthesis. The oxygen is released into the environment.
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Solar Dependence and Food Production. Some organisms can carry out photosynthesis, whereas others cannot. An autotroph is an organism that can produce its own food. The Greek roots of the word autotroph mean "self" (auto) "feeder" (troph).Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae (). ...
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Plant are one part of common words used in day-to-day life conversations. If you are interested to learn Plant names in Hausa, this place will help you to learn all Plant names in English to Hausa language. Plant vocabulary words are used in daily life, so it is important to learn all Plant names in English to Hausa and play Hausa quiz.
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photosynthesis: the process by which plants and other photoautotrophs generate carbohydrates and oxygen from carbon dioxide, water, and light energy in chloroplasts. photoautotroph: an organism that can synthesize its own food by using light as a source of energy. chemoautotroph: a simple organism, such as a protozoan, that derives its energy ...
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Plants are also photoautotrophs, a type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. All organisms carrying out photosynthesis require sunlight. Figure 11.1.1.1 11.1.1. 1: (a) Plants, (b) algae, and (c) certain bacteria, called cyanobacteria, are photoautotrophs that ...
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The experimental plots were exposed to levels of CO2 that were about 150% of present-day levels. Cellular respiration and photosynthesis both involve oxiterm-1dation-reduction reactions. Select the correct statements about these processes. -CO2 molecules are reduced to sugar in photosynthesis.
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