complete word equation for photosynthesis

The Balanced Chemical Equation for Photosynthesis

Photosynthesis Overall Chemical Reaction

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Photosynthesis is the process in plants and certain other organisms that uses the energy from the sun to convert carbon dioxide and water into glucose (a sugar) and oxygen.

Here is the balanced equation for the overall reaction:

6 CO 2  + 6 H 2 O → C 6 H 12 O 6  + 6 O 2  

Where: CO 2  = carbon dioxide   H 2 O = water light is required C 6 H 12 O 6  = glucose O 2  = oxygen

Explanation

In words, the equation may be stated as: Six carbon dioxide molecules and six water molecules react to produce one glucose molecule and six oxygen molecules .

The reaction requires energy in the form of light to overcome the activation energy needed for the reaction to proceed. Carbon dioxide and water don't spontaneously convert into glucose and oxygen .

• What Are the Products of Photosynthesis?
• Chlorophyll Definition and Role in Photosynthesis
• Photosynthesis Vocabulary Terms and Definitions
• Examples of Chemical Reactions in Everyday Life
• Calvin Cycle Steps and Diagram
• Examples of 10 Balanced Chemical Equations
• Photosynthesis Basics - Study Guide
• What Is the Primary Function of the Calvin Cycle?
• The Photosynthesis Formula: Turning Sunlight into Energy
• Chemosynthesis Definition and Examples
• Synthesis Reaction Definition and Examples
• Equation for the Reaction Between Baking Soda and Vinegar
• Chloroplast Function in Photosynthesis
• Understanding Endothermic and Exothermic Reactions
• How to Balance Chemical Equations
• Combustion Reactions in Chemistry

Photosynthesis – Equation, Formula & Products

Core concepts.

In this tutorial, you will learn all about photosynthesis . We begin with an introduction to photosynthesis and its balanced chemical equation. Then, we analyze the two key stages involved in this process and take a look at the final products. Lastly, we consider the different types of photosynthesis.

Topics Covered in Other Articles

• What is a Chemical Reaction? Physical vs Chemical Change Examples
• What is a Reactant in Chemistry?
• How to Balance Redox Reactions
• Common Oxidizing Agents & Reducing Agents
• What is Gluconeogenesis?

Introduction to Photosynthesis

The process by which plants and other organisms convert light energy (sunlight) into chemical energy (glucose) is known as photosynthesis. Sunlight powers a series of reactions that use water and carbon dioxide to synthesize glucose and release oxygen as a byproduct. Energy is stored in the chemical bonds of glucose and can be later harvested to fuel the organism’s activities through cellular respiration or fermentation .

Photosynthesis is an endergonic process because it requires an input of energy from the surroundings in order for a chemical change to take place. Furthermore, photosynthesis is a reduction-oxidation (redox) reaction , meaning that it involves the transfer of electrons between chemical species. During the process, carbon dioxide is reduced (i.e., gains electrons) to form glucose, and water is oxidized (i.e., loses electrons) to form molecular oxygen.

The complex process of photosynthesis takes place in chloroplasts (i.e., membrane-bound organelles in plant and algal cells). Chloroplasts have an outer membrane and an inner membrane. The stroma is the fluid-filled space within the inner membrane; it surrounds flattened sac-like structures known as thylakoids. Thylakoids consist of a thylakoid space (lumen) surrounded by a thylakoid membrane. The thylakoid membrane contains photosystems, which are large complexes of proteins and pigments. There are two types of photosystems: photosystem I (PSI) and photosystem II (PSII).

Chemical Equation for Photosynthesis

The overall balanced equation for photosynthesis is commonly written as 6 CO 2 + 6 H 2 O → C 6 H 12 O 6 + 6 O 2 (shown below). In other words, six molecules of carbon dioxide and six molecules of water react in the presence of sunlight to produce one molecule of glucose (a six-carbon sugar) and six molecules of oxygen. 

Stages of Photosynthesis

There are two main stages of photosynthesis: the light-dependent reactions and the Calvin cycle.

Light-Dependent Reactions

The light-dependent reactions use light energy to make ATP (an energy-carrying molecule) and NADPH (an electron carrier) for use in the Calvin cycle. In addition, oxygen is released as a result of the oxidation of water. In plants and algae, the light-dependent reactions take place in the thylakoid membrane of chloroplasts. The most common form of the light-dependent reactions is a process known as non-cyclic photophosphorylation. This process involves two key steps: ATP synthesis (via photosystem II) and NADPH synthesis (via photosystem I).

• Step 1 (ATP Synthesis): Pigments in photosystem II (such as chlorophylls) absorb light and energize electrons. A proton gradient is formed as these excited electrons travel down an electron transport chain and release energy that pumps hydrogen ions from the stroma to the thylakoid lumen. The splitting of water molecules through photolysis produces hydrogen ions (as well as oxygen molecules) that further contribute to this electrochemical gradient. As hydrogen ions flow down their gradient (i.e., back across the thylakoid membrane and into the stroma), they travel through an enzyme known as ATP synthase. ATP synthase catalyzes the formation of adenosine triphosphate (ATP) using ADP (adenosine diphosphate) and inorganic phosphate (P i ).
• Step 2 (NADPH Synthesis): Electrons are transferred to photosystem I and energized by the light absorbed by PSI pigments. The electrons reach the end of the electron transport chain and are passed to an enzyme known as ferredoxin-NADP + reductase (FNR). FNR catalyzes the reaction by which NADP + is reduced to NADPH.

Calvin Cycle

The Calvin cycle (also referred to as the light-independent reactions) takes place in the stroma of chloroplasts and is not directly dependent on sunlight. Instead, this stage utilizes the products of the light-dependent reactions (ATP and NADPH), along with carbon dioxide, to synthesize glucose. The Calvin cycle consists of three basic steps: carbon fixation, reduction, and regeneration.

• Step 1 (Carbon Fixation): RuBisCO (the most abundant enzyme on Earth) catalyzes the carboxylation of ribulose-1,5-biphosphate (RuBP) by carbon dioxide to produce an unstable six-carbon compound. This six-carbon compound is then readily converted into two molecules of 3-phosphoglyceric acid (3-PGA).
• Step 2 (Reduction): An enzyme known as phosphoglycerate kinase catalyzes the phosphorylation of 3-PGA by ATP to produce 1,3-biphosphoglyceric acid (1,3-BPG) and ADP. Next, another enzyme (glyceraldehyde 3-phosphate dehydrogenase) catalyzes the reduction of 1,3-BPG by NADPH to produce glyceraldehyde 3-phosphate (G3P) and NADP + .
• Step 3 (Regeneration): Every turn of the Calvin cycle produces two molecules of G3P. Therefore, six turns of the cycle produce twelve molecules of G3P. Two of these G3P molecules exit the cycle and are used to synthesize one molecule of glucose. Meanwhile, the other ten molecules of G3P remain in the cycle and are used to regenerate six RuBP molecules. The regeneration of RuBP requires ATP, but it allows the cycle to continue.

Products of Photosynthesis

The major product of photosynthesis is glucose, a simple sugar with the molecular formula C 6 H 12 O 6 . Plants and other photosynthetic organisms use glucose for numerous functions, including those listed below.

• Cellular Respiration: Glucose is broken down in order to produce ATP (which can be used to fuel other cellular activities) through a process known as cellular respiration.
• Biosynthesis of Starch and Cellulose: Glucose molecules can be linked together to form complex carbohydrates such as starch and cellulose. Plants and other organisms use starch to store energy and cellulose to support/rigidify their cell walls.
• Protein Synthesis: Glucose can be combined with nitrates (from the soil) to produce amino acids, which can then be used to build proteins.

In addition, oxygen is released into the atmosphere during the process of photosynthesis. Plants (along with many other organisms) use oxygen to carry out aerobic respiration.

Types of Photosynthesis

There are three main types of photosynthesis: C3, C4, and CAM (crassulacean acid metabolism). They differ in the way that they manage photorespiration, a wasteful process that occurs when the enzyme rubisco acts on oxygen instead of carbon dioxide. Photorespiration competes with the Calvin cycle and decreases the efficiency of photosynthesis (by wasting energy and using up fixed carbon).

C3 Photosynthesis

The majority of plants use C3 photosynthesis, a process in which no special features or adaptations are used to combat photorespiration. Hot, dry climates are not ideal for C3 plants (e.g., rice, wheat, and barley) because of the increased rate of photorespiration, which is due to the buildup of oxygen that occurs when plants close their stomata (leaf pores) in order to prevent water loss.

C4 Photosynthesis

C4 photosynthesis reduces photorespiration by performing the initial carbon dioxide fixation and Calvin cycle in two different cell types. This process utilizes an additional enzyme known as phosphoenolpyruvate (PEP) carboxylase. PEP carboxylase does not react with oxygen (unlike rubisco) and is able to catalyze a reaction between carbon dioxide and PEP in the mesophyll cells to produce the intermediate four-carbon compound oxaloacetate. Oxaloacetate is then reduced to malate and transported to bundle sheath cells. In these cells, malate undergoes decarboxylation, forming a special compartment for the concentration of carbon dioxide around rubisco.

As a result, the Calvin cycle can proceed as normal, and an opportunity for rubisco to bind to oxygen is prevented. C4 plants (e.g., maize and sugarcane) have a competitive advantage over C3 plants in hot, dry environments where the benefits of reduced photorespiration outweigh the additional energy costs associated with C4 photosynthesis.

CAM Photosynthesis

Crassulacean acid metabolism, also known as CAM photosynthesis, reduces photorespiration by performing the initial carbon dioxide fixation and Calvin cycle at separate times. CAM plants (e.g., cactus and pineapple) open their stomata at night, allowing carbon dioxide to enter the leaf. The carbon dioxide is converted to oxaloacetate by PEP carboxylase, the same enzyme used in C4 photosynthesis. Oxaloacetate is subsequently reduced to malate, which is stored as malic acid in vacuoles .

During the day (when light is readily available), CAM plants close their stomata and prepare for the Calvin cycle. Malate is transported into chloroplasts and broken down to release carbon dioxide, which is heavily concentrated around the enzyme rubisco. Similar to C4 photosynthesis, crassulacean acid metabolism is an energetically expensive process. However, it is quite useful for plants in hot, arid climates that need to minimize photorespiration and conserve water.

Further Reading

• What is Gibbs Free Energy?
• Endothermic vs Exothermic Reactions
• Catalysts & Activation Energy
• Proteins and Amino Acids
• Claisen Condensations

PHOTOSYNTHESIS

- the most important process on earth, the equation for photosynthesis.

Why are 2 words written above the arrow?

> they are not reactants or products - essential but chlorophyll is not used up

What are the similarities and differences between the (word) equations for photosynthesis and aerobic respiration?

> same substances, different direction (respiration needs no light/chlorophyll)

What are the main parts of a plant where photosynthesis takes place?

> leaves

What does the word photosynthesis mean?

> putting together with light

Where is the chlorophyll? Be as specific as possible.

> inside chloroplasts inside mesophyll cells of leaf

What happens to photosynthesis at night?

> it stops

Taking each of the 4 main ways that plants use glucose from photosynthesis in turn, say whether this could be passed on to you if you were to eat the plant. Explain why, and answer the supplementary question in each case.

By what process does the plant obtain energy? > respiration

In what chemical form is glucose/food stored for later use?> starch/oil

For what purpose is glucose converted into cellulose? > cell walls

By the addition of which element can carbohydrates such as glucose be used for the synthesis of proteins?> nitrogen

Limiting factors in photosynthesis

carbon dioxide concentration > proportionate increase in photosynthesis

light intensity > proportionate increase in photosynthesis up to plateau

Which of these would be a limiting factor in a normal warm day?

> carbon dioxide concentration The principles of manipulating the previously mentioned factors required for photosynthesis can be used in order to provide optimum conditions for plant growth in glasshouses, and in an ecological context to improve the efficiency of energy tranfer in the production of food. For instance, with some crops, horticulturists find it is worthwhile installing gas heating, and releasing the exhaust gases directly into the glasshouses where they grow. Give a logical chain of explanation for this finding.

> Extra warmth speeds up metabolism, and the extra carbon dioxide results in extra photosynthesis, extra food, extra growth, extra yield, extra PROFIT!

Photosynthesis in the garden...

> This allows more light (and water etc?) to reach the grass plants below Some gardeners like to grow varieties of plants with leaves which are not as green as the usual plant,e.g. "golden" privet.

Why do they sometimes find that these plants are overtaken by green sections?

> Greener plants grow more efficiently

... and in the cereal bowl

This food produced by plants is the same sort of food which we might eat (carbohydrates, fats, proteins, etc.). See the side panel of the Cornflakes packet ( data from an old packet - modern data values differ slightly in detail ), and answer the questions below. Refer to the units on the respiration process to see what might happen to it!

What biological justification is there for the claim that this breakfast cereal has a link with sunshine?

> the corn plant makes food by photosynthesis

> starch > 75 %

Plant Mineral Nutrition

In fact the main inorganic nutrients used by plants are carbon dioxide gas from air (how much in the atmosphere? > 0.04 %) and water from soil.

The distinction between organic and inorganic compounds is so important that it is worthwhile sorting some substances into groups, with formulae if possible:

( List of examples: carbon dioxide, glucose, nitrate ion, oxygen, protein, starch, water - add more if you can)

Virtually all other forms of life - including Man - depend on plants for these complex organic substances, either as building blocks for their growth, or as fuel - recovering the energy taken from the sun in the first place. As such they are hijacking the products of plants" activities!

It is a curious fact that oxygen is produced by green plants as a waste by- product of the process, and because not much of it is needed by plants, they release it into the atmosphere! Avas Flowers , and the miracle of photosynthesis , to thank for some of the oxygen you breathe! -->

What is this process (getting rid of waste) called?

> excretion

What process in living organisms uses up oxygen? (2 words)

> aerobic respiration

What sort of organisms carry out this process?

> almost all

What is the general name for the process which uses up oxygen, not in living organisms?

> combustion/burning

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AP®︎/College Biology

Course: ap®︎/college biology   >   unit 3.

• Photosynthesis

Intro to photosynthesis

• Breaking down photosynthesis stages
• Conceptual overview of light dependent reactions
• The light-dependent reactions
• The Calvin cycle
• Photosynthesis evolution
• Photosynthesis review

Introduction

What is photosynthesis.

• Energy. The glucose molecules serve as fuel for cells: their chemical energy can be harvested through processes like cellular respiration and fermentation , which generate adenosine triphosphate— ATP ‍   , a small, energy-carrying molecule—for the cell’s immediate energy needs.
• Fixed carbon. Carbon from carbon dioxide—inorganic carbon—can be incorporated into organic molecules; this process is called carbon fixation , and the carbon in organic molecules is also known as fixed carbon . The carbon that's fixed and incorporated into sugars during photosynthesis can be used to build other types of organic molecules needed by cells.

The ecological importance of photosynthesis

• Photoautotrophs use light energy to convert carbon dioxide into organic compounds. This process is called photosynthesis.
• Chemoautotrophs extract energy from inorganic compounds by oxidizing them and use this chemical energy, rather than light energy, to convert carbon dioxide into organic compounds. This process is called chemosynthesis.
• Photoheterotrophs obtain energy from sunlight but must get fixed carbon in the form of organic compounds made by other organisms. Some types of prokaryotes are photoheterotrophs.
• Chemoheterotrophs obtain energy by oxidizing organic or inorganic compounds and, like all heterotrophs, get their fixed carbon from organic compounds made by other organisms. Animals, fungi, and many prokaryotes and protists are chemoheterotrophs.

Leaves are sites of photosynthesis

The light-dependent reactions and the calvin cycle.

• The light-dependent reactions take place in the thylakoid membrane and require a continuous supply of light energy. Chlorophylls absorb this light energy, which is converted into chemical energy through the formation of two compounds, ATP ‍   —an energy storage molecule—and NADPH ‍   —a reduced (electron-bearing) electron carrier. In this process, water molecules are also converted to oxygen gas—the oxygen we breathe!
• The Calvin cycle , also called the light-independent reactions , takes place in the stroma and does not directly require light. Instead, the Calvin cycle uses ATP ‍   and NADPH ‍   from the light-dependent reactions to fix carbon dioxide and produce three-carbon sugars—glyceraldehyde-3-phosphate, or G3P, molecules—which join up to form glucose.

Photosynthesis vs. cellular respiration

Attribution.

• “ Overview of Photosynthesis ” by OpenStax College, Biology, CC BY 3.0 . Download the original article for free at http://cnx.org/contents/5bb72d25-e488-4760-8da8-51bc5b86c29d@8 .
• “ Overview of Photosynthesis ” by OpenStax College, Concepts of Biology, CC BY 3.0 . Download the original article for free at http://cnx.org/contents/[email protected] .

Works cited:

• "Great Oxygenation Event." Wikipedia. Last modified July 17, 2016. https://en.wikipedia.org/wiki/Great_Oxygenation_Event .

Additional references

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What Is the Photosynthesis Equation?

10 Facts on Photosynthesis

Photosynthesis, derived from the Greek words photo – meaning “light” – and synthesis – “putting together or to make” – is a process used by plants and some bacteria to harness the energy from sunlight to convert water and carbon dioxide to produce sugar (glucose) and oxygen.

The Photosynthesis Equation

The equation for the process of photosynthesis follows:

This balanced chemical equation (meaning it has equal reactants and products on both sides) depicts the process by which plants and some bacteria produce glucose from carbon dioxide and water using light energy from the sun, as indicated in Jones and Jones' Advanced Biology Textbook (1997). In most plants, water is supplied from the roots, with the leaves collecting carbon dioxide via the stomata and sunlight captured by the chloroplasts in the leaves. For plants, oxygen is just a byproduct of the reaction, but it is vital for humans and animals to survive around the world.

The Light-Dependent and Independent Reactions

Photosynthesis consists of two stages, the light-dependent reaction and the light-independent reactions, as explained in Jones and Jones.

The light-dependent reaction uses energy captured from sunlight by the chloroplasts in plant leaves to produce a supply of energy for the light-independent reactions in the form of ATP and NADPH. ATP is produced through an electron transport chain where electrons and hydrogen ions lead to the storage of chemical energy.

The light-independent reaction, also called the Calvin Cycle, uses energy from the supply of ATP and NADPH to reduce molecules of water and carbon dioxide to produce glucose and molecules of oxygen. These processes occur in the stroma. Part of these processes are dark reactions, where carbon fixation (the conversion of carbon to biological molecules) takes place.

Products of Photosynthesis

The resulting glucose is converted to adenosine triphosphate (ATP) through cellular respiration, as explained on the Estrella Mountain Community College photosynthesis web page, to provide energy. In addition to glucose, this reaction produces oxygen that is released by the plants into the atmosphere.

Biology and Chemistry of Photosynthesis

When looking at the chemical equation for photosynthesis there are key components to note. Photosynthesis produces sugars, or carbohydrates. Carbohydrates are a form of energy in everyday food, and they consist of carbon, hydrogen, and oxygen. We can see this in one of the products of photosynthesis:

This is a glucose molecule, and it stores a large amount of chemical energy for later use and consumption.

The chloroplast in plant cells performs the chemical reactions for photosynthesis taking in molecules of carbon dioxide and water with energy to complete the chemical process.

Chlorophyll is a pigment contained in the chloroplast that gives many plants their vibrant green color. It filters out green frequencies of light (reflecting them instead) to absorb energy efficiently.

Plants and other organisms that perform photosynthesis are known as autotrophs, as they produce their own energy and a surplus.

Impacts of Photosynthesis

The conversion of solar energy into another form (like sugar molecules or chemical energy) is an invaluable process for the ecosystem of the planet. Plants and other living things create a system that recycles carbon and oxygen with the use of an endlessly available energy from the sun. Plants create their own food through photosynthesis, and they also create a surplus of energy for a variety of other organisms to survive on.

Related Articles

What are the functions of photosynthesis, explain photosynthesis, what is the sun's role in photosynthesis, how does photosynthesis work in plants, steps to photosynthesis for middle school science, organelles involved in photosynthesis, what is nadph in photosynthesis, what provides electrons for the light reactions, how are photosynthesis & cellular respiration related, chemical ingredients of photosynthesis, how do plant cells obtain energy, describe what a photosystem does for photosynthesis, what happens in the light reaction of photosynthesis, what happens during stage one of photosynthesis, phases of photosynthesis & its location, how does photosynthesis benefit heterotrophs, what is pq, pc, & fd in photosynthesis, how do plants store energy during photosynthesis.

• The Estrella Mountain Community College Website online Photosynthesis web page
• "Advanced Biology;" M. Jones and G. Jones; 1997
• Photosynthesis – National Geographic

About the Author

Based in Manchester, England, John Newton has been writing since 2006. His work has appeared in "Floreat Castellum" and "The Castle Society" magazine. He holds a Bachelor of Science in geography from Durham University.

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The photosynthesis equation made easy.

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The balanced equation for photosynthesis is:

6CO 2   + 6H 2 O + Sunlight ———> C 6 H 12 O 6   + 6O 2

The balanced photosynthesis equation

That may be all you needed, but just in case, let's give a bit more detail.

The photosynthesis equation in words is:

Carbon Dioxide + Water + Sunlight ———> Glucose (simple sugar) + Oxygen

Here's a breakdown of that equation

• The reactants of photosynthesis are everything to the left of the "———>" arrow, thus the reactants of photosynthesis are carbon dioxide, water, and sunlight energy.
• The products of photosynthesis are everything to the right of the "———>" arrow, thus the products of photosynthesis are glucose and oxygen.

Quick Studying Tip:

If you memorize the photosynthesis equation, you've also memorized the cellular respiration equation. That's because respiration is the exact opposite as photosynthesis with one small difference. Instead of sunlight energy input, respiration outputs usable energy.

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Respiration equation: C 6 H 12 O 6   + 6O 2 ———> 6CO 2   + 6H 2 O + ATP (energy)

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5.11B: Main Structures and Summary of Photosynthesis

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In multicellular autotrophs, the main cellular structures that allow photosynthesis to take place include chloroplasts, thylakoids, and chlorophyll.

Learning Objectives

• Describe the main structures involved in photosynthesis and recall the chemical equation that summarizes the process of photosynthesis
• The chemical equation for photosynthesis is 6CO2+6H2O→C6H12O6+6O2.6CO2+6H2O→C6H12O6+6O2.
• In plants, the process of photosynthesis takes place in the mesophyll of the leaves, inside the chloroplasts.
• Chloroplasts contain disc-shaped structures called thylakoids, which contain the pigment chlorophyll.
• Chlorophyll absorbs certain portions of the visible spectrum and captures energy from sunlight.
• chloroplast : An organelle found in the cells of green plants and photosynthetic algae where photosynthesis takes place.
• mesophyll : A layer of cells that comprises most of the interior of the leaf between the upper and lower layers of epidermis.
• stoma : A pore in the leaf and stem epidermis that is used for gaseous exchange.

Overview of Photosynthesis

Photosynthesis is a multi-step process that requires sunlight, carbon dioxide, and water as substrates. It produces oxygen and glyceraldehyde-3-phosphate (G3P or GA3P), simple carbohydrate molecules that are high in energy and can subsequently be converted into glucose, sucrose, or other sugar molecules. These sugar molecules contain covalent bonds that store energy. Organisms break down these molecules to release energy for use in cellular work.

The energy from sunlight drives the reaction of carbon dioxide and water molecules to produce sugar and oxygen, as seen in the chemical equation for photosynthesis. Though the equation looks simple, it is carried out through many complex steps. Before learning the details of how photoautotrophs convert light energy into chemical energy, it is important to become familiar with the structures involved.

Photosynthesis and the Leaf

In plants, photosynthesis generally takes place in leaves, which consist of several layers of cells. The process of photosynthesis occurs in a middle layer called the mesophyll. The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata (singular: stoma ), which also play a role in the plant’s regulation of water balance. The stomata are typically located on the underside of the leaf, which minimizes water loss. Each stoma is flanked by guard cells that regulate the opening and closing of the stomata by swelling or shrinking in response to osmotic changes.

Photosynthesis within the Chloroplast

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. A stack of thylakoids is called a granum, and the liquid-filled space surrounding the granum is the stroma or “bed.”

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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• Biology Article

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 .

Also Read:   Biological Pigments

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.

Frequently Asked Questions

1. what is photosynthesis explain the process of photosynthesis., 2. what is the significance of photosynthesis, 3. list out the factors influencing photosynthesis., 4. what are the different stages of photosynthesis, 5. what is the calvin cycle, 6. write down the photosynthesis equation..

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Please What Is Meant By 300-400 PPM

PPM stands for Parts-Per-Million. It corresponds to saying that 300 PPM of carbon dioxide indicates that if one million gas molecules are counted, 300 out of them would be carbon dioxide. The remaining nine hundred ninety-nine thousand seven hundred are other gas molecules.

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2.8: Cellular Respiration and Photosynthesis

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How do trees help you breathe?

Recall that trees release oxygen as a byproduct of photosynthesis. And you need oxygen to breathe. Do you know why? So your cells can perform cellular respiration and make ATP.

Connecting Cellular Respiration and Photosynthesis

Photosynthesis and cellular respiration are connected through an important relationship. This relationship enables life to survive as we know it. The products of one process are the reactants of the other. Notice that the equation for cellular respiration is the direct opposite of photosynthesis :

• Cellular Respiration: C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O
• Photosynthesis: 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2

Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide, which is used in photosynthesis. While water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water. While photosynthesis requires carbon dioxide and releases oxygen, cellular respiration requires oxygen and releases carbon dioxide. It is the released oxygen that is used by us and most other organisms for cellular respiration. We breathe in that oxygen, which is carried through our blood to all our cells . In our cells, oxygen allows cellular respiration to proceed. Cellular respiration works best in the presence of oxygen. Without oxygen, much less ATP would be produced.

Cellular respiration and photosynthesis are important parts of the carbon cycle. The carbon cycle is the pathways through which carbon is recycled in the biosphere. While cellular respiration releases carbon dioxide into the environment, photosynthesis pulls carbon dioxide out of the atmosphere. The exchange of carbon dioxide and oxygen during photosynthesis (Figure below) and cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels.

• The equation for cellular respiration is the direct opposite of photosynthesis.
• The exchange of carbon dioxide and oxygen thorough photosynthesis or cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels.

Explore More

Use the resource below to answer the questions that follow.

• Photosynthesis and Respiration at http://www.youtube.com/watch?v=JEnjph9miK4 (3:46)

• What is needed for photosynthesis to occur? Be specific.
• What is needed for cellular respiration to occur?
• What is ATP?
• Do autotrophs need to carry out cellular respiration? Why or why not?
• How are the equations for photosynthesis and cellular respiration related?
• What keeps atmospheric oxygen and carbon dioxide at stable levels?