How Plants Use Water

Monday, March 01, 2021

A person waters flowers.

Water is an essential nutrient for plants and comprises up to 9 5% of a plant’s tissue. It is required for a seed to sprout, and as the plant grows, water carries nutrients throughout the plant. Water is responsible for several important functions within plant tissues. 

Water is necessary for photosynthesis, which is how plants use energy from the sun to create their own food. During this process, plants use carbon dioxide from the air and hydrogen from the water absorbed through their roots and release oxygen as a byproduct. This exchange occurs through pore-like stoma on the leaves.  

Water is evaporated on the leaves, as well, in a process called transpiration, which keeps plants from overheating. Warm temperatures, wind and dry air increase the rate of transpiration. As water evaporates through the leaves, more water is pulled up through the roots of the plant.  

Nutrients and sugars from photosynthesis are dissolved in water and move from areas of high concentration, like the roots, to areas of lower concentration, such as the blooms, stem and leaves, for growth and reproduction.  

Water is responsible for cell structural support in many plants, creating a constant pressure on cell walls called turgor, which makes the plant flexible yet strong and allows it to bend in the wind or move leaves toward the sun to maximize photosynthesis. 

Low moisture will cause browning of plant tissues and leaf curling, eventually leading to plant death.  When watering garden plants, it’s important to provide a thorough, deep watering rather than frequent, light watering to encourage deeper root growth.

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By Jodi Richmond , WVU Extension Service Agent – Mercer County

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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Science News Explores

Explainer: how photosynthesis works.

Plants make sugar and oxygen with the power of water, carbon dioxide and sunlight

green leaves lit up from behind with sunlight

Green plants take in light from the sun and turn water and carbon dioxide into the oxygen we breathe and the sugars we eat.

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By Bethany Brookshire

October 28, 2020 at 6:30 am

Take a deep breath. Then thank a plant. If you eat fruit, vegetables, grains or potatoes, thank a plant too.  Plants and algae provide us with the oxygen we need to survive, as well as the carbohydrates we use for energy. They do it all through photosynthesis.

Photosynthesis is the process of creating sugar and oxygen from carbon dioxide, water and sunlight. It happens through a long series of chemical reactions. But it can be summarized like this: Carbon dioxide, water and light go in. Glucose, water and oxygen come out. (Glucose is a simple sugar.)

Photosynthesis can be split into two processes. The “photo” part refers to reactions triggered by light. “Synthesis” — the making of the sugar — is a separate process called the Calvin cycle.

Both processes happen inside a chloroplast. This is a specialized structure, or organelle, in a plant cell. The structure contains stacks of membranes called thylakoid membranes. That’s where the light reaction begins.

a diagram showing the inside of a chloroplast

Let the light shine in

When light hits a plant’s leaves, it shines on chloroplasts and into their thylakoid membranes. Those membranes are filled with chlorophyll , a green pigment. This pigment absorbs light energy. Light travels as electromagnetic waves . The wavelength — distance between waves — determines energy level. Some of those wavelengths are visible to us as the colors we see . If a molecule, such as chlorophyll, has the right shape, it can absorb the energy from some wavelengths of light.

Chlorophyll can absorb light we see as blue and red. That’s why we see plants as green. Green is the wavelength plants reflect, not the color they absorb.

While light travels as a wave, it also can be a particle called a photon . Photons have no mass. They do, however, have a small amount of light energy.

When a photon of light from the sun bounces into a leaf, its energy excites a chlorophyll molecule. That photon starts a process that splits a molecule of water. The oxygen atom that splits off from the water instantly bonds with another, creating a molecule of oxygen, or O 2 . The chemical reaction also produces a molecule called ATP and another molecule called NADPH. Both of these allow a cell to store energy. The ATP and NADPH also will take part in the synthesis part of photosynthesis.

Notice that the light reaction makes no sugar. Instead, it supplies energy — stored in the ATP and NADPH — that gets plugged into the Calvin cycle. This is where sugar is made.

But the light reaction does produce something we use: oxygen. All the oxygen we breathe is the result of this step in photosynthesis, carried out by plants and algae (which are not plants ) the world over.

Give me some sugar

The next step takes the energy from the light reaction and applies it to a process called the Calvin cycle. The cycle is named for Melvin Calvin, the man who discovered it.

The Calvin cycle is sometimes also called the dark reaction because none of its steps require light. But it still happens during the day. That’s because it needs the energy produced by the light reaction that comes before it.

While the light reaction takes place in the thylakoid membranes, the ATP and NADPH it produces end up in the stroma. This is the space inside the chloroplast but outside the thylakoid membranes.

The Calvin cycle has four major steps:

  • carbon fixation : Here, the plant brings in CO 2 and attaches it to another carbon molecule, using rubisco. This is an enzyme , or chemical that makes reactions move faster. This step is so important that rubisco is the most common protein in a chloroplast — and on Earth. Rubisco attaches the carbon in CO 2 to a five-carbon molecule called ribulose 1,5-bisphosphate (or RuBP). This creates a six-carbon molecule, which immediately splits into two chemicals, each with three carbons.
  • reduction : The ATP and NADPH from the light reaction pop in and transform the two three-carbon molecules into two small sugar molecules. The sugar molecules are called G3P. That’s short for glyceraldehyde 3-phosphate (GLIH- sur-AAL-duh-hide 3-FOS-fayt).
  • carbohydrate formation : Some of that G3P leaves the cycle to be converted into bigger sugars such as glucose (C 6 H 12 O 6 ).
  • regeneration : With more ATP from the continuing light reaction, leftover G3P picks up two more carbons to become RuBP. This RuBP pairs up with rubisco again. They are now ready to start the Calvin cycle again when the next molecule of CO 2 arrives.

At the end of photosynthesis, a plant ends up with glucose (C 6 H 12 O 6 ), oxygen (O 2 ) and water (H 2 O). The glucose molecule goes on to bigger things. It can become part of a long-chain molecule, such as cellulose; that’s the chemical that makes up cell walls. Plants also can store the energy packed in a glucose molecule within larger starch molecules. They can even put the glucose into other sugars — such as fructose — to make a plant’s fruit sweet.

All of these molecules are carbohydrates — chemicals containing carbon, oxygen and hydrogen. (CarbOHydrate makes it easy to remember.) The plant uses the bonds in these chemicals to store energy. But we use the these chemicals too. Carbohydrates are an important part of the foods we eat, particularly grains, potatoes, fruits and vegetables.

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Why Do Plants Need Water in Photosynthesis?

High School Science Experiments With Plants

High School Science Experiments With Plants

Photosynthesis is a wondrous and yet simple chemical reaction that occurs when plants use sunlight, water and carbon dioxide to make energy-packed food molecules. Plants pull water from their roots and absorb molecules of atmospheric carbon dioxide to gather the necessary ingredients for synthesizing glucose (sugar).

Water (H 2 O) molecules split and donate electrons to carbon dioxide molecules as light energy from the sun is converted into the chemical bonds of glucose (sugar) during photosynthesis.

Photosynthesis Equation

The recipe for glucose is six molecules of water (H 2 O) plus six molecules of carbon dioxide (CO 2 ) plus exposure to sunlight. Photons in light waves initiate a chemical reaction in the cell that breaks the bonds of water and carbon dioxide molecules and reorganizes these reactants into glucose and oxygen – a by-product.

The formula for photosynthesis is commonly expressed as an equation:

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

Early Origins of Photosynthesis

Nearly 3.5 billion years ago, cyanobacteria changed the course of the world with their photosynthetic power to convert light energy and inorganic substances into chemical energy for food. According to Quanta Magazine , archaic micro-organisms created the planetary conditions that gave rise to a cascade of diverse plants with a shared ability to photosynthesize and release oxygen.

Although the details are still being studied and debated, adaptation of photosynthetic centers in early life forms such as unicellular plants and algae appears to have jump-started evolution.

Why Is Photosynthesis Important?

Photosynthesis is essential for life and sustainability in a balanced ecosystem. Photosynthetic organisms are at the bottom of the food web , meaning they directly or indirectly produce food energy for herbivores, omnivores, secondary and tertiary consumers, and apex predators. When water molecules split during the photosynthetic reaction, oxygen molecules are formed and released into the water and air.

Without oxygen, life would not exist as it does today.

Further, photosynthesis plays a vital role in sinking carbon dioxide. The process of converting carbon dioxide to carbohydrates is called carbon fixation. When carbon-based living organisms die, their buried remains can become compressed, and over time, turn to fossil fuel .

Water Requirements of Plants

Water helps transport food and nutrients within cells and between tissues to provide nourishment to all parts of a living plant. Large vacuoles within cells contain water that strengthens the stem, fortifies the cell wall and facilitates osmosis in leaves.

Undifferentiated cells in the meristem could not properly specialize into leaves, blooms or stems if cells in the tissue were badly dehydrated. Stems and leaves droop when water needs are unmet, and photosynthesis slows.

Plants and Water: Related Science Projects

Students interested in learning more about plants and water requirements may enjoy experimenting with sprouted bean seeds. Lima beans and pole beans grow quickly, which makes them well-suited for a feeding plants science project or classroom demonstration. Teachers can plant the seeds about a week before students start experimenting to determine which environmental factors, such as adequate water, influence plant growth.

For instance, a science class could continue growing, watering and measuring five or more bean sprouts next to a window for two weeks or longer. For purposes of comparison, they could introduce variables in experimental groups of sprouts and develop a hypothesis. Experimental groups of five plants or more are recommended for a bigger sample size.

For example:

  • Experimental group 1: Withhold water to see how soon bean sprout growth is impacted by dehydration.
  • Experimental group 2: Place a paper bag over the bean sprouts to observe how low light can affect photosynthesis and chlorophyll production. 
  • Experiment group 3: Wrap plastic sandwich bags around bean sprouts to study effects of disrupted exchange of gases.
  • Experimental group 4: Place bean sprouts in a refrigerator each night to see how colder temperatures may affect growth.

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  • Royal Society of Chemistry: Photosynthesis
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About the Author

Dr. Mary Dowd studied biology in college where she worked as a lab assistant and tutored grateful students who didn't share her love of science. Her work history includes working as a naturalist in Minnesota and Wisconsin and presenting interactive science programs to groups of all ages. She enjoys writing online articles sharing information about science and education. Currently, Dr. Dowd is a dean of students at a mid-sized university.

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Understanding Global Change

Discover why the climate and environment changes, your place in the Earth system, and paths to a resilient future.

Photosynthesis

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Photosynthesis is the processes of using sunlight to convert chemical compounds (specifically carbon dioxide and water ) into food . Photosynthesizing organisms (plants, algae, and bacteria) provide most of the chemical energy that flows through the biosphere.  They also produced most of the biomass that led to the fossil fuels that power much of our modern world. Photosynthesis takes place on land, in the ocean, and in freshwater environments. The first photosynthesizing single-celled bacteria evolved over 3.5 billion years ago. The subsequent rise in atmospheric oxygen (a byproduct of photosynthesis) about a billion years later played a major role in shaping the evolution of life on Earth over the last 2.5 billion years. Today the vast majority of land, freshwater, and oceanic organisms require oxygen for respiration , the biochemical process that generates energy from food.

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What is photosynthesis, earth system model about photosynthesis, explore the earth system, investigate, links to learn more.

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what is role of water in photosynthesis

Global Change Infographic

Photosynthesus is an essential part of How the Earth System Works.  Click the image on the left to open the Understanding Global Change Infographic . Locate the photosynthesis icon and identify other Earth system processes and phenomena that cause changes to, or are affected by, photosynthesis.

Photosynthesis is the chemical process by which plants, algae, and some bacteria use the energy from sunlight to transform carbon dioxide (a greenhouse gas ) from the atmosphere, and water , into organic compounds such as sugars. These sugars are then used to make complex carbohydrates, lipids, and proteins, as well as the wood, leaves, and roots of plants.  The amount of organic matter made by photosynthesizing organisms in an ecosystem is defined as the productivity of that ecosystem.  Energy flows through the biosphere as organisms (including some animals) eat photosynthesizing organisms (called herbivores), and as organisms then eat those herbivores (carnivores) , etc., to get their energy for growth, reproduction, and other functions.  This energy is acquired through the process of cellular respiration , which usually requires oxygen.   Oxygen is a byproduct of photosynthesis. About 70% of the oxygen in the atmosphere that we breathe comes from algae in the ocean. Atmospheric oxygen from photosynthesis also forms the ozone layer , which protects organisms from harmful high-energy ultraviolet (UV) radiation from the Sun . Because photosynthesis also requires water , the availability of water affects the productivity and biomass of the ecosystem, which in turn affects how much and how rapidly water cycles through the ecosystem.

Fossil fuels are derived from the burial of photosynthetic organisms, including plants on land (which primarily form coal) and plankton in the oceans (which primarily form oil and natural gas). While buried, the carbon in the organic material is removed from the carbon cycle for thousands of years to hundreds of millions of years. The burning of fossil fuels has dramatically increased the exchange of carbon from the ground back into the atmosphere and oceans. This return of carbon back into atmosphere as carbon dioxide is occurring at a rate that is hundreds to thousands of times faster than it took to bury it, and much faster than it can be removed by photosynthesis or weathering . Thus, the carbon dioxide released from the burning of fossil fuels is accumulating in the atmosphere, increasing average temperatures and causing ocean acidification .

A simplified diagram showing the overall inputs – carbon dioxide, water, and sunlight, and products – oxygen and sugar (glucose), of photosynthesis.

A simplified diagram showing the overall inputs – carbon dioxide, water, and sunlight, and products – oxygen and sugar (glucose), of photosynthesis.

The rate of photosynthesis in ecosystems is affected by various environmental conditions, including:

  • Climatic conditions, such as the amount of sunlight available at different latitudes , temperature , and precipitation For example, ecosystems at low latitudes, such as tropical rainforests, have higher productivity and biomass than ecosystems near the poles because of they receive more sunlight and rainfall than regions at higher latitudes.
  • Nutrients , especially nitrogen and phosphorus , which when limited can decrease productivity, but when abundant can increase productivity and biomass. Photosynthesizing organisms extract nutrients from the environment, and return them to the soil when they die and decay.
  • Numerous other abiotic environmental factors, including soil quality (often related to nutrient levels), wildfires , water acidity , and oxygen levels .
  • Species interactions , including the resources species provide for each other, and how they compete for resources such as water, light, and/or space. Species that reduce or increase the success of other species alter population sizes , thus affecting productivity and biomass .
  • Evolutionary processes that can change the growth and reproduction rates of photosynthesizing organisms over time, as well as the growth and reproduction of rates of the organisms that eat them.

Humans have altered the rate of photosynthesis, and in turn productivity , in ecosystems through a variety of activities, including:

  • Deforestation , habitat destruction , and urbanization , which remove plants and trees from the environment and disrupt ecosystems.
  • Agricultural activities that increase the amount of crops available to feed the growing global human population .
  • The use of fertilizers for agricultural activities that increase the amount of nutrients , especially nitrogen and phosphorous , in soil or water. These nutrients increase plant and algae growth, including growth of species that are toxic to other organisms. Increased nutrients is not always a good thing. For example, in aquatic environments, nutrient-rich runoff can cause large amounts of algae to grow – when these algae die, they are consumed by bacteria which can reduce oxygen levels in the water, killing fish and other species. This process is known as eutrophication.
  • Human freshwater use , which can limit the amount of water available for plants and trees in an ecosystem.
  • The release of pollutants and waste , which can reduce growth and reproduction or kill plants.
  • Activities that release carbon dioxide and other greenhouse gases that cause global warming, such as the burning of fossil fuels , agricultural activities , and deforestation . Increasing carbon dioxide levels may increase photosynthesis rates in some plants, but this can also make plants less nutritious . Increasing average global land and ocean temperatures and changes in precipitation patterns also affect plant and algae growth, and can make certain species more susceptible to disease .
  • Activities such as the burning of fossil fuels , agricultural activities , and deforestation that release carbon dioxide into the atmosphere, which is absorbed by the ocean causing acidification . The decreasing pH of ocean waters (along with ocean warming) causes physiological stress for many plant and algae species, which can decrease growth, reproduction, species population sizes, and biomass .
  • Introducing invasive species that compete with native plant or algae species for nutrients, water, light, or other resources, reducing native species populations.

The Earth system model below includes some of the processes and phenomena related to photosynthesis.  These processes operate at various rates and on different spatial and temporal scales. For example, carbon dioxide is transferred among plants and animals over relatively short time periods (hours-weeks), but the deforestation alters ecosystems over decades to centuries, or longer.  Can you think of additional cause and effect relationships between photosynthesis and other processes in the Earth system?

Photosynthesis system model

Click the bolded terms (e.g. respiration , productivity and biomass , and burning of fossil fuels ) on this page to learn more about these process and phenomena. Alternatively, explore the Understanding Global Change Infographic and find new topics that are of interest and/or locally relevant to you.

Learn more in these real-world examples, and challenge yourself to  construct a model  that explains the Earth system relationships.

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  • New York Times: ‘Global Greening’ Sounds Good. In the Long Run It’s Terrible
  • USGCRP: Climate and Health Assessment, Food Safety, Nutrition, and Distribution
  • HHMI BioInteractive: Photosynthesis

Why do plants need water? – Emma, 9, New York

When I’m thirsty, I pick up a glass of water with my paws and drink it—just like you do. But plants don’t have paws or mouths, so how (and why) do they drink it?

To find the answer, I talked with my friend Helmut Kirchhoff . He’s a scientist at Washington State University. He studies plants and biochemistry.

He told me plants need water inside their cells. Water makes plant cells strong and flexible. It also dissolves stuff. That makes it possible for chemical reactions to happen inside plant cells —like the reactions a plant uses to make energy during photosynthesis. Plants also need water to move around nutrients and other molecules required for life.

“Water is essential for life, but plants must move nutrients from the soil to the leaves,” Kirchhoff said. “So, they have this very nice transport system called xylem. Xylem is an ancient Greek word that means wood. It works like a straw to move water and nutrients from the roots to the leaves.”

what is role of water in photosynthesis

We usually think of water flowing down, so it might seem weird that water is moving up the plant. The way water moves from the roots to the stem and up to the leaves is called the transpiration stream . First, it moves from the soil into very fine hairs on the roots. Then it travels from cell to cell up the plant’s roots.

That’s when the pull of transpiration really kicks in. Transpiration is how plants release water into the air through their leaves. It works because there are super tiny openings on the underside of a plant’s leaves. They are so small you need a microscope to see them. They’re called stomata. They look like itty bitty mouths with lips. The “lips” are guard cells. They open and close the stomata to release water or keep it inside.

what is role of water in photosynthesis

When the stomata open, water evaporates into the air. That causes suction—sort of like sucking on a straw. The suction pulls water—and the nutrients dissolved in the water—from the roots up the plant stem and out to the leaves.

One big way that plants use water is photosynthesis. Plants use the sun’s light to change water and carbon dioxide into oxygen and sugar. Then, the plant moves some of the sugar back down the plant using another transport system called phloem. The plant stores the sugar partly in its roots. When the plant needs energy, it can break down the sugar and use the energy stored there.

Water is important for the phloem, too. It dissolves the sugar and other stuff the plant needs moved down to the roots. Or up to the flowers and small growing leaves that still need sugar from older leaves to thrive.

Plants might not have paws or mouths, but their bodies still need water. It’s just another way plants aren’t so different from us after all.

Dr. Universe

WATER Latest WATER Information News

How does water affect photosynthesis explained, introduction: understanding photosynthesis and water.

Hello and welcome, dear readers! Today, we are going to explore the fascinating relationship between water and photosynthesis. Photosynthesis is a crucial process that plants use to produce oxygen and energy for themselves and all living organisms. It is a complex process that requires several inputs, including sunlight, carbon dioxide, and of course, water. Water plays a vital role in photosynthesis, and without it, this process cannot happen effectively.

In this article, we will look at the different ways water affects photosynthesis, the advantages and disadvantages of this process, and answer some frequently asked questions about it. We will also provide a detailed explanation of how the process works, so buckle up and let’s dive in!

What Is Photosynthesis?

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy from the sun into chemical energy in the form of glucose. This process occurs in the chloroplasts of plant cells and involves two primary stages: the light-dependent reactions and the light-independent reactions.

During the light-dependent reactions, light energy is absorbed by chlorophyll, which breaks down water molecules into oxygen and hydrogen ions. The oxygen is released into the atmosphere as a byproduct, and the hydrogen ions are used to produce ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy carriers that power the next stage of photosynthesis.

The light-independent reactions, also known as the Calvin cycle, involve using the ATP and NADPH produced in the previous stage to convert carbon dioxide into glucose. This process is vital for the survival of all living organisms, as it produces the oxygen we breathe and the energy we need to live.

How Does Water Affect Photosynthesis?

Water is a crucial component of photosynthesis, as it is one of the primary reactants in the light-dependent reactions. Without water, plants cannot break down the water molecules and produce the hydrogen ions necessary for ATP and NADPH production.

Water also helps keep the plant hydrated, which is essential for the plant’s survival and growth. When there is not enough water available, the plant will wilt, and photosynthesis will slow down or stop altogether.

However, too much water can also be harmful to photosynthesis. When plants are overwatered, their roots can become waterlogged, which reduces oxygen availability and can lead to root rot. This can cause the plant to die or become less productive in photosynthesis.

Advantages and Disadvantages of Water in Photosynthesis

While water is necessary for photosynthesis, it also has its advantages and disadvantages.

One of the advantages of water in photosynthesis is that it helps regulate the plant’s temperature. During photosynthesis, plants can absorb a lot of heat from the sun, which can cause their temperature to rise rapidly. However, water helps cool the plant down by evaporating from the leaves and carrying away the excess heat.

Water also helps transport nutrients throughout the plant, as it is absorbed through the roots and transported to the leaves, where it is used in photosynthesis.

Disadvantages

One of the disadvantages of water in photosynthesis is that it can be a limiting factor. In areas where water is scarce, plants may not be able to perform photosynthesis as efficiently, which can limit their growth and productivity.

Additionally, too much water can be harmful to photosynthesis, as mentioned earlier. When plants are overwatered, they can suffer from root rot, which can cause them to die or become less productive.

Table: How Does Water Affect Photosynthesis?

Faqs: frequently asked questions about how water affects photosynthesis, 1. can photosynthesis occur without water.

No, photosynthesis cannot occur without water. Water is one of the primary reactants in the light-dependent reactions, and without it, plants cannot produce the hydrogen ions necessary for ATP and NADPH production.

2. How does water help regulate the temperature of plants during photosynthesis?

Water helps cool the plant down by evaporating from the leaves and carrying away excess heat. This is known as transpiration, and it is an essential mechanism for regulating the plant’s temperature.

3. What happens when a plant is overwatered?

When a plant is overwatered, its roots can become waterlogged, which reduces oxygen availability and can lead to root rot. This can cause the plant to die or become less productive in photosynthesis.

4. How does water affect the nutrient transport in plants?

Water helps transport nutrients throughout the plant, as it is absorbed through the roots and transported to the leaves, where it is used in photosynthesis.

5. Why is water a limiting factor in photosynthesis?

Water can be a limiting factor in photosynthesis because in areas where water is scarce, plants may not be able to perform photosynthesis as efficiently, which can limit their growth and productivity.

6. Can too much water be harmful to photosynthesis?

Yes, too much water can be harmful to photosynthesis. When plants are overwatered, they can suffer from root rot, which can cause them to die or become less productive.

7. What happens if a plant does not get enough water for photosynthesis?

If a plant does not get enough water for photosynthesis, it will wilt, and photosynthesis will slow down or stop altogether. This can be harmful to the plant’s growth and productivity.

8. How does water affect the rate of photosynthesis?

Water affects the rate of photosynthesis by providing the hydrogen ions necessary for ATP and NADPH production. If there is not enough water available, photosynthesis will slow down or stop altogether.

9. Why is water essential for photosynthesis?

Water is essential for photosynthesis because it is one of the primary reactants in the light-dependent reactions, and without it, plants cannot produce the hydrogen ions necessary for ATP and NADPH production.

10. How does water affect the quality of the glucose produced during photosynthesis?

Water does not directly affect the quality of the glucose produced during photosynthesis. However, if the plant is not adequately hydrated, its growth and productivity may be affected, which can indirectly affect the quality of the glucose produced.

11. Can plants absorb water through their leaves during photosynthesis?

Yes, plants can absorb water through their leaves during photosynthesis. This is known as foliar feeding, and it is a useful method for providing plants with essential nutrients and water.

12. Can photosynthesis occur in saltwater?

No, photosynthesis cannot occur in saltwater. Saltwater contains too much salt, which can damage the plant’s cells and prevent photosynthesis from occurring.

13. Can photosynthesis occur at night?

No, photosynthesis cannot occur at night since it requires light energy from the sun. However, some plants, such as cacti, perform a type of photosynthesis called CAM (Crassulacean Acid Metabolism), which allows them to store carbon dioxide at night and use it during the day when photosynthesis can occur.

Conclusion: Take Action Today!

Congratulations, you have made it to the end of this article! We hope you have learned something valuable about how water affects photosynthesis. Remember, water is an essential component of this process, and without it, life as we know it could not exist.

We encourage you to take action today by conserving water whenever possible, whether it is by taking shorter showers, fixing leaky faucets, or using drought-resistant plants in your garden. Together, we can ensure that water remains available for future generations to enjoy.

Closing/Disclaimer

This article is intended for informational purposes only and should not be used as a substitute for professional advice or treatment. If you have any concerns about your health or the health of your plants, please consult a qualified professional.

Watch Video:How Does Water Affect Photosynthesis? Explained

  • 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.

what is role of water in photosynthesis

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.

Photosynthesis Reaction

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

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

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

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 cycle

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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  • What is Photosynthesis

When you get hungry, you grab a snack from your fridge or pantry. But what can plants do when they get hungry? You are probably aware that plants need sunlight, water, and a home (like soil) to grow, but where do they get their food? They make it themselves!

Plants are called autotrophs because they can use energy from light to synthesize, or make, their own food source. Many people believe they are “feeding” a plant when they put it in soil, water it, or place it outside in the Sun, but none of these things are considered food. Rather, plants use sunlight, water, and the gases in the air to make glucose, which is a form of sugar that plants need to survive. This process is called photosynthesis and is performed by all plants, algae, and even some microorganisms. To perform photosynthesis, plants need three things: carbon dioxide, water, and sunlight.

Infographic showing photosynthesis

Just like you, plants need to take in gases in order to live. Animals take in gases through a process called respiration. During the respiration process, animals inhale all of the gases in the atmosphere, but the only gas that is retained and not immediately exhaled is oxygen. Plants, however, take in and use carbon dioxide gas for photosynthesis. Carbon dioxide enters through tiny holes in a plant’s leaves, flowers, branches, stems, and roots. Plants also require water to make their food. Depending on the environment, a plant’s access to water will vary. For example, desert plants, like a cactus, have less available water than a lilypad in a pond, but every photosynthetic organism has some sort of adaptation, or special structure, designed to collect water. For most plants, roots are responsible for absorbing water. 

The last requirement for photosynthesis is an important one because it provides the energy to make sugar. How does a plant take carbon dioxide and water molecules and make a food molecule? The Sun! The energy from light causes a chemical reaction that breaks down the molecules of carbon dioxide and water and reorganizes them to make the sugar (glucose) and oxygen gas. After the sugar is produced, it is then broken down by the mitochondria into energy that can be used for growth and repair. The oxygen that is produced is released from the same tiny holes through which the carbon dioxide entered. Even the oxygen that is released serves another purpose. Other organisms, such as animals, use oxygen to aid in their survival. 

If we were to write a formula for photosynthesis, it would look like this: 

6CO 2 + 6H 2 O + Light energy → C 6 H 12 O 6 (sugar) + 6O 2 

The whole process of photosynthesis is a transfer of energy from the Sun to a plant. In each sugar molecule created, there is a little bit of the energy from the Sun, which the plant can either use or store for later. 

Imagine a pea plant. If that pea plant is forming new pods, it requires a large amount of sugar energy to grow larger. This is similar to how you eat food to grow taller and stronger. But rather than going to the store and buying groceries, the pea plant will use sunlight to obtain the energy to build sugar. When the pea pods are fully grown, the plant may no longer need as much sugar and will store it in its cells. A hungry rabbit comes along and decides to eat some of the plant, which provides the energy that allows the rabbit to hop back to its home. Where did the rabbit’s energy come from? Consider the process of photosynthesis. With the help of carbon dioxide and water, the pea pod used the energy from sunlight to construct the sugar molecules. When the rabbit ate the pea pod, it indirectly received energy from sunlight, which was stored in the sugar molecules in the plant. 

Collage of bread and wheat

Humans, other animals, fungi, and some microorganisms cannot make food in their own bodies like autotrophs, but they still rely on photosynthesis. Through the transfer of energy from the Sun to plants, plants build sugars that humans consume to drive our daily activities. Even when we eat things like chicken or fish, we are transferring energy from the Sun into our bodies because, at some point, one organism consumed a photosynthetic organism (e.g., the fish ate algae). So the next time you grab a snack to replenish your energy, thank the Sun for it! 

This is an excerpt from the  Structure and Function  unit of our curriculum product line, Science and Technology Concepts TM  (STC). Please visit our publisher,  Carolina Biological , to learn more. 

[BONUS FOR TEACHERS] Watch "Photosynthesis: Blinded by the Light" to explore student misconceptions about matter and energy in photosynthesis and strategies for eliciting student ideas to address or build on them.

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Photosynthesis

What is photosynthesis.

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Animals need to eat food to get their energy. All animals, including humans, eat food that was, or is, a plant or an animal.

But green plants and algae can use light energy to make their own food! This process called photosynthesis .

Almost all life on Earth depends upon this process.

what is role of water in photosynthesis

Why is photosynthesis so important?

Photosynthesis is really important for animals, including humans because

  • without photosynthesis we wouldn’t have food because it converts energy from the sun into chemical energy for the food chains.
  • photosynthesis keeps the levels of oxygen and carbon dioxide in the atmosphere in balance – without it we would very quickly run out of oxygen.

Photosynthesis is really important for the plant because it provides the plant with food:

  • some of the glucose is used immediately, to give the plant energy in the process of respiration.
  • some of the glucose is changed into starch and stored in all parts of the plant. When it is needed, it is converted back into glucose.

Adaptations of the leaf

In most plants photosynthesis happens in the leaves. Leaves have adapted so that photosynthesis takes place efficiently. The table describes some of its adaptations:

what is role of water in photosynthesis

A leaf usually has a large surface area, so that it can absorb a lot of light. It's top surface is protected from water loss, disease and weather damage by a waxy cuticle, which does not stop light entering the leaf.

The upper part of the leaf is where the light falls, and it contains many cells called palisade cells. This has many chloroplasts, with lots of chlorophyll to trap as much light as possible. It is shaped like a tall box which helps pack them closely together.

Carbon dioxide

Plants get the carbon dioxide they need from the air through their leaves. It moves by diffusion through small holes in the underside of the leaf called stomata. Guard cells control the size of the stomata so that the leaf does not lose too much water in hot, windy or dry conditions.

The lower part of the leaf is a spongy layer with loose-fitting cells. Between the cells in this layer there are 'air spaces' - a bit like a sponge. These allow the gases to diffuse through the leaf.Stomata let carbon dioxide enter the leaf, and let the oxygen produced in photosynthesis leave the leaf easily. In many plants, stomata are open during the day and closed at night.

The water needed for photosynthesis is absorbed through the roots and transported through tubes to the leaf.The roots have a type of cell called a root hair cell. These project out from the root into the soil, and have a big surface area and thin walls. This lets water pass into them easily.Note that root cells do not contain chloroplasts, as they are normally in the dark and cannot carry out photosynthesis.

what is role of water in photosynthesis

Results Only the areas of the leaf that were originally green tested positive for starch. The discoloured areas tested negative. As the green areas contained chlorophyll and the white did not, this proves that chlorophyll is needed for photosynthesis.

Investigating the production of oxygen

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Food Chains

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Gas Exchange and Respiration

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Biology LibreTexts

4.8: Photosynthesis - The Role of Light

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  • Page ID 4634

  • John W. Kimball
  • Tufts University & Harvard

The heart of photosynthesis as it occurs in most autotrophs consists of two key processes:

  • the removal of hydrogen (H) atoms from water molecules
  • the reduction of carbon dioxide (CO 2 ) by these hydrogen atoms to form organic molecules .

The second process involves a cyclic series of reactions named (after its discoverer) the Calvin Cycle .

The electrons (e − ) and protons (H + ) that make up hydrogen atoms are stripped away separately from water molecules.

\[\ce{2H2O -> 4e^{-} + 4H^{+} + O2}\]

The electrons serve two functions:

  • They reduce NADP + to NADPH for use in the Calvin Cycle.
  • They set up an electrochemical charge that provides the energy for pumping protons from the stroma of the chloroplast into the interior of the thylakoid.

The protons also serve two functions:

  • They participate in the reduction of NADP + to NADPH.
  • As they flow back out from the interior of the thylakoid (by facilitated diffusion), passing down their concentration gradient), the energy they give up is harnessed to the conversion of ADP to ATP .
  • Because it is drive by light, this process is called photophosphorylation .

\[\ce{ADP + P_i -> ATP}\]

The ATP provides the second essential ingredient for running the Calvin Cycle.

The removal of electrons from water molecules and their transfer to NADP + requires energy. The electrons are moving from a redox potential of about +0.82 volt in water to −0.32 volt in NADPH. Thus enough energy must be available to move them against a total potential of 1.14 volts. Where does the needed energy come from? The answer: Light .

The Thylakoid Membrane

Chloroplasts contain a system of thylakoid membranes surrounded by a fluid stroma . Six different complexes of integral membrane proteins are embedded in the thylakoid membrane. The exact structure of these complexes differs from group to group (e.g., plant vs. alga) and even within a group (e.g., illuminated in air or underwater). They are as follows:

Photosystem I

The structure of photosystem I in a cyanobacterium ("blue-green alga") has been completely worked out. It probably closely resembles that of plants as well. It is a homotrimer with each subunit in the trimer containing:

  • 12 different protein molecules bound to
  • 2 molecules of the reaction center chlorophyll P 700
  • 4 accessory molecules closely associated with them
  • 90 molecules that serve as antenna pigments
  • 22 carotenoid molecules
  • 4 lipid molecules
  • 3 clusters of Fe 4 S 4
  • 2 phylloquinones

Photosystem II

Photosystem II is also a complex of

  • > 20 different protein molecules bound to
  • 2 molecules of the reaction center chlorophyll P 680
  • 2 accessory molecules close to them
  • 2 molecules of pheophytin (chlorophyll without the Mg ++ )
  • the remaining molecules of chlorophyll a serve as antenna pigments .
  • some half dozen carotenoid molecules. These also serve as antenna pigments.
  • 2 molecules of plastoquinone

Light-Harvesting Complexes (LHC)

  • LHC-I associated with photosystem I
  • LHC-II associated with photosystem II

These LHCs also act as antenna pigments harvesting light and passing its energy on to their respective photosystems.

The LHC-II of spinach is a homotrimer, with each monomer containing

  • a single polypeptide
  • 8 molecules of chlorophyll a
  • 6 molecules of chlorophyll b
  • 4 carotenoid molecules

Cytochromes b 6 and f

Atp synthase, how the system works.

  • Light is absorbed by the antenna pigments of photosystems II and I .
  • The absorbed energy is transferred to the reaction center chlorophylls, P 680 in photosystem II, P 700 in photosystem I.
  • Absorption of 1 photon of light by Photosystem II removes 1 electron from P 680 .
  • With its resulting positive charge, P 680 is sufficiently electronegative that it can remove 1 electron from a molecule of water.
  • When these steps have occurred 4 times, requiring 2 molecules of water, 1 molecule of oxygen and 4 protons (H + ) are released
  • The electrons are transferred (by way of plastoquinone — PQ in the figure) to the cytochrome b 6 /f complex where they provide the energy for chemiosmosis .
  • Activation of P 700 in photosystem I enables it to pick up electrons from the cytochrome b 6 /f complex (by way of plastocyanin — PC in the figure) and raise them to a sufficiently high redox potential that, after passing through ferredoxin ( Fd in the figure),
  • they can reduce NADP + to NADPH .

The sawtooth shifts in redox potential as electrons pass from P 680 to NADP + have caused this system to be called the Z-Scheme (although as I have drawn the diagram, it looks more like an "N"). It is also called noncyclic photophosphorylation because it produces ATP in a one-way process (unlike cyclic photophosphorylation and pseudocyclic photophosphorylation described below).

Chemiosmosis in Chloroplasts

The energy released as electrons pass down the gradient between photosystem II and plastocyanin (PC) is harnessed by the cytochrome b 6 /f complex to pump protons ( H + ) against their concentration gradient from the stroma of the chloroplast into the interior of the thylakoid (an example of active transport). As their concentration increases inside (which is the same as saying that the pH of the interior decreases), a strong diffusion gradient is set up. The only exit for these protons is through the ATP synthase complex. As in mitochondria, the energy released as these protons flow down their gradient is harnessed to the synthesis of ATP . The process is called chemiosmosis and is an example of facilitated diffusion.

alt

Cyclic Photophosphorylation

  • Each CO 2 taken up by the Calvin cycle ) requires 2 NADPH molecules and 3 ATP molecules
  • Each molecule of oxygen released by the light reactions supplies the 4 electrons needed to make 2 NADPH molecules.
  • The chemiosmosis driven by these 4 electrons as they pass through the cytochrome b 6 /f complex liberates only enough energy to pump 12 protons into the interior of the thylakoid.
  • But in order to make 3 molecules of ATP, the ATPase in chloroplasts appears to have 14 protons (H + ) pass through it.
  • So there appears to be a deficit of 2 protons.
  • How is this deficit to be made up?
  • One likely answer: cyclic photophosphorylation .

In cyclic photophosphorylation,

  • the electrons expelled by the energy of light absorbed by photosystem I pass, as normal, to ferredoxin (Fd).
  • But instead of going on to make NADPH,
  • they pass to plastoquinone (PQ) and on back into the cytochrome b 6 /f complex.
  • Here the energy each electron liberates pumps 2 protons (H + ) into the interior of the
  • thylakoid — enough to make up the deficit left by noncyclic photophosphorylation.

This process is truly cyclic because no outside source of electrons is required. Like the photocell in a light meter, photosystem I is simply using light to create a flow of current. The only difference is that instead of using the current to move the needle on a light meter, the chloroplast uses the current to help synthesize ATP.

Pseudocyclic Photophosphorylation

Another way to make up the deficit is by a process called pseudocyclic photophosphorylation in which some of the electrons passing to ferredoxin then reduce molecular oxygen back to H 2 O instead of reducing NADP + to NADPH.

At first glance, this might seem a fruitless undoing of all the hard work of photosynthesis. But look again. Although the electrons cycle from water to ferredoxin and back again, part of their pathway is through the chemiosmosis-generating stem of cytochrome b 6 /f. Here, then, is another way that simply by turning on a light, enough energy is imparted to electrons that they can bring about the synthesis of ATP.

Antenna Pigments

Chlorophylls a and b differ slightly in the wavelengths of light that they absorb best (although both absorb red and blue much better than yellow and green). Carotenoids help fill in the gap by strongly absorbing green light. The entire complex ensures that most of the energy of light will be trapped and passed on to the reaction center chlorophylls.

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Water and carbon dioxide enter the leaf through the stomata (small holes on the underside of the leaf that are controlled by gaurd cells) by diffusion .

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  • Published: 04 March 2024

Widespread photosynthesis reaction centre barrel proteins are necessary for haloarchaeal cell division

  • Shan Zhao 1   na1 ,
  • Kira S. Makarova   ORCID: orcid.org/0000-0002-8174-2844 2   na1 ,
  • Wenchao Zheng 1 ,
  • Le Zhan 1 ,
  • Qianqian Wan 1 ,
  • Yafei Liu 1 ,
  • Han Gong 1 ,
  • Mart Krupovic   ORCID: orcid.org/0000-0001-5486-0098 3 ,
  • Joe Lutkenhaus   ORCID: orcid.org/0000-0002-8228-2114 4 ,
  • Xiangdong Chen 5 ,
  • Eugene V. Koonin   ORCID: orcid.org/0000-0003-3943-8299 2 &
  • Shishen Du   ORCID: orcid.org/0000-0002-9809-8653 1  

Nature Microbiology volume  9 ,  pages 712–726 ( 2024 ) Cite this article

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  • Archaeal biology
  • Archaeal physiology

Cell division is fundamental to all cellular life. Most archaea depend on either the prokaryotic tubulin homologue FtsZ or the endosomal sorting complex required for transport for division but neither system has been robustly characterized. Here, we show that three of the four photosynthesis reaction centre barrel domain proteins of Haloferax volcanii (renamed cell division proteins B1/2/3 (CdpB1/2/3)) play important roles in cell division. CdpB1 interacts directly with the FtsZ membrane anchor SepF and is essential for cell division, whereas deletion of cdpB2 and cdpB3 causes a major and a minor division defect, respectively. Orthologues of CdpB proteins are also involved in cell division in other haloarchaea, indicating a conserved function of these proteins. Phylogenetic analysis shows that photosynthetic reaction centre barrel proteins are widely distributed among archaea and appear to be central to cell division in most if not all archaea.

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Data availability

Data generated and analysed during this study are presented in the text or in the Supplementary Information and Supplementary Data . Plasmids and strains that support the findings of this study are available from the corresponding authors. Source data are provided with this paper.

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Acknowledgements

We thank members of the Du laboratory, Koonin laboratory, Chen laboratory and Krupovic laboratory for advice and helpful discussions to carry out this study. We thank Y. Liao and I. Duggin at University of Technology, Sydney, for sending us the ftsZ depletion/deletion strains and plasmids for construction of fluorescent protein fusions. We thank T. Allers at University of Nottingham and X. Liu at Shanghai Jiao Tong University for sending us the H. volcanii strains and plasmids. We thank M. Li and H. Xiang at the Institute of Microbiology Chinese Academy of Sciences for providing us with the H. hispanica strains and plasmids. We would also like to thank J. Liu and Y. Yang at Shandong University for insightful discussions on the function of the PRC barrel domain of CdvA. This study was supported by National Natural Science Foundation of China (grant nos. 32270049 and 32070032, http://www.nsfc.gov.cn/ ), the Fundamental Research Funds for the Central Universities (grant no. 2042021kf0198) and Wuhan University ( https://www.whu.edu.cn/ ) to S.D.; the research of K.S.M. and E.V.K. is supported by the Intramural Research Program at the National Library of Medicine, National Institute of Health, USA.

Author information

These authors contributed equally: Shan Zhao, Kira S. Makarova.

Authors and Affiliations

Department of Microbiology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China

Shan Zhao, Wenchao Zheng, Le Zhan, Qianqian Wan, Yafei Liu, Han Gong & Shishen Du

National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA

Kira S. Makarova & Eugene V. Koonin

Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris, France

Mart Krupovic

Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA

Joe Lutkenhaus

State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China

Xiangdong Chen

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Contributions

S.D., S.Z. and E.V.K. conceptualized this study. S.Z., K.S.M., W.Z., Y.L., L.Z., Q.W. and H.G. developed the methodology and carried out the investigations and acquired the data. S.D., S.Z., K.S.M., X.C., J.L. M.K. and E.V.K. interpreted the data. S.D., X.C., K.S.M. and E.V.K. obtained resources. S.D., X.C., J.L. and E.V.K. undertook supervision. S.D., S.Z., K.S.M., M.K., X.C., J.L. and E.V.K. wrote the original draft and reviewed and edited the final manuscript.

Corresponding authors

Correspondence to Eugene V. Koonin or Shishen Du .

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The authors declare no competing interests.

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Nature Microbiology thanks Daniela Barilla, William Margolin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

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Extended data

Extended data fig. 1 cdpb1 does not depend on ftsz1 for colocalization with ftsz2 and sepf..

a . Representative images of CdpB1-GFP and FtsZ2-mCherry localization in the presence or absence of FtsZ1, respectively. b . Representative images of CdpB1-GFP and SepF-mCherry localization in the presence or absence of FtsZ1, respectively. Depletion of FtsZ1 was achieved by removal of tryptophan from the cultures. Strain ID56 (H98, P tna ::ftsZ1 ) harbouring plasmid pZS284 ( P phaR ::cdpB1-gfp - ftsZ2-mCherry ) or pZS285 ( P phaR :: c dpB1-gfp - sepF-mCherry ) were grown in Hv-Cab medium with or without tryptophan. Percentage of protein colocalization (%) were indicated, number of GFP/mCherry structures or foci (n > 200). Scale bars 5 μm.

Extended Data Fig. 2 CdpB1 does not depend on FtsZ2 for colocalization with FtsZ1 and SepF.

a . Representative images of CdpB1-GFP and FtsZ1-mCherry localization in the presence or absence of FtsZ2, respectively. b . Representative images of CdpB1-GFP and SepF-mCherry localization in the presence or absence of FtsZ2, respectively. Depletion of FtsZ2 was achieved by removal of tryptophan from the cultures. Strain ID57 (H98, P tna ::ftsZ2 ) harbouring plasmid pZS239 ( P phaR ::cdpB1-gfp - ftsZ1-mCherry ) or pZS285 ( P phaR :: c dpB1-gfp - sepF-mCherry ) were grown in Hv-Cab medium with or without tryptophan. White arrows indicate the colocalization of the GFP and mCherry fluorescence signal, cyan arrows indicate the CdpB1-GFP foci or aggregates. Percentage of protein colocalization (%) were indicated, number of GFP/mCherry structures or foci (n > 200). Scale bars 5 μm.

Extended Data Fig. 3 CdpB1 depends on SepF for correct localization.

a . Representative images of CdpB1-GFP and FtsZ2-mCherry localization in the presence or absence of SepF, respectively. Depletion of SepF was achieved by removal of tryptophan from the cultures. Strain HZS2 (H98, P tna ::sepF ) harbouring plasmid pZS284 ( P phaR :: cdpB1-gfp - ftsZ2-mCherry ) were grown in Hv-Cab medium with or without tryptophan. White arrows indicate the colocalization of the GFP and mCherry fluorescence signal, cyan arrows indicate the CdpB1-GFP foci or aggregates. Percentage of protein colocalization (%) were indicated, number of GFP/mCherry structures or foci (n > 200). Scale bars 5 μm.

Extended Data Fig. 4 Determination of the level of CdpB1 necessary for complementation.

a-b . CdpB1-depleted cells resume normal cell shape and size following restoration of CdpB1 expression. HZS1 (H98, P tna :: cdpB1 ) or HZS24 (H98, P tna ::his- cdpB1 ) grown in Hv-Cab (+50 μg/mL uracil) without tryptophan for 24 hours was diluted 1:100 in fresh medium with indicated concentrations of tryptophan. 15 hours later, samples were spotted onto a BSW agarose pad for microscopy. Scale bars 5 μm. c . Western blot to check the level of His-CdpB1 at the indicated concentration of tryptophan. Samples from panel b were prepared for SDS–PAGE and Western blot. The level of His-CdpB1 increased as the concentration of tryptophan in the medium increased. Strain H98, which did not express any His-tagged protein, was run as a negative control. Upper panel, Western blot; lower panel, Coomassie brilliant blue staining.

Source data

Extended data fig. 5 cell morphology and protein localization upon depletion and repletion of division proteins..

a-c . Representative images of FtsZ1-GFP localization and cell morphology after depletion of FtsZ2 ( a ), SepF ( b ) or CdpB1 ( c ). Strains ID57 (H98, P tna ::ftsZ2 ), HZS2 (H98, P tna ::sepF ) or HZS1 (H98, P tna ::cdpB1 ) harbouring plasmid pZS208 ( P native :: ftsZ1-gfp ) were grown in Hv-Cab medium without tryptophan to deplete CdpB1. Samples were taken at the indicated time points after the removal of tryptophan. Red arrows indicate multiple spiral and large abnormal FtsZ1-GFP localization in rod-shaped and large cells. Scale bars 5 μm. d-f . Representative images of FtsZ1-GFP ( d ), FtsZ2-GFP ( e ) and SepF-GFP ( f ) localization and cell morphology in CdpB1 repleted cells. Strain HZS1 (H98, P tna ::cdpB1 ) harbouring plasmids expressing fluorescent division protein fusions was grown in Hv-Cab medium without tryptophan for 24 hours and then inoculated into fresh Hv-Cab medium with 1 mM tryptophan. Samples were taken at the indicated time points after the addition of tryptophan. Red arrows indicate the nearly normal localization of FtsZ1-GFP, FtsZ2-GFP and SepF-GFP 9 hours after the addition of tryptophan to induce CdpB1. Scale bars 5 μm.

Extended Data Fig. 6 CdpB1 displays interaction with FtsZ1 and FtsZ2 in Split-FP assay.

a . Representative images of Split-FP assay showing the interaction signal between CdpB1 and SepF. b . Representative images of Split-FP assay showing the interaction signal between CdpB1 and FtsZ2. c . Representative images of Split-FP assay showing the interaction signal between CdpB1 and FtsZ1. An exponential culture of strain H26 (DS70, ΔpyrE2 ) harbouring the Split-FP plasmid expressing the indicated protein(s) was treated as in Fig. 3a and the fluorescence signal and localization were observed by microscopy. Scale bars 5 μm.

Extended Data Fig. 7 Co-IP experiments show that CdpB1 does not interact with FtsZ1 and FtsZ2.

The experiment was carried out as in Fig. 3c . a . CdpB1-His did not co-immunoprecipitated with FtsZ1-GFP. b . CdpB1-His did not co-immunoprecipitated with FtsZ2-GFP.

Extended Data Fig. 8 Alignment of PRC barrel proteins and their predicted structures.

a . Amino acid sequences of PRC barrel domain containing proteins from H. volcanii , Natrinema sp. J7-1 and H. hispanica were downloaded from Uniprot: https://www.uniprot.org/ , aligned by Clustal Omega: https://www.ebi.ac.uk/Tools/msa/clustalo/ and then depicted using ESPRIPT 3.0: http://espript.ibcp.fr/ . b . Phylogenetic tree of the PRC barrel domain containing proteins from H. volcanii , Natrinema sp. J7-1 and H. hispanica generated by Clustal Omega. c . Superimposition of the predicted structures of CdpB1, CdpB2, CdpB3 and HVO_1607 of H. volcanii . Structure models were generated by AlphaFold and were downloaded from Uniprot and aligned by PyMOL. CdpB1, green; CdpB2, cyan; CdpB3, magenta; HVO_1607, yellow.

Extended Data Fig. 9 Interaction between the CdpB proteins in vivo .

a-c . Interaction between the CdpB proteins determined by Split-FP assay. a . Representative images showing the interaction signal between CdpB1 and CdpB2. b . Representative images showing the interaction signal between CdpB2 and CdpB3. c . Representative images showing the interaction signal between CdpB1 and CdpB3. An exponential phase culture of strain H26 (DS70, ΔpyrE2 ) harbouring the Split-FP plasmid expressing the indicated protein(s) was treated as in Fig. 3a and the fluorescence signal and localization were examined by microscopy. Scale bars 5 μm. d-f . Co-IP experiments to determine the interactions between CdpB proteins. d . CdpB1-His and CdpB2-GFP immunoprecipitated with each other. e . CdpB2-His and CdpB3-GFP immunoprecipitated with each other. f . CdpB1-His and CdpB3-GFP did not immunoprecipitate with each other. The experiment was carried out as in Fig. 3c . Supernatants were incubated with rabbit antibodies coated magnetic beads, while the following Western blotting analysis used mouse antibodies.

Extended Data Fig. 10 Localization dependence of PRC barrel proteins in Natrinema sp. J7 and comparison of the PRC barrel domains of CdpB1 and CdvA from S. acidocaldricus .

a . Midcell localization of NJ7G_2779 and NJ7G_3497 depends on NJ7G CdpB1 in Natrinema sp. J7. Strain HZS4 (CJ7-F, P tna :: NJ7G cdpB1 ) carrying plasmid pZS513 ( P native ::NJ7G_2729-gfp ) or pZS514 ( P native ::NJ7G_3497-gfp ) was grown in Hv-Cab medium with or without tryptophan to check cell morphology and protein localization. White arrows indicate the midcell localization of NJ7G_3479-GFP. Scale bars 5 μm. b . AlphaFold structural models of H. volcanii CdpB1 and CdvA from S. acidocaldricus . Structural models of CdpB1 ( D4H036 ) and CdvA ( Q4J923 ) were downloaded from Uniprot and aligned with PyMOL.

Supplementary information

Supplementary information.

Supplementary Figs. 1–4 and Note.

Reporting Summary

Peer review file, supplementary data 1 and 3–7.

Supplementary Data 1, Complete list of PRC barrel domain proteins for genomes from arCOG database. Data 3, PRC barrel genes neighbourhoods. Data 4, Strains used in this study. Data 5, Plasmids used in this study. Data 6, Primers used in this study. Data 7, Reagents and chemicals used in this study.

Supplementary Data 2

The complete phylogenetic tree of PRC barrel genes in Newick format.

Source Data for Supplementary Fig. 3c

Raw data for RT–qPCR.

Source Data for Supplementary Fig. 3d

OD 600 of WT and CdpB1 depletion strains growing in the presence and absence of tryptophan.

Source Data Fig. 1e

Unprocessed western blot and gel for Fig. 1e.

Source Data Fig. 3c,d

Unprocessed western blots for Fig. 3c,d.

Source Data Extended Data Fig. 4c

Unprocessed western blots for Extended Data Fig. 4c.

Source Data Extended Data Fig. 7a,b

Unprocessed western blot and gel for Extended Data Fig. 7a,b.

Source Data Extended Data Fig. 9d–f

Unprocessed western blots for Extended Data Fig. 9d–f.

Source Data Fig. 3b

Statistical source data for Fig. 3b.

Source Data Colocalization

Statistical source data for protein colocalization.

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Zhao, S., Makarova, K.S., Zheng, W. et al. Widespread photosynthesis reaction centre barrel proteins are necessary for haloarchaeal cell division. Nat Microbiol 9 , 712–726 (2024). https://doi.org/10.1038/s41564-024-01615-y

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Received : 28 March 2023

Accepted : 19 January 2024

Published : 04 March 2024

Issue Date : March 2024

DOI : https://doi.org/10.1038/s41564-024-01615-y

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Biology library

Course: biology library   >   unit 13.

  • Conceptual overview of light dependent reactions
  • Light dependent reactions actors
  • Photosynthesis: Overview of the light-dependent reactions

Light and photosynthetic pigments

  • The light-dependent reactions

Introduction

What is light energy, pigments absorb light used in photosynthesis, chlorophylls, carotenoids, what does it mean for a pigment to absorb light, attribution:.

  • “ The light-dependent reactions of photosynthesis ,” by OpenStax College ( CC BY 3.0 ). Download the original article for free at http://cnx.org/contents/f829b3bd-472d-4885-a0a4-6fea3252e2b2@11 .
  • " Bis2A 06.3 Photophosphorylation: the light reactions of photosynthesis ," by Mitch Singer ( CC BY 4.0 ). Download the original article for free at http://cnx.org/contents/c8fa5bf4-1af7-4591-8d76-711d0c1f05f9@2 .

Works cited:

  • Chlorophyll a. (2015, October 11). Retrieved October 22, 2015 from Wikipedia: https://en.wikipedia.org/wiki/Chlorophyll_a .
  • Speer, B.R., (1997, July 9) Photosynthetic pigments. In UCMP glossary . Retrieved from http://www.ucmp.berkeley.edu/glossary/gloss3/pigments.html .
  • Bullerjahn, G. S. and A. F. Post. (1993). The prochlorophytes: are they more than just chlorophyll a/b-containing cyanobacteria? Crit. Rev. Microbiol. 19(1), 43. http://dx.doi.org/10.3109/10408419309113522 .
  • Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., and Jackson, R. B. (2011). Photosynthesis. In Campbell biology (10th ed.). San Francisco, CA: Pearson, 193.

Additional references:

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Great Answer

COMMENTS

  1. Role of Water in Photosynthesis

    Plants rely on the process of photosynthesis to capture, convert and store energy directly from the sun. To do this, they require carbon dioxide (CO 2) and water (H 2 O). In the presence of sunlight, these molecules break apart and form glucose (C 6 H 12 O 6) and oxygen (O 2 ). The chemical formula for this reaction is 6CO 2 + 6H 2 O ------> C ...

  2. How Plants Use Water

    Water is an essential nutrient for plants and comprises up to 9 5% of a plant's tissue. It is required for a seed to sprout, and as the plant grows, water carries nutrients throughout the plant. Water is responsible for several important functions within plant tissues. Water is necessary for photosynthesis, which is how plants use energy from ...

  3. Photosynthesis

    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.

  4. Intro to photosynthesis (article)

    Photosynthesis is the process in which light energy is converted to chemical energy in the form of sugars. In a process driven by light energy, glucose molecules (or other sugars) are constructed from water and carbon dioxide, and oxygen is released as a byproduct. The glucose molecules provide organisms with two crucial resources: energy and ...

  5. Photosynthesis

    photosynthesis, the process by which green plants and certain other organisms transform light energy into chemical energy.During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.. It would be impossible to overestimate the importance of photosynthesis in the maintenance of life on Earth.

  6. Explainer: How photosynthesis works

    Photosynthesis is the process of creating sugar and oxygen from carbon dioxide, water and sunlight. It happens through a long series of chemical reactions. But it can be summarized like this: Carbon dioxide, water and light go in. Glucose, water and oxygen come out. (Glucose is a simple sugar.) Photosynthesis can be split into two processes.

  7. 6.6: Photosynthesis

    Photosynthesis is a multi-step process that requires sunlight, carbon dioxide (which is low in energy), and water as substrates (Figure 4). After the process is complete, it releases oxygen and produces glyceraldehyde-3-phosphate (GA3P), simple carbohydrate molecules (which are high in energy) that can subsequently be converted into glucose ...

  8. 5.1: Overview of 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.

  9. Photosynthesis, Chloroplast

    Figure 5: The light and dark reactions in the chloroplast. The chloroplast is involved in both stages of photosynthesis. The light reactions take place in the thylakoid. There, water (H 2 O) is ...

  10. Photosynthesis in organisms (article)

    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.

  11. Photosynthesis in ecosystems (article)

    Photosynthesis drives the movement of matter, or atoms, between organisms and the environment. Photosynthetic organisms take in and use carbon dioxide and water from the air and soil. Photosynthetic organisms release oxygen into the air. Organisms throughout the ecosystem use this oxygen to breathe. Photosynthetic organisms produce sugars ...

  12. Why Do Plants Need Water in Photosynthesis?

    By Mary Dowd. Photosynthesis is a wondrous and yet simple chemical reaction that occurs when plants use sunlight, water and carbon dioxide to make energy-packed food molecules. Plants pull water from their roots and absorb molecules of atmospheric carbon dioxide to gather the necessary ingredients for synthesizing glucose (sugar).

  13. Photosynthesis

    Photosynthesis changes sunlight into chemical energy, splits water to liberate O 2, and fixes CO 2 into sugar.. Most photosynthetic organisms are photoautotrophs, which means that they are able to synthesize food directly from carbon dioxide and water using energy from light. However, not all organisms use carbon dioxide as a source of carbon atoms to carry out photosynthesis ...

  14. Photosynthesis

    Photosynthesis. Photosynthesis is the processes of using sunlight to convert chemical compounds (specifically carbon dioxide and water) into food. Photosynthesizing organisms (plants, algae, and bacteria) provide most of the chemical energy that flows through the biosphere. They also produced most of the biomass that led to the fossil fuels ...

  15. Why do plants need water?

    One big way that plants use water is photosynthesis. Plants use the sun's light to change water and carbon dioxide into oxygen and sugar. Then, the plant moves some of the sugar back down the plant using another transport system called phloem. The plant stores the sugar partly in its roots. When the plant needs energy, it can break down the ...

  16. How Does Water Affect Photosynthesis? Explained

    Photosynthesis is a crucial process that plants use to produce oxygen and energy for themselves and all living organisms. It is a complex process that requires several inputs, including sunlight, carbon dioxide, and of course, water. Water plays a vital role in photosynthesis, and without it, this process cannot happen effectively.

  17. Photosynthesis

    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. 3,12,343.

  18. Photosynthesis review (article)

    In photosynthesis, solar energy is harvested as chemical energy in a process that converts water and carbon dioxide to glucose. Oxygen is released as a byproduct. In cellular respiration, oxygen is used to break down glucose, releasing chemical energy and heat in the process. Carbon dioxide and water are products of this reaction.

  19. What is Photosynthesis

    By taking in water (H2O) through the roots, carbon dioxide (CO2) from the air, and light energy from the Sun, plants can perform photosynthesis to make glucose (sugars) and oxygen (O2). CREDIT: mapichai/Shutterstock.com. Just like you, plants need to take in gases in order to live. Animals take in gases through a process called respiration.

  20. Photosynthesis

    Water. The water needed for photosynthesis is absorbed through the roots and transported through tubes to the leaf.The roots have a type of cell called a root hair cell. These project out from the ...

  21. 4.8: Photosynthesis

    The heart of photosynthesis as it occurs in most autotrophs consists of two key processes: the removal of hydrogen (H) atoms from water molecules; the reduction of carbon dioxide (CO 2) by these hydrogen atoms to form organic molecules. The second process involves a cyclic series of reactions named (after its discoverer) the Calvin Cycle.

  22. Light-dependent reactions (photosynthesis reaction) (article)

    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.

  23. What is the function of water in photosynthesis?

    Water is one of the reactants in photosynthesis, it provides the hydrogen needed to form glucose (a hydrocarbon). carbon dioxide+water +energy → glucose + oxygen. 6CO2 +6H2O → C6H12O6 + 6O2. Water and carbon dioxide enter the leaf through the stomata (small holes on the underside of the leaf that are controlled by gaurd cells) by diffusion.

  24. Widespread photosynthesis reaction centre barrel proteins are ...

    Here, we show that three of the four photosynthesis reaction centre barrel domain proteins of Haloferax volcanii (renamed cell division proteins B1/2/3 (CdpB1/2/3)) play important roles in cell ...

  25. Role of Carbon Nanotube Wetting Transparency in Rapid Water Transport

    A carbon nanotube (CNT) may facilitate near-frictionless water transport within it. In this work, we elucidate the slip flow characteristics for a CNT embedded in a silicon nitride matrix using the molecular dynamics (MD) method. We reveal that the wetting transparency of a CNT, the transmission of the membrane matrix wetting property over a CNT, cannot be ignored. Due to the effect of CNT ...

  26. Light and photosynthetic pigments

    Plants, on the other hand, are experts at capturing light energy and using it to make sugars through a process called photosynthesis. This process begins with the absorption of light by specialized organic molecules, called pigments, that are found in the chloroplasts of plant cells.Here, we'll consider light as a form of energy, and we'll also see how pigments - such as the chlorophylls ...