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Activities and Experiments to Explore Photosynthesis in the Classroom

Photosynthesis can be a difficult concept to grasp, that’s why we’ve compiled a selection of hands-on activities and experiments to help show students some of the concepts in action.

In addition to the ideas below, PLT’s new Explore Your Environment: K-8 Activity Guide and PLT’s PreK-8 Environmental Education Activity Guide both offer a wealth of hands-on, creative activities and resources for lessons about photosynthesis. Each guide includes a comprehensive Topic Index to help you quickly find a list of relevant activities that fit your needs and every activity includes a background section for educators that gives a science-based introduction to the activity’s content. We also have a few abridged versions related to the physiology of trees and photosynthesis for families to try out together at home, for example, How Plants Grow and Tree Factory .

Introduction to Photosynthesis

The word “photosynthesis” comes from Greek root words that combine to mean “to put together with the help of light.”

All plants, algae, and some microorganisms like bacteria photosynthesize to make their own food. This makes them part of a group of organisms called autotrophs. Unlike heterotrophs, which include animals that feed off other living organisms, autotrophs make nutritional organic substances from simple inorganic substances. What a superpower!

To undergo photosynthesis, plants need carbon dioxide from the air, water from the soil, and sunlight. These elements combine in a chemical reaction that takes place inside of a plant’s leaves to create glucose and oxygen.

Absorbing Carbon Dioxide and Water

Carbon dioxide can be produced naturally from the decomposition of living things and events like volcanic eruptions, and from human activity like burning fossil fuels.

Animals respirate by inhaling gases in the air, retaining oxygen, and releasing carbon dioxide. However, when plants breathe, they take in carbon dioxide, which is a key ingredient required for photosynthesis. Carbon dioxide enters a plant through its stomata, tiny pores that are usually located on the underside of leaves and sometimes stems. Most plants also soak up another substance through their roots that they need for photosynthesis: water.

Adding Energy

Once a plant has carbon dioxide and water, it needs energy to enable these two substances to chemically react with each other. It gets energy from a steady stream of sunlight hitting its leaves. Chlorophyll, a green pigment found in tiny structures called chloroplasts within leaves, absorbs energy from blue and red light waves from the sun. The sunlight’s energy is then transferred to two types of energy-storing molecules within the plant.

The energy already stored from the sun fuels a reaction in the leaves’ chloroplasts that splits water molecules (H 2 0) into pure hydrogen (H) and oxygen (O 2 ). The hydrogen reacts with carbon dioxide (CO 2 ) to produce glucose, a type of sugar. The full chemical equation of photosynthesis looks like this:

6CO 2 + 6H 2 0 + Sunlight → C 6 H 12 O 6 + 6O 2

In other words, the carbon dioxide and water that go into the plant combine with energy from sunlight to produce glucose, and also oxygen.

Storing and Using Glucose

Once this sugar is made, it can be stored as energy (food) that the plant uses for growth and repair. Plants also use the energy from nutrients in the soil along with glucose to grow and develop leaves, flowers, and fruits.

Students often wonder how a gas like carbon dioxide that you can’t see helps form a giant tree or the apple they eat for lunch. It’s because a chemical reaction doesn’t have to start with a solid (like soil) to end with a solid (like a tree or apple). It helps for students to understand the carbon cycle – and PLT has a variety of content to support this.

Glucose is a carbohydrate, which is simply a molecule containing carbon, hydrogen, and oxygen. Smaller glucose molecules can build bigger carbohydrates like cellulose or starch.

Similar to a human skeleton, cellulose is the main component of plant cell walls that help strengthen the plant. Humans can’t digest cellulose, but the fiber found in cellulose-heavy foods like celery and broccoli aids with digestion and can lower the risk of diseases like cancer. These strong fibers are also used to make clothes and paper. Animals like cows, horses, and sheep can digest cellulose, so it makes sense that they eat grass for quick energy and nutrients.

Plants can also convert glucose into starch, which is a larger carbohydrate molecule that can store its energy. Humans break down starches found in foods like potatoes and rice into glucose, and it, in turn, gives them energy.

Though you may not use sunlight to create your food, when you eat something like chicken or rice, you take in energy plants used from the sun. And not only does a plant produce food animals need for their energy as a result of photosynthesis, but it also releases oxygen as a byproduct through its stomata into the atmosphere.

Photosynthesis is critical for the survival of all living organisms — not just plants.

Hands-On Photosynthesis Activities

Photosynthesis can be a difficult concept to grasp, especially for younger learners. That’s why we’ve compiled these interactive activities and experiments that show some of the concepts in action.

Photosynthesis Visuals

These photosynthesis modeling activities will help students visualize and better understand what a plant needs to undergo photosynthesis and what it produces as a result. The 3D and 2D representations will also help them absorb some of the vocabulary associated with photosynthesis.

3D Photosynthesis: Tree Leaf Model 

Older students can create these more complex 3D models of a leaf’s front and backside where all of the photosynthesis action takes place, like on its stomata and chloroplasts. They will attach labels to the leaf that describe the different substances involved.

The Ins and Outs of Photosynthesis

Younger learners will enjoy this less complex visual activity that involves a leaf with “IN” and “OUT” envelopes into which they’ll place the respective chemical reactants or products of photosynthesis.

Photosynthesis Paper Craft  

Take your lesson in an artistic direction by letting students create these bright and fun paper flower and sun displays, complete with the basic photosynthesis terms.

Exploring Leaves with STEM 

These STEM experiments requiring real leaves will spark valuable critical thinking when students observe leaf structure, stomata, plant respiration, and more.

Respirating Leaves

The invisible chemical process of a leaf exchanging carbon dioxide, water, and sunlight for oxygen will become visible when your class observes what happens when they submerge leaves in water.

Stomata Microscope Investigation

Students will use microscopes to explore the structure of a leaf that makes the exchange of gasses during photosynthesis possible. They can also explore other parts of leaves and how plants gain mass.

Stomata Microscope Comparison

Compare the stomata sizes and numbers of different plant species under a microscope and examine leaf texture by creating cool “nail polish imprints.”

Exploring Plants and Sunlight

Plants need sunlight for survival, so it makes sense that their behavior or appearance would change if their access to sunlight is altered. These activities explore this concept.

Measuring Plant Growth with Sunlight 

This activity takes a couple of weeks but will give your students valuable insight into how a plant’s growth and green coloration is affected by varying levels of sunlight over time. They’ll flex their critical thinking skills as they take daily notes and conclude what happens to a seed under different light conditions.

Rotating Plants

Track how plants bend towards the sun wherever they are with this great exercise that introduces young students to just how active plants can be when it comes to gaining precious sun energy. You can grow seedlings or even experiment with a larger plant you have and see how its color or growth is affected when you rotate or move closer or further from the sun.

Fun with Plant Pigmentation 

There’s a lot of fun that can be had with the chlorophyll in leaves, including art and color experimentation! 

Chlorophyll Paintings 

Chlorophyll pigment not only turns plants green – it makes leaves great mediums for “green” art projects! Kids will love this out-of-the-box painting style, learn about chlorophyll firsthand, and expand their creativity all at once.

Leaf Color Chemistry Experiment 

When the school year begins, recreate how leaves change color in autumn with green leaves, rubbing alcohol, coffee filters, and other easy-to-find items. The pigments of chlorophyll will fade and leave behind hidden pigments that demonstrate why leaves change color in the fall – which is also when your class can reflect back on this eye-opening experiment.

Let Project Learning Tree Be Your Guide

Introduce students to photosynthesis with these PLT activities from the new Explore Your Environment: K-8 Activity Guide :

• Here We Grow Again (for grades K-2), Every Tree for Itself , and Signs of Fall (for grades 3-5) in PLT’s Explore Your Environment: K-8 Activity Guide
• How Plants Grow and Sunlight and Shades of Green (Activities 41 and 42 in PLT’s PreK-8 Environmental Education Activity Guide ), and
• Power Plants (Activity 4 in PLT’s Energy & Ecosystems E-Unit).

Watch an example of an activity! This video walks viewers through PLT’s activity Signs of Fall. In this activity, participants are introduced to different leaf pigments and use chromatography to pull out leaf pigments using simple household items. It helps answer the question, “Why do leaves change color?”.

For further guidance on how to relay the essential concepts of photosynthesis to your classroom and more great activities, check out this Unit of Instruction by Project Learning Tree. It suggests linking select PLT activities to help students learn more about the topic of photosynthesis using a storyline technique. Storylines ensure connectivity and continuity between individual activities and can serve as the “instructional glue” that bind many areas of knowledge and skills. The Unit of Instruction includes a guiding question, concepts addressed, and connections to the Next Generation Science Standards (NGSS) and PLT’s Forest Literacy Framework.

To boost your teaching with 50 field-tested, hands-on multidisciplinary activities that educate and connect elementary students with nature in powerful ways, and more suggested Units of Instruction , look no further than Project Learning Tree’s new Explore Your Environment: K-8 Activity Guide .

Rebecca Reynandez

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17 Creative STEM Activities Using Sticks for the Classroom 

Sticks are a versatile and cost-free resource that offers endless possibilities for engaging in STEM activities. Enlist the help of your students to gather sticks, then explore a variety of fun, hands-on activities that promote critical thinking, problem-solving, and creativity!

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Elementary Teaching Blog

Last updated by Linda Kamp on December 9, 2022 • 2 Comments

Breathing Leaves Photosynthesis Experiment for Kids

When we discuss the importance of plants in nature in second grade, it can be hard for students to fully grasp plants’ ability to create oxygen for us to breathe. This simple photosynthesis experiment is a great opportunity for hands-on learning in any Plants, Animals, & Life Cycles science unit.

How do plants create oxygen?

Plants release oxygen that all living things need. Plants also clean out air and absorb harmful pollutants through their leaves. This makes plants extremely important for other living things to survive on Earth.

As we breathe, the air we inhale is 21% oxygen. After we breathe in oxygen, we exhale carbon dioxide. Carbon dioxide is needed by plants for them to survive. Plants use carbon dioxide and sunlight to help them make oxygen. Leaves convert sunlight into energy as part of a process called photosynthesis. As the leaf takes in sunlight to create that energy, it expels, or breathes out, oxygen. But how can we see oxygen? Can plants produce oxygen without sunlight?

Think about when you are underwater holding your breath. If you release a little bit of air, you see bubbles. In this activity, students will observe a leaf using sunlight to create oxygen. Students will do a  demonstration using leaves in water to help them see the oxygen a leaf expels, or breathes out.

Pose this question to students to help introduce the lab: How can you see a plant creating oxygen?

The changes that take place in this lab activity occur over a 1-2 hour period, so make sure to plan for that ahead of time. I have found that it works for me to set up the lab in the morning and check it after lunch.

Easy photosynthesis experiment

• clear plastic cup or bowl
• fresh leaves
• small rocks

Place students in groups and pass out two cups of water, two fresh leaves, 2 small rocks, a hand lens, and a lab sheet.

Students place a leaf in a clear cup of water. Then, they place the other leaf in the other cup of water. Put one of the cups in a sunny spot and one in a dark spot.

Place a small rock on the leaf to keep it completely submerged in water.

After about 20 minutes, you will see tiny bubbles begin to form on the edges of the leaf. Many float upwards and stick to the side of the cup.

For a better look, students should use a hand lens to observe the bubbles. Explain to students that the small air bubbles are oxygen released by the leaf. The leaf remains active for a couple of hours. The process of photosynthesis will continue for a while if the cup is placed in the sun. During this process, the leaf expels oxygen into the water, which caused bubbles to form.

Students should check the cups every 30 minutes and record changes to both cups on their lab sheets. Ask students: “Which leaf produced the most oxygen? How can you tell?” Students should notice that the leaf that produced more oxygen has more bubbles.

Next, ask: “Why did one leaf produce more oxygen than the other leaf?” Guide students to notice that the leaf in the dark did not have sunlight, so it did not produce as much oxygen. A fresh leaf will remain “active” and still convert sunlight to energy and release oxygen for several hours.

Have students complete the questions on their lab sheets to consolidate their knowledge and make interpretations about the lab’s outcome.

Finally, discuss how this lab shows the importance of plants to animals. Besides food, what do plants provide for animals?

More Plants, Animals, & Life Cycles experiments and lesson plans

This photosynthesis experiment is perfect for helping students better understand the process of leaves producing oxygen. It’s an amazing way for students to really see the process of photosynthesis at work!

This fun photosynthesis experiment is part of a complete  Plant and Animal Needs, & Life Cycles unit for 2 nd grade that is also available in a digital format with narrated lesson slides.

Click here to see the yearlong 2nd grade science series.

Pin this photosynthesis experiment for later so you have it when you teach about plants!

Click on these these pictures for more hands-on science activities:

Happy teaching!

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August 15 at 10:16 am

Hi , is this lab sheet available for purchase on its own?

August 21 at 8:38 am

Hi Sarah, Thanks for reaching out! Unfortunately, I don’t have any of the labs available separately.

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I’m Linda Kamp, a 20 year primary grade teacher with a passion for creating educational materials that excite students and make learning fun! I'm so glad you're here!

Photosynthesis: Step by Step Guide (Experiments Included)

• May 10, 2021
• Science Facts

Have you ever wondered how plants eat or drink? How do they get energy? Well, just like we need food and water to live, plants do too. However, unlike humans, they make their food from sunlight and carbon dioxide! How? They do it by a process known as photosynthesis.

This article will explore photosynthesis and learn the difference between chemical compounds like carbon dioxide, sugar, and energy. We’ll look at how plants store energy as starch.

What is Photosynthesis?

Plants and a few other organisms “put together” organic matter from carbon dioxide and water, using the energy of sunlight to power the process.

It is derived from the Greek word, ‘photo’ meaning light, and ‘synthesis’ meaning putting together.

Plants are the basis for almost all life on Earth: animals (including humans) either eat plants or eat other animals that eat plants. Also, plants provide us with oxygen.

Ingredients for Photosynthesis

When you’re hungry, you may ask your mom for food. However, plants can’t do that. So, they use the nutrients and water present in the soil, light energy from the sun, and Carbon Dioxide from the air to form a compound called glucose.

Glucose is a sugar that plants need to survive on. It’s their form of food, like you eat rice or noodles, they consume glucose for energy!

Why is photosynthesis important for life?

All living organisms on Earth are dependent on photosynthesis. Plants would not survive without photosynthesis, and thus, neither would animals that depend on the plants for food. Autotrophs, like plants and algae, produce glucose through photosynthesis.

Animals cannot do this. Therefore, they eat plants and use this energy in the process of cellular respiration. Otherwise, they get their energy through organisms that feed off autotrophs.

Organisms, who cannot synthesize their own food independently, are known as heterotrophs. These include:

• Herbivores such as cows and deer, who eat plants.
• Carnivores such as lions and wolves, who eat other animals.
• Omnivores such as humans and bears, who eat both plants and animals.

So, the plants are the start of all food chains and sustain all organisms. For example:

How Green Plants Make their Food

Green plants carry out photosynthesis by using a special green pigment called chlorophyll.

The chlorophyll inside the leaves captures the energy from sunlight, combines carbon dioxide with water, and makes sugar (glucose).

The plant transports this simple sugar to every part of its body. All in all, the steps involved in this process are:

●     Absorption of Light Energy

Have you seen the sunflower plant moving towards the sun when kept in the shade? This is because the trapping of light energy is key to the process of photosynthesis.

Without sunlight, there will be no energy to make food. So, the first and most crucial step is that the chlorophyll in green plants absorbs sunlight.

●     Conversion of Light Energy to Chemical Energy

Plants cannot directly utilize sunlight. So, they convert it into ATP (Adenosine TriPhosphate), a form of chemical energy.

When sunlight is absorbed, the chlorophyll atoms become photochemically excited and lose an electron, thus undergoing a process known as oxidation.

This electron is then used to convert non-usable sources of energy such as ADP and NADP+ compounds to primary chemical energy sources such as ATP and NADPH.

Then, to replace the electron lost in by the photochemically excited chlorophyll, the water absorbed by the plants splits into its two components- Hydrogen and water.

Since, hydrogen has only one electron, it breaks into protons and electrons, and then it uses the electron to bring the chlorophyll back to its original state.

This completes the process of conversion to immediate chemical energy, which is used to form glucose.

●     Conversion of Carbon Dioxide to Glucose

When the water splits into hydrogen and oxygen, it undergoes an oxidation reaction as it loses Hydrogen. Similarly, carbon dioxide undergoes a reduction reaction as it gains electrons. So, as a result, water is converted to oxygen gas, and carbon dioxide is converted to glucose.

This is known as a redox reaction. Observe the following diagram to understand it better. A is water converting to oxygen, and B is Carbon Dioxide converting to simple carbohydrates (glucose) in photosynthesis.

Photosynthesis Chemical Reaction in Words

Now that you understand how reactions occur and the resultant products are formed, it’s essential to know how to put them into words. One glance over this summarises everything explained above- that is what a chemical formula does!

The above equation represents the following chain of processes:

• Sunlight coming in contact with the chlorophyll in the thylakoid membrane of the chloroplast.
• Chlorophyll molecules get excited, and water splits into hydrogen and oxygen.
• Electrons from hydrogen (from the water) combine with Carbon Dioxide. This process is known as reduction, and glucose is formed.
• Oxygen is a by-product. Since it is of no use, it is excreted or thrown out from the cell.

Chemical Reaction Formula for Photosynthesis

Physical chemistry can be tricky because there are so many terms and factors to keep track of. So, you must understand these simple equations before you are allowed to work with natural chemicals.

A chemical equation is simply a list of all the chemical reactants and products and their relative quantities at its heart.

Chemicals are complex systems that can exist in very different states. Nonetheless, they can easily be represented as simple lists of these elements and their numbers. So, one can describe photosynthesis as:

However, this isn’t a balanced equation. According to the Law of Conservation of Mass, mass can neither  be created nor destroyed. Count the number of Carbon atoms on the reactant side (the left side.)

Now, count the number of Carbons on the product side (the right side.) One carbon can’t magically turn into six carbons, right? So, to rectify it, form a balanced equation of the reaction.

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

Note that the number before the Carbon Dioxide, Water, and Oxygen represents the individual compound molecules.

Therefore, the number of Carbons on both sides of the equation is 6, oxygens are 18 (twelve from Carbon Dioxide and six from water), and hydrogens is 12.

Since the total number of atoms from each element are equal on the reactant and product side, this is now a balanced equation!

What does photosynthesis produce?

The release of chemical energy due to the formation of ATP and NADPH compounds, and the synthesis of oxygen, are light-dependent reactions.

However, a series of light-independent reactions- constituting the Calvin Cycle, actually form the food.

How is glucose formed? Does excess glucose undergo some changes? Read to find out.

The Calvin Cycle

This cycle consists of a series of light-independent reactions- which means they do not directly require sunlight to work. So, they can take place at night or day. They include:

• Carbon Fixation

One of the most critical functions of carbon is that it can be converted from Inorganic compounds (carbon dioxide in the atmosphere) to organic compounds such as G3P and glucose. This process is known as Carbon fixation.

Before glucose is formed in plants, first, they synthesize an intermediate compound known as glyceraldehyde-3-phosphate. Here, the carbon from carbon dioxide is used to manufacture G3P- C 3 H 7 O 6 – a three-carbon molecule.

• Formation of glucose and other carbohydrates

G3P is a raw material used in the formation of glucose. The Calvin Cycle involves 18 ATP and 12 NADPH molecules to synthesize one molecule of C 6 H 12 O 6 (glucose).

It’s also used to form starch, sucrose, and cellulose, depending on the plant’s needs.

Starch also plays a significant role in nutrition in animals. When animals eat plants, their digestive processes break down the starch present to form glucose again.

This glucose is then used as a source of energy for metabolic processes. So, the starch in animals sustains the plant, the herbivore, the carnivore, and the decomposer.

What happens to excess carbohydrates which are not utilized immediately?

When carbohydrates are not utilized immediately, they are stored in various parts of the plant’s body in the form of starch. It’s a polysaccharide- a compound formed by binding a chain of

glucose molecules together. It stores a significant amount of energy for cell metabolism.

The stored starch gives the cell energy to perform all the processes necessary for its survival. Any unused energy is stored as a fat deposit.

Factors that affect the Rate of Photosynthesis

Just as human beings need various nutrients to survive, plants need several environmental conditions for photosynthesis to happen appropriately.

Even if one of the optimum requirements is affected, so is the rate of photosynthesis in plants. So, photosynthesis is based upon several factors. They include:

1. Light Intensity

If the light energy provided to plants is too low, the plants cannot photosynthesize properly. At the optimum amount of sunlight, the plant makes the food faster.

However, the speed slows down again if the light energy given increases above the plant’s maximum tolerance level. In winter or colder areas, the rate decreases and falls to zero at night.

Therefore, light intensity plays a vital role in the rate of photosynthesis.

2. Carbon Dioxide Concentration

Up to the maximum tolerance of carbon dioxide in plants, increasing the amount of exposure to gas maximizes the rate of photosynthesis.

After that, increasing carbon dioxide concentration in the air will not affect the plants.

This is because the plants can only intake a certain amount of carbon dioxide to convert into glucose. So, one can represent the rate of photosynthesis as:

3. Temperature

In photosynthesis, a lot of enzymes need to work to fulfill the requirement of energy. However, they can only work at the optimum temperature.

Raising the temperature increases kinetic energy. So the molecules start moving at a higher speed and collide faster, increasing the rate of photosynthesis.

Like in all the other cases, very high temperature is just as bad as very high temperature. In both cases, the enzymes will gradually be destroyed, and the photosynthesis will eventually stop.

Energy Result of Photosynthesis

As we have seen, there are two types of reactions in photosynthesis- the light reactions and the dark reactions.

The light-dependent processes synthesize energy in the form of ATP and NADPH.

The dark reaction uses already made energy to manufacture glucose and other carbohydrates, which are further used in metabolic processes required for the plant’s survival.

So, let’s look at these chemical processes from the perspective of energy used and released.

1. Light-Dependant Reactions

Sunlight gives plants the energy to photochemically excite the chlorophyll, which leads to the splitting of water. This allows the conversion of ADP and NADP+ molecules into ATP and NADPH, which can be used in other processes.

2H 2 O + 2 NADP+ + 3 ADP + 3 P i + Light Energy → 2 NADPH + 2 H + + 3 ATP + O 2

2. Dark Reactions

The energy synthesized in the light-dependant reactions is used to reduce carbon dioxide and form glucose. The carbon fixation process takes place here; that is, the carbon gets converted from an inorganic form to an organic compound.

3 CO 2 + 9 ATP + 6 NADPH + 6 H + → C 3 H 6 O 3 -phosphate + 9 ADP + 8 P i + 6 NADP+ + 3 H 2 O

Further, it takes 18 ATP and 12 NADPH compounds to convert the G3P molecule into glucose.

3. Respiration

When the glucose molecule is formed, the plant performs a process known as respiration. The glucose molecule is combined with oxygen and breaks down into carbon dioxide and water.

In this process, a considerable amount of energy is released.

This energy is used to help the plant perform all its metabolic functions needed to survive. It’s a constant cycle, which the following diagram can explain:

How Do Plants Absorb Energy From the Sun?

As we’ve seen, photosynthesis cannot take place without energy from the Sun. So, the plants have a mechanism set in place to observe light energy.

This is done by the pigment chlorophyll, present in chloroplasts, present in the cells of green leaves of plants. Let’s look at the structure of the chloroplast to help you understand.

Sunlight has a lot of components. All the parts have a certain amount of energy. The main components of sunlight used by the plants are blue, red, and green.

With the thylakoid’s help in the chloroplasts (observe the diagram), which contain chlorophyll, the light energy is absorbed—specifically, the blue and red components.

The green is reflected into the environment. Now, can you answer the question, ‘why do plants look green?’ It’s because of the reflected green light!

Look at the diagram again. Can you see that the thylakoids are present in stacks? These are known as grana, which is the site of converting light energy to chemical energy!

The aqueous fluid surrounding them is known as the stroma. The transformation is completed here.

Where Do Plants Get the Carbon Dioxide Needed?

Just like we breathe through our noses, plants have millions of tiny openings on the surface of their leaves. These are known as stomata.

These stomata pores are protected by a pair of guard cells, which regulate the opening and closing of these pores.

When they do open, the atmosphere’s carbon dioxide flows through the stomata, from where it’s sent to the chloroplast- the site of photosynthesis.

Various environmental stimuli control the guard cells. When all the optimum conditions (water and sunlight) are present, the guard cells swell and curve.

This movement is because it takes in water through a process known as osmosis, which triggers the opening of the guard cells and allows the carbon dioxide to enter.

At night, when there’s no light or the plant wants to conserve water, the stomatal pores lose water through osmosis.

This causes the stomata to become straight, and once again, they are closed. One can also show this process with a diagram:

Why Do Plants Produce Glucose?

Now that we know how plants produce glucose, it’s essential to understand why? Why are these six-carbon molecules so crucial for life? Let’s find out.

1.   Storage

Sun is essential for the release of energy. Therefore, during the winter or the night, when there is not enough sunlight, the plant uses the glucose stored in various parts of the plant.

The process of respiration takes place, and the energy for metabolic processes is released without the presence of the Sun.

Without the stored glucose, the plant would’ve died during the night or the long winters.

2.   Seed Formation and Flowering

Glucose is stored in the seed in the structures known as cotyledons. They allow the seedling to stay alive even deep inside the soil, without leaving to synthesize food.

Furthermore, they provide the energy required for germination and encourage leaf growth. Moreover, glucose stored in some plants also helps in the flowering of some unique plants.

Hyacinths, daffodils, and tulips are some plants that depend upon the glucose to flower. These beautiful flowers attract pollinating agents towards them, which helps the plant to reproduce.

3.   Formation of other nutrients

Several glucose molecules combine to form starch- a complex carbohydrate present in plants.

They also react with nitrates present in the soil to form amino acids, which eventually form proteins. Carbohydrates and proteins are major nutrients for both humans and plants.

Thus, glucose plays an essential role in nutrition.

4.   Circadian Rhythms

Plants need to maintain their body temperature and stay in tune with the day-and-night cycles. So, the formation of glucose in the day and respiration during the night helps the plant to maintain its daily clock and energy reserves.

How Do Plants Eat?

Now, since glucose has been synthesized, the next step is transportation and utilization. So, the sugar is transported through various parts of the plant, where it’s needed.

A vascular tissue known as phloem accomplishes this movement.

Then, similar to humans, cellular respiration takes place in plants as well. Plants convert glucose and other sugars, in the presence of oxygen, into energy.

Carbon Dioxide and water are by-products of this process. Just like you need the energy to breathe, walk, run, study, and survive- plants need it for:

• Growth processes
• Making more food
• Other cellular maintenance functions

So, just like we eat our food, plants synthesize glucose and other carbohydrates and convert them to energy!

Since it doesn’t require light energy, it can take place during the day or the night. So, the plant doesn’t starve.

Role of Leaves in Photosynthesis

Leaves are sites of photosynthesis. So, they have a series of features that help them perform their function efficiently. Leaves have adapted to the environment in various ways, such as:

• Large Surface Area

Broader leaves can absorb more light energy and thus, increase the surface area for photosynthesis.

• Shorter Width

The leaves are thin so that the absorbed carbon dioxide has to travel a short distance to reach the chloroplasts (sites of photosynthesis).

Otherwise, a considerable amount of energy would have to be spent on CO 2 transport, which the plant couldn’t afford.

Observe the given diagram. Have you ever touched a vein? Is it harder or softer than the surface of the leaf?

Veins in the leaf provide support, and transport food, water, and minerals as well. They are extensions of the vascular bundles- Xylem (which transports water and minerals) and Phloem (which transports synthesized food.)

• Chloroplasts

Of course, the main adaptation of leaves is the chloroplasts with the pigment chlorophyll inside of them.

These absorb light energy, then convert it into a usable form- chemical energy. Without these small components, photosynthesis wouldn’t take place, and life wouldn’t exist.

Role of Water in Photosynthesis

• Converts NADP+ to NADPH

When photosynthesis takes place, water splits into its components- hydrogen and oxygen. The H + ions are then used to reduce the NADP molecules to NADPH molecules, which can be used to synthesize glucose. It also eventually leads to the formation of ATP- the energy currency of the cell.

• Provides Oxygen

The oxygen, which is obtained from the splitting of water, is released into the atmosphere and used by animals and humans for respiration. Most living organisms on the face of this planet need this oxygen released by plants to survive.

• Reduces chlorophyll

When the sunlight hits chlorophyll, it becomes photochemically excited, loses an electron, and undergoes oxidation. So, to return to its original state- water donates an electron and acts as a reducing agent.

Do All Plants Photosynthesize?

We sometimes look at photosynthesis as the defining characteristic in plants. However, there are some plants, which do not have chlorophyll and do not perform photosynthesis.

Instead, they choose to get their energy by stealing from their neighboring plants. These are known as holoparasites.

They are entirely dependent on their host and obtain nutrients required from living off of them. So, they do not need to perform photosynthesis, but the host eventually dies due to the continuous stealing of nutrients by the parasites.

Photosynthesis in Oceans

Have you ever wondered how marine plants perform photosynthesis in seas or oceans, where there is a limited amount of light and carbon dioxide?

So, most marine plants stay near the surface of the water to fulfil their requirements. Furthermore, chemical molecules known as phycobiliproteins are present in some tiny organisms known as cyanobacteria, which absorb the light available in the ocean and convert it into light energy that the chlorophyll can use.

Marine organisms release half the Earth’s oxygen, even though their biomass is less in magnitude than bulky terrestrial organisms. They reproduce faster, a new generation every day or two! More significant numbers help in the process of photosynthesis as well.

Science Experiments that Prove Photosynthesis in Plants

Experiments on photosynthesis in plants are fascinating. Children will soon find out that there is no need to fear biology because it’s been fun all along. The four experiments on photosynthesis in this article will create joy and excitement among children who love science.

Experiment #1

Aim: To prove that plants need sunlight to grow

Materials Required:  A potted plant, a boiling tube, 70% alcohol, iodine solution, bunsen burner, forceps, beaker, water, dropper, black paper, and a petri dish.

• Place the potted plant in the dark for about 72 hours. This inhibits the process of photosynthesis, and all the leaves become free of starch.
• After three days, take a strip of black paper and put it on a section of one of the potted plant leaves on both sides.
• Put the plant in the sunlight for a few hours.
• Detach the partially covered leaf from the plant and remove the black covering.
• Boil this leaf in a 70% alcohol solution using a bunsen burner until it loses its green color. This is because we are removing chlorophyll.
• Wash the leaf with water and add iodine solution with a dropper.

Observation: The whole leaf turns blue-black, except for the section covered with black paper. This is because iodine changes color in the presence of starch. However, since the covered portion did not come in contact with the sun, it didn’t photosynthesize, and thus, starch wasn’t present.

Conclusion: We realize that plants need sunlight to photosynthesize and manufacture food.

Experiment #2

Aim: To prove that Carbon Dioxide is necessary for photosynthesis.

Materials Required: A healthy potted plant with long and narrow leaves, Potassium Hydroxide solution, 70% alcohol solution, a jar with a large mouth and cork, grease or vaseline, bunsen burner, petri dish.

• Open the jar and pour in a couple of millimeters of potassium hydroxide. This absorbs the carbon dioxide gas present in the atmosphere.
• After three days, choose a long and narrow leaf and put half of it in the jar.
• Seal the jar and make sure it’s airtight. Put grease on the corners of the cork.
• Detach the leaf from the plant and boil it in a 70% alcohol solution using a bunsen burner until it loses its green color.

Observation: The half of the leaf exposed to the air turns blue-black due to the presence of starch. The other half was deprived of CO 2, and therefore, it didn’t form starch.

Conclusion: Carbon Dioxide gas is necessary for the process of photosynthesis.

Experiment #3

Aim:  To prove that oxygen gas is released during photosynthesis.

Materials Required: A large beaker filled with water, a short transparent funnel, pondweed, or an aquatic plant such as Hydrilla, and a test tube.

• Place a few twigs of the aquatic plant into the transparent funnel.
• Immerse the funnel into the beaker full of water.
• Now, fill the test tube until it’s almost overflowing with water. Cover the mouth of the tube with your thumb.
• Invert the test tube and put it over the funnel, as shown in the diagram.
• Place the setup in the sunlight.
• Observe until the test tube is completely filled with gas.
• Take out the test tube carefully without letting the gas out.
• Bring a burning splinter in contact with the gas. Observe.

Observations: After a few hours in sunlight, there are bubbles in the water, proving the presence of a gas. The burning splint reignites with a pop sound when it’s brought in contact with the test tube- confirming the presence of oxygen.

Conclusion: Photosynthesis releases oxygen.

The Conclusion

Next time you see a tree, stop to hug it. It does a lot of work to make sure that we, humans can live by being one of our resources.

Knowing how photosynthesis works and how it nourishes all the animals in the world should help us realize that plants give us life.

Learning about photosynthesis also explains what makes plants unique. With the information and activities in the article, you now understand what photosynthesis is; and what it means to the environment.

One comment

Dear Angela, Great article on photosynthesis. I could comprehend it easily. It’s explanation method was superb.

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9 Photosynthesis Lab Experiments for Your Class

Photosynthesis is one of the fundamental processes that occur in living organisms, particularly in plants. Understanding photosynthesis helps students appreciate the role of plants in the biosphere and their significance in sustaining life on earth. 

Teaching this topic in the science classroom helps students develop a deep understanding of the natural world, its complexity, and its interconnectedness. It also helps prepare them for future studies in biology, ecology, and other related fields. We’ve outlined both in-person experiments and virtual labs you can use to teach photosynthesis!

1. In-person lab: Measure rate of photosynthesis in spinach leaves

Prepare a solution of water and sodium bicarbonate by dissolving 1 g of baking soda in 1 liter of water. Collect several spinach leaves and place them in a beaker of water for a few minutes to hydrate them. Fill several test tubes or small beakers with the sodium bicarbonate solution. Place spinach leaves in each test tube or beaker, ensuring they are fully submerged. After 5 minutes, measure the amount of oxygen produced by the spinach leaves using a Vernier LabQuest or other data-logging equipment.

2. Virtual lab: Pigment Extraction

In Labster’s simulation, Pigment Extraction: Use photosynthesis to produce biofuel and reduce pollution , Roxy, the leader of a team of engineers, will take students on a journey over the sea and show them the most problematic facilities are the coal power plant and the fish farm. To mitigate the problem, students will help create a sustainable plan for energy production using sunlight, heat from a coal power plant, and nutrients from a fish farm.

3. In-person lab: Chromatography experiment

This experiment provides a hands-on opportunity for students to develop important scientific skills, such as making observations, collecting and analyzing data, and drawing conclusions based on evidence. Extract pigments from different leaves using rubbing alcohol and filter paper. The resulting chromatogram will show the different pigments present in each leaf, such as chlorophyll, carotenoids, and anthocyanins. By separating these pigments, students can investigate their individual roles in the process of photosynthesis.

4. Virtual lab: Algae Pigment Analysis

In Labster’s online lab, Photosynthesis: Algae pigment analysis , students will help Roxy, the lead engineer in an environmental project, determine if dark-colored algae can do photosynthesis using green light. They’ll use the Hill reaction and spectrophotometry to measure electron flow and find out if the pigments in the algae can use green light for photosynthesis.

5. In-person lab: Oxygen production experiment

This is an activity used to investigate the production of oxygen during photosynthesis in aquatic plants. It involves placing an aquatic plant, such as elodea or Cabomba, in a beaker of water and exposing it to light while measuring oxygen levels in the water over time.

6. Virtual lab: Electron Transport Chain 1

In Labster’s digital lab, Photosynthesis: Electron transport chain , students will observe the inner workings of the electron transport chain inside a plant cell and learn about the process of photosynthesis. Watch electrons flow, and molecules move during each step of the electron transport chain. How can a photon of light be converted into chemical energy?

7. In-person lab: Starch production experiment

This is an activity used to investigate the role of light in the production of starch in plants. The experiment involves placing a leaf in the dark for a period of time to deplete its starch reserves and then exposing it to light to observe the production of starch during photosynthesis.

8. Virtual lab: Electron Transport Chain 2

In Labster’s simulation, Electron Transport Chain: A rollercoaster ride that produces energy , students will help a group of engineers figure out if a mysterious dark alga can do photosynthesis using green light and measure this process with the Hill reaction. If it is, your work will help create a sustainable plan using sunlight and pollution sources for biofuel production.

9. In-person lab: Light intensity experiment

This experiment helps to understand the interplay between light and photosynthesis and how plants adapt to different light conditions in their environment. Use a light source of varying intensities and measure the rate of photosynthesis in a water plant, such as elodea, using a probe or sensor. Observe how the rate of photosynthesis increases with higher light intensity up to a certain point.

Questions for reflection

• Were any of these in-person or virtual labs new ideas for you?
• Which one can you implement in your classroom?

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Photosynthesis - A Simple Experiment

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Goals: Students now know that for photosynthesis to occur, a plant needs sunlight, water and carbon dioxide. In the experiment, students will observe if plants can thrive without all three of the essential elements for photosynthesis – water, sunlight and carbon dioxide. Materials:

• three empty, peeled 2-liter bottles
• scotch tape
• pitcher with water
• box in which the planter can fit (and a closet or dark cabinet in which to put bottle 3)

Procedures: 1. Cut the tops off the plastic bottles. 2. Dig up three small plants (about the same size) from the schoolyard with their surrounding dirt. 3. Place each into one of the 2-liter bottles. 4. Place two of the planters in the sunlight and one under a box in a closet, (so that it gets no sunlight). 6. One of the planters in the light will be Bottle 1 – the control bottle receiving water daily and sunlight.      Bottle 2 (in the sunlight) gets no water. Bottle 3 (in the dark), gets watered every day, but receives no sunlight. 7. After 10 days, look at the terrariums side by side. 

Observation: Can you see any differences between the plants?

Thinking Moment: Is this the result you expected? Explain and Discuss. Conclusions?

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• Bubbling Plants Experiment to Quantify Photosynthesis

Hands-on Activity Bubbling Plants Experiment to Quantify Photosynthesis

Grade Level: 6 (5-7)

Time Required: 1 hour

Expendable Cost/Group: US $3.00

Group Size: 3

Activity Dependency: Do Plants Eat? All About Photosynthesis

Subject Areas: Biology, Life Science

NGSS Performance Expectations:

Activities Associated with this Lesson Units serve as guides to a particular content or subject area. Nested under units are lessons (in purple) and hands-on activities (in blue). Note that not all lessons and activities will exist under a unit, and instead may exist as "standalone" curriculum.

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Students perform data analysis and reverse engineering to understand how photosynthesis works. Both are important aspects of being an engineer.

After this activity, students should be able to:

• Explain that photosynthesis is a process that plants use to convert light energy into glucose, a source of stored chemical energy for the plant.
• Describe photosynthesis as a set of chemical reactions in which the plant uses carbon dioxide and water to form glucose and oxygen.
• Describe a simple experiment that provides indirect evidence that photosynthesis is occurring.
• Describe the effects of varying light intensity on the amount of photosynthesis that occurs.

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• 5 liters (about 1¼ gallons) of aged tap water (tap water in an open container that has been allowed to sit for 36-48 hours to eliminate the chlorine used in municipal water supplies)
• 15-20 total Elodea plants; these are hardy freshwater aquarium plants sold in bunches at pet stores and suppliers such as Carolina Biological Supply Company (www.carolina.com)
• string, yarn or twist ties for tying Elodea plants into bunches
• small rocks or similar objects to serve as weights to hold the Elodea plants underwater
• 500-ml beakers, 1 per team
• baking soda, a few tablespoons (sodium bicarbonate)
• timers or watches with second hands, 1 per team
• small adjustable desk lamps that can be set up so that their light bulbs are a few inches above the beakers and shine vertically down onto them; flashlights with strong beams that are mounted on ring stands also work; 1 light source per team

An understanding of photosynthesis, as presented in the associated lesson, Do Plants Eat?

(Get the class' attention and ask them to do as you say.) With one hand, pinch your nose closed. Raise your other hand high in the air. Now take a deep breath and hold it for as long as you can. When you cannot hold your breath any longer, lower your raised hand and unpinch your nose. (Once all hands are down and no one is left holding their breath, move on.) Why did you need to start breathing again? (From their elementary school studies, expect students to be able to tell you that their bodies need air in order to survive.)

What, exactly, is in air? (Students may not know that air contains more than oxygen.) Most of the air we breathe—the atmosphere—consists of nitrogen gas (about 78%). Oxygen is the next largest component (about 21%) and a tiny part (1%) is made up of argon (an inert gas), water vapor and carbon dioxide.

So, specifically what component(s) of air do our bodies need? (Expect them to be able to answer that it is oxygen.) And what do our bodies do with oxygen? That's right, oygen from the air is picked up in the lungs by the blood and carried to all parts of the body, where it is used by muscles and the brain and all the other organs and tissues of the body. We cannot live without it.

From where did the oxygen in the atmosphere come? (They may know or be able to reason that it is the result of all the plants that have lived on the Earth and have been doing photosynthesis for many millions of years.) Today, you will work in teams to conduct an experiment to see if the amount of light plants receive can affect this production of oxygen.

Overall Experiment Plan

• In a class discussion format, students establish a hypothesis to be tested by the class in the experiment.
• Working in teams, students set up and conduct the experiment. Each team conducts two trials: one with the plants lit only by the ambient light available in the classroom when some or all of the room lights are turned off, and one with the plants receiving bright light from the desk lamps. The data collected are the number of bubbles of oxygen that are given off by the plants in a five-minute period, first at low-light levels, and then at high-light levels.
• Then the groups come together to pool their data from each of the two trials. From these data, students individually determine the mean, median and modes for the numbers of bubbles produced during the two different light conditions.
• Then students individually graph the data, using bar graphs that show the mean numbers of bubbles and the ranges for each test condition.

Part 1: Generating a Hypothesis

Explain to the class that before researchers start experiments, they first create a prediction about the expected outcome of the experiment. This prediction is known as a hypothesis. A hypothesis is not simply a guess, however. Instead, it is a prediction based on prior knowledge of or experience with the subject. For example, if a gardener wanted to find out if it was really necessary to fertilize zucchini plants, they might grow 12 zucchini plants, but fertilize only half of them. In this case, the hypothesis being tested might be: Fertilized zucchini plants produce more zucchinis than unfertilized zucchini plants. The data collected to support or refute the hypothesis would be the total number of zucchinis produced by the fertilized plants, compared to the total number produced by the unfertilized plants.

Point out that in the zucchini experiment, the gardener collected data that involved numbers. In science, this is usually the case, because numbers can easily be compared and are cumulative for many things that actually happen, as opposed to things that the experimenter thought might happen.

Then, explain briefly how the photosynthesis experiment will be set up and ask the class to determine a hypothesis to be tested. It shouldn't take them long to come up with a statement such as: The plants that receive more light produce more bubbles than the plants that receive less light.

Part 2: Setting up the Experiment

Perform the following steps with some or all of the classroom lights turned off. Ideally, the room should not be brightly lit, nor should it be dark; adequate light should be present for students to easily see.

• Each team fills a beaker with about 500 ml of aged water for the Elodea. To this water, add a scant one-quarter teaspoon of sodium bicarbonate (baking soda) to provide a source of carbon dioxide for the plants, since they cannot get it from the atmosphere like terrestrial plants do. Stir the water until the sodium bicarbonate is dissolved and the water looks clear.
• Each team obtains enough sections of Elodea plants so that it has about 18-24 inches of total plant length. Arrange them so that all of the plants are at least 1½" under the water in the beaker. Use string or twist ties to hold them together, and then add a small rock to keep the plants from floating to the surface. Point out that the more area exposed to the light above the plant, the more photosynthesis can occur within the leaves. If students form clumps of Elodea, many of leaves will be shaded by those above, and thus may not be able to perform as much photosynthesis. It is best to form the plants into loops that cover the entire bottom of a beaker, instead of a single clump in the middle of the beaker.

Part 3: Running the Experiment

• As soon as the plants are arranged in the beakers, have the team start timing for five minutes. Direct two team members to have their eyes glued to the beaker for those five minutes, watching for bubbles to rise to the water surface. Announce to the third team member the sighting of any bubbles that rise, so s/he can keep count (using tally marks is helpful) and monitor the time, indicating when the five minutes are up. The bubbles are fairly large, about 2 mm in diameter, and so are easily seen when they rise to the surface.
• When all teams have counted bubbles for five minutes (it is quite possible that some teams see no bubbles at all), turn on the room lights and have students position the desk lamps directly above the beakers with the light bulbs only be a few inches above the beakers. Once the lights are in place, have the teams again begin timing and counting/recording bubbles for five minutes.

Part 4: Pooling and Analyzing the Data

• Make a large chart on the classroom board in which teams can fill in the number of bubbles they counted during each of the two light conditions.
• Once the chart is filled in, have students work individually to determine the mean, median, mode and range of each of the two data sets. Allow enough time so that all students arrive at the same answers.
• Provide students with grid paper and direct them to make vertical bar graphs that compare the mean number of bubbles in the two light conditions. Be sure that students include titles, axes labels and legends if different colors are used for the two bars. Then show them how they can indicate the ranges of the data by adding a vertical line segment to the center top of each bar, with the lower end of the line segment situated at the lowest number of bubbles observed by a team, and the upper end of the line segment at the highest number of bubbles observed.

Part 5: Interpreting the Data

• As a class, examine all the data and graphs and revisit the hypothesis. What do these numbers tell us about the amount of photosynthesis that occurred in each of the two light conditions. In other words, was the hypothesis the class tested supported or not?
• Continue with a class discussion to analyse the data. How do you know that the bubbles you saw rise to the surface were bubbles of oxygen? Students may answer that they know photosynthesis produces oxygen, so the bubbles must have been oxygen. However, without a way to determine the chemical composition of the bubbles, it is only an assumption that the bubbles contain oxygen. They might just as well have been bubbles of nitrogen or carbon dioxide, or some other gas from some other process that was occurring in the plants instead of photosynthesis. Nevertheless, since the plants were exposed to light, the bubbles were most likely made of oxygen. Point out that it is important for researchers to make sure they recognize the difference between what they know about an experiment and what they assume about it.

mean: The sum of all the values in a set of data, divided by the number of values in the data set; also known as the average. For example, in a set of five temperature measurements consisting of 22 ºC, 25 ºC, 18 ºC, 22 ºC and 19 ºC, the mean temperature is 106 ºC divided by 5, or 21.2 ºC.

median: Tthe middle value in a set of data, obtained by organizing the data values in an ordered list from smallest to largest, and then finding the value that is at the half-way point in the list. For example, in a set of five temperature measurements consisting of 22º C, 25º C, 18º C, 22 º C, and 19º C, the ordered list of temperatures would be 18º C, 19º C, 22º C, 22º C, and 25º C. The middle value is the third value, 22º C. If the data set consists of an even number of values, the median is determined by averaging the two middle values. For example, in a set of six temperature measurements consisting of 20 ºC, 22 ºC, 25 ºC, 18 ºC, 24 ºC and 19 ºC, the middle values are 20 ºC and 22 ºC. Thus, the median value is the average of 20 ºC and 22 ºC, which is 21 ºC.

mode : The value in a set of data that occurs most frequently. For example, in a set of five temperature measurements consisting of 22 ºC, 25 ºC, 18 ºC, 22 ºC and 19 ºC, the measurement of 22 ºC occurs most frequently, so it is the mode. It is possible to have two or more modes in a set of data, if two or more values occur with equal frequency.

Questions : Evaluate students' comprehension by asking them questions such as:

• What "things" are needed in order for photosynthesis to occur?
• What are the products of photosynthesis?
• Where in the plant does photosynthesis occur?
• Why do plants need water in order to survive?

Graph Analylsis: Provide a graph of data from an experiment similar to the one students just performed, and ask them to draw conclusions from it. For example, the data could represent the heights of corn plants, half of which were grown in the shade of a forest and half of which were grown in an open field.

• What do you think would happen if you left some plants in a completely dark closet for two or three weeks? Why do you think that?
• Why is it important for crop plants to receive enough rainfall?
• The Earth's atmosphere did not always contain as much oxygen as it does now. In fact, at one time it probably contained no oxygen at all. How do you think the oxygen in the Earth's atmosphere got there? Why do you think that?

The light that comes from the sun consists of light waves of many different wavelengths. In the visible spectrum of light, these range from red with the longest wavelength, to violet with the shortest wavelength. Chlorophyll does not respond equally to all wavelengths, or colors of light. Have students use the same experimental setup to determine what color or colors of light result in the most photosynthetic activity. The only modification they need to make is to loosely cover the beaker with colored plastic wrap or cellophane during the five minutes of bubble counting. Since blue wavelengths are the best for most plants, be sure that this is one of the colors available. If possible, have red and one other color available as well.

Through a teacher-led discussion, students realize that the food energy plants obtain comes from sunlight via the plant process of photosynthesis. By counting the number of bubbles that rise to the surface in a five-minute period, students can compare the photosynthetic activity of Elodea in the pre...

Students learn about photosynthesis and cellular respiration at the atomic level and study the basic principles of electromicrobiology—a new field of research that may enable engineers to harness energy at the molecular level.

Contributors

Supporting program, acknowledgements.

This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Last modified: July 12, 2023

The Biology Corner

Biology Teaching Resources

Photosynthesis Virtual Lab

This lab was created to replace the popular waterweed simulator which no longer functions because it is flash-based. In this virtual photosynthesis lab , students can manipulate the light intensity, light color, and distance from the light source.

A plant is shown in a beaker and test tube which bubbles to indicate the rate of photosynthesis. Students can measure the rate over time. There is an included data table for students to type into the simulator, but I prefer to give them their own handout ,

The handout is a paper version for students to write on as the work with the simulator. The document is made with google docs so that it can be shared with remote students.

There are several experiments that can be done in the lab that would complement this virtual experiment. For example, students can use elodea and measure the number of bubbles released when the plant is under a bright light. Algae beads can also be used to measure changes in pH as the plants consume carbon dioxide.

In experiment 2, students specifically look at light color to determine which wavelength of light increases the rate of photosynthesis. Students should discover that green light has a very slow rate. Their collected data is then compared to a graph of the absorption spectrum of light.

Shannan Muskopf

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Photosynthesis Lab Experiments

Grade 7 Science Project Ideas

The science of photosynthesis can be difficult for students, especially younger students, to understand without hands-on activities allowing them to see what they are being taught. Lab experiments that teach the fundamentals of photosynthesis can be conducted with children as young as elementary school. These experiments are designed to supplement the more theoretical elements of photosynthesis since they illustrate the effects of sunlight deprivation on plants, rather than explicitly showing how plants convert sunlight into food.

Sunlight Deprivation

After explaining the basics of photosynthesis, how plants make sugar out of sunlight, you can illustrate the effects of sunlight deprivation on plants. Using bean sprouts or another type of inexpensive and fast-growing plant, give each child two plants potted in small paper cups. Each child places one plant on a sunny windowsill and the other in a closet with no windows. Each plant is given equal soil and watered over the course of a week. At the end of the week, have the children compare the plants. The droopy sun-deprived plant demonstrates how the inability to photosynthesize harms plants.

Experiments with Chlorophyll

Fundamental to a lesson about photosynthesis is an explanation of chlorophyll and the vital role it plans in helping plants harness the power of the sun. A simple lab experiment uses simple materials: scissors, glass jars, coffee filters, and acetone. Students cut up two or three large leaves (which need not be green). Mix the leaf pieces in acetone and let sit for a day. Cut the coffee filters into strips and dip one end into the acetone. As the plant chemicals released by the acetone move up the filter paper, a strip of green becomes visible, this is the chlorophyll.

The Chemical Reactions of Photosynthesis

Once students understand the fundamentals of photosynthesis, educators can lead them through a simple experiment where they can witness first-hand the one of the chemical reactions of photosynthesis. Using small plants purchased at an aquarium store, student place samples of the plant in water-filled test tubes which they cork. Over the course of half an hour tiny air bubbles will develop on the walls of the test tube. These bubbles are evidence of the chemical reaction whereby plants covert carbon dioxide and water (hydrogen) into carbohydrates (food).

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Based in Seattle, Antonia Lawrence has been writing and editing since 2007. Lawrence has worked and traveled extensively in both Europe and Asia. She holds a Bachelor of Arts in history and French language from Agnes Scott College and a Master of Business Administration from the University of Florida.

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Plant Growth Experiment

Ever wonder what makes plants grow the best? Try this fantastic plant growth experiment , where you explore how light, water, and temperature affect plant growth. Follow along to see which conditions will help your plants thrive the most!

Fun and Easy Plant Experiment for Students

Plants need certain things to survive and grow: light, water, and the right temperature. Explore how light, water, and temperature changes impact plant growth. This fun activity also teaches important biology concepts like photosynthesis and plant adaptation, along with applying scientific methods .

💡Explore our Biology Projects , including osmosis , capillary action , and plant cells .

Recommended Grade Level: 4-6th Grade

📝 A printable journal page is included to track your plant’s progress and add to a science notebook!

Here’s what you need to get started:

• 6 small potted plants (all the same type)
• Potting soil
• Ruler (for measuring plant height)
• Watering can
• Thermometer
• Grow lights or access to sunlight
• Labels for each plant
• Printable observation journal (included below)
• Camera (optional for photo observations)

How to Set Up: Hands-on Plant Growth Activity

Step 1: Set Up Your Experiment Divide your six plants into three groups of two and label each plant with a number. Each group will test different conditions: light, water, or temperature.

• Group 1: Light Experiment : Place one plant in a sunny spot and the other in a dark room.
• Group 2: Water Experiment : Water one plant daily and the other once a week.
• Group 3: Temperature Experiment : Put one plant in a warm spot (room temperature) and the other in a cooler place.

Step 2: Make Observations Measure each plant’s height every two days with a ruler and record your findings. Pay attention to the color, size, and health of the leaves. Write these observations in your journal.

Step 3: Create a Growth Chart Using the printable observation sheet below, chart each plant’s growth, including the plant’s height, the number of leaves, and any visible signs of health or stress. Compare how the plants in each condition grow over time.

Step 4: Analyze the Results After two to three weeks, review your data. Which plants grew the most? Which conditions seemed to help the plants grow best? Encourage students to reflect on how light, water, and temperature affected plant health.

Applying the Scientific Method

The scientific method helps students explore how light, water, and temperature affect plants. Here’s an example:

• Ask a Question : How does light, water, or temperature affect plant growth?
• Research : Learn about plant needs, like photosynthesis and proper hydration.
• Hypothesis : Make a prediction. Example: “If a plant gets more sunlight, it will grow taller.”
• Experiment : Follow the steps, changing only one variable (light, water, or temperature) while keeping the rest constant.
• Record Data : Track plant height and health in the journal every few days.
• Analyze : Look at the results. Did the plants with more sunlight grow more? Did temperature affect growth?
• Conclusion : Was the hypothesis correct? What did you learn?

💡Learn more about the scientific method [here] .

Free Printable Plant Growth Observation Chart

The Science Behind Plant Growth:

Light is crucial for photosynthesis , the process by which plants make food. In this experiment, you’ll see that plants in full sunlight grow better than those kept in darkness. This is because, without light, the plant can’t perform photosynthesis, leading to slower growth and poor health.

Water is necessary for transporting nutrients throughout the plant. When a plant doesn’t get enough water, it may wilt or not grow as quickly. By comparing a plant watered daily to one watered weekly, you’ll notice the differences in growth and vitality.

Temperature:

Plants also grow best within a certain temperature range. Warmer temperatures can speed up a plant’s metabolism and growth, while cooler temperatures may slow it down. This experiment allows you to observe how plants in warm versus cool environments develop over time.

The Role of Photosynthesis:

Plants use light, water, and carbon dioxide to make food essential for growth. In the light experiment , plants kept in the dark won’t be able to photosynthesize effectively, so their growth will be slower or stunted. The experiment shows how important sunlight is for plant health and survival.

💡Learn more about photosynthesis and grab a free project!

Printable Plant Growth Observation Chart:

Use this printable chart to track your plant growth during the experiment. It helps organize your observations and makes comparing each plant’s progress easy.

This chart includes spaces to record the condition (light, water, temperature), plant height on specific days, and color and leaf health notes. At the end of the experiment, students will have a complete record of their observations to analyze.

Related Activities:

More plant science activities.

💡Investigate our complete collection of Plant Science Activities [here].

• Plant Cell Collage
• How Do Leaves Drink
• How Do Plants Breathe?
• Why Do Leaves Change Color?
• Seed Germination
• Flower Dissection Lab

Printable Plant Project Pack

Explore 20+ Plant Activities for Kids! 🌱 Looking for fun and educational plant-themed activities? This comprehensive Plant Activity Pack is perfect for early elementary school grades, providing hands-on learning experiences that fit any skill level! Whether it’s for fall or spring science lessons, these activities are ideal for classroom and at-home learning.

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ENCYCLOPEDIC ENTRY

Photosynthesis.

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

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Learning materials, instructional links.

• Photosynthesis (Google doc)

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

The process

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

Chlorophyll

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

Light-dependent Reactions vs. Light-independent Reactions

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

C3 and C4 Photosynthesis

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

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Related Resources

Elodea Photosynthesis Lab

Use this classroom dataset from a classic lab to see how light intensity affects photosynthesis. You can also collect, upload, and analyze your own data from this classic biology and life science lab.

What do you notice in this short video (1:38)? What do you think is causing the bubbles to form? Why do you think that?

Green plants use light energy to produce their own food with photosynthesis You may have already learned that plants require water and carbon dioxide and light for photosynthesis and produce oxygen and glucose sugar in the process. If one of those three inputs (water, carbon dioxide, or light) is in short supply, then photosynthesis will slow down or even stop. How does light intensity affect the rate of photosynthesis?

By analyzing data from a classic lab experiment we can draw some conclusions about the effect of light intensity (or strength) on photosynthesis.

This classroom experiment used an aquatic plant called Elodea that commonly grows in lakes and ponds and is sold in pet stores for use in home aquariums. A freshly cut stem of Elodea was placed in a beaker of water. A small desk lamp was used as a light source while all other sources of light in the classroom were darkened. Students counted the number of oxygen bubbles what were produced by the plant during a two minute period.

Each of five groups of students repeated this experiment with the light source at five different distances (10cm, 20cm, 30cm, 40cm, 50cm). Their data are recorded in this class dataset. Each row in the dataset is a single observation recorded and each column represents a different variable.

Distance Treatment- This categorical variable records which of the five set distances the light source was set at for a specific observation. It is coded as a categorical variable because there are five fixed distances (10, 20, 30, 40, 50). You can change this variable type to numeric for different graphing or analyses options if you wish.

Student Lab Group- This categorical variable records which student lab group made a particular observation. There are five lab groups. Each lab group made one observation for each Distance Treatment.

Number of Oxygen Bubbles- This numeric variable is the number of bubbles observed during the two minute observation period.

You can click the edit button to the right of this document to begin editing your own copy of this document in Google Docs. You will first need to save your own copy of this dataset to do this.

1) Make a graph showing Number of Oxygen Bubbles on the Y-Axis and Distance Treatment on the X-axis. Click the Descriptive stats check box on the right to add the mean and standard deviation for each treatment to your graph. Use the camera icon to copy and paste your graph to this answer sheet.

2) How does the average value of Number of Oxygen Bubbles change as the distance of the Elodea plant from the light source increases? Look to the graph you made above for specifics to use in this answer.

3) Why does the distance from the light source change the amount of oxygen bubbles observed?

4) The number of bubbles produced in this experiment were the dependent variable that we measured (by counting) and indicate that photosynthesis is occurring. Based on what you know about photosynthesis, which products is the plant producing during the time the bubbles were observed?

5) Based on what you observed in this experiment and what you know about photosynthesis, what would you expect to happen to a plant that was kept in the dark for a long period of time (several weeks)? Why?

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Top 11 Experiments on Photosynthesis in Plants

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The following points highlight the top eleven experiments on photosynthesis in plants. Some of the experiments are: 1. Simple Demonstration of Photosynthesis 2. To Study the ”Primary Photochemical Reaction” of Photo­synthesis 3. To Study the “Dark Reaction” of Photosynthesis 4. To Study the Essentiality of the Factors for the Photosynthetic Process and Others.

Experiment # 1

Simple demonstration of photosynthesis:.

(a) With the help of a beaker and a funnel:

Experiment:

A large beaker of capacity 500 ml is taken and are filled two-thirds with distilled water containing 0.1 % KHCO 3 which acts as a source of CO 2 . Some fresh and healthy aquatic plants like Hydrilla are taken in a beaker and the plants are cut obliquely at their bases under water.

Cut ends are tied together with the help of a thread and are kept towards the neck of an inverted funnel in such a way that the limb of the funnel almost covers the Hydrilla plants and the stem of the funnel remains about one centimeter under the water surface.

The whole set-up is now exposed to bright light and observed from time to time. Another set-up is similarly prepared and kept under a very low light intensity.

Observation:

It is observed that evolution of bubbles from cut ends of the plants takes place in the set-up exposed to light. Little evolution of bubbles takes place in the set-up maintained in low light intensity.

In light, evolution of oxygen bubbles takes place due to photosynthesis. This is further proved by the fact that little evolution of bubbles takes place in the set-up placed in low light intensity.

(b) With the help of Wilmott’s bubbler:

The apparatus consists of a flask of capacity 500 ml fitted with a rubber cork having a central hole through which passes a glass tube. The lower end of the tube reaches the middle of the flask while its upper end forms a jet within a cylindrical cup. A graduated tube having a stopcock at one end remains inverted over the jet (Figure 27).

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• Biology Article
• Photosynthesis Early Experiments

Early Experiments on Photosynthesis

Table of contents, introduction, photosynthesis discovery – early experiments, experiment to prove carbon dioxide is essential for photosynthesis, other experiments.

Photosynthesis is a light-dependant process that plants use to produce their own food. It is the process by which plants convert light energy into chemical energy, which can be used later for plants’ own processes. During this process, oxygen is produced as a byproduct. Photosynthesis was discovered only in 1800. To prove the existence of photosynthesis in plants, many scientists performed numerous experiments.

Let us have a detailed look at the early experiments on photosynthesis.

Also Read:  What is Photosynthesis

Since photosynthesis is a light-dependant process, it only takes place in the presence of sunlight. But along with sunlight, the plant also requires water and carbon dioxide as raw materials for this process to synthesise carbohydrates. Green plants also possess a green pigment known as chlorophyll which helps in capturing light energy. All these key features of photosynthesis were revealed later during the mid-nineteenth century when numerous scientific studies were conducted on photosynthesis.

Below mentioned are the experiments that were conducted by the early scientists in support of photosynthesis.

Materials required: A healthy potted plant, a wide-mouthed glass bottle with a split cork, potassium hydroxide solution (KOH), and starch solution.

Experiment:

• Select a healthy potted plant and place it in the darkroom for two to three days to ensure the leaves are free from starch.
• In a wide-mouthed glass bottle, add 10-15 ml of potassium hydroxide solution and split the cork vertically.
• Now carefully insert half part of a leaf into a glass bottle through the split cork and the other half exposed to air.
• Place the complete unit undisturbed in sunlight for about 3 – 4 hours.
• After 4 hours, detach the leaf from the plant and slowly remove it from the bottle and test it with the starch solution.
• We can observe that the half part leaf which was inside the glass bottle (KOH solution) did not show any colour change, but the other half part exposed to the surroundings turned its colour to dark brown, indicating the presence of starch in it.

Conclusion: In this experiment, we can conclude that carbon dioxide is essential for photosynthesis. Both the portion of the leaf received the same amount of water, chloroplasts , and sunlight but the half part which was inside the glass bottle did not receive carbon dioxide.

After discovering the importance of carbon dioxide in photosynthesis, many experiments were conducted to understand other essential factors for this process. Joseph Priestly was one of the first scientists to perform these experiments.

Experiment by Joseph Priestley

In 1770, after a series of experiments, Joseph Priestley came to a conclusion regarding the essentiality of air for photosynthesis and also for the growth of plants.

Materials required: A bell jar, candle, rat, and a plant.

• Priestley kept a burning candle and a rat together in the single bell jar.
• After some time, the candle was extinguished, and the rat died.
• For the second time, he kept a burning candle, a rat, and a green plant together in the bell jar.
• He observed that neither the candle got extinguished nor did the rat die.

Conclusion: Based on his observations, Priestley concluded that in the first case, the air in the bell jar got polluted by the candle and rat. However, in the second case, the plant reinstated the air that was spoiled by the candle and the rat.

But it took another few years to reveal what was exactly released by the plant to keep the rat alive and the candle burning.

Jan Ingenhousz: He proved that sunlight is essential for the photosynthesis process during which carbon dioxide is used and oxygen is produced.

Jean Senebier: He demonstrated that during photosynthesis, carbon dioxide in the air is absorbed, and oxygen is released by the plant.

Julius Robert Mayer: Mayer proposed the idea that light energy is being converted into chemical energy during photosynthesis.

Julius Von Sachs: He discovered that the photosynthesis process leads to the production of glucose molecules.

T.W.Engelmann: Engelmann was the scientist who discovered the importance of chlorophyll in photosynthesis.

Cornelius van Niel: He introduced the chemical equation of the photosynthesis process when he revealed that the oxygen released by plants at the end of photosynthesis comes from water and not from carbon dioxide.

Also Read:  Photosynthesis in Higher Plants

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Are any experiments that had been done but related to other factors which affecting the rate of photosynthesis?, If so then I would be grateful if you can send me any of them. I am very interested to do such experiment and that will be also a part of my assessment task that I will be doing next week. Most of the information that I get from the source really help me, and I hope that it is vital for me.

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Practical Biology

A collection of experiments that demonstrate biological concepts and processes.

Observing earthworm locomotion

Practical Work for Learning

Published experiments

Investigating factors affecting the rate of photosynthesis, class practical.

In this experiment the rate of photosynthesis is measured by counting the number of bubbles rising from the cut end of a piece of Elodea or Cabomba .

Lesson organisation

The work could be carried out individually or in groups of up to 3 students (counter, timekeeper and scribe).

Apparatus and Chemicals

Students may choose to use:.

Thermometer, –10 °C –110°C

Coloured filters or light bulbs

Push-button counter

Potassium hydrogencarbonate powder or solution (Hazcard 95C describes this as low hazard)

For each group of students:

Student sheets, 1 per student

Beaker, 600 cm 3 , 1

Metre ruler, 1

Elodea ( Note 1 ) or other oxygenating pond plant ( Note 2 )

Electric lamp

Clamp stand with boss and clamp

Health & Safety and Technical notes

Normal laboratory safety procedures should be followed. There is a slight risk of infection from pond water, so take sensible hygiene precautions, cover cuts and wash hands thoroughly after the work is complete.

Read our standard health & safety guidance

1 Elodea can be stored in a fish tank on a windowsill, in the laboratory or prep room. However it is probably a good idea to replace it every so often with a fresh supply from an aquarist centre or a pond. (It’s worth finding out if any colleague has a pond.) On the day of the experiment, cut 10 cm lengths of Elodea , put a paper-clip on one end to weigh them down and place in a boiling tube of water in a boiling tube rack, near a high intensity lamp, such as a halogen lamp or a fluorescent striplight. Check the Elodea to see if it is bubbling. Sometimes cutting 2–3 mm off the end of the Elodea will induce bubbling from the cut end or change the size of the bubbles being produced.

2 Cabomba (available from pet shops or suppliers of aquaria – used as an oxygenator in tropical fish tanks) can be used as an alternative to Elodea , and some people find it produces more bubbles. It does, though tend to break apart very easily, and fish may eat it very quickly.

3 If possible, provide cardboard to allow students to shield their experiment from other lights in the room.

Ethical issues

Look out for small aquatic invertebrates attached to the pond weed used, and remove them to a pond or aquarium.

Plant Maze Experiment

NASA/GSFC

Plants tend to grow and stretch toward a source of light, like the Sun. This phenomenon is known as phototropism. This experiment demonstrates how a plant can even move around obstacles to find its way to the light.

Plant Maze Experiment Word Doc

Sep 20, 2024

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Plant Maze Experiment PDF

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Optimal light intensity for lettuce growth, quality, and photosynthesis in plant factories.

1. Introduction

2.1. effects of different led light intensities on the growth of lettuce, 2.2. effects of different led light intensities on the quality of lettuce, 2.3. effects of different led light intensities on the photosynthetic and transpiration characteristics of lettuce, 2.4. heatmap analysis of lettuce character index under different light intensities, 2.5. comprehensive evaluation of lettuce by membership function values, 3. discussion, 4. materials and methods, 4.1. plant material and growth condition, 4.2. treatment design, 4.3. phenotype measurement, 4.4. physiological index detection, 4.4.1. detection of total soluble sugar, 4.4.2. detection of soluble protein, 4.4.3. detection of plant cellulose, 4.4.4. detection of plants nitrate, 4.4.5. detection of total free amino acids, 4.4.6. detection of vitamin c, 4.4.7. detection of photosynthetic and transpiration index, 4.5. evaluation and analysis, 4.6. statistical analysis, supplementary materials, author contributions, data availability statement, conflicts of interest.

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Click here to enlarge figure

Treatment	Phenotypic Index	Quality Index	Photosynthetic Index
L1	769	666	937
L2	974	897	822
L3	776	767	733

Treatment	Phenotypic Index	Quality Index	Photosynthetic Index	Total Membership Value	Rank
L1	0.00	0.00	1.00	0.33	3
L2	1.00	1.00	0.44	0.81	1
L3	0.03	0.44	0.00	0.16	2

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Dai, M.; Tan, X.; Ye, Z.; Ren, J.; Chen, X.; Kong, D. Optimal Light Intensity for Lettuce Growth, Quality, and Photosynthesis in Plant Factories. Plants 2024 , 13 , 2616. https://doi.org/10.3390/plants13182616

Dai M, Tan X, Ye Z, Ren J, Chen X, Kong D. Optimal Light Intensity for Lettuce Growth, Quality, and Photosynthesis in Plant Factories. Plants . 2024; 13(18):2616. https://doi.org/10.3390/plants13182616

Dai, Mengdi, Xiangfeng Tan, Ziran Ye, Jianjie Ren, Xuting Chen, and Dedong Kong. 2024. "Optimal Light Intensity for Lettuce Growth, Quality, and Photosynthesis in Plant Factories" Plants 13, no. 18: 2616. https://doi.org/10.3390/plants13182616

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