essay on photosynthesis for class 5

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Photosynthesis

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

Table of Contents

• What is Photosynthesis?
• Site of photosynthesis

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

What Is Photosynthesis in Biology?

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

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

A visual representation of the photosynthesis reaction

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

Where Does This Process Occur?

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

Also Read:  Photosynthesis Early Experiments

Photosynthesis Equation

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

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

Structure Of Chlorophyll

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

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

Also Read:   Biological Pigments

Process Of Photosynthesis

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

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

Structure of Chloroplast. Note the presence of the thylakoid

“Photosynthesis Steps:”

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

The process of photosynthesis occurs in two stages:

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

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

Light Reaction of Photosynthesis (or) Light-dependent Reaction

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

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

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

Dark Reaction of Photosynthesis (or) Light-independent Reaction

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

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

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

* G3P – glyceraldehyde-3-phosphate

Calvin photosynthesis Cycle (Dark Reaction)

Also Read:  Cyclic And Non-Cyclic Photophosphorylation

Importance of Photosynthesis

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

Frequently Asked Questions

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

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Please What Is Meant By 300-400 PPM

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

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Photosynthesis

5th Class Science Plants Photosynthesis

Category : 5th Class

            Photosynthesis

Photosynthesis is derived from two words, photo + synthesis. 'Photo' means light and 'synthesis' means manufacturing, i.e. manufacturing food in the presence of light.

All green plants prepare its own food with the help of carbon dioxide and water in the presence of chlorophyll and sunlight.

In this process solar energy is converted into chemical energy.

The function of chlorophyll is to absorb solar energy.

Absorption of carbon dioxide and evolution of oxygen takes place through the leaves.

Water is obtained from the soil through the roots and transported to leaves for photosynthesis. Food prepared in the leaves transported to all the parts of the plants. Both the process are carried out with the help of veins.

Roots absorb water from the soil

Path way of carbon dioxide and oxygen in and out of the plant body:

Mushrooms are grown in the dark places. It doesn't undergo photosynthesis process, rather it feeds on dead and decayed organic matter.

Mushroom obtains its food from dead decayed plant product

Some plants are parasitic in nature. They eat insects trapped by them. Such types of plants are called insectivorous plants, e.g. sundew, venus fly trap, pitcher plant etc.

Insectivorous plants appear very attractive as they need to attract insects. They can even trap frogs, birds etc.

    Venus fly trap                                     Pitcher plant                                          Sundew  

Like animals, plants also need energy; but to a little extent. Because plants don't have to move from one place to another in search of food like animals. This energy comes from the oxidation of the food prepared by leaves. Hence we can say that in the presence of oxygen food is broken down into CO 2 and H 2 O along with the release of energy. Photosynthesis is a synthesis process and respiration is a breaking down process. Respiration is an opposite process of the process of photosynthesis.

Adaptations are favorable changes that enable an organism to increase its chances of survival.

(a) To absorb solar energy

(b) To look beautiful

(c) To excite water molecule

(d) To break water and carbon dioxide into oxygen

(e) All of these

Answer: (a)

Explanations

Chlorophyll receives sunlight to initiate the photosynthesis process.

Therefore, option (A) is correct and rest of the options is incorrect.

Statement X: Xerophytes plants are tall and have large leaves.

Statement Y: Hairy and spiny plants are an adaptation to disperse the seed from one place to another.

Which one of the following is correct about the above statements?

(a) Statement X is true

(b) Statement Y is true

(c) Both X and Y are true

(d) Both X and Y are false

(e) None of these

Answer: (b)

Explanation

Xerophytes plants are short and leaves modified to spines to prevent water loss through transpiration. Hairy and spiny plants get stuck to the animal's body and hence dispersed from one place to another.

Therefore, option (B) is correct and rest of the options is incorrect.

        Seed

Seed is a part of the flower which gives birth to a new plant. It is surrounded or protected by seed coat that contains food in it. It is the result of fusion of male and female sex gametes. Embryo develops inside it. Seed enclosed in an ovary is an essential feature of the flowering plant.

Look at the following picture of internal parts of seed:

Immature plant from which new plant is grown is called embryo. Embryo consists of precursor tissues for the leaves, roots, stems etc. it has cotyledons, radical and plumule.

It provides food thus this is the first photosynthetic organ of the plants.

Radicle develops into root system so called - ve phototrophic, or + vely geotropic.

Plumule grows into shoot system thus called + vely phototrophic or –vely geotropic.

Seed is protected by seed coat which is called as testa. It is usually hard and tough.

Micropyle allows the pollen tube to enter the ovuie for fertilization. Water also enters into the seed through the micropyle for germination. Germination is defined as the growing and developing of embryo into a mature plant.

See the given picture of growth of embryo into a mature plant:

Food (Which comes from cotyledons)

Seed dispersal means transportation of seeds from one place to another.

  The following agents help in the dispersal of seed:

(b) Animals

(e) Explosion method

Dispersal of seeds avoid gathering of many plants to grow at one place. Nature has developed mechanism to scatter the seeds of plants to different places to ensure proper water, sunlight and soil etc to the developing seeds.

Winged seeds can be easily carried by the wind. e.g. maple, pine.

Seeds have hairs that help in dispersing through wind e.g. dandelion, poplar etc.

           Dandelion                                               Maple                                                           Orchid  

A type of seeds floats in water so called buoyant seeds. E.g. water lily.

These seeds are dispersed by the water bodies. E.g. coconut has fibrous outer covering that helps in floating from one place to another. Other examples are milkweed mangrove, palm trees etc.

          Milkweed                                                  Palm                                                       Water lily  

Seeds which dispersed by animals are brightly colored.

It has tasty pulp, e.g. raspberry

It has spines or hooks, which get stacked on the animal's body, e.g. date, goose grass.

                   Raspberry                                    Fig                                                       Strawberry  

Certain fruits explode on becoming dry. This explosion flies away seed with great force at places away from the mother plant. E.g. balsam, pea, geranium, touch me not, cucumbers etc..

           Exploding geranium                        Exploding balsam                     Cucumber ready to explode    

Some seeds are oil producing, e.g. sunflower, mustard, groundnut etc. And some seeds are fibre yielding, e.g. cotton, jute etc.

     Oil producing                                   Fibre yielding seed    

(a) Gymnosperms have seeds enclosed in an ovary

(b) Embryo is the baby plant inside the seed

(c) Germination is the process of growing baby plant from the embryo

(d) Maize has one cotyledon in the seed

Gymnosperms have naked seeds. Hence, the statement which is given in the option (A) is incorrect. Therefore, option A is correct and rest of the options is incorrect.

(a) Ayush's mother kept the soaked seed in a moist cloth in the kitchen

(b) Ayush's mother kept the soaked seed in the dark room'

(c) Ayush's mother kept the soaked seed in a dry cloth

(d) Ayush's mother kept the soaked seed in an air tight container

(e) All B, C and D

Answer: (e)

Several factors are essential for the germination process. These are water, oxygen, temperature and light. Absence of any of these factor could lead to stoppage of germination process. Therefore, option (E) is correct and rest of the options is incorrect.

Other Topics

• play_arrow Plants
• play_arrow Plants Classification
• play_arrow Photosynthesis
• play_arrow Types of Crops
• play_arrow Plant life
• play_arrow Notes - Plant Life

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photosynthesis

Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. Chlorophyll is a substance in all green plants, especially in the leaves. Plants take in water from the soil and carbon dioxide from the air.

Photosynthesis starts when chlorophyll absorbs energy from sunlight. Green plants use this light energy to change water and carbon dioxide into oxygen and nutrients called sugars. The plants use some of the sugars and store the rest. The oxygen is released into the air.

Photosynthesis is very important because almost all living things depend on plants for food. Photosynthesis is also important because of the oxygen it produces. Humans and other animals need to breathe in oxygen to survive.

Some living things other than plants also make their own food through photosynthesis. They include certain types of bacteria and algae.

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Development of the idea

Overall reaction of photosynthesis.

• Basic products of photosynthesis
• Evolution of the process
• Light intensity and temperature
• Carbon dioxide
• Internal factors
• Energy efficiency of photosynthesis
• Structural features
• Light absorption and energy transfer
• The pathway of electrons
• Evidence of two light reactions
• Photosystems I and II
• Quantum requirements
• The process of photosynthesis: the conversion of light energy to ATP
• Elucidation of the carbon pathway
• Carboxylation
• Isomerization/condensation/dismutation
• Phosphorylation
• Regulation of the cycle
• Products of carbon reduction
• Photorespiration
• Carbon fixation in C 4 plants
• Carbon fixation via crassulacean acid metabolism (CAM)
• Differences in carbon fixation pathways
• The molecular biology of photosynthesis

Why is photosynthesis important?

What is the basic formula for photosynthesis, which organisms can photosynthesize.

photosynthesis

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• Khan Academy - Photosynthesis
• Biology LibreTexts - Photosynthesis
• University of Florida - Institute of Food and Agricultural Sciences - Photosynthesis
• Milne Library - Inanimate Life - Photosynthesis
• National Center for Biotechnology Information - Chloroplasts and Photosynthesis
• Roger Williams University Pressbooks - Introduction to Molecular and Cell Biology - Photosynthesis
• BCcampus Open Publishing - Concepts of Biology – 1st Canadian Edition - Overview of Photosynthesis
• photosynthesis - Children's Encyclopedia (Ages 8-11)
• photosynthesis - Student Encyclopedia (Ages 11 and up)
• Table Of Contents

Photosynthesis is critical for the existence of the vast majority of life on Earth. It is the way in which virtually all energy in the biosphere becomes available to living things. As primary producers, photosynthetic organisms form the base of Earth’s food webs and are consumed directly or indirectly by all higher life-forms. Additionally, almost all the oxygen in the atmosphere is due to the process of photosynthesis. If photosynthesis ceased, there would soon be little food or other organic matter on Earth, most organisms would disappear, and Earth’s atmosphere would eventually become nearly devoid of gaseous oxygen.

The process of photosynthesis is commonly written as: 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2 . This means that the reactants, six carbon dioxide molecules and six water molecules, are converted by light energy captured by chlorophyll (implied by the arrow) into a sugar molecule and six oxygen molecules, the products. The sugar is used by the organism, and the oxygen is released as a by-product.

The ability to photosynthesize is found in both eukaryotic and prokaryotic organisms. The most well-known examples are plants, as all but a very few parasitic or mycoheterotrophic species contain chlorophyll and produce their own food. Algae are the other dominant group of eukaryotic photosynthetic organisms. All algae, which include massive kelps and microscopic diatoms , are important primary producers.  Cyanobacteria and certain sulfur bacteria are photosynthetic prokaryotes, in whom photosynthesis evolved. No animals are thought to be independently capable of photosynthesis, though the emerald green sea slug can temporarily incorporate algae chloroplasts in its body for food production.

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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 . If photosynthesis ceased, there would soon be little food or other organic matter on Earth. Most organisms would disappear, and in time Earth’s atmosphere would become nearly devoid of gaseous oxygen. The only organisms able to exist under such conditions would be the chemosynthetic bacteria , which can utilize the chemical energy of certain inorganic compounds and thus are not dependent on the conversion of light energy.

Energy produced by photosynthesis carried out by plants millions of years ago is responsible for the fossil fuels (i.e., coal , oil , and gas ) that power industrial society . In past ages, green plants and small organisms that fed on plants increased faster than they were consumed, and their remains were deposited in Earth’s crust by sedimentation and other geological processes. There, protected from oxidation , these organic remains were slowly converted to fossil fuels. These fuels not only provide much of the energy used in factories, homes, and transportation but also serve as the raw material for plastics and other synthetic products. Unfortunately, modern civilization is using up in a few centuries the excess of photosynthetic production accumulated over millions of years. Consequently, the carbon dioxide that has been removed from the air to make carbohydrates in photosynthesis over millions of years is being returned at an incredibly rapid rate. The carbon dioxide concentration in Earth’s atmosphere is rising the fastest it ever has in Earth’s history, and this phenomenon is expected to have major implications on Earth’s climate .

Requirements for food, materials, and energy in a world where human population is rapidly growing have created a need to increase both the amount of photosynthesis and the efficiency of converting photosynthetic output into products useful to people. One response to those needs—the so-called Green Revolution , begun in the mid-20th century—achieved enormous improvements in agricultural yield through the use of chemical fertilizers , pest and plant- disease control, plant breeding , and mechanized tilling, harvesting, and crop processing. This effort limited severe famines to a few areas of the world despite rapid population growth , but it did not eliminate widespread malnutrition . Moreover, beginning in the early 1990s, the rate at which yields of major crops increased began to decline. This was especially true for rice in Asia. Rising costs associated with sustaining high rates of agricultural production, which required ever-increasing inputs of fertilizers and pesticides and constant development of new plant varieties, also became problematic for farmers in many countries.

A second agricultural revolution , based on plant genetic engineering , was forecast to lead to increases in plant productivity and thereby partially alleviate malnutrition. Since the 1970s, molecular biologists have possessed the means to alter a plant’s genetic material (deoxyribonucleic acid, or DNA ) with the aim of achieving improvements in disease and drought resistance, product yield and quality, frost hardiness, and other desirable properties. However, such traits are inherently complex, and the process of making changes to crop plants through genetic engineering has turned out to be more complicated than anticipated. In the future such genetic engineering may result in improvements in the process of photosynthesis, but by the first decades of the 21st century, it had yet to demonstrate that it could dramatically increase crop yields.

Another intriguing area in the study of photosynthesis has been the discovery that certain animals are able to convert light energy into chemical energy. The emerald green sea slug ( Elysia chlorotica ), for example, acquires genes and chloroplasts from Vaucheria litorea , an alga it consumes, giving it a limited ability to produce chlorophyll . When enough chloroplasts are assimilated , the slug may forgo the ingestion of food. The pea aphid ( Acyrthosiphon pisum ) can harness light to manufacture the energy-rich compound adenosine triphosphate (ATP); this ability has been linked to the aphid’s manufacture of carotenoid pigments.

General characteristics

The study of photosynthesis began in 1771 with observations made by the English clergyman and scientist Joseph Priestley . Priestley had burned a candle in a closed container until the air within the container could no longer support combustion . He then placed a sprig of mint plant in the container and discovered that after several days the mint had produced some substance (later recognized as oxygen) that enabled the confined air to again support combustion. In 1779 the Dutch physician Jan Ingenhousz expanded upon Priestley’s work, showing that the plant had to be exposed to light if the combustible substance (i.e., oxygen) was to be restored. He also demonstrated that this process required the presence of the green tissues of the plant.

In 1782 it was demonstrated that the combustion-supporting gas (oxygen) was formed at the expense of another gas, or “fixed air,” which had been identified the year before as carbon dioxide. Gas-exchange experiments in 1804 showed that the gain in weight of a plant grown in a carefully weighed pot resulted from the uptake of carbon, which came entirely from absorbed carbon dioxide, and water taken up by plant roots; the balance is oxygen, released back to the atmosphere. Almost half a century passed before the concept of chemical energy had developed sufficiently to permit the discovery (in 1845) that light energy from the sun is stored as chemical energy in products formed during photosynthesis.

This equation is merely a summary statement, for the process of photosynthesis actually involves numerous reactions catalyzed by enzymes (organic catalysts ). These reactions occur in two stages: the “light” stage, consisting of photochemical (i.e., light-capturing) reactions; and the “dark” stage, comprising chemical reactions controlled by enzymes . During the first stage, the energy of light is absorbed and used to drive a series of electron transfers, resulting in the synthesis of ATP and the electron-donor-reduced nicotine adenine dinucleotide phosphate (NADPH). During the dark stage, the ATP and NADPH formed in the light-capturing reactions are used to reduce carbon dioxide to organic carbon compounds. This assimilation of inorganic carbon into organic compounds is called carbon fixation.

Van Niel’s proposal was important because the popular (but incorrect) theory had been that oxygen was removed from carbon dioxide (rather than hydrogen from water, releasing oxygen) and that carbon then combined with water to form carbohydrate (rather than the hydrogen from water combining with CO 2 to form CH 2 O).

By 1940 chemists were using heavy isotopes to follow the reactions of photosynthesis. Water marked with an isotope of oxygen ( 18 O) was used in early experiments. Plants that photosynthesized in the presence of water containing H 2 18 O produced oxygen gas containing 18 O; those that photosynthesized in the presence of normal water produced normal oxygen gas. These results provided definitive support for van Niel’s theory that the oxygen gas produced during photosynthesis is derived from water.

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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Photosynthesis

By Lisa Algee

3 rd –5 th  Grade (upper elementary/primary)

Note: This is lesson 2 in a 4-part series on the water cycle, photosynthesis, exploring ecosystems, and scientific inquiry in local ecosystems. Find lessons 1 , 3 and 4 here (click relevant link).

(a)    What is photosynthesis and why is it important?

(b)   How to decipher the meaning of a concept (photosynthesis) by looking at the prefix ( photo ) and root word ( synthesis ).

(c)    To understand the important role rainforests play with regard to photosynthesis, i.e., lots of trees = more oxygen and water in Earth’s atmosphere.  All animals depend on oxygen for survival.  In addition, the water cycle (Lesson 1) depends on moisture (water) in the atmosphere, i.e., some of which comes directly from trees through the process of transpiration which occurs during photosynthesis.

Purpose:   To build knowledge and awareness about the power of photosynthesis and how all life depends upon this process.  With this knowledge, students, teachers, and parents can co-construct meaningful, productive action through activities and future endeavors.

Key concepts:   photosynthesis, deforestation, non-renewable sources of energy, greenhouse gas, organelles, chloroplasts, chlorophyll, stomata, absorb, carbon dioxide, transpiration

Research based:   Sociocultural theory with an emphasis on co-constructing knowledge and negotiating meaning using  Wells (1999, 2002, 2010) model, ‘Spiral of learning and teaching through inquiry ’.

Materials:  Internet access, books, articles, pen, colored pencils, crayons, markers, and recycled paper.

Common Core Standards:

English Language Arts Standards:

Vocabulary Acquisition and Use:

CCSS.ELA-Literacy.L.3.4c (third) Use a known root word as a clue to the meaning of an unknown word with the same root (e.g., company, companion).

CCSS.ELA-Literacy.L.4.4b (fourth) Use common, grade-appropriate Greek and Latin affixes and roots as clues to the meaning of a word (e.g., telegraph, photograph, autograph).

CCSS.ELA-Literacy.L.5.4b (fifth) Use common, grade-appropriate Greek and Latin affixes and roots as clues to the meaning of a word (e.g., photograph, photosynthesis).

Next Generation Science Standards (NGSS):

Disciplinary Core Idea Progression:

Earth Space Science Progression (ESS3.A): Energy and fuels humans use are derived from natural sources and their use affects the environment.  Some resources are renewable over time, others are not. 

Life Science Progression (LS1.C): Food provides animals with the materials and energy they need for body repair, growth, warmth, and motion.  Plants acquire material for growth chiefly from air, water, and process matter and obtain energy from sunlight, which is used to maintain conditions necessary for survival. 

Physical Science Progression (PS3.D): Energy can be “produced,” “used,” or “released” by converting stored energy.  Plants capture energy from sunlight, which can later be used as fuel or food. 

Wells’ model,   “Spiral of learning and teaching through inquiry,” in action:

I.  Tapping into students’ prior knowledge and experiences:

Pre-assessment:   (Use pdf)

• When you think of the sun, what do you think of?
• What are some fun experiences you have with the sun?  Share them with a peer in class.
• Do you think the sun is important?  If so, why?  If not, explain why?
• Do you think we could live without the sun?  Why, or why not?  (Explain your answer.)
• When you look at the word  photosynthesis , can you see the prefix  photo ?
• Do you know what  photo  means?  Can you make a guess?
• Can you see another word within  photosynthesis ?  Can you see the root word  synthesis ?
• Do you know what  synthesis  means?  Can you make a guess?
• Now that you have examined the prefix ( photo ) and the root word ( synthesis ), can you make a guess as to what photosynthesis means?
• What do you think photosynthesis relates to?  In other words, this word relates to ______________________________________________________________?
• Can you describe the process of photosynthesis?  What happens?  (Draw a picture also to explain your answer)
• Do you think the process of photosynthesis is important?  Why or why not?

Then, use the pre-assessment questions to open up a dialogue about what students know about photosynthesis and the importance of the sun to our planet.  Allow students to share their knowledge and experiences in pairs, small groups, and whole class.  Both you and the students can write the word photosynthesis on the whiteboard or Smart-board and examine the word and its parts together.

II. Gathering information:

Students can seek information in books, articles, the Internet, consulting an expert, etc., on photosynthesis.  Allow students time to gather information to answer the questions in the  Student Photosynthesis Worksheet  (pdf).

III. Co-constructing knowledge together:

Note:  Allow students time to share their information from their  Students Photosynthesis   Worksheet  with you.  You can use the  Teacher Information Sheet  (pdf) to supplement their information.

IV. Understanding:

Demonstrating understanding through post-assessment and activities (see activities at the end of lesson):

Post-assessment:   (Use pdf)

• Do you think we could live without the sun?  Why, or why not?  (Explain your answer)

Activities:

1. photosynthesis mobile, 2. rainforest food web, 3. food and exercise, 4. sun or tree metaphor, 5. impressionism.

Credit: All content created by Lisa Algee. You can contact Lisa at algeelisa[at]gmail.com 

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5th Grade Lesson Plan on Photosynthesis

The complex chemical processes involved in photosynthesis can keep college students up all night studying for botany exams. Lucky for fifth-graders, the National Next Generation Science Standards do not include details of the chemical reaction for photosynthesis at this time. The main concepts fifth-graders should understand are: energy is needed to change things, energy released from food once was energy captured from the sun by plants, and plants acquire what they need to grow from air and water in reactions powered by the sun.

Energy Changes Things

Students by the fifth grade may or may not have learned about chemical changes. If not, don't worry. The basic goal is to recognize that energy can cause change. Strike a match and watch it burn or put a radiometer in a sunny spot and watch it spin. Slowly pour egg whites into a beaker of boiling water and watch the clear, slippery liquid become a white solid; it changes. Ask students, “What was the energy needed to make that change?” After seeing many examples of how energy is necessary for any change, students will see that plants making their own food is just one of many amazing chemical changes going on around us every day.

Tracing it Back to Plants

All food we eat, from the burger to the bun, can be traced back to plants. Since plants get energy from the sun to build the molecules they are made of, all energy we have originated from the sun's energy. Help students grasp this concept by making simple food chains that can be displayed in the classroom. On blue index cards, write a popular food product. On white index cards, write each intermediate step -- with the name of the plant written in green. Finish with "Sun" on the final, yellow index card. Have students draw simple pictures of each on the card. Attach the cards with red arrows and display in your room. For example, Sun-->>Corn-->>Chicken; Sun-->>Wheat-->>Bread; Sun-->>Rice.

Photosynthesis Play: Act One

Buy five large T-shirts from a craft store which will serve as costumes for student actors in the photosynthesis play. Write "Sun" on the yellow shirt, "Water" on the blue shirt, "Carbon Dioxide" on the black shirt, "Oxygen" on the white shirt and "Sugar" on the green shirt. Draw a plant on the front of a large cardboard box. This will act as a photosynthesis machine. Turn the box so the open side faces away from the class. Stand behind the box. The student acting as Water will place blue paper circles into the box, and the student playing Carbon Dioxide will deposit black squares in the box. A narrator describes where the materials are obtained -- water from rain and carbon dioxide from air -- and continues explaining the process throughout the play.

Photosynthesis Play: Act 2

Your hands are hidden in the back of the box. When the student in yellow playing the Sun shines a flashlight on the box, you toss the products you have hidden inside -- oxygen and sugar-- out the other side of the box. Oxygen can be represented by white squares and sugar by small green triangles. The student playing Sugar picks up the green papers and the student playing Oxygen picks up the white papers and both place them into their own clear containers. The process keeps going as long as the carbon dioxide and water are being put into the side of the box and the flashlight sun is shining. In groups, glue pieces of green "sugar" paper pieces into the shape of a plant to demonstrate that plants are made of materials built in photosynthesis. Students then make a diagram to summarize the process of photosynthesis as demonstrated in the play.

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With degrees in biology and education, Jennifer VanBuren now utilizes her research and instructional skills as a writer. She has served as educational columnist for "Austin Family Magazine" for four years and also reports on area businesses for "Faces and Places" magazine.

INFOGRAPHIC

Photosynthesis.

Learn about the process that plants, algae, and some bacteria use to make their own food and the oxygen we breathe.

Biology, Ecology

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October 19, 2023

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Photosynthesis

Photosynthesis for kids - learn all about photosynthesis, what is photosynthesis.

Photosynthesis = “Photo” + “Synthesis”. “Photo” which means light, “Synthesis” which means putting together.

Just think, plants cannot move, but they need food to survive and grow. But how do they manage their food or who helps them?

The answer is, plants are the most independent living thing on earth. They make their own food without any help from people.

Plants use sunlight, water, CO2 ( carbon dioxide i.e. present in air) to make their food. And this process of making food is called. photosynthesis . Now we will explore more about photosynthesis for kids.

✍ How Photosynthesis Works Step by Step?

Let’s explore how photosynthesis works step by step. For photosynthesis, plants need 3 essential things.  Water and Minerals CO2 (Carbon Dioxide) Sunlight Step 1 -The root of the plant takes water and minerals from the soil . There are veins in the plant named Xylem , transport water and minerals to the whole plant, including its leaves.

The leaves are the food factory of the plant. Because the photosynthesis process takes place in the leaves of plants. So, every necessary thing needs to reach the leaves to make food .

Step 2 – Carbon dioxide (CO2) from the air enters through tiny pores (holes) in the leaves. These pores are called stomata.

We can say that plants also breathe like us through stomata. The only difference is, we breathe in oxygen and breathe out carbon dioxide but plants breathe in carbon dioxide and breathe out oxygen. What a fantastic understanding between us and plants!!

Step 3 – The leaves are basically made of tiny cells . If we see the structure of Plant Cells , we will find that inside these cells there is a small part called chloroplasts . Each chloroplast contains a green substance called Chlorophyll , which actually absorbs energy from sunlight.

Did you know? Chlorophyll is the substance that gives leaves their green color. 

✍ What Happens During Photosynthesis Step by Step?

Let’s understand what happens during photosynthesis step by step.

The plant needs to make Glucose or Food. For that they need two ingredients; Hydrogen and Carbon dioxide .

• First , Chlorophyll absorbs energy from sunlight.
• Second , roots transport water (H2O) to the leaves. [H2O is the molecular structure of the water. Two Hydrogen and One Oxygen.] Plants use sunlight energy to separate water molecules into hydrogen and oxygen.
• Third – Stomata receives Carbon dioxide (CO2) from the air.
• Fourth , After a series of chemical reactions, hydrogen and carbon dioxide combined together to produce glucose or food for the plant. After preparing food, there are veins, named Phloem , distributes glucose to all the parts of the plant.
• Fifth , oxygen is released into the air as a waste product, which becomes vital for us.

Chemical structure of photosynthesis

✍ Some Photosynthesis Facts 

FACT #1. The energy for photosynthesis comes from light.

FACT #2. During photosynthesis, plants use sunlight, water, carbon dioxide to make their food. 

FACT #3. Light energy is converted to chemical energy by chlorophyll.

FACT #4. The green color of leaves is due to chlorophyll.

FACT #5. Leaves change color in autumn because plants slow down the process of photosynthesis

FACT #6. Plants perform photosynthesis in organelles called chloroplasts. There are two parts of chloroplast i.e. grana and stroma

FACT #7. Only plants do not use photosynthesis. Rather some bacteria, such as cyanobacteria, and proteases, such as algae, are also producers. These single-celled organisms also contain chlorophyll.

FACT #8. All living things on this planet depend on organic molecules synthesized by plants as a result of photosynthesis.

In Conclusion,  

• Photosynthesis means “Photo” (means light) and “Synthesis” ( means putting together.)
• The process of making food by plant is called photosynthesis . 
• During photosynthesis, plants use sunlight, water, CO2 ( carbon dioxide i.e. present in air) to make their food. 
• The leaves are the food factory of the plant.
• Chlorophyll absorbs energy from sunlight.
• Stomata receives Carbon dioxide (CO2) from the air.
• After preparing food, Phloem distributes glucose (food) to all the parts of the plant.

I hope you understand the topic of photosynthesis for kids. Don’t forget to attempt a photosynthesis quiz for kids to check your knowledge. V isit here to know more about photosynthesis for kids.

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• Photosynthesis for Kids

What is Photosynthesis?

Have you ever wondered where plants get food? Well, it is through the process of photosynthesis. So, what is photosynthesis? Let’s find out! Due to the fact that sunlight is energy, photosynthesis is the process through which plants convert carbon dioxide and water into food. Plant cells contain elements called chloroplasts. These structures serve as homes for the chlorophyll. The terms "photo" and "synthesis" combine to form the phrase "photosynthesis." Light is referred to as "photo" whereas production is referred to as "synthesis," i.e., making food while being exposed to light.

Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. Chlorophyll, which is typically found in leaves of green plants, is present in all such plants. Plants take up both carbon dioxide from the air and water from the soil. Photosynthesis is started by chlorophyll absorbing sun energy. Green plants use this light energy to transform water and carbon dioxide into oxygen and nutrients that contain sugar. After using some of the sugars, the plants store the rest. There is oxygen present in the air. This will clear your thoughts on what photosynthesis is .

The Process of Photosynthesis

Photosynthesis is a very important process. It is the process through which plants make food and release oxygen that sustains life on earth. The process of photosynthesis is divided into two basic stages. The chloroplasts in the first stage absorb sunlight, and the energy is then stored in a substance called ATP. In the second stage, sugar and organic chemicals are produced using ATP. Plants require these foods to survive and develop.

Sunlight is necessary for the first stage of the process, while the second stage can take place at night or even without it. Since scientist Melvin Calvin discovered and documented the second phase, it is known as the Calvin Cycle.

Calvin Cycle

Although all plants require water and sunlight to survive, the amounts required vary depending on the species. While some plants just require a little water, some require a lot. While some plants like the shade, others enjoy spending the entire day in direct sunlight. Knowing what a plant needs to survive will help you decide where to place it in your yard and how much water it needs to survive. This is how the process of photosynthesis works.

The following image represents the photosynthesis diagram :

Process of Photosynthesis

How Do Plants Breathe?

To survive, plants require three essential elements: water, sunshine and carbon dioxide. Similar to how humans breathe oxygen, plants also breathe carbon dioxide. Plants exhale oxygen after taking in carbon dioxide. On earth, plants are the main source of oxygen, which keeps us alive.

As plants breathe in carbon dioxide, receive water from rain, and utilise sunlight as a source of energy, the process of photosynthesis occurs and we get food, clear air and fresh oxygen to breathe. Photosynthesis is the process of turning these three essential elements into meals.

Where Does Photosynthesis Take Place?

Photosynthesis takes place in chloroplasts. Chloroplasts are unique structures found only in plants. Chlorophyll, the most significant pigment that powers photosynthesis, is present in it. A double membrane that includes an inner membrane known as the thylakoid membrane encircles the chloroplasts. It creates lengthy folds inside the cell.

We now understand that plants require carbon dioxide, water, and sunlight to survive. These three elements are taken by them, and chlorophyll aids in their transformation into food, which they use for energy, and oxygen, which they exhale and which we use to survive. Since photosynthesis is a process used by all plants, sunlight is required.

Since practically all living creatures rely on plants for food, photosynthesis is crucial. The oxygen produced by photosynthesis is another reason for its significance. Animals and humans alike depend on oxygen for survival. Other than plants, other living creatures also produce their own food through photosynthesis. Some varieties of bacteria and algae are among them.

FAQs on Photosynthesis for Kids

1. Do plants perform photosynthesis at night?

No, photosynthesis is not carried out at night by plants. Only when exposed to artificial light with the appropriate wavelengths can plants carry out photosynthesis at night. With the aid of the light-absorbing pigment chlorophyll, light energy is transformed into chemical energy during photosynthesis.  Both the light reaction and the dark reaction, often known as the biosynthetic phase, occur during photosynthesis. The Calvin cycle is used in the dark reaction to create sugar. It also indirectly depends on light since ATP and NADPH generated during the light reaction are used to synthesise sugar during the dark reaction.

2. How does understanding photosynthesis aid farmers in producing more food?

Three components are known to influence photosynthesis, according to scientists. These are:

The air's carbon dioxide content

Temperature

In a field, farmers can't really manage these variables, but if the plant is cultivated in a greenhouse, they can. Additionally, plants require minerals, which they obtain from the soil. Farmers can make sure the plant is grown in the proper soil type to ensure a healthy growth. Through microscopic openings called stomata, carbon dioxide is sucked into the plant. Oxygen, which we need to breathe, is likewise expelled by stomates. Through its roots, the plant takes up water. All of our food is produced through photosynthesis.

3. What would happen if photosynthesis was not carried out by plants?

The majority of creatures would vanish, there would be massive food shortage or other organic stuff on earth. Moreover, the atmosphere would ultimately be almost barren of gaseous oxygen if photosynthesis stopped.

Photosynthesis Lesson Plans for 5th Grade

• Lynn-nore Chittom
• Categories : Lesson plans & worksheets for grades 3 to 5
• Tags : Teaching grades pre k to 5

Breaking Down Photosynthesis

Photosynthesis is the big name for the process by which plants convert energy from sunlight into energy for food. This process also requires water and carbon dioxide. Plants are able to absorb rain water through their roots and receive carbon dioxide from the air through their leaves. The carbon dioxide is in the air as a result of the air that animals, including humans, breath out. Plants are able to store these chemicals in their leaves.

Plant leaf cells are unique in that they also contain special components called chloroplasts. Chloroplasts are filled with a green substance called chlorophyll. It is this substance which gives plant leaves their green appearance and enables them to absorb sunlight. When plant cells have water, carbon dioxide and sunlight the chemical process of photosynthesis occurs. When this happens the water, carbon dioxide and sunlight join together to form a sugar called glucose, plus water, and oxygen. In this form the plants can use the glucose,and water for food and release the oxygen back into the air for consumption by animals, including humans.

Teaching Kids the Basics

While many 5th Grade science text books include chapters on plant cells and the process of photosynthesis, extra resources are always useful for creative educators. Here are a few websites that offer additional teacher resources for 5th Grade photosynthesis lesson plans.

• Plant Cell Diagram – this site includes a well-labeled diagram of the plant cell
• Photosynthesis – this site includes information on the process of photosynthesis as well as multiple diagrams of leaf structures
• Plant Cell Anatomy - this site includes both a labeled diagram and a glossary of terms

Finding the Fun in Photosynthesis

Teaching photosynthesis does not have to be a dry, boring lecture and flat pictures in a text-book. In fact, it is one of the easiest lessons to transform into a kinesthetic learning experience , a science experiment or an art lesson. Through these activities every learning style will have an opportunity to truly understand the process of photosynthesis .

Dramatic Photosynthesis – Each student assumes a role in the process of photosynthesis. The rolls are: the sun, the plant, water, carbon dioxide, energy, sugar and a narrator. The sun shines in the center of the room. Plants are surrounded by energy, water and carbon dioxide which walk around them and then sit down. Sugar and oxygen then take a turn to walk around the plants. The narrator describes the process as it happens. Animals can also be included giving off carbon dioxide and receiving oxygen. The students might wish to repeat the process over and over to show how the relationship continues.

Science Experiment – Plants can be observed in various amounts of light to show the effects of light on plant growth. Plants grown in darkness will die. Plants with much light will thrive because of the process of photosynthesis.

PHOTO synthesis -- Students can draw the process of photosynthesis taking effort to include every element of the process.

Why Photosynthesis Matters?

Fifth Grade photosynthesis lesson plans would not be complete without an emphasis on the significance of photosynthesis for the entire population of the world’s plants and animals. Without photosynthesis plants would not produce oxygen. Without oxygen to breathe animals could not live. Without animals plants would not receive carbon dioxide. Likewise neither could exist without sunlight and water. Fifth graders should learn from this lesson that photosynthesis is the backbone of the most basic and necessary relationship on earth.

How to Teach Photosynthesis to Fourth and Fifth Grade Kids

Yes, you can teach photosynthesis so kids understand it. Keep it macro! First, roots pull in water. Second, leaves take in carbon dioxide. Then energy from the Sun causes a chemical reaction, and glucose is formed. A variety of fourth and fifth grade science standards support conceptualization of this important process.

Mr. Grow Prepares to Teach Photosynthesis

Our favorite fourth grade teacher, Ms. Sneed sat at the side table with her former student teacher. “As you prepare to teach fifth grade,” she said to Mr. Grow, “it’s important to understand the role of photosynthesis in life science standards. It’s all about making connections .”

Begin with Plant Structures and Functions

Ms. Sneed opened her laptop. Then she positioned it so Mr. Grow could see. “If you remember, fourth grade students explore plant structures and functions .” She pointed to the plant unit on the screen.

“Right. Roots take in water and stems transport it. In my class, kids explored plant parts with hands-on activities. And actually, we did touch on photosynthesis a bit. That function occurred in leaves .”

“Exactly. And if you think about it, most plant structures support one key process: photosynthesis.”

Mr. Grow wrinkled his brow. “Hmm, I never thought of that.” Then he smiled. “I guess that’s an important point to make with my students.”

Ms. Sneed nodded. “Yep. You’ve made your first curricular connection. For those of us teaching the Next Generation Science, these activities support NGSS 4-LS1-1.”

Use Hydroponics to Show That Photosynthesis Only Requires Air and Water

Ms. Sneed clicked away on her device. Soon, a hydroponics unit appeared on the screen. “In fifth grade,” she said, “you’ll teach NGSS 5-LS1-1. To address it, kids need to ‘support an argument that plants get the materials they need for growth chiefly from air and water.’ Basically, it boils down to hydroponics . I’m sure your students will enjoy these activities.

“First, kids germinate seeds in baggies. Then they take it a little farther with a hydroponics STEM challenge .”

Mr. Grow scratched his head. “I get it,” he said. “More photosynthesis. Obviously, air and water are the ingredients needed for photosynthesis.”

The mentor teacher’s eyes twinkled. “Right,” and as the teacher, you will help kids make the connections.”

Remember, Photosynthesis Is a Chemical Change

Next, she opened a matter unit . “Here,” she explained, “chemistry meets biology. The connection, however, is not so obvious. As your kids move through these physical science activities , they’ll learn all about matter. For NGSS 5-PS1-4, they develop particle models . Then, for 5-PS1-2, they explore all kinds of changes, as well as conservation of mass . In NGSS 5-PS1-3, they explore properties of matter .

“But the most important link to photosynthesis is NGSS 5-PS1-4: ‘Conduct an investigation to determine whether the mixing of two or more substances results in new substances.'”

“Ahh, chemical change .”

“Right. Clearly, you should teach matter before photosynthesis. That way, you can make connections.”

“Because photosynthesis is a chemical change.”

Ms. Sneed nodded in agreement.

Photosynthesis Is Necessary Part of the Food Chain

“Next, let’s talk about energy. In fourth grade, kids spend lots of time on forms of energy . Most of their exploration, however, focuses on kinetic energy.”

“I remember,” said Mr. Grow. “Sound, light, heat, and electricity.”

“Yes, and also motion.”

Mr. Grow nodded but looked a little puzzled. He wasn’t sure where she was going with this.

“In fifth grade,” his mentor continued, “you’ll teach potential energy. Specifically, the chemical energy stored in plants.”

The mentee’s face brightened. Then he shook his head. “Never in a million years,” he said, “would I have made that connection. You’re giving me such great ideas for reviewing fourth grade standards. Not only that, I can actually connect prior learning to fifth grade concepts.”

Ms. Sneed chuckled. “Yup. That’s the idea.”

On the laptop, she now opened a food chain resource . “For NGSS 5-PS3-1, kids must describe how energy for animals’ food originally came from the Sun.”

Mr. Grow pointed to the screen. “I see. Knowledge of photosynthesis helps kids understand food chains .”

“Right again. First, students explore producers, consumers, and decomposers. But ultimately, they will explain how the energy flows from the Sun to plants to animals.”

Energy from the Sun Moves Through Ecosystems

After a little more searching, Ms. Sneed pulled up an ecosystems unit . “This set of resources teaches NGSS 5-LS2-1. While it deals with the movement of matter, you can also make connections here. Not only does photosynthesis power individual food chains, it also flows through entire ecosystems .”

Ms. Sneed referred to her standards document. “Additionally, photosynthesis plays a big part in interactions between Earth’s spheres . Kids need to understand it for NGSS 5-ESS2-1. First, water from the hydrosphere enters a plant through its roots. Simultaneously, carbon dioxide from the atmosphere enters leaves. Then, through a chemical reaction, energy from the Sun converts them to glucose. Voila! Food for the entire biosphere is formed.”

In Fourth and Fifth Grades, the Cellular Level Is Optional

Mr. Grow sat back in his chair. “What about cells?” he asked.

“Well, that’s a tough one. While the standards don’t address the cellular level until middle school, I still like to introduce them. Nothing elaborate, though. As a matter of fact, we do only a tiny bit of microscope work and an introduction to organelles .”

“Yeah, a little knowledge of chloroplasts makes one more connection. But I’ll consider cells to be optional.”

Connections = Effective Teaching

“Let’s review,” said Ms. Sneed.

In fourth grade, we teach kids about plant structures. Basically, all functions directly support photosynthesis. In fifth grade, understanding that plants mainly need air and water reinforces that. Then kids learn about chemical changes. And what’s the most important chemical change? Furthermore, fourth grade standards focus on transfer of energy. Then in fifth, you’ll teach them how the Sun transfers light energy to plants. And ultimately, that energy fuels all life in every ecosystem.”

“Wow,” said Mr. Grow, “as a new teacher, I never would have made all of these connections. This background information will allow me to teach so much more effectively.”

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Lesson Plan on Photosynthesis

How do plants get energy, developed by chantier 7 project team members.

Instructional goals: 

Students will be able to: 1. Describe the phenomena of transpiration, photosynthesis and cellular respiration 2. Illustrate the relationship between light and photosynthesis (i.e., you need light source for plants to grow; more light more photosynthesis)   3. Illustrate the relationship between carbon dioxide and photosynthesis 4. Gather evidence of inputs and outputs of photosynthesis     

Grade level: Grade 7, 8

Duration: 50-150 minutes depending on activities chosen (3-4 periods of 75 minutes)

Instructional Materials: Whiteboard (or smart board, black board) for creating public record for students’ thinking. For the materials needed for specific activities, please see below:

Activity #1: An Oxygen Factory

Plants (both aquatic and terrestrial plants) Plastic bag or plastic wrap Terrarium or 2L plastic bottle Flask 500ml or 1L beaker Water Desk Lamp

Activity #2: Light! Light! (Optional)

Any submersed aquatic plant that is in good health and appears capable of photosynthetic activity (i.e., not dried or wilted). (e.g.,  Canadian waterweed (Elodea canadensis) or coontail (Ceratophyllum demersum)) – you can buy waterweed from any pet store where they sell fish/aquarium supplies Glass test tubes (20 × 150 mm) Racks to hold test tubes A light source (e.g., desk lamp) Large to medium sized drinking straws Thermometer

Activity #3: More Carbon Dioxide (Optional)

Elodea, an aquatic plant available at many pet or gardening stores Bromothymol blue solution (acid-base indicator available for purchase online.  Yellow pH less than 6.0, blue pH above 7.6) Lights with clamp attachment Test tubes (one for each color and two additional as controls) Plastic wrap Aluminum foil

Worksheet: Please see appendices.

QEP POLs for secondary cycle 1 relevant to the concept of photosynthesis:

Elementary school:

Students explain the essential needs of living organisms (e.g. food, respiration) and describe metabolic activity (transformation of energy, growth, maintenance of systems and body temperature). They describe the function of photosynthesis, which they distinguish from respiration.

Secondary cycle 1:

​​Names the inputs and outputs involved in photosynthesis. Names the inputs and outputs involved in respiration.

Children’s preconceptions relevant to the concept of photosynthesis:

There is no difference between respiration and breathing. The main component of air is oxygen. There is no oxygen in exhaled air. Lighting a candle in a sealed jar with water proves that air is 21% oxygen (the water moves up the jar because the 21 % oxygen is consumed). All essential components for plants are absorbed from the soil via rots. Roots supply plants with energy. The sun keeps plants warm, and so they grow better. Plants breath. They inhale carbon dioxide, and they exhale oxygen. Plants get energy directly from the sun.

(Adapted from: https://scienceinquirer.wikispaces.com/file/view/RespirationCorr.pdf )

Assessment Items to explore or uncover students’ preconceptions around the concept of photosynthesis:

Question 1. Which of the following is TRUE about the sugar molecules in plants? A. The sugar molecules come from the soil. B. The sugar molecules are the result of a chemical reaction. C. The sugar molecules are one of many sources of food for plants. D. The sugar molecules are made from molecules of water and minerals.

(Retrieved from AAAS Item ME095005, http://assessment.aaas.org/items/ME095005#/0 )

Question 2. Where does the food that a plant needs come from? A. The food comes in from the soil through the plant’s roots. B. The food comes in from the air through the plant’s leaves. C. The plant makes its food from carbon dioxide and water. D. The plant makes its food from minerals and water.

  (Retrieved from AAAS Item ME029006, http://assessment.aaas.org/items/ME029006#/0 )

Questiom 3. What is TRUE about the inside of a plant cell? A. The inside of a plant cell is completely solid. B. The inside of a plant cell is completely filled with air. C. The inside of a plant cell is completely filled with liquid water. D. The inside of a plant cell contains liquid water and solid structures.

(Retrieved from AAAS Item CE065001, http://assessment.aaas.org/items/CE065001#/0 )

Description of the Lesson:

The goal of this lesson is for students to (1) engage in experiments that enable students to gather evidence of inputs and outputs of photosynthesis, (2) understand the relationship between light and photosynthesis, and (3) understand the relationship between carbon dioxide and photosynthesis. This lesson plan includes the following steps:

Step 1: Introduction – Engage Students in Learning : In this step, teacher introduces the driving question of this lesson: “ Plants need energy to stay alive and grow. How do you think plants get energy? ”

Step 2: Background Knowledge Probes (BKPs) : In this step, teacher use the assessments listed above to elicit students’ prior understanding and ideas of photosynthesis.

Step 3: Collecting and Making Sense of Data : In this step, teacher will conduct the Activity #1 – An Oxygen Factory . Teachers will then choose one of the option activities (i.e., Activity Option #2 – Light! Light! or Activity Option #3 – Role of Carbon Dioxide and Light ) to provide students with more evidences for the upcoming discussion at the end of the lesson. While students are engaging in these activities, teacher can ask discussion questions to track students’ understanding of the concept. Students are also invited to record their observation on the worksheet given.

Step 4: Developing Evidence-Based Explanations : Following the activities, teacher engages in this step by inviting students to share their data with other groups and the whole class. Teacher may also post summary data on a class summary chart on the board.

Step 5: Evaluation : Teacher can assess students’ learning outcomes by choosing one of the post-assessment strategies: (1) Question and Answer/Exit Cards; (2) Create a multimedia poster; (3) Using the assessment questions listed above.

Details and procedures of each step are explained as follow:

Step 1 of The Lesson: Introduction – Engage Students in Learning

In Step 1, teacher will help students to connect the idea of food-web with photosynthesis. The goal of this step is to introduce the important role of photosynthesis plays in our ecosystem.

(1)  Introduction of the topic by saying: “ Hello, we are going to learn about photosynthesis today. Before starting the lesson, does there anyone know where plants get their energy from? ”

(2)  Teacher can prepare a feed-web (see Figure 1.) on transparency, doc cam, computer screen, or draw the figure on the board. Teacher can than ask the following questions to guide the discussion:

• All living things need energy to survive. How do us, human get energy?
• From this food-web figure (Figure 1), how do fox and rabbits gain their energy from?
• From this food-web figure (Figure 1), how do grass and trees gain their energy from? Do grass and trees ‘eat’ any other organisms?

(3)  Based on students’ response, teacher can re-voice students’ responses and write the responses on the board.

(4)  After students sharing their ideas about food-web, teacher can begin the class by introducing the driving question of this lesson: “ Plants need energy to stay alive and grow. How do you think plants get energy? ”

Step 2 of The Lesson: Background Knowledge Probes (BKPs) - Eliciting Student Thinking

The goal of this step is to elicit students’ prior understanding and ideas of the topic without evaluating their response or correcting their answers at this point.

(1)  Administer the instrument: To help teachers determine effective starting points for the students and to get to know students’ background knowledge, skills, attitudes, experience and motivation, before starting the lesson, you can administer the 3 assessment question provided above, in order to uncover students’ preconceptions around the concept of photosynthesis.

Teacher can use clickers to obtain students’ responses. If the school does not have clickers, teacher can ask the questions to the whole class and ask students to raise their hands for the answer. If there is no answer from students, teachers can also ask students to write their answer on a piece of paper and put them in a box. Teacher will then write some response on a board (or a chart paper) for discussion.

(2)  Pressing for explanations: After administering the test, teacher can share the data with students and ask students for the explanations. You may re-voice their explanations and write their response on a board. For example, teacher can ask: “ We see that many of you choose option C as an answer. Does anybody want to share why they chose option C? What is your evidence for saying that? ”

(3)  Introducing the term : Teacher can use the term “photosynthesis” to further probe students’ prior understanding. Teacher will then start the lesson by asking students what they think “photosynthesis” means and write down their responses on the board (or a chart paper).

Step 3 of the Lesson: Collecting and Making Sense of Data

The goal of this step is to help students to (1) develop their questions and/or predictions to learn more about the topic, and (2) test their predictions through hands-on inquiries, challenges, problems.

Teacher will first conduct the Activity #1 – An Oxygen Factory . Afterward, teachers can choose one of the option activities (i.e., Activity Option #2 – Light! Light! or Activity Option #3 – Role of Carbon Dioxide and Light ) to provide students with more evidences for the upcoming discussion at the end of the lesson. These optional activities could help teacher to engage in ongoing, formative assessments to track students’ learning (e.g., walking around class to listen to their ideas, recording and displaying their ideas, observations, worksheets, student journals, students’ work products, etc.).

Details and procedures of each activity are explained as follow:

Part 1: Preparation: Teacher will have two different demo stations (i.e., Demo Station #1– Photosynthesis of an aquatic plant and Demo Station #2– Growth factors of a plant ) prepared at least three days prior to the activity. Both teachers and students can create the demo stations.

Demo Station #1: Photosynthesis of an aquatic plant:

(1)  Place a submersed aquatic plant (e.g., Canadian waterweed (Elodea canadensis) or coontail (Ceratophyllum demersum) in a flask. (2)  Fill a 500mL or 1L beaker with water. (3)  Place the flask (with aquatic plants) into the beaker. Make sure that the aquatic plants are submerged in water. (4)  Place a light source (e.g., desk lamp) near the beaker.

Demo Station #2: Growth factors of a plant:

(1)  Prepare 3 different pots of plants that are the same size (relevantly same size). (2)  Prepare 3 terrariums (or 2 Liter soft drink bottles with the top cut off and saved for lid) with soil and 1 plant. (3)  Terrarium 1: Add some oxygen gas, and seal the terrarium (or bottle lid). Label the terrarium. Note: If you do not have access to oxygen gas, just seal the terrarium. Make sure the plant had been in a closed system at least for 3 days. (4)  Terrarium 2: Add some carbon dioxide gas, and seal the terrarium (or lid for the bottle.) Label the terrarium. Note: If you do not have access to carbon dioxide gas, place alkalizer in water, in an erlenmyer flask with a one-hole stopper, an elbow tube and glass tubing. Insert the tubing into the lid of the terrarium as the carbon dioxide is being produced). (5)  Terrarium 3: The third terrarium is a control. Leave the plant in an unsealed terrarium.

Part 2: Observation: Students observe the plants at the two demo stations (i.e., Demo Station #1– Photosynthesis of an aquatic plant and Demo Station #2– Growth factors of a plant ). Teacher can ask questions to elicit students’ ideas.

For example, for the Demo Station #1 , teacher can ask the follow questions:

• What do you think is being produced in the flask?
• What is the evidence for this: Oxygen is being produced.
• The flask is foggy Inside. Why? ”

For the Demo Station #2 , teacher can ask the follow questions:

• What do you observe in the three terrariums?
• Where do you think the bubble comes from in the second terrarium?
• What gas do you think the bubbles are?
• What is happening in the third terrarium? Explain.
• What differences do you see between the first and second terrarium? ”

Part 3: Recording observation: Teacher will ask students to observe the three different terrariums and write down their observation on their worksheet (Appendix A). Note: The following Activity #2 and #3 are optional. These optional activities would allow teachers to help students collect more evidence/data for the final discussions at the end of the lesson.

Step 4 of the Lesson: Developing Evidence-Based Explanations

The goal of this step is to help students in changing their preconceptions through developing complex evidence-based explanations after their investigations in light of the data they gathered in the above activities. Teacher can ask students to share their data with other groups. Teacher may also post summary data on a class summary chart on the board.

(1)  Divide students into groups. (Groups of 2-3). Ask students to answer the questions on the worksheet (Appendix B). For example:

• Where does the water that appears on the side of the terrariums (Activity 1 – An Oxygen Factory) come from?
• Which conditions are necessary for bubbles to appear in the water (Activity 2 – Light! Light!)?
• Which gas in the atmosphere encourages plant growth?

Facilitate the discussion as teacher walk around the classroom. Note: The important aspect here is that you allow students to make connection between evidence/data provided from the activities and their explanations for their answer.

(2)  Once students are finished with the worksheet, facilitate a class discussion. Teacher can lead a discussion about the similarities and differences in the group analysis. Note: Teacher may go over the questions with students and have them present their answers and explanations. Or, teacher may ask students to present their data to the rest of class while teacher write down similarities and differences emerging from different groups’ data.

(3)  Go back to the driving question on the board: “ Plants need energy to stay alive and grow. How do you think plants get energy? ” Ask students if their view have changed and ask why. Again, encourage students to draw their explanations from the evidence/data from the activities. Teacher can use the following strategies:

Ø  Orienting students to each other’s thinking: For example, teacher can ask: Do you agree with what Student A said? and Why? Ø  Pressing for explanation : For example, teacher can ask: Group A and B , both of you found results/data that are different than your previous predictions. Why do you think so?

Note: If time allows, you can show your students “photosynthesis song”: this video summarizes the process of photosynthesis, offering visual and musical sources: https://www.youtube.com/watch?v=C1_uez5WX1o https://www.youtube.com/watch?v=C1_uez5WX1o

Step 5 of the Lesson: Evaluation

Three strategies can be used to do a post-assessment; they are:

Option #1: Question and Answer/Exit Cards : Have students to fill out the worksheet page individually (see Appendix). After students fill out most part of the worksheet, ask them to discuss in a small group (3-4 students). Teacher can facilitate the group discussion while walking around the classroom by asking questions such as: “ With regards to Input and its origin: Why do you think so? What evidence do you have from the activities we have done in class? ” After going of worksheet page. 100 together, teacher may give the assessment items tested in the beginning and/or have them write exit cards (i.e., write a short reflection on what they learned and what they still unsure about).

Option #2: Create a multimedia poster: By creating a multimedia poster on what students have learned in lessons, they can draw various ways of representing ideas (e.g., write summaries of the facts, create visual arts, add sound). This will be done as a group project. As a group, students have another opportunity to discuss about their understandings on photosynthesis with their peers in informal ways. Specific steps are describe as follow:

(1)  In a group of 3-4, students will make a multi-media poster. The poster should represent their understanding of photosynthesis using multi-media of their choice (e.g., podcast, songs, YouTube, visual arts etc.). Students can draw from already existing sources (e.g., song from YouTube, pictures from encyclopedia).

(2)  Ask students to connect what they observe in their daily life to the concept of photosynthesis.

(3)  In their everyday life (e.g., home, school garden, or on the way to school), students can take a photo, make a collage, or draw a painting to connect the concept of photosynthesis to a moment in their daily life.

(4)  With the photo/collage/drawing, students are instructed to write a short essay or record a podcast that explains how their photo/collage/drawing (e.g., photos of flowers, collages of cows eating grass, cooking meals) relates to the concept of photosynthesis.

For example, a group of students may write: “ The meals we eat are the products of photosynthesis. Vegetables grow because of photosynthesis. Meat is a product of animals eating producers or other consumers. Energy from photosynthesis is transferred to the consumer. Humans eat both vegetables and meat which are both products of photosynthesis. ”

(5)  Teachers give specific guidelines and rubrics for students to follow. It is important for students to include the following key points in their short essays:

• The process of photosynthesis;
• Inputs and outputs of photosynthesis;
• Factors influencing the photosynthesis and the connection with their daily life experience.

(6)  After the completion of the multimedia posters, class can have a symposium, where students will have an opportunity to present their multimedia posters to other students in the classroom.

Option #3: Assessment question : administer the same question and to see if students’ responses had been change. Teacher can use the clickers to obtain students’ responses. If the school does not have clickers, teacher can ask the questions to the whole class and ask students to raise their hands for the answer. If there is no answer from students, teachers can also ask students to write their answer on a piece of paper and put them in a box. Teacher will then write some response on a board (or a chart paper) for discussion. Note: You may re-voice their explanations and write their response on a board.

This lesson plan is inspired by the following sources: Education.com: http://www.education.com/pdf/photosynthesis-of-elodea/ Eureka!: Science and Technology, Secondary Cycle One; Student Textbook B (Activity 8: An Oxygen Factory, pp. 36-37); Worksheet (U1 38, U1 39); Teaching Resource Guide, Volume 1 (p.53). Ray, A. M., & Beardsley, P. M. (2008). Overcoming student misconceptions about photosynthesis: A model-and inquiry-based approach using aquatic plants. Science Activities: Classroom Projects and Curriculum Ideas , 45 (1), 13–22.

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5.1.1: Overview of Photosynthesis

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

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

CONCEPT IN ACTION

Click the following link to learn more about photosynthesis.

Solar Dependence and Food Production

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

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

BIOLOGY IN ACTION: Photosynthesis at the Grocery Store

Major grocery stores in the United States are organized into departments, such as dairy, meats, produce, bread, cereals, and so forth. Each aisle contains hundreds, if not thousands, of different products for customers to buy and consume (Figure \(\PageIndex{3}\)).

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

Main Structures and Summary of Photosynthesis

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

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

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

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

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

ART CONNECTION

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

The Two Parts of Photosynthesis

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

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

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

Art Connections

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

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

Contributors and Attributions

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

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• 1.1 Vaste stowwe, vloeistowwe en gasse
• 1.2 Verandering van toestand
• 1.3 Die watersiklus
• 2.1 Vastestowwe is orals om ons
• 2.2 Rou en vervaardigde materiale
• 2.3 Eienskappe van materiale
• 2.4 Verskillende materiale vir dieselfde doel
• 3.1 Maniere om materiale te versterk
• 4.1 Stutte en raam strukture
• 4.2 Inheemse strukture
• 1.1 Energie vir lewe
• 1.2 Energie van die Son
• 2.1 Energie
• 2.2 Inset- en uitset-energie
• 3.1 Beweging en musiekinstrumente
• 3.2 Beweging veroorsaak klank
• 3.3 Inheemse musiekinstrumente in Suid-Afrika
• 4.1 Vibrasies en klank
• 4.2 Geraasbesoedeling
• 1.1 Kenmerke van die maan
• 1.2 Die aarde in die ruimte
• 2.1 Die Son is die naaste ster
• 3.1 Beweeg om die son
• 3.2 Die aarde en ander planete
• 3.3 Die Son en lewe
• 4.1 Die Thunderbolt Kids het 'n vuurpyl nodig
• 4.2 Hoe werk vuurpyle?
• 4.3 'n Model van 'n vuurpyl
• 5.1 Kenmerke van die Maan
• 5.2 Die fases van die Maan
• 5.3 Maanstories
• 1.1 Baie verskillende plante en diere
• 1.2 Interafhanklikheid in 'n ekosisteem
• 1.2 Diersoorte
• 2.1 Geraamtes van gewerwelde
• 2.2 Beweging in werweldiere
• 3.1 Strukture
• 4.1 Voedsel en voeding in plante en diere
• 4.2 Voedselkettings
• 5.1 Groei en ontwikkeling
• 5.2 Plantlewensiklusse
• 5.3 Dierelewensiklusse
• 1.1 Eienskappe van metale
• 1.2 Eienskappe van nie-metale
• 2.1 Spesiale eienskappe van metale
• 2.2 Gebruike van metale
• 3.1 Kombineer stowwe
• 4.1 Eienskappe en gebruike
• 4.2 Tradisionele verwerking
• 1.1 Wat is brandstowwe?
• 1.2 Verbrand brandstowwe
• 1.3 Veiligheid by vure
• 2.1 Selle en batterye
• 2.2 Hooflyn-elektrisiteit
• 2.2 Veiligheid en elektrisiteit
• 3.1 Rekke en springe
• 4.1 Wiele en asse
• 1.1 Die Aarde beweeg
• 2.2 Grond kom van rotse
• 2.3 Grondsoorte
• 3.1 Hoe vorm afsettingsgesteentes
• 3.2 Gebruike van afsettingsgesteentes
• 4.1 Fossiele in rots
• 4.2 Liggaams- en spoorfossiele
• 4.3 Belangrikheid van Suid-Afrika se fossiele
• 1.1 Plante en kos
• 1.2 Voedsel uit fotosintese
• 1.3 Plante en lug
• 2.1 Voedselgroepe
• 3.1 'n Gebalanseerde dieet
• 3.2 Siektes veroorsaak deur 'n ongesonde dieet
• 4.1 Hoekom het ons voedselverwerking nodig?
• 4.2 Hoe word voedsel geprosesseer?
• 5.1 Verskillende ekosisteme
• 5.2 Lewende en nie-lewende dinge in ekosisteme
• 5.3 Voedselwebbe
• 1.1 Rangskikking van deeltjies
• 2.1 Mengsels van materiale
• 3.1 Oplossigs
• 3.2 Oplosbare stowwe
• 3.3 Versadigde oplossings
• 4.1 Wat is oplossing?
• 4.2 Tempo van oplossing
• 5.1 Waterbesoedeling
• 5.2 Belangrikheid van vleilande
• 6.1 Skoon water
• 1.1 'n Eenvoudige stroombaane
• 1.2 Stroombaandiagramme
• 2.1 Wat is geleiers en nie-geleiers?
• 2.2 Goeie elektriese geleiers en isolators
• 3.1 Gebruik van elektriese stroombane
• 3.2 Wees 'n elektriese ingenieur of 'n tegnikus
• 4.1 Fossielbrandstof
• 4.2 Koste van elektrisiteit
• 1.1 Die Son, planete en astroïedes
• 2.1 Rotasie (aarde)
• 2.2 Omwenteling (aarde)
• 3.1 Rotasie / draai (maan)
• 3.2 Omwenteling (maan)
• 4.1 Voertuie wat op mars gebruik word
• 4.2 Voertuie wat op die maan gebruik word
• 4.3 Ontwerp en maak 'n voertuig om rotse op die maan te versamel
• 5.1 Teleskope

Photosynthesis

• Why can a plant make its own food but an animal cannot?
• What is needed for photosynthesis to happen?
• How do plants make food and store food?
• Why do plants need so much water?
• Can plants live in the dark?
• Why are plants mostly green?

Teachers are encouraged to make a large circle on the wall using large arrows that can be cut from blue or even black plastic bags. Then cut out white letters to say "Photosynthesis" in the centre of the circle and stick large posters on the arrows to say:

• Plants absorb carbon dioxide
• Plants release oxygen
• Animals breathe in oxygen
• Animals breathe out carbon dioxide

Perhaps cut out pictures of plants or get learners to make plants and animals in Art and stick them next to the specific labels they illustrate. Create a glossary by placing words relating to the topic around the classroom. Tell the learners that they are going to be plant investigators, and that their job is to find out what the words mean, and how they relate to plants and photosynthesis.

When introducing this topic remind them of the work on interdependence they covered in Gr. 5. Discuss how animals and plants are interdependent upon each other - plants produce food and oxygen for animals, while animals - when they die - decay, replacing nutrients in the soil for plants, and releasing carbon into the air to continue the carbon cycle.

Plants and food

Green plants are just like factories! They make food for themselves and every animal on earth using sunlight energy, water and the gas carbon dioxide. They also recycle the air and make oxygen for us to breathe.

Scientists have found out exactly how plants are able to do all all these things. Let's take a closer look at how scientists did this and see how plants make food for themselves and us.

What happens in a factory? Why do you think we can say plants are like factories?

A factory is a place where goods or products are made/assembled/manufactured and then delivered to other places to be used. Plants are therefore like factories as they use raw products to make new products (food).

Plants make food for themselves and plants are the beginning of the food chain, therefore all other animals, whether herbivores which eat plants directly, or carnivores which eat the herbivores, depend on plants for food.

The process of photosynthesis

Photosynthesis is the process that plants use to change the energy from sunlight into energy for food. Plants change light energy from the sun into food energy. Photosynthesis happens in all green parts of a plant. Leaves are usually the greenest parts. So plants do this mostly in their leaves.

There are some important requirements for photosynthesis to happen:

1. Chlorophyll : Chlorophyll is a green substance that plants use to capture light energy from the sun. Chlorophyll is very important. Without chlorophyll plants cannot use the sunlight energy to make food. Also, oxygen levels in the air will go down. If that happens plants and animals will suffocate.

As a fun activity, take learners outside to see if there are other colours found in leaves, and not just the green pigment chlorophyll. Although green chlorophyll is predominant, there are also yellow, orange and purple pigments found in leaves, especially in autumn when the leaves change colour. In the body, the pigment melanin, is the main determinant of skin colour and it is also found in hair and the iris in the eye.

2. Sunlight: Sunlight has energy. Plants use this energy to make sugars from water and carbon dioxide.

3. Water : The roots of a plant absorb water and nutrients from the soil. Water is a solvent in all living things. Dissolved substances are moved around the body to where they are needed. Just like you, plants have veins for this movement. They move minerals from the roots upwards. They move sugars from the leaves downwards. Photosynthesis can only happen in a water solution. Water is also important because it provides support to the plant to keep it upright. Like you, plants have skeletons. But unlike you many plants have water skeletons!

In the second term in Matter and Materials, learners will do more on mixtures, solutions and dissolving, and this will therefore make sense. Refer back to this section when you are doing solutions and discussing water as a solvent.

4. Carbon dioxide: The plant absorbs or takes in carbon dioxide from the air through little holes. These holes are found all over the plant, mostly under the leaves.

5. Soil : The soil provides mineral nutrients and water for the plant that are necessary during photosynthesis. Soil also provides anchorage to the plant, otherwise the plant cannot stand up straight.

A really good website on photosynthesis http://www.realtrees4kids.org/sixeight/letseat.htm

How does photosynthesis occur?

Plants use chlorophyll, sunlight, water and carbon dioxide to make food. Here is a simple illustration to show how this process occurs:

• Chlorophyll captures the sunlight energy.
• This energy splits the water into hydrogen and oxygen.
• The oxygen is released into the air.
• The hydrogen is used with the carbon dioxide to make glucose (sugars).
• The sugars are moved from the leaves to other parts of the plants where they are stored.
• The water in the plant veins carries the sugars. When the sugars reach the storage parts they are changed into starch.
• leaves (cabbage, spinach, lettuce)
• fruit (apples, banana, peaches)
• stem (sugar cane)
• seeds (wheat or mealies)
• flowers (nasturtiums, broccoli and cauliflower)
• roots (carrots or beetroot)

Starch is insoluble in water which is why plants store starch and not glucose, which is soluble in water. Refer back to this section when doing soluble and insoluble substances in the second term.

Dramatise the process of photosynthesis

Prepare beforehand by collecting the different materials needed. The characters need different colours to identify themselves as what they are, possibly some t-shirts that they can pull over their clothes, or else a scarf or ribbon or coloured piece of paper to pin onto their front. You will also need tin foil, glitter and string for the roots. For the animals, you can make masks out of paper plates with the eyes cut out, and tied around the head with a piece of string. Learners can draw animal faces on the front.

INSTRUCTIONS:

• Your teacher will explain to you how to act out the process of photosynthesis.
• Characters needed for this dramatisation:
• Narrator to describe the process. This can be a teacher or a learner. It might be a good idea to make short notes from the information above to remember in what order everything is happening.
• Sun - this learner can dress in yellow and perhaps get some old tin foil or shiny paper to decorate their head or body to show the light and heat energy that the sun produces.
• Plants - a few learners can dress in green and perhaps tie a few strings to their feet to represent roots. They need to hold some rice or shiny glitter in their hands or their pockets to show that the water evaporates after photosynthesis.
• Rain / water - a few learners can dress in blue and perhaps have some rice, shiny glitter, small pieces of tin foil or something similar to represent the rain falling.
• Carbon dioxide - attach signs to the learner's chests that say 'Carbon dioxide' and dress in purple.
• Oxygen - attach signs to the learner's chests that say 'Oxygen' and dress in orange.
• Glucose energy as fruit and vegetables - dress up or make posters from scrap cardboard to show large carrots, apples, potatoes, or something similar.
• Some learners need to be animals who breathe out carbon dioxide and eat the plants. You can make masks out of paper plates with eyes cut out.

The dramatisation: When the dramatisation starts, the glucose and oxygen actors sit quietly in small groups around the plants with their heads down, not looking at the audience.

The narrator introduces the play and explains the different processes as these occur.

The sun shines in the centre of the stage and can turn and/or raise their arms to show the sunlight radiating from it.

The plants stand away from the sun and the rainwater actors can 'water' them by gently throwing the rice or similar little objects over their heads. Then sit down around the plants.

The carbon dioxide actors run from the animals and circle the plants, and then sit down around the plants.

Now the oxygen and glucose actors rise and run around the plants, and then run to the animals to show they are receiving oxygen and food.

You might want to repeat this a few times to show that this cycle continues.

Why do plants die when there is a drought?

There are many processes which shut down without water, photosynthesis being one of them. Plants cannot photosynthesise sunlight without water. If they cannot photosynthesise they cannot create glucose to support life processes within the plant. If the plant cannot support its own life processes it dies. The plant also loses its support from the water in the veins acting as a 'skeleton'.

• Design a poster for your Gr. 4 friends to explain the process of photosynthesis to them. You can use sentences and short paragraphs but make sure you use many illustrations.

Soil was looked at in Gr. 5 Earth and Beyond, especially the particles of soil and which types of soil plants grow best in. However, it would be useful to also emphasise soil in this section and have a discussion on what makes up soil, namely organic and inorganic material, water, air, rocks and sand. Where possible, bring examples of different soil types to class (such as loam soil, clay, beach sand) and get the learners to touch and feel the soil and explore what makes up soil.

Food from photosynthesis

Photosynthesis is the process inside plants that changes the energy from the sun's light into a form of energy that animals can eat and use to carry out their life processes.

Plants changes the glucose into starch, for example mealies (mealies and maize flour), rice (rice flour and rice) and wheat (flour).

Plants then store this food in different parts of the plant that an animal will eat. They can store it in their leaves, stems or roots, flowers, fruits or seeds.

Look at the images below of different plant products. For each image, identify which part of that plant we eat (for example: When we eat an apple, are we eating the leaf, the stem, the root, the fruit or the seed of the plant?) Use the space below to draw a table for your answers.

We know that plants make glucose (a sugar) but they store starch. Let's now find out what the difference is.

Difference between a starch and a sugar

Prepare beforehand: Prepare at least 10 different plant products in advance of this lesson and mark each item from 1 - 10. Cut up fruit/potato/sweets into bite-sized cubes. Place flour/cooked rice/etc. into bowls. Use teaspoons to taste the flour/cooked rice/etc.

IMPORTANT: Before doing this activity find out if any of the learners have any allergies to these foods and if learners with diabetes are allowed to eat/taste the fruit/sweets.

• mealie flour
• cooked rice, potato, bread
• glucose sweets
• sugar cane, if possible
• fresh fruit
• Work in pairs.
• One partner must be blindfolded.
• On a piece of paper list the numbers 1 - 10.
• The other partner must let the blindfolded partner taste each of the foods marked 1 - 10. If it is a flour, use a teaspoon to spoon the flour into your partner's mouth. If it is a kernel like a rice or mealie kernel, or a cube of fruit, put it in the palm of their hand and let them eat it themselves.
• After each taste your blindfolded partner must guess if it is a sugar or a starch based on the taste.
• Record your partners answers on the piece of paper containing the numbers 1 - 10.
• Swap with your partner and repeat the test.

While learners are swapping with their blindfolded partners, rearrange the foods with the numbers to ensure fairness. The aim of the test is not to establish the exact name of the fruits and foods but to establish that taste is not a suitable method to test for sugar or starch. Generally sugars are sweet and starches are not, but not always.

Was it easy to distinguish between the sugar and the starch each time? Which foods did you find difficult to classify?

What can you say about the difference between a starch and a sugar based on taste?

Sugars are sweet, starches are not.

Using TASTE to check if a food is a sugar or a starch is not very reliable.

There is a special test that scientists use to see if a food product is a starch or not. It is called the iodine starch test .

Iodine solution is a special solution that is normally a brown liquid .

Iodine is what we call an indicator .

When iodine solution is dropped on starch, the iodine and starch combine and produce a blue colour. We use this to test whether there is starch in a food product.

Let's see how this works!

The iodine starch test

Note: There will be NO tasting in this activity.

• the same foods used in the taste test (they should be marked 1 - 10 )
• include some other foods such as cheese and a boiled egg
• Write the food or plant product that you chose in the first column below.
• You are going to test whether this food product is a starch or not. When the iodine solution turns blue-black you will know it is a starch.

Explanation for starch turning blue-black when iodine is placed on it: Starch is composed of polymers of glucose. Long linear chains are amylose. Amylose coils into a structure resembling a tube with a hollow core. Certain molecules, including iodine, can lodge inside the core. The complex of iodine stuck inside the amylose coil produces a characteristic blue-black colour. The starch itself is not altered. NB: This explanation is not necessary for learners, but do say that the iodine reacts with the starch to form a blue-black colour.

• Use a dropper and drop iodine solution onto each food group.
• Put a tick next to the food product that turns blue-black - this is a starch. Put a cross next to the food product that stays brown - this is not a starch.

QUESTI ONS:

Which test do you think is more accurate to test for starch - the taste test or the iodine starch test?

Did the animal products, such as cheese and boiled egg, contain starch? Why do you think so?

Animals do not produce or store starch. Starch is only stored in plant products.

Animals do store carbohydrates, but not in the form of starch. Only plants produce and store starch. Animals store glucose in the form of glycogen.

Plants and air

All animals and plants need oxygen to live and carry out their life processes.

Animals breathe in oxygen and breathe out carbon dioxide, all through the day and the night. Oxygen is used to release energy from food inside the body, which is used for the life processes.

Do you remember what the seven life processes of living things are? Write them down below.

Movement, reproducing, sensing, feeding, excreting, breathing, growing.

Just like animals, plants also use oxygen throughout the day and the night. Oxygen is necessary for plant growth and the development of new plants, seeds, leaves and shoots for example. Plants, therefore, also produce carbon dioxide as a 'waste product' once the oxygen has been used.

Plants do not photosynthesise through the night because there is no sunlight energy available to do that. This means that plants only need carbon dioxide during the day, for photosynthesis.

This cycle of using and producing both oxygen and carbon dioxide is very important to life on Earth.

The oxygen and carbon dioxide cycle

• Carefully study the following illustration.
• Answer the questions that follow.

Make a list of living organisms that produce both oxygen and carbon dioxide in this picture.

Tree, reeds, water plants, and shrubs on the bank

Identify three living organisms that cannot produce oxygen in this picture.

Fish, duiker (buck), squirrel, dragonfly

Predict what you think would happen if all the animals were removed from this habitat.

Probably not much would change as the leaves that decay would still give off carbon dioxide for the plants to use, as well as the carbon dioxide that the plants produce themselves.

What two life processes are involved in the carbon dioxide/oxygen cycle?

breathing in oxygen and giving off carbon dioxide

Complete this cycle by filling in the missing information for the two arrows on the left hand side of the illustration. Supply the labels for arrows 1 and 2.

• Arrow 1: Plants produce oxygen
• Arrow 2: Animals breathe out carbon dioxide

Explain why animals would not survive if all the plants on earth were to suddenly die.

• Animals need oxygen for their cells to work and to carry out life processes.
• If animals do not have oxygen they cannot carry out the life processes and will die.
• Plants also produce food from the sun that animals need to eat for energy to carry out the life processes.

Why do we say the oxygen and carbon dioxide are in a cycle?

For life on Earth to continue, there needs to be an unlimited supply of carbon dioxide and oxygen. It is in a cycle to ensure that similar amounts of both are produced.

• Plants produce their own food (glucose) by a process called photosynthesis.
• Photosynthesis takes place mainly in the leaves.
• During photosynthesis the plant uses chlorophyll, sunlight energy, carbon dioxide (from the atmosphere) and water to make glucose.
• Plants change some of the glucose (sugar) into starch which they store in their leaves, stems and roots, flowers, fruits and seeds.
• Animals take in oxygen from the air and produce carbon dioxide when they breathe.
• Plants recycle carbon dioxide and make oxygen during the process of photosynthesis.

List the four things that are vitally important for plants and photosynthesis.

Sunlight energy, water, carbon dioxide, chlorophyll

• The process when the green parts of plants make food is named _____.
• Water and minerals are absorbed by the _____ of plants.

Soil is made up of _____, _____, _____, _____.

• The process when the green parts of plants make food is named photosynthesis.
• Water and minerals are absorbed by the roots of plants.
• Soil is made up of organic and inorganic material, water, air, sand and rocks .

The seedlings that were planted in the newspaper cuttings or cotton wool did not grow very well at all, even though they had sunlight and water. What could they not get from the newspaper or cotton wool that plants normally get from soil?

Nutrients and minerals

Where does photosynthesis usually take place? Explain your answer.

Photosynthesis usually takes place in the leaves. The leaves are green as they contain chlorophyll. Leaves also face the sunlight and are exposed to the most sun to drive the process of photosynthesis.

Do you think photosynthesis takes place at night? Explain your answer.

No, it will not take place. At night there is no sunlight energy to drive the process of photosynthesis.

What is the name given to the sugar that plants produce during photosynthesis?

What do plants store glucose as? List some places where it is stored.

Starch, stored in leaves, stems, roots, flowers, seeds, fruits.

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Photosynthesis - 5th Grade

18 questions

Introducing new   Paper mode

No student devices needed.   Know more

What gas do plants give off after conducting photosynthesis that humans/animals need in order to live?

Plants take in ________ from the air as one key ingredient for photosynthesis

carbon dioxide

The main source of energy for all life comes from ____.

the food we eat/make

• 4. Multiple Choice Edit 30 seconds 1 pt Why are producers (plants) important for all life on Earth?  They make our world more beautiful They make the planet look green They use carbon dioxide and give us oxygen They provide shade for insects

__________ energy from the sun is changed into __________ energy during photosynthesis

Chemical energy to light energy

Light energy to chemical energy

Thermal energy to light energy

Electrical energy to chemical energy

• 6. Multiple Choice Edit 30 seconds 1 pt What are the 3 key ingredients needed for photosynthesis glucose, oxygen, carbon dioxide carbon dioxide, water, glucose water, soil, sunlight sunlight, water, carbon dioxide
• 7. Multiple Choice Edit 45 seconds 1 pt Which of the following statement is true regarding photosynthesis creates oxygen for animals to breath creates energy for consumers to use creates food for plants to use all of these are correct

What is the tiny openings that let in the carbon dioxide needed for photosynthesis?

chloroplast

• 9. Multiple Choice Edit 1.5 minutes 1 pt Which of the following examples go through the process of   photosynthesis? bees algae humans mushrooms

A student is collecting the gas given off from a plant in bright sunlight. The gas being collected is probably ________.

What is the name of the sugars a plant produces after photosynthesis?

• 12. Multiple Choice Edit 30 seconds 1 pt Why do producers need humans? Producers use the oxygen humans make Producers need someone to water them Producers use the carbon dioxide humans make and turn it into oxygen Producers use the glucose humans give them
• 13. Multiple Choice Edit 2 minutes 1 pt What does chlorophyll capture? Chlorophyll captures water from the air. Chlorophyll captures carbon dioxide from the air. Chlorophyll captures the energy of sunlight. Chlorophyll captures baseballs.
• 14. Multiple Choice Edit 30 seconds 1 pt Where does photosynthesis take place? The leaves. The roots. The branches. The kitchen.

How does oxygen get released by the producer (plant)? Name the structure in the leaf.

What is the function of a plant's stem?

To support the plant and transport nutrients and water between the plant's roots and leaves

To make the plant taller

To help the plant reproduce

To keep the plant in the ground

What is the function of a plant's roots?

To help the plant grow next to other plants

To keep the plant in the ground and absorb nutrients and water

To help the plant collect sunlight

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