Getting to Know Photosynthesis Scientific words can seem complex For example if you read somewhere that plants make food using photosynthesis you might be confused by a term that sounds so technical Actually it is easy to guess the meaning of the word photosynthesis The first part of the word ldquophotordquo refers to light The second part ldquosynthesisrdquo refers to making something In this case plants make a chemical compound Plants use photosynthesis to produce chemical compounds from light

Photosynthesis enables plants to grow If you eat a salad you are consuming nutrients made by photosynthesis

How does photosynthesis work Photosynthesis is a remarkable series of complex chemical reactions A plant takes in carbon dioxide from the air and water from the soil and turns these into a sugar called glucose releasing oxygen and water as byproducts A plant uses light energy to power this reaction The equation below represents a simplified version of the reaction that occurs during photosynthesis

6CO2 + 12H

2O + light rarr C

6H

12O

6 + 6 O

2 + 6 H

2O

As you can see carbon hydrogen and oxygen atoms are combined to make glucose The extra oxygen and water molecules are released into the environment

Is glucose another word for table sugar Glucose is similar to table sugar but it is not the same Table sugar is sucrose Although photosynthesis produces glucose plants cannot store glucose for long They convert this sugar to starch or to sucrose If we eat a plant our bodies convert the sucrose and starch in the plant to glucose which is used in cellular respiration When you eat rice or potatoes you are eating plant starch Thatrsquos how we get energy from our food

Misconception 1 Photosynthesis is just a plant version of cellular respiration

That is incorrect Photosynthesis produces glucose which plants then use for energy during cellular respiration Plants use cellular respiration to provide the energy they need for growth During cellular respiration plants release carbon dioxide just as animals do

Concept Photosynthesis Getting to Know wwwdiscoveryeducationcom

1copy Discovery Education All rights reserved

Discovery Education is a subsidiary of Discovery Communications LLC

Do plants make glucose for animals Plants produce glucose to meet their own needs Glucose helps them store energy from the Sun They use this energy for their own growth and reproduction Animals that eat plants simply take advantage of the plantsrsquo ability to produce glucose from water and carbon dioxide That is why plants form the beginning of the food chain Energy passes from the Sun to plants and then from plants to animals

Misconception 2 I thought the point of photosynthesis was to produce oxygen for animals to breathe

Photosynthesis does produce oxygen but oxygen is just a byproduct of photosynthesis The only reason why plants photosynthesize is to produce glucose a sugar the plant uses for energy to grow and reproduce

What parts of the plant perform photosynthesis Most photosynthesis is carried out in the plantrsquos leaves The leaf is made up of cells Organelles inside the cells called chloroplasts contain a green pigment called chlorophyll Thatrsquos why leaves are green The chlorophyll absorbs light energy so that a cell can use this energy to manufacture glucose All of the reactions of photosynthesis take place inside the chloroplasts

Do plants need other substances in addition to carbon dioxide and water to grow

Plants do need other substances to grow Sometimes when you grow a plant it might turn yellow This is caused by a lack of nitrogen Plants use nitrogen and other nutrients to form proteins and fats However nitrogen is not directly necessary for the chemical reactions in photosynthesis

Why is it important to understand photosynthesis

Understanding the chemistry of photosynthesis also has many practical applications For example the world is running out of oil Biotechnology companies are researching ways to use photosynthesizing algae to produce fuels These fuels may one day be the basis of our energy supply Plants are the foundation of the food chain in any ecosystem and photosynthesis is the process that keeps plants alive If we are to keep ourselves and our environment healthy it is important to understand the value of photosynthesis

A leaf is a living factory where a plant performs photosynthesis

Concept Photosynthesis Getting to Know wwwdiscoveryeducationcom

2 copy Discovery Education All rights reserved

Discovery Education is a subsidiary of Discovery Communications LLC