The word photosynthesis can be separated to make two smaller words:-
“photo” which means light
“synthesis” which means putting together
Plants need food but they do not have to wait on people or animals to provide for them. Most plants are able to make their own food whenever they need it. This is done using light and the process is called photosynthesis.
Photosynthesis is the process by which plants make their own food.
To make food plants need:
- carbon dioxide
- Carbon dioxide from the air passes through small pores (holes) in the leaves. These pores are called stomata.
- Water is absorbed by the roots and passes through vessels in the stem on its way to the leaves.
- Sunlight is absorbed by a green chemical in the leaves.
The Process of Photosynthesis
Photosynthesis takes place in the leaves of plants. The leaves are made up of very small cells. Inside these cells are tiny structures called chloroplasts. Each chloroplast contains a green chemical called chlorophyll. It is the chlorophyll that absorbs the sun’s energy. The chlorophyll also gives leaves their green color.
In the chloroplasts, energy from sunlight is used to convert water and carbon dioxide into glucose or food for plants. Oxygen is also produced and it is released from the leaves into the atmosphere. Some of the glucose is used to provide energy for the growth and development of plants while the rest is stored in fruits or roots for later use.
Here is the process in greater detail:
Photosynthesis occurs in two stages commonly known as Light dependent Reactions and Light independent Reactions.
Light dependent Reactions
Light dependent reactions occur in the thylakoid membrane of the chloroplasts and take place only when light is available. During these reactions light energy is converted to chemical energy.
- Chlorophyll and other pigments absorb energy from sunlight. This energy is transferred to the photosystems responsible for photosynthesis.
- Water is used to provide electrons and hydrogen ions but also produces oxygen. Do you remember what happens to the oxygen?
- The electrons and hydrogen ions are used to create ATP and NADPH. ATP is an energy storage molecule. NADPH is an electron carrier/donor molecule. Both ATP and NADPH will be needed in the next stage of photosynthesis.
Details about the flow of electrons through Photosystem I, b6-f complex, Photosystem II and NADP reductase have not been included here but can be found under The Process of Photosynthesis in Plants.
Light independent Reactions
Light independent reactions occur in the stroma of the chloroplasts. Although these reactions can take place without light the process requires ATP and NADPH which were created using light in the first stage. Carbon dioxide and energy from ATP along with NADPH are used to form glucose.
What have you learned so far?
You already know that plants need carbon dioxide, water and sunlight to make their food. You also know that the food they make for themselves is called glucose. In addition to glucose, plants also produce oxygen. This information can be written in a word equation as shown below.
The equation below is the same as the one above. It shows the chemical formula for carbon dioxide, water, glucose and oxygen for those who need that information.
Earlier you learned that photosynthesis is the process by which plants make their own food. Now that we know what plants need to make their food (glucose) we can add that information as shown below.
Photosynthesis is the process by which plants make their own food using carbon dioxide, water and sunlight.
Why is Photosynthesis Important?
Photosynthesis is important because it provides two main things:-
Some of the glucose that plants produce during photosynthesis is stored in fruits and roots. This is why we are able to eat the foods that we enjoy including carrots, potatoes, apples, water melons and all the others. These foods provide energy for humans and animals that eat them.
Oxygen that is produced during photosynthesis is released into the atmosphere. This oxygen is what we breathe and we can not live without it.
While it is important that photosynthesis provides food and oxygen, its impact on our daily lives is far more extensive. Photosynthesis is so essential to life on earth that most living organisms, including humans, can not survive without it.
All of our energy for growth, development and physical activity comes from eating food from plants and animals. Animals obtain their energy from eating plants and plants obtain energy from glucose made during photosynthesis.
Our major sources of energy such as natural gas, coal and oil were made millions of years ago from the remains of dead plants and animals which, as we already know, got their energy from photosynthesis.
Photosynthesis is also responsible for balancing oxygen and carbon dioxide levels in the atmosphere. Plants absorb carbon dioxide from the air and release oxygen during the process of photosynthesis.
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The following resources can be used to enhance the teaching and learning experience.
Photosynthesis learning poster for kids
Size: 17″ x 22″
Description: Takes kids through the steps of photosynthesis. Vivid, detailed illustrations. Back of chart features reproducible sheets, activities, and helpful teaching tips.
Plants and Photosynthesis Poster
Size: 5 1/2ft tall
Description: Shows the main parts of a plant and explains the steps involved in photosynthesis. Package also includes activities.
Photosynthesis and Respiration Visual
Size: 11″ x 17″
Description: Laminated, “Write-On/Wipe-Off” visual aid.
Includes 4 panels:
- Panel 1 features an illustrated overview of the topic
- Panel 2 includes labeling and review exercises
- Panel 3 presents a graphic organizer
- Panel 4 provides assessment and review questions
Photosynthesis and Respiration Multimedia
Description: Multimedia lessons consisting of narrated lesson presentations, images, animations, review questions and much more…
- Features comprehensive array of multimedia lessons and activities
- Perfect for use on interactive whiteboard or individual computer
- Features multimedia tutorials; interactive activities and labs
- Compatible with Windows or Mac
- Designed for multisensory learning
Introduction to Photosynthesis DVD
Description: An introduction to the basic features of photosynthesis in plants. Introduces the concepts light-dependent and light-independent stages and their relation to chloroplast structures. Also includes simple classroom experiments, animation, and graphical presentations. With teacher’s manual. 30 minutes.