David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.
You put a seed in the ground, sprinkle a little water, and from that grows a gigantic tree. Trees grow over time in the same way as humans do, but unlike humans they don't eat food. They don't have jaws, or stomachs, or intestines. So how do trees create the energy they need to live?
They do it by a process called photosynthesis. Photosynthesis is a process where plants convert light energy from the Sun into sugar (glucose) that the plant can use for energy. For a plant to photosynthesize, it needs several things: light, carbon dioxide, and water. It gets light from the Sun, absorbing it through its leaves. It gets carbon dioxide gas from the air around it, breathing it in through tiny stomata, which are holes on the underside of each leaf. And it gets water from its roots, which is why you only have to water the soil to get a plant to grow.
 |
Photosynthesis is a chemical reaction, and so like all chemical reactions, it has a chemical equation to describe it. That chemical equation looks like this:
 |
One thing you might notice about this is that it takes a lot of stuff to produce a single sugar molecule: it takes six carbon dioxide molecules and six water molecules. But you might also notice there is a byproduct: oxygen. Where as humans breathe in oxygen and give out carbon dioxide, plants do the opposite: they take in carbon dioxide and give out oxygen. That's why trees are sometimes described as the lungs of the Earth. Without them, humans wouldn't be able to breathe.
Plants that photosynthesize tend to be the same color: they tend to be green. The reason they're green is that the leaves contain a substance called chlorophyll. As we'll discover, chlorophyll is vital for photosynthesis.
While different plants perform photosynthesis slightly differently, the need for chlorophyll is the same. That's because it's chlorophyll that does the job of absorbing the Sun's light in the first place. Light contains tiny particles called photons. When one of those photons hits one of the molecules contained inside chlorophyll, it gives energy to the electrons orbiting the atoms that make it up. It gives those electrons so much energy they're able to escape their atoms completely.
This electron passes to a different chlorophyll molecule, and then to another molecule, and then another in a process called the electron transport chain. The steps that follow are super complex, but eventually glucose is produced. And this reaction was all fueled by the energy provided by the photons of light.
Chlorophyll is green because green photons don't have the right amount of energy to free the electron. White light contains a rainbow of colors inside it, and chlorophyll absorbs most of the rainbow. However it doesn't absorb the green part, giving it a green pigment.
 |
Photosynthesis is a process where plants convert light energy from the Sun into sugar (glucose) that the plant can use for energy. Photosynthesis uses light energy, carbon dioxide and water and produces two products: energy in the form of sugar (glucose) and oxygen. This is the same oxygen humans breathe, and so trees are often described as the lungs of the Earth.
Chlorophyll is a vital part of the photosynthesis process, because chlorophyll is the part that absorbs the light in the first place. Light contains photons of energy, which have so much energy that they can free the electrons orbiting the atoms that make up chlorophyll. These free electrons transfer to another molecule, followed by another, and continue along the electron transport chain, eventually leading to the creation of glucose. But the entire process is started by chlorophyll absorbing the light energy from the Sun.
To unlock this lesson you must be a Study.com Member.
Create your account
Already a member? Log In
BackAlready registered? Log in here for access
Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.
To learn more, visit our Earning Credit Page
Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.
Back To Course
TExES Life Science 7-12 (238): Practice & Study Guide32 chapters | 257 lessons | 31 flashcard sets
{{courseNav.course.topics.length}} chapters | {{courseNav.course.mDynamicIntFields.lessonCount}} lessons | {{course.flashcardSetCount}} flashcard set{{course.flashcardSetCoun > 1 ? 's' : ''}}
Your Cart is Empty. Please Choose a Product.
Watch 5 minute video clips, get step by step explanations, take practice quizzes and tests to master any topic.
Study.com has a library of 550,000 questions and answers for covering your toughest textbook problems
I love the way expert tutors clearly explains the answers to my homework questions. Keep up the good work!
- Maritess, College StudentStudy.com video lessons have helped over 30 million students.
"I learned more in 10 minutes than 1 month of chemistry classes"
- Ashlee P.
"I learned more in 10 minutes than 1 month of chemistry classes"
- Ashlee P.
"I aced the CLEP exam and earned 3 college credits!"
- Clair S.
Over 65 million users have prepared for {{displayNameByProductKey[registrationData.product || testPrepCocoon]}} and other exams on Study.com
"The videos have changed the way I teach! The videos on Study.com accomplish in 5 minutes what would take me an entire class."
- Chris F.
Over 65 million users have prepared for {{displayNameByProductKey[registrationData.product || testPrepCocoon]}} and other exams on Study.com
Over 65 million users have prepared for {{displayNameByProductKey[registrationData.product || testPrepCocoon]}} and other exams on Study.com
