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How do plants with purple leaves photosynthesize?
How do plants with purple leaves photosynthesize?β
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But every photosynthesis diagram found in our biology textbooks shows a green plant. So it begs the question: How do purple plants photosynthesize?
Let's start with a refresher on photosynthesis.
A simple explanation of photosynthesis
Photosynthesis is a process plants use to convert solar energy, water, and carbon dioxide into chemical energy (sugar) and oxygen. It's a great deal: Plants get to eat and we get to breathe. Win-win.
Why are plants (normally) green?
Plants are typically green because of the presence of chlorophyll in their leaves. Chlorophyll is a natural compound found in the chloroplasts of plants' leaves that absorbs sunlight, kicking off the whole photosynthesis process.
"Plagiomnium affine laminazellen" by Fabelfroh is licensed under CC BY-SA 3.0 DEED. |
Chlorophyll is green because it is fantastic at absorbing all the light on the spectrum, with the exception of green light. As a result, green light gets reflected back to us, making plants appear green to our eyes. In other words, plants don't need to be green to photosynthesize, it's just a byproduct of chlorophyll absorbing all but green light.
But why wouldn't a plant want to absorb green light?
Plants evolved to reflect green light in order to protect themselves from taking into too much solar energy. During the middle of the day, solar energy is strongest at the green part of the light spectrum. By reflecting back most of this green light, plants are shielding themselves from damaging, excessive light exposure.
So it makes sense that most plants are green, but...
Why are some plants purple?
Purple plants contain a compound called anthocyanin, which absorbs green light. Because purple plants have a higher concentration of anthocyanin than chlorophyll, they appear as a deep red or purple to our eyes.
Purple plants are able to photosynthesize because they still contain chlorophyll, which kicks off the photosynthesis process. Anthocyanin is a bonus.
Having purple leaves has some advantages, including additional sun protection. Anthocyanin absorbs the excess green light photons that would otherwise hit chlorophyll. If a plant gets more light than it can use, its ability to photosynthesize can become less efficient and even damage the plant's cells.
Purple leaves act like a sort of sunscreen for the plant, but they're perfectly able to photosynthesize thanks to chlorophyll.
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π Book of the week
βHow to Invent Everything: A Survival Guide for the Stranded Time Traveler by Ryan Northβ
This is already my favorite book of the year. The premise is that you're a stranded time traveler and this book is the manual that was included in your machine to help you rebuild civilization from scratch in the unlikely event that you got stranded back in time. But don't worry! These pages contain all the must-have info on everything from how to invent eyeglasses, rotate your crops, discover penicillin, get a head start on logic, and so much more.
This is a science, technology, and history book all wrapped up in one β in other words, it's a book perfect for the person reading this newsletter!
π Catch up on other curious questions
- βWhy do we need antioxidants if we need oxygen to survive?β
- βWhat does βadopt a highwayβ mean and how does it work?ββ
- βWhy doesn't honey go bad?ββ
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