|Hi, I am an 8th grade student who is taking living environment. In the cellular respiration and photosynthesis explanation for plants, some information says the plant “makes” energy. Although it might turn stored energy into usable energy, energy cannot be created nor destroyed.What do you mean when saying that a plant “makes” energy? Just wanted to clear up any further misconceptions as it is just a minor detail that could lead to someone seeking information having the wrong idea. I appreciate your time and help your website has given me!|
|Question Date: 2019-12-12|
You are absolutely right! I cringe when anyone talks about making energy. In biology, we should be talking about CONVERTING energy from one form to another. So the plant makes food from matter and energy. You could stretch this a bit and say it makes food energy from light energy, but “converts” is a better word.
If you’re talking about nuclear physics, you might describe turning mass into energy, but that’s not a biological process.
It sounds like you’re already thinking about this on an advanced level, so I’m going to ask you a question that stumps many of my college students. How can both the first law of thermodynamics (energy and mass not being created or destroyed) with the second (that every time energy is converted, there’s a loss in usable energy)?
Thanks for asking,
Great question, and I believe the wording might be the culprit here. It's true that energy cannot be created or destroyed, and an interesting point to note is that the energy converted by plants from the sun comes all the way from the initial energies and matter from the beginning of the cosmos, known commonly as the Big Bang.
Now, as for the wording and a brief lesson on words, "make" in a semantic sense is correct as the word refers to fashioning something from existing things, while the word "create" usually refers to bringing something from nothing. However, the word should probably be replaced with "produce" or "form", but its use might be to convey the difference between a plant which is an autotroph, an organism that forms/"makes" the necessary chemical energy for its cells, both the glucose and the subsequent ATP; and a heterotroph, which derives/"consumes" the necessary chemical energy for its cells from other organisms.
Any explanation which claims that plants "make" energy is using imprecise/incorrect language. Plants convert energy from light into chemical energy that is stored in glucose molecules. Sunlight powers the process of photosynthesis, which is the process plants use to combine CO2 and water to make glucose. [This answers the question as asked. An extensive description of photosynthesis can be found here for anyone seeking further information.]
Well you are correct! Energy can be transformed from one sort into another but never created from nothing….
The short answer is that photons or sunlight are used to generate glucose, a type of sugar. The glucose is then converted into another chemical called pyruvate which releases ATP (adenosine triphosphate) by cellular respiration.
In more detail, once a glucose molecule has been made using the energy of sunlight, then the glucose breaks down within the cell to produce pyruvate. The pyruvate is then used to provide energy anaerobically (no oxygen used) or by aerobic respiration (uses oxygen)… these latter reactions produce energy that the cell uses as part of its metabolic process.
The biochemistry here is complex but well understood, the bottom line is that sunlight gets converted into chemicals and then these chemicals undergo further reactions with other chemicals and these reaction generate energy that is used by the cell to serve various functions.
It looks like you have discovered a mistake in the textbook! There are a lot of books with a lot of mistakes out there, especially if they haven’t been written by scientists. And even the ones that are written by knowledgeable people can contain mistakes! It would be more correct to say that plants convert the energy from their surroundings (in the case of photosynthesis, the sun) into energy stored in chemical bonds (in the form of ATP, usually, though it depends on the exact process). The author of the textbook was likely trying to describe this process of converting one type of energy into another type of energy, and made a poor choice of words. Either that or they themselves don’t have as good an understanding of energy transfer as you do!
Thanks for your interest - Plants turn energy from the sun into food energy.
As you know - Matter and energy cannot be created or destroyed, but they can be changed from one form to another.
You are correct that energy cannot be created or destroyed. By “make energy”, they are probably referring to converting light energy into chemical energy in the form of the carbohydrates that make up the plant. Since chemical energy is a more “useful” form of energy to most humans and other animals, some may considering this “making” energy. This seems to be in line with what you had gathered, so I think you have a good grasp of the concept. Any confusion could be solved if they were more specific and said “plants make chemical potential energy.” If this does not answer your question let us know! Perhaps I could clarify more if there is a specific part of the photosynthesis process where these resources typically use the confusing language?
The idea that energy cannot be created or destroyed still stands in plant physiology. We just need to clarify some terms. In biology, when we say that plants "make" energy, we do not mean that plants make literal quantities of energy out of nothing. We mean that plants make molecules (such as sugars) that carry energy obtained through other means. Plants cannot use sunlight directly to power their biochemical reactions, so they must turn sunlight energy into other forms of energy they can use, hence the processes of photosynthesis and respiration. Therefore, "making" energy for biological organisms means making things that these organisms can use as energy supplies after getting the energy itself from other sources.
Yes, language can be imprecise!
Plants have two ways of acquiring energy. One is by getting it from sunlight, via photosynthesis; the other is by burning sugars to create carbon dioxide and water, the same way that animals do it. They normally use photosynthesis during the day when light is available, and store the extra energy that they collect in the form of starch (i.e. sugars), which they then burn at night when there isn't enough light to photosynthesize.
You are correct in that energy itself can neither be created nor destroyed. However, metabolically free energy of the sort that is useful to living things can be created (by extracting it from another source) and destroyed (by storing it, or by using it, which causes it to become metabolically useless heat).
From the Google search results, it seems that this phrase has been used to describe how plants harvest energy from sunlight through photosynthesis in the sense that high energy molecules are produced through this process. In general, energy indeed cannot be created nor destroyed and "make" is a poor choice of word.
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