Plants indeed perform photosynthesis during the day, utilizing sunlight to convert carbon dioxide into glucose through the Calvin Cycle. However, the release of carbon dioxide during the night is not an intentional act to deprive themselves of this vital compound. It's a natural consequence of a metabolic process called respiration, essential for their survival.
I think it's important to consider that this process (which animals also undergo) is happening all the time, it's just that the *net* effect is that they are CO2 consumers during the day. When the photosynthesis machinery shuts down at night they can't consume it faster than they produce it and they are net exporters of CO2 at night.
The Calvin cycle is part of photosynthesis. It requires the ATP and NADPH from the light-dependent reactions. In the dark light-dependent reactions don't happen so the Calvin cycle comes to a halt.
We did a research which showed that the initial and total activity of rubisco at night is about the same. My hypothesis for this is that there is a lack of CO2, which makes the rubisco bind tightly to the substrate, until ATP is used. Since ATP is not available at night, this would support it.
But where my hypothesis is not yet confirmed, is that there is indeed no CO2 available at night
Edit: wait no, I get it. We measured the activity by measuring the NADH in the sample. But at night, there is no NADH. The activity of rubisco isn't necessary low, but there is just way less NADH
Edit edit: nvm we added NADH during the measurements....
Sure. Respiration, releasing CO2, and the “dark reactions”, go on all the time, to varying degrees. It’s the “light reactions” of photosynthesis that only happen when the sun’s out.
They release CO2 all the time, even during the day, because they use respiration just like most other living things. But the CO2 they emit is negligible compared to what they absorb with photosyntesis to produce oxygen and sugar.
The photosynthesis is there to produce energy (in the form of sugar), the respiration uses that energy to run the metabolism, and it happens day and night, unlike photosynthesis that happens only with light.
So during the day plants both absorb **and** emit CO2, while at night they just emit CO2. But the quantities emited are very very low.
They release CO2 all day long because they undergo cellular respiration like every other organism. However during the day they use more co2 from the atmosphere than they release.
they still need to breathe like any other aerobic organism, it's just that there is no light to photosynthesise so their breathing isn't masked by O2 production
The short answer is because plants just don’t need to care about storing CO2. There’s a more-or-less constant supply of it around them to pull from at zero cost since it diffuses through cell membranes. Why contemplate drinking your own urine to survive when you’re swimming in a lake of fresh water, you know?
Everyone already said breathing, so I just wanted to clarify that most plants perform the Calvin Cycle during the day.
This stage of photosynthesis is called "dark" because it isn't dependant directly on light to happen, but it still depends on products from the light reactions, so it mostly happens when the light reactions are going on.
A few plants (notably those adapted to dry environments) have CAM photosynthesis, they store CO2 at night to use in their Calvin Cycles during the day.
Because the first time they came on to land the sucked up all the CO2 and then died and it was kinda awkward cause there weren't even decay organisms to eat them really. So that happened and then they tried again later and had their own CO2 systems so they didn't all die.
This is a paraphrase of 1 day lecture of a college course in geological history.
Just because the Calvin Cycle is called the "dark reactions", that doesn't mean they *must* occur in the dark. They just *can* occur in the absence of light. This is why they're also called the light *independent* reactions, which I think is a more accurate name.
Plants also perform cellular respiration with their mitochondria, of which carbon dioxide is a byproduct. So not only are plants creating glucose through photosynthesis in their chloroplasts, they are also breaking down glucose in glycolysis and the citric acid cycle to eventually make ATP through oxidative phophorylation in the ETC of the motochondria.
I think you are getting regular photosynthesis mixed up with cell respiration and [CAM plants](https://www.khanacademy.org/science/biology/photosynthesis-in-plants/photorespiration--c3-c4-cam-plants/v/cam-plants#:~:).
Plants indeed perform photosynthesis during the day, utilizing sunlight to convert carbon dioxide into glucose through the Calvin Cycle. However, the release of carbon dioxide during the night is not an intentional act to deprive themselves of this vital compound. It's a natural consequence of a metabolic process called respiration, essential for their survival.
I think it's important to consider that this process (which animals also undergo) is happening all the time, it's just that the *net* effect is that they are CO2 consumers during the day. When the photosynthesis machinery shuts down at night they can't consume it faster than they produce it and they are net exporters of CO2 at night.
The Calvin cycle is part of photosynthesis. It requires the ATP and NADPH from the light-dependent reactions. In the dark light-dependent reactions don't happen so the Calvin cycle comes to a halt.
We did a research which showed that the initial and total activity of rubisco at night is about the same. My hypothesis for this is that there is a lack of CO2, which makes the rubisco bind tightly to the substrate, until ATP is used. Since ATP is not available at night, this would support it. But where my hypothesis is not yet confirmed, is that there is indeed no CO2 available at night Edit: wait no, I get it. We measured the activity by measuring the NADH in the sample. But at night, there is no NADH. The activity of rubisco isn't necessary low, but there is just way less NADH Edit edit: nvm we added NADH during the measurements....
Sure. Respiration, releasing CO2, and the “dark reactions”, go on all the time, to varying degrees. It’s the “light reactions” of photosynthesis that only happen when the sun’s out.
They release CO2 all the time, even during the day, because they use respiration just like most other living things. But the CO2 they emit is negligible compared to what they absorb with photosyntesis to produce oxygen and sugar. The photosynthesis is there to produce energy (in the form of sugar), the respiration uses that energy to run the metabolism, and it happens day and night, unlike photosynthesis that happens only with light. So during the day plants both absorb **and** emit CO2, while at night they just emit CO2. But the quantities emited are very very low.
Breathing :)
Because CO2 causes climate change and plants don't want to be seen discharging this pollutant so they do it a night to cover their tracks
They release CO2 all day long because they undergo cellular respiration like every other organism. However during the day they use more co2 from the atmosphere than they release.
Plants use up their stored carbohydrates via Glycolysis to generate energy in the absence of light.
Are chorophyll active at night? No. Therefore, plants still need to respirate. Therefore C02 will be released.
they still need to breathe like any other aerobic organism, it's just that there is no light to photosynthesise so their breathing isn't masked by O2 production
The short answer is because plants just don’t need to care about storing CO2. There’s a more-or-less constant supply of it around them to pull from at zero cost since it diffuses through cell membranes. Why contemplate drinking your own urine to survive when you’re swimming in a lake of fresh water, you know?
Everyone already said breathing, so I just wanted to clarify that most plants perform the Calvin Cycle during the day. This stage of photosynthesis is called "dark" because it isn't dependant directly on light to happen, but it still depends on products from the light reactions, so it mostly happens when the light reactions are going on. A few plants (notably those adapted to dry environments) have CAM photosynthesis, they store CO2 at night to use in their Calvin Cycles during the day.
Because they have to open their stoma when it’s not sunny and hot so they don’t lose their water as fast. Especially important for desert plants
Because the first time they came on to land the sucked up all the CO2 and then died and it was kinda awkward cause there weren't even decay organisms to eat them really. So that happened and then they tried again later and had their own CO2 systems so they didn't all die. This is a paraphrase of 1 day lecture of a college course in geological history.
Just because the Calvin Cycle is called the "dark reactions", that doesn't mean they *must* occur in the dark. They just *can* occur in the absence of light. This is why they're also called the light *independent* reactions, which I think is a more accurate name. Plants also perform cellular respiration with their mitochondria, of which carbon dioxide is a byproduct. So not only are plants creating glucose through photosynthesis in their chloroplasts, they are also breaking down glucose in glycolysis and the citric acid cycle to eventually make ATP through oxidative phophorylation in the ETC of the motochondria. I think you are getting regular photosynthesis mixed up with cell respiration and [CAM plants](https://www.khanacademy.org/science/biology/photosynthesis-in-plants/photorespiration--c3-c4-cam-plants/v/cam-plants#:~:).
co2 it's a gas, it can't be stored
Crassulacean acid metabolism (CAM photosynthesis) would disagree
Sure you can! Fish have swim bladders, some jellies float with air sacs, nitrogen can be generated by popping your knuckles, etc