32

Green is the most common color for plants, but they are not exclusively green already on our planet. Cyanobacteria, for example, uses other pigments together with chlorophyll, and same do red algae (from which the obvious name). Chlorophyll is just the most widespread, but there are examples of other colors, like the Cordyline australis Coming to your ...


18

Lifetime/Growth rate trade-off The reason plants do not absorb in the green is to avoid damage. As a PhD student working on organic solar cells, I can tell you that finding organic materials that can sustain light exposure over extended periods of time is very challenging. Perhaps on your planet different lifetime/harvest strategies could co-exist: some ...


14

Absolutely! Besides agriculture, humans would still benefit from technology for: Improved defense against predators. Improved weaponry for defending territory from rivals. Improved medicine. Improved shelter from the elements. Improved nutrition--just because they photosynthesize doesn't remove the needs for vitamins, minerals, or most importantly, water. ...


12

So the premise of your question is flawed in a couple ways... Picture this, humans (or human-like sentient beings) having the innate ability to photosynthesize their food in a similar manner to plants - thus providing all the nutrients required for sustained life. So...plants don't magically make nutrients right. They absorb nutrients and water from ...


12

You don't need to look far. Our bodies manufacture vitamin D when the sun's ultraviolet B (UVB) rays interact with 7-dehydrocholesterol (7-DHC) present in the skin. This is a very specific and real kind of photosynthesis.


11

You would need to make it worth their while. Photosynthesis is not all that powerful. It's roughly 3-6% efficient. The human skin is roughly 2 square meters in area. If we pretend that all of it is covering the ground like a solar panel, we could pretend we could consume the energy from 2 square meters of area (obviously this is a massive overestimation)....


11

Animals do it in our world, for sustainance. Kleptoplasty or kleptoplastidy is a symbiotic phenomenon whereby plastids, notably chloroplasts from algae, are sequestered by host organisms. The word is derived from Kleptes (κλέπτης) which is Greek for thief. The alga is eaten normally and partially digested, leaving the plastid intact. The plastids are ...


10

If I've understood your question correctly I'm going to basically ignore the biochemical science and jump straight to what I feel is the meat (actually, veg) of the question: What happens if plants grow 4x faster, but animals get 4x less nutrition from them Please note that above I'm using 'plant' as a synonym for autotroph and 'animal' as a synonym for ...


10

The colour of plants — or any other solar-powered autotrophic lifeform that may or may not be capable of description by the term "plant" — is a function of chemistry and evolution. Put quite simply, there are only so many viable compounds that allow photosynthesis to take place in a given environment, and they vary in efficiency. Some may be faster than ...


10

like if a refrigerator powered itself by absorbing the heat from the items in it That's called a perpetual motion machine. It's not how heat engines work. Heat engines work by utilizing differences of temperature to create some type of pressure, then using that pressure to cause mechanical work. The heat can be generated in various ways, but it has to be ...


10

I would say yes, if one of the pigments was not the result of the need to attract light. Suppose the planet had a secondary source of nutrients ( possibly older, e.g. geothermic vents) that was much more prevalent than on Earth. That source could influence the pigmentation of the plants that feed on it. In order not to be relegated into niches like pools of ...


10

No There are a lot of issues with that assumption, but I'll go through it all as concisely as I can. Oxygen isn't the only limiting factor to arthropod size Arthropods are exoskeletal by definition. Ultimately, that means that they are an organic creature inside a hard shell, more or less. By comparison to endoskeletal creatures, that means that their ...


10

You couldn't just replace the Magnesium directly without making other changes. Taking beryllium as the first example. In Plant-like organisms there are at least two different types of Chlorophyll, they work in pairs synergistically, one as an oxidizing agent and one as a reducing agent in the ATP and NADPH cycle (synthesis of glucose), (more on ...


9

The average adult human has a surface area of 1.75 square meters. Now, obviously at least half of that is going to be pointed away from the sun at any given point in time, plus a bit for the skin on the sides of the body instead of on the front or back. I don't know precisely how much skin is actually usable, but for simplicity we'll assume that 0.75 square ...


9

Plants create oxygen as a byproduct of photosynthesis, using energy from sunlight to break apart molecules of water and carbon dioxide and reform them into carbohydrates (such as glucose) and oxygen. If you want a substantial amount of oxygen in your atmosphere, that oxygen has to come from somewhere- either from oxides in the ground (most likely quartz ...


9

I initially thought this is not about world building, but then you asked about switching magnesium for something else. Most chlorophylls have mangesium in their chlorin core. Chlorophylls absorb energy from light and then transfer that energy to other chlorophylls by ressonance. This is a very delicate and fine tuned (no pun intended) mechanism. Changing ...


8

There are two situations I can foresee in which two or more pigments might co-exist: niche lighting; if one pigment takes up red light preferentially while the rest of the spectrum passes through then other photosynthesisers, lower in the biosphere, may use pigments with high efficiencies on other wavelengths to get all they can out of the light that makes ...


8

I feel like oxygen is kind of crashing the chlorine party here. On our world, oxygen is the readily available oxidizer and carbon is the energy currency. CO2 is the maximally oxidized carbon and CH4 the least oxidized. Some creatures oxidize CH4 to CO2. Eukaryotic life uses partly oxidized carbons like sugars and fats and alcohol - presumably because it ...


8

To learn how low you can go, let us consider the illustrative example of the gentle Lampenflora. Lampenflora (translated page from German Wikipedia) Totality of all autotrophic plants, which are located in caves in the field of fixed lighting fixtures These are plants which are adapted to very low light such as occurs in show caves. They occur on the ...


7

The way I am reading your question, you are asking about the mechanism of photosynthesis in alien plants, which would affect the colour of the leaves (or whatever sunlight collecting mechanism these plants use). On Earth, the primary pigment for photosynthesis is chlorophyll, and green chlorophyll pigments evolved to take advantage of the major component ...


7

Kill parasites, or other unwelcome passengers. In a competition between host and parasite, the host can take on stresses that it can deal with but which are too much for the parasite to withstand. An example is the black noddy. It lies in the sun and its black feathers get very very hot. Lice die. Bird does not! Sunning by Black Noddies (Anous ...


7

It might be possible. We've known for around a century (since at least 1933) that ultraviolet light can inhibit photosynthesis and possibly damage photosynthetic mechanisms inside an organism. Phytoplankton in particular have been recent targets of this sort of research, and it's been shown that their photosynthetic systems are negatively impacted by ...


6

Get your oxidizers here! Get them while they're hot! The fundamental question is where do you get your oxidizer from? All oxygen on this methane+H2 planet is wrapped up in water or something else. Candidate oxidizers might be Fluorine or chlorine but both have their problems. Fluorine is so reactive it never stays free for long. Chlorine is also never ...


6

The amount of energy provided by photosynthesis over the surface area of the human body is nowhere near enough to provide for any active "animal" lifestyle. Even if they became completely sedentary, sitting out in the sun all day, the amount of energy used by just thinking would at least make a serious dent in the energy produced, probably using more than ...


6

Not really. Sun is 400,000 times brighter than full Moon. Doubling and even quadrupling Moon's brightness would still have negligible effect on plant's life. However, it may be a game changer for nocturnal animals.


6

It's still way too dim to be useful. You'd have less than 1 lux worth of light, but you need a bare minimum of 50 lux to make any difference at all, and preferably 500 lux to see some significant (but small) amount of extra growth. Plants' light requirements fall into one of the four categories below, depending on the plant. "Most plants will survive ...


6

As noted in other answers, multiple colors will be equally viable and thus exist side-by-side if there are multiple ways to achieve equivalent energy. One way that might occur is a planet in a binary star system. The two stars could have each a different spectrum. As the planet turns, the planet would see different suns at different hours. Some plants may ...


5

I would say that yes, it's borderline possible. The organism should be very resistant to ionizing radiation; a Universe that allows Deinococcus radiodurans to exist would have little trouble in producing this new critter, even limiting ourselves to DNA. The organism would of course need to consume ordinary matter to replicate; it would therefore find it ...


5

In a comment the OP asked... If the sun currently provides 163 W/sq ft to the earth's surface, what if it suddenly produced 1630? Bad things happen. What you're asking for is a 10x increase in luminosity, the total energy the Earth receives from the Sun. As climate change has taught us, the Earth's climate is remarkably fragile to small increases in ...


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