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32

71% of the earth's surface is taken up by water. Not surprisingly therefore, the seas are an important source of oxygen. National Geographic claims that photosynthesis by phytoplankton (mostly single-celled phototrophs, such as cyanobacteria, green algae and diatoms) account for half of the earth's oxygen production. The other half, they claim, is produced ...


18

Photosynthesis is nearly all visible light. There's usually not enough UV and thermodynamics more or less rules out infrared. Chris covered that pretty spectacularly, but that nearly is significant. There is some evidence that certain kinds of fungi can use gamma rays or other ionizing radiation for energy, but they're not particularly common. Melanin is ...


15

Photosynthesis only occurs in the visible light.have a look at the absorption spectra of the different pigments involved in photosynthesis, you see that all these pigments absorb light between 400 and 700nm (from a diagram from here): You see that the absorption spectra of chlorophyll a and b are located from 400 to 500nm and again from 630 to 700nm. The ...


9

Yes, planting trees and burning them afterwards is a way to harvest energy from plants that's with us since millenia.


7

It is not possible to do this directly. Indirectly, it is possible, this is actually done by harvesting fruits - they contain the energy of the sunlight conserved in chemical compounds like sugars or starch and their cellular structures. The basic process for this is photosynthesis. The products from the fields are used technically to produce gas by ...


7

I am not sure which class of organisms have the highest contribution in oxygen production but diatoms do have a significant contribution. The introduction in this paper says that diatoms account for 40% of marine photosynthesis which according to this site is "1/4 of the oxygen we breathe."


6

I found surprisingly little information about harvesting energy from photosynthesis Photosynthesis does not produce energy as such, it produces sugars/carbohydrates/chemical energy, which the plant then converts into energy via respiration. You can burn the sugar to produce heat. But this is basically what your doing when you burn a plant. So ...


6

Check out the excellent Wikimedia picture of the carbon cycle: All the numbers are in billions of tons of carbon: white = stored, yellow = natural flux, red = human contribution. Notice that the deep ocean stores much more accessible carbon than any other carbon cycle source, and is only surpassed by the lithosphere* in overall quantity of carbon stored ...


5

The solubility of the solutes is the same at all points in the chromatography process. The solutes are clustered together at the beginning (at the solvent front) because none of them has moved very far yet. The reason for the separation of the solutes isn't that they become less soluble, it's that the solutes are moving at different speeds, like cars in an ...


5

The most basic example of what I would like to talk about seems to be the algae powered lamp that has (apparently) been developped. I think you misunderstood the idea. That lamp uses bioluminescence and not electric power. Normally living cells don't like to give you energy. The trick we use is anaerob fermentation. Without the presence of oxygen ...


5

The rate-limiting step of photosynthesis is the CO2 assimilating enzyme Rubisco (short for ribulose-1,5-bisphosphate carboxylase/oxygenase) (Jensen, 2000). It uses ribulose-1,5-bisphosphate and CO2 as substrates to generate glucose. Given that Rubisco is the rate limiting step in photosynthesis, an increase in its substrate CO2 would expectedly lead to an ...


5

Yes, it is possible, but not necessarily the case. Non-green leaves with chlorophyl: There are leaves that don't appear green, but do have chlorophyl and therefore can conduct photosynthesis. (See, for instance, refraction effects in white caladiums or the link in the answer by Resonating). Non-green leaves without chlorophyl: There are leaves that don't ...


5

Trees are definitely not the only source of oxygen. First, all green plants do photosynthesis, not only trees. Moreover, about half of all photosynthesis on earth is done by microorganisms in the oceans known as phytoplankton.


4

You can say that but chloroplasts do not have uniform morphology across different species. Moreover some organisms such as red algae have chloroplasts of different origin. Real indicator would be lets say number of chloroplast ATP synthases and/or light harvesting photosystems; these can be perhaps indirectly approximated by the total surface area of the ...


4

Here's an overview of both the Light and Dark cycles of photosynthesis, which looked particularly useful to me as it shows that the energy-carriers ATP and NADPH2 generated through solar energy are used in the dark cycle to generate sugars. . Here is another one that shows more details on the precursors involved in the Calvin cycle: As commented by ...


4

The energy transfer is achieved by a process called "resonance energy transfer". It needs the positioning of the donor and the acceptor in very close proximity to each other - the light harvesting complexes are optimized for this. This allows the collection of small amounts of light energy and still enables photosynthesis. The figure shows how this works ...


4

There are photosynthetic archaea (such as Halobacterium) but the mechanism is different. They use rhodopsin-like ion pumps (bacteriorhodopsin and halorhodopsin) to move ions against the gradient and produce ATP via chemiosmosis (like mitochondria).


4

In biology phosphorylation marks the addition of inorganic phosphate groups to proteins or other organic molecules. The phospho-group usually comes from ATP which is converted into ADP in this process. In the context of the Calvin Cycle there are two positions where molecules get phosphorylated. The first is the phosphorylation of 3-phosphogylcerate to ...


3

I cannot say anything about the general case, or specifically for day-neutral plants. However, Sforza et al. (2012) have studied the effects of light conditions on algae (used for biofuel production), and their results indicate several problems with continuous light. In continuous light conditions they find lower chlorophyll contents and higher carotenoid ...


3

First thing to note is that the absorption spectrum of chlorophyll A and chlorophyll B is similar but not the same. The reason for the appearance of absorption spectra is because the light is composed of photons of light. Different photon has different oscillation frequency and energy. The essence of Chlorophyll absorption is absorbing photons. After ...


3

As @wysiwig already pointed out the different morphology of chloroplasts is something that is hard to come by. This influences the amount of chlorophyll in these organelles which is the key for photosynthesis. So it is very difficult (to impossible) to compare chloroplasts of different plants as they differ pretty much. There is one paper from 1929 which ...


3

You need to account for free phosphates (Pi) that derive from ATP and are released in phosphatase reactions. The regeneration of 3 ribulose-1,5-2P has the overall reaction 5 glyceraldehyde-3P + 3 ATP $\rightarrow$ 3 ribulose-1,5-2P + 3 ADP + 2 Pi So in total eight phosphates (here counting ATP as 1) are redistributed, 6 of which end up in ribulose-1,5-2P, ...


3

They do have chlorophyll, at least in general. There are a couple very rare exceptions, but if it can stand up on its own, it contains chlorophyll. The green is just washed out by a very bright red pigment.


2

This question is related to the question: Why are some things transparent and others opaque? Being able to see something requires that it is opaque and that sufficient light illuminates it. UV and shorter wavelengths are not as prevalent as visible light on earth. The world would appear too dark to see if we used UV and shorter wavelengths. This is ...


2

I had to re-read your last sentence a few times to make sure I understood it correctly, but I think that now I do, and I can answer your question. What you're talking about are thermophiles. They're small organisms that love hot conditions - up to nearly 250 degrees Fahrenheit. They can be found places with a lot of hot water, such as hot springs - and, ...


2

Lets start with the absorption spectrum first (image from the Wikipedia page in chlorophyll): What you see in the figure is the absorption of light thoughout the visible spectrum by chlorophyll a (blue) and b (red). The higher the peaks get, the higher the absorption is. What we can see, is that chlorophyll absorbs light roughly until 500 nanometers (nm) ...


2

Water is split in chloroplasts in the light reaction of photosynthesis. Chlorophyll, acting as a photopigment, captures sunlight and transfers that energy to an electron pair of a water molecule. Under the influence of a water-splitting enzyme (George et al, 1989) it is separated into 2 protons, molecular oxygen and a free electron pair. Reference George et ...


2

1) Your understanding of taxonomy is outdated by a few hundred years. Linneaus' original system was based on flower morphology, but we since realized that the most effective taxonomy takes into account many different traits. In today's times, we mainly use DNA sequencing to determine relationships between organisms. 2) The leaf structure is not necessarily ...


2

Ignoring parameters such as: Leaf shapes Difference in photosynthetic efficiency due to other metabolic factors Unequal illumination of leaves Nutrient content of the soil Photosynthesis rate of a plant1 depends on the [total number of leaves] × [surface area of a leaf]. Assuming that a tree occupies same ground area as a shrub, there will be same ...


2

I thought it was fairly well understood that trees make NO net contribution to the oxygen supply. As a tree (or any plant) grows, it locks carbon within itself and releases the O from the CO2 into the atmosphere. When that tree dies, it decays by being consumed. All of the C gets recombined with O2 during the decay. Therefore, a quantity of oxygen is lost ...



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