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34

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 ...


9

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 ...


8

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

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.


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 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

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).


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 ...


4

The difference in energy requirements of a motile species make photosynthesis an unsuitable form of primary energy generation for them. Since plants are sessile, their energy consumption rates are lower. Plants have approximate respiration:photosynthesis rates of 0.35-0.9, as can be seen in this table (click to enlarge): Once the energy consumption ...


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 ...


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 several parts to my answer. First, evolution has selected the current system(s) over countless generations through natural selection. Natural selection depends on differences (major or minor) in the efficiency of various solutions (fitness) in the light (ho ho!) of the current environment. Here's where the solar energy spectrum is important as ...


4

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, ...


4

As far as I can understand your question, you wish to know why a plant cell consumes ATP to produce glucose when it can directly use the ATP as an energy molecule. ATP is an energy currency and is required in different biochemical pathways. However, it is not a good energy storage molecule. Following are the reasons why production of an energy molecule ...


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.


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

Equation you have mentioned is balanced chemical equation. In reality these are series of Redox reactions, major two as follows, Oxidation of oxygen from water in presence of light (energy from photon), $ 2H_2O \xrightarrow{Photons} O_2 + 4H^*$ Ions produced from above reaction reduces carbon dioxide , $4H^* + CO_2 \rightarrow (CH_2O) + H_2O$ So ...


3

OVERVIEW (verbatim from the article) Plastidic ferredoxin−NADP+ reductases (FNRs) accept electrons by two sequential one-electron transfer steps from two molecules of the one-electron donor ferredoxin to generate their fully reduced hydroquinone state, FNRrd, through the formation of an intermediate neutral semiquinone form, FNRsq. FNRrd then ...


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

Some of the water that's split is regenerated when the hydroxyl radicals (reactive oxygen species) are converted to hydrogen peroxide, water, etc. by superoxide dismutases and antioxidative mechanisms in the chloroplast (peroxisomes/catalases, etc. take care of this). There's also some evidence that the presence of mannitol, ascorbate and glutathione protect ...


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 ...


2

All photosynthesis reaction does need chlorophyll,even in cyanobacteria and algae the difference is the type of chlorophyll ( which depends on available wavelength of light and energy efficiency ) fully parasite plants on the other hand doesn't contain chlorophyll and this force them to live as parasites ( keep in mind that we do have half parasitic plants ...


2

Why be mobile? To follow the sun? Plants are mobile. Their seeds are. We have plants living on other plants. Once they have a spot on the sun though moving does not necessarily improve your situation, being stationary and defending your territory though does. (Growing taller, deeper roots, wider crowns)


2

The main purpose of crystallizing a molecule or molecular complex like a Photosystem is usually to provide a crystal for X-ray crystallography. A crystal has its molecular components arranged in a structured systematic repeating pattern, and this repeated pattern allows the X-rays to reveal the 3-dimensional shape of one of the components. Knowing the ...


2

Electricity may be indirectly generated from plants through the use of a microbial fuel cell, in which biologically-catalyzed chemical reactions are used to drive an electrochemical cell. A non-technical description of the technology can be found here. The basic idea is that plants produce organic compounds, which are broken down by soil microorganisms to ...


1

There is at least one species of highly mobile animal that can photosynthesize, depending on your definition of "highly mobile": Sea Sheep? This Adorable Sea Slug Eats So Much Algae It Can Photosynthesize The catch is that this animal does not produce its own chloroplast.


1

Parasitic plants such as Orobanche lack chlorophyll and cannot photosynthesize. They obtain all of their energy from paratising another organism.


1

Not 6, but 9 molecules of Pi are formed in the Calvin cycle, from the conversion of 9 ATP to 9 ADP: Source: Columbia University



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