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8

The reason that chlorophyll is green is because it absorbs other colors of light such as red and blue, so in a way the green light is reflected out since the pigment does not absorb it. Because life might have been purple: It is possible that the very first life form to process light may have been purple colored. This would mean it was reflecting red ...


7

From the link given by @Kendall Such a gradient can be maintained because the thylakoid membrane is essentially impermeable to protons. I think this solves your dilemma of 'why not maintaining equilibrium' totally. The reason for this difference is that the thylakoid membrane is quite permeable to Cl- and Mg2+. The light-induced transfer of H+ ...


7

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 ...


5

Disclaimer: This is going to be a very mathematical answer. Before answering it, I assume that you are only asking about humans, assuming that all other organisms don't require $O_2$ to survive (as it will complicate the answer many many times). List of variables: V = total volume of air on earth (in l) V' = total volume of oxygen on earth (in l) ...


4

Sorry for the poor quality of the image, but its just as a reference for my answer. You have made the question too complex. From the figure, we find that 1 H2O gives 2 H+ and 2 e-. 2 e-, through quinone cycle, provide 4 H+ i.e. total 6 H+ which form 6/3 = 2 ATP i.e. 1 H2O => 6 H+ => 2 ATP Multiply this equation by 8 and you get: 8 H2O => 48 H+ => 16 ATP ...


4

To answer if the equivalent could be done with plants, we have to understand the histological and anatomical differences between plants and animals. Just as spraying a nutritive solution over an animal (like you and me) doesn't work, spraying a nutritive solution over the leaves doesn't work as well: the nutritive molecules (let's use glucose in our ...


3

I can see your frustration if you meet errors such as NADPH2 but that is the price you pay for approaching as complex a subject as photosynthesis without a good biochemistry textbook. Even the on-line versions (e.g. Berg et al.) are unsatisfactory because of their layout. You will have to sit down and spend a couple of hours on the topic — all you can expect ...


3

I answered this implicitly in a comment to my answer to: Light and Dark Reaction of photosynthesis?. Anyway: There is no such thing as NADPH2. There is only NADP+ and NADPH. Consult Wikipedia or a reputable text such as Berg. The nicotinamide portion of NADP that undergoes oxidation and reduction is exactly the same as in NAD. The changes undergone are: ...


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 ...


3

Short answer: Electrons flow through membranes by floating through kind of channels made out of iron-sulfur clusters. Long answer: Let's take a look at the electron transport chain in the inner mitochodrial membrane. There is a proton gradient across the membrane building up a potential difference by pumping protons across the membrane as electeons flow ...


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

The answer above gives a nice calculation how much oxygen there is, and how much we use. There are some BIG other factors that warrant a second answer IMO. Starting at 371 thousand years (above). Animals: according to http://xkcd.com/1338/ (probably sourced somewhere reliable) humans make up only ~20% of the walking biomass, so we would burn through the ...


2

It’s not about the oxygen! This question indicates two misplaced concerns. One is with oxygen. I imagine that this is because of its importance to us as animals; however as far as photosynthesis is concerned oxygen is just a waste product. The other is with a chemical equation, which is as informative as the top line of a commercial balance sheet. One's ...


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

The photolysis of water is coupled to the reduction of plastaquinone (Q) in photosystem II (PSII) as summarized in this diagram, adapted from Berg et al.: The overall reaction (which balances) is: 2 H2O + 2 Q + 4 H+ = O2 + 2 QH2 + 4 H+ But the 4 H+ on both sides of the equation are not the same. The generation of the hydrogen ions in the thylakoid lumen ...


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 ...


2

It's not really possible to break it down this way. The CO2 fixated by the RUBISCO enzyme generates two phosphoglycerate (2 x 3C) molecules from one ribulose bisphophate molecule (5C), while the rest of the Calvin cycle serves to regenerate 3 ribulose bisphophate from 5 phosphoglycerate. Hence, one 3-carbon sugar (glyceraldehyde phosphate or dihydroxyacetone ...


2

I think we can look at it like this Your noncyclic pathway liberates 4H+ from two water molecules. We're doing that because to get one O2, you've got to split 2H2O. This happens in photosystem II. So in the next step (you know, really broadly) the electrons are passed to cytochrome b6-f complex, where each electron allows it to pump 2H+ into the thylakoid ...


2

The energy is "stored" in every bond. The primary bonds that break are either the first and second phosphate or the second and third phosphate creating AMP or ADP. The middle letter stands for Mono, Di or Tri (meaning 1, 2 or 3 phosphates).


2

This is a homework question but I will answer it (forgive me moderators ;). You will get your answer from this answer: Sucrose and starch are more efficient in energy storage when compared to glucose and fructose, but starch is insoluble in water. So it can't be transported via phloem and the next choice is sucrose, being water soluble and energy ...


2

But cyanobacteria do not seem to use polysaccharides in the same way as plant cells do (building materials, for example) The Calvin-Benson cycle produces glucose which is the starting material for a lot of biosynthetic pathways including that of the nucleotides (ribose from the pentose-phosphate pathway). Glycolytic intermediates are also involved in the ...


2

I would say Nucleus is the odd one out. Chloroplast (which have Grana in them) and Mitochondria are involved in the process of creating/breaking down energy, whereas the Nucleus is, so to speak, the blue-prints of the cell. To summarize: Chloroplast is involved in Photosynthesis to create energy Grana are in the Chloroplast, which is involved in ...


2

I think it should be grana.. Reasons- 1. It is not a cell organelle 2. It is not having double membrane 3. It does not have its own dna or ribosomes...


2

Your answers are correct, but there are more to consider: Nucleus is odd because it's the only one not directly involved in cell metabolism and has nothing to do with endosymbionts. Most cells also only have one nucleus but multiple mitochondria and chloroplasts - and multiple grana per chloroplast. Granum is odd because it's neither a eukaryotic cell ...


2

First question: B. The net gain of ATP in Photosynthesis is 0, so it cannot be A. C & D are obviously not true. Second question: B. D is not true, C is not true (it is actually the opposite- Chloroplasts absorb all BUT green, so only green would be bad). Like another commentator said, the level of CO2 only aids the rate to a point, at which the rise is ...


2

Survive without eating: no Survive without photosynthesis: 1. Yes, and 2. Yes-if considering only "nutritional" aspect of photosynthesis Some parasitic plants lack photosynthesis (see the beautiful ghost plant) Plants also grow during the night, and plants are able of respiration, which can exceed photosynthesis - and trees do so excessively when they ...


1

Why do you think that the only benefit from photosynthesis is polysaccharide synthesis? Photosynthesis allows an organism to convert photons into chemical energy. That chemical energy can be stored as polysaccharides and used as a building material, but it can also just be converted into some other compound, or just used to run the organisms metabolism, ...


1

Light Reaction (also known as light dependent reaction) The light reaction uses chlorophyll (which is the main photosynthetic pigment) to capture light, and then uses the light energy to make ATP and NADPH. Water is also broken apart in this process so the electrons can be extracted, yielding hydrogen ions and oxygen gas. The stimulation of chlorophyll ...


1

You can find two chlorophylls in most plant leaves, chlorophyll a and b. We'll use as a reference Leaf characteristics and chlorophyll concentration of Schyzolobium parahybum and Hymenaea stilbocarpa seedlings grown in different light regimes. The most important observation is that in shade-tolerant leaves, chlorophyll b dominates chlorophyll a. And the ...


1

Before answering the question, I assume that the plant is somehow getting enough O2 to survive. There can be a number of variations in the answer depending upon the more particular situation you give. You can have a look here to see a list of factors affecting rate of photosynthesis in plants. I put graphs of factors important for this question: If we ...



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