Study of the normal functioning of plants and plant cells

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Why do organisms excrete nitrogenous wastes?

All plants and animals excrete nitrogenous wastes in the form of urea, uric acid or ammonia. But isn't that a bit of a waste? I mean, there is a shortage of biologically available oxygen in the ...
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1answer
53 views

What is the cause of the spots on this leaf?

On a hiking trip to the Alps I found trees whose leaves showed those spots you see on the picture. I am curious about what the cause is. Higher resolution pictures of front and back side.
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2k views

How do plant cell divide without centrioles?

Most plants do not have centrioles , so who does their function ?
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1answer
116 views

How would a warm winter affect maple sap production?

The past winter (2011-2012) was warmer than usual. Trees are normally tapped in late February when the daily maximum temperature goes above freezing. However, assuming that there have been ...
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2answers
3k views

How will rising carbon dioxide levels in the troposphere affect photosynthetic producers?

Much discussion has been had about the affects of climate change on plantlife, but how will rising carbon dioxide concentrations affect the photosynthetic process itself? Since CO2 is a reagent in ...
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1answer
703 views

How do lilies sense day and night and open and close their flowers?

We have lots of lily flowers inside our garden. Their flowers are open in day and closed in night. How do lilies sense day and night and open and close their flowers?
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1answer
199 views

How do pineapples and lemongrass grow?

You can't plant the leaves, you can't plant the fruit, but, if you plant the part where leaves and fruit meet you will grow a whole pineapple plant. The part of the pineapple where the leaves meet ...
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97 views

Is there a standard definition for plant “maturity”?

Is there a species-agnostic metric for identifying plant maturity? There seems to be plenty of literature defining life-history stages for specific crops, but it is not clear if there is a generic ...
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334 views

Water potential in plants?

The concept of water potential in plants tries (and succeeds) to explain various movement and transports in plants. I have learnt that it can be though of being composed of various components like the ...
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453 views

Do plant-animal cross races exist?

Plants and animals have the following distinct properties: Plants live from solar energy by photosynthesis, they use solar energy to make sugar and oxygen out of carbon dioxide, which gives them ...
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209 views

Confusion regarding photosynthesis and respiration in plants

During 24 hours there is a time in i.e. twilight when plants neither give oxygen nor carbon dioxide why is it so? This also suggests that neither of the two vital processes i.e. respiration or ...
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1answer
88 views

Electron transport in granal stacks

See paper for distribution of PS-I and PS-II within grana As explained in the above paper, the PS-I complex is primarily located within non-appressed thylakoid region and stroma lamella, while PS-II ...
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2answers
457 views

Is there any kind of immortality in plants?

I asked a question about immortality of hydra and leaned good things about senescence. Now I like to know about immortality signs in plants. If there is some kind of immortality in plants its process ...
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82 views

Photosynthesis regulation

I read about the regulation of Calvin cycle by thioredoxin which activates key enzymes essentially by converting disulphide linkages on inactive enzymes into sulfhydryls. Another regulatory mechanism ...
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77 views

Measuring sugar content of a tree

I would like to grow mushrooms on oak trees I can harvest from my property. I've read that the best results will be when the sap is rising but the tree hasn't budded yet. The mycelium feeds on the ...
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197 views

Relationship between biomass and net primary productivity

I want to do validation on simulated net primary productivity. But I don't have measured NPP data, Eddy covariance flux measurement data. I have only field measurement biomass data. So can I directly ...
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2answers
757 views

What chemicals and structures control the *direction* of plant growth in leaves, stems and roots?

If you want a specific plant, let's say the snap peas I am growing that I bought at Agway. I noticed that they grow towards the light source through the nearby window. Also I think roots work the same ...
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1answer
127 views

Why does the PR form of phytochrome exist?

I know how it gets converted because PR is more stable and when there is neither red or far red light PFR naturally converts to PR. But what is the point of it? If PFR is the biologically active one ...
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20 views

What controls the southern range of willows?

Many willows (Salix spp.) grow in northern states but do not grow in southern states, for example Salix viminalis. What mechanisms control the southern range of temperate hardwoods such as willow? Is ...
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1answer
95 views

What part of the cactus photosynthesizes?

In general, plants photosynthesize through their leaves and, to a much lesser extent, through their stems. Cacti, however, have no visible leaves, but instead spines. In what part of the cactus does ...
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1answer
40 views

What's the simplest set-up to demonstrate soiless plant growth to middle school students?

I'm looking for a simple, inexpensive way to demonstrate that soil is not needed for plant growth to middle school students. I plan to germinate bean seeds in cotton, but where do I take it from ...
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2answers
1k views

Does Sansevieria trifasciata really absorb Carbon Dioxide at night?

There's a claim that Sansevieria trifasciata (Mother-in-law’s Tongue) generates oxygen from carbon dioxide during the night. This seems surprising to me: that process requires energy; plants generate ...
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1answer
9k views

What factors affect the rate of transpiration in plant leaves?

I'm trying to get my head around factors which affect transpiration in leaves. For example, how would applying petroleum jelly to the surface of plant leaves affect their rate of transpiration? I ...
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1answer
204 views

Why dont “growing degree days” have units of degrees Celsius (or do they)?

From Wikipedia: Growing degree days (GDD), also called growing degree units (GDUs), are a heuristic tool in phenology. GDD are a measure of heat accumulation used by horticulturists, gardeners, ...
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279 views

Can I estimate leaf temperature from air temperature? What other information would be required?

Physiological measurements such as respiration rate and assimilation rate depend on temperature. Most papers report tissue temperature (e.g. leaf temperature for leaf measurements), although some ...
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1answer
30 views

Can a plant be induced to accelerate transpiration?

Just what the title states. I wonder whether it is possible to fire a chemical switch - sort-of like injecting adrenaline in a human, to accelerate a particular process in a plant. For example, ...
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1answer
55 views

Arabidopsis thaliana RCSB active site gene mutant

I'm looking for an Arabidopsis thaliana gene listed in RCSB with a clear mode of function and active site. In addition it needs to have an obvious phenotype when knocked out like severely retarded ...
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78 views

How can GMO contaminate biologic plants?

Let consider two use cases : I am the only farmer within a 200km radius. I first grow GMO plants. A few cycles later I decide to grow bio plants, so I uproot all of the GMO plants and plant fresh ...
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107 views

How does a plant decide when to grow a branch? [duplicate]

As a plant grows, at some point the first branch forms. As it continues, branches grow new branches, and so on, in a seemingly random way. Is it random, or is it driven by the environment (heat or ...
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90 views

Does a theory exist for the formation of thylakoid structure?

I'm interested in how the structure of the thylakoid forms into its characteristic highly rugose stacks of grana. What causes the thylakoid to invaginate and self-associate, albeit with what appear to ...
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1answer
911 views

Can any plant regenerate missing tissue?

I have not yet found a plant that, when an insect eats a hole in one of its leaves, it can regenerate the lost tissue. Many plants will grow a new stem if the old one is cut, but it is not a perfect ...
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83 views

Exactly which amino acids are phosphorylated in higher plants during state transitions?

I know it is usually stated as the threonine residue near the N-terminus of either light harvesting complex (lhc) b1 or lhcb2, but if this is somehow lost, say in a mutant, is the system flexible ...
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2answers
688 views

What is the effect of a pure-oxygen environment on a plant?

Just read What's the effect of oxygen deficit on plants? ; and wondered whether the opposite would have any effect on a plant. That is to say, if a potted plant were placed under a bell-jar and ...
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161 views

Black bumps on the cut surface of an avocado

I cut an underripe avocado in half and put half of it, without the pit but with the peel, in the refrigerator. A day later, I see very small black bumps along the cut surface. What are they? What ...
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1answer
88 views

Would a plant survive if it was watered using hard-water?

Hard water is water with high mineral/salt content. I'm told that a potted plant watered with a salt solution dries out sooner or later. Is this true? If so, would a plant survive if watered using ...
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1answer
250 views

How does a plant cutting develop roots?

Please correct me if my understanding is incorrect; I understand branch/stem, and root are composed of different types of cells. Yet in some plants (e.g. rose, bougainvillea) a cutting from the stem ...
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1answer
263 views

Will fruit/seed of a bonsai yield another bonsai plant/tree?

With practice one can create a bonsai; no complicated modification of the DNA in a high-end lab required. The bonsai will even beget bonsai fruit. What I am curious about is - if such bonsai fruit ...
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36 views

Where can I find approximate rates of sequestration of CO2 for different species of algae?

For a study, I want to compare the rates of CO2 sequestration and fixation of a few different species of algae. I could not find any data on the sequestration rates. Any pointers to where I can find ...
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1answer
323 views

Do all plants photosynthesize with equal efficiency?

Just what the title states. Given identical, necessary and favourable conditions (Probably nutrients, humidity, and light but what I mean is all necessary requirements are fulfilled) - Is ...
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4answers
971 views

How do trees manage to grow equally in all directions?

I was walking down a road with these beautifully huge trees when this question occurred to me. Large trees with many thick branches have to grow equally in all directions, or they would tip over. Is ...
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1answer
202 views

Compare and contrast “Rubisco activity” and “assimilation rate” (is there a difference, and if so, what is it)?

I am confused about the variable "RuBisCO activity". How is it measured, and is it any different from the net assimilation rate? Based on some background reading (e.g. Kling, 2008; Lambers et al ...
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187 views

How do plants intake minerals through their leaves?

How do plants intake the fertilizer when it is sprayed all over the leaf surface as a foliar feed?
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1k views

Why animals can move and plants cannot in general?

To clarify, I think the answer should be able to explain: What are animals? What are plants? What's the difference between animals and plants (How do biologists differentiate them, if they ...
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1answer
51 views

Why are some plants frost tender?

Why do some plants have the ability to stand frost, while others can't? Does it have to do with the size of the water vacuoles in the plant cells?
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1answer
1k views

What's the effect of oxygen deficit on plants?

As I know all cells require oxygen. So my question is how efficiently can plants operate in no-oxygen atmosphere? Do all plants produce enough oxygen for themselves? Can they consume their own oxygen ...
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1answer
163 views

If only dicots have pith, what is the foam in the middle of cornstalks?

I've heard that the only plants that have pith are dicots, because of the shape of their vascular bundle. If that is true, what is the foam inside of the corn plants, which are monocots?
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1answer
183 views

What is the maximum potential sucrose concentration of plant sap? What keeps plants below this potential?

I am interested in identifying the maximum potential dissolved sucrose (%w/w) that plant sap could have, and which (biological, physical, chemical) factors constrain the observed sucrose ...
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2answers
2k views

How would a plant sprout and grow in a zero gravity environment?

Have any experiments been carried out involving sprouting and growing plants in a zero gravity environment? If so, what was the outcome? How did the plants sprout out of the soil without gravity? Did ...
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373 views

Why can you graft two unrelated cacti successfully, but you cannot do this on garden trees?

Any cactus can be grafted onto any other cactus, and even the most unlike of them grow together. My latest graft was a Schlumbergera truncata scion on an Opuntia microdasys rootstock. This kind of ...
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1answer
2k views

Why did the sensitive plant (Mimosa pudica) evolve its leaf-closing mechanism?

Why did the sensitive plant, Mimosa pudica, evolve its leaf closing mechanism? Does it heip in a heavy storm? Does it scare off whatever animals might think it a good meal?