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Complete list of touch sensitive plants
I am not sure whether the word "touch sensitive" is precise enough. What I am looking for is a list of plants that respond to touch noticably  like Mimosa Pudica. I only know of Mimosa Pudica example. Is there any other such plant?

Venus fly-traps have three touch sensitive hairs which trigger closing.

Cuscuta could be an example.

Some of the plants that respond to mechanical stimuli:

Dionaea muscipula

'Venus’ Flytrap (Dionaea muscipula) accomplishes one of the more spectacular thigmonastic movements resulting in a swap of the role of predator with animals (Simons, 1992). Indeed, Darwin referred to it as ‘one of the most wonderful in the world’ (Darwin, 1893). The specialized bi-lobed leaves with needle-shaped tines on the leaf margins are generally spread open as invitations to visitors. When an unsuspecting insect crawls along the ventral leaf surfaces and bumps into the three small trigger hairs (Curtis, 1834), intercellular electrical signals are generated (Burdon-Sanderson, 1873; Jacobs, 1954; Jacobson, 1965; Simons, 1981) and are thought to trigger differential enlargement of lobe cells (Fagerberg & Allain, 1991), resulting in trap closure in less than a second. Generally, multiple stimulations of one or more of the trigger hairs are required for a response.1

Drosera rotundifolia

Distinct touch-induced carnivorous behavior is demonstrated by Drosera rotundifolia, a species examined in detail by Darwin (Darwin, 1893). The mucilage on the ends of the Drosera's tentacles glisten in the sunlight (Fig. 2a,b) and give the plant its common name ‘Sundew’. Over 100 tentacles can cover the surfaces of its modified leaves. This showy appearance attracts insects, which upon alighting on the tentacle surfaces become trapped in the gluey substance. The tactile sensitive tentacles detect the presence and further movements of the insect as it struggles to be released. In response, neighboring tentacles bend towards the ones directly stimulated by the prey's presence.1

Utricularia (Bladderwort)

The Utricularia trap, attached via a stalk to the rootless plant body (Fig. 3a), is a thin-walled hollow sac with a watertight trapdoor. When the trap is set, the outer walls are concave and the chamber is under negative hydrostatic pressure. Various appendages, some with mucilage-secreting glands, have roles in luring prey to the trap door entrance and others near the bottom of the door are the touch-sensitive triggers. Small creatures, such as water fleas, are examples of those that fall prey to Utricularia traps.1

Mimosa pudica

Mimosa pudica, known as the sensitive plant, and some of its relatives are other well-known thigmonastic plants. A touch stimulation results in a very rapid folding up of the small leaflets composing the doubly compound leaves. Remarkably, the touch response is not restricted to the stimulated leaflet, but can propagate to all the neighboring leaflets of the leaf (Simons, 1981; Malone, 1994). A stronger stimulus, resulting in wounding, can elicit folding behavior at distantly located leaf petioles (Simons, 1981; Malone, 1994).1

Bryonia dioica

Elmar Weiler and colleagues have found that an increased level of octadecanoids, in particular 12-oxo-phytodienoic acid (OPDA), correlates with touch-induced Bryonia dioica tendril coiling (Stelmach et al., 1998; Blechert et al., 1999) and that OPDA, and related analogs that cannot be converted to jasmonic acid (JA), are sufficient to cause tendril coiling with physiologically relevant kinetics in the absence of a mechanical stimulus (Weiler et al., 1993, 1994; Blechert et al., 1999).1

Monstera (Vine)

The Monstera vine has an unusual technique for finding a host tree to climb. It travels by growing along the ground in search of the darkness of a tree's shadow; this movement towards darkness is called skototropism (Strong & Ray, 1975). The vine completes its journey when the vine apex senses arrival at the host tree by the resulting touch encounter. A dramatic change in growth direction then occurs. The Monstera vine begins an upward climb of its host tree (Strong & Ray, 1975), and leaf and stem development changes in anticipation of increased light and productive photosynthesis.1

Ficus costaricensis (Strangler fig)

The strangler fig (Ficus costaricensis) has a more sinister interaction with host trees (Putz & Holbrook, 1986; Putz & Holbrook, 1989). Roots of the epiphyte form grow downward from its host tree and, in addition to wrapping around the trunk, roots that touch each other fuse together (Fig. 5). As the roots continue to grow and fuse, they eventually encircle and prevent further growth of the host trunk. Further differentiation of the fig's roots result in such constricting pressure that it damages and eventually kills the host in a manner befitting its name. In this way, the strangler remains alone without competition from its former host.1

Catasetum (Flower)

Male flowers are poised to respond to visitors that contact antennae in the center of the flower by the release of stamen filaments held under tension by petals. The force by which a sticky disc with pollen sacs hits the chosen pollinator can be strong enough to knock a bee from the flower (Simons, 1992). This experience and the burden of the attached large pollen sac can be so traumatic that the bee will carefully evaluate potential future visiting sites and strongly prefer female flowers rather than the explosive male ones (Romero & Nelson, 1986). In this way, male Catasetum flowers may have evolved to compete for exclusive pollination rights of female flowers (Romero & Nelson, 1986).1

Arabidopsis

When Arabidopsis roots encounter glass barriers, gravitropism appears to be compromised and thigmotropism occurs instead. The touch-stimulated roots neglect their propensity to grow towards gravity vector and instead grow away from the perceived point of mechanical contact. The interaction of touch and gravity may occur at the subcellular level; touch can delay one of the earliest known graviresponses, the falling of starch granules in the root columella cells (Massa & Gilroy, 2003).1

References:
 1) In touch: plant responses to mechanical stimuli [Janet Braam]
 2) Thigmomorphogenesis: a complex plant response to mechano-stimulation [E.Wassim Chehab ; Elizabeth Eich ; Janet Braam]

It would be better if you define what you mean by touch in your answer.

then all flowering plants are responsive to touch by pollen.

Thanks. Its a great answer.  Do the Monstera vine and Arabidopsis root react noticably in realtime as Mimosa Pudica and venus flytrap do?


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How are oncogenes targeted for therapy?
How would oncogenes be targeted for therapy and are there any examples of existing therapies for such cancers if the gene was upregulated (i) as a result of copy number variation and (ii) due to increased promoter activity?

You mean by targeting the mutated gene in the cells or by targeting the gene product of the mutation?

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


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Histology tissue

Can anybody tell me from where is this tissue taken and in with techique is it colored please ?

Welcome to Biology.SE! What research have you done before asking it here?

I might as well be wrong, not being an histologist, but that's probably a classic: mammal liver tissue, (poorly) H&E stained, also showing Kupfer cells having phagocytosed something black (carbon particles from indian ink?).

It looks like a classic HE stain. (https://en.wikipedia.org/wiki/H%26E_stain)
Unfortunately I cannot help with identifying the source of the tissue as you have not specified a organism of origin.

Why did I get down voted? I identified the stain and provided a source. Also I simply pointed out that identification of the source of the tissue may depend on which organism it derives from. Please remember that histology is a broad field and covers both plants and animals! (https://en.wikipedia.org/wiki/Histology)

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Health effect of electromagnetic and acoustic waves on brain function
What if any effects are there on brain function from prolonged exposure to electromagnetic or acoustic stimulation?

Welcome to Biology.SE! What research have you done before asking it here?

Nothing formal, just been thinking about some things I've been noticing

Homework questions are off-topic here unless you have shown an effort for an answer. Please show some research effort lest the question is likely to be closed.

The title is very uninformative. The title (which I now have edited) should not state whether you estimate the post will be interesting or not and stating that it is about biology carry no information as everything is about biology on Biology.SE.

https://en.wikipedia.org/wiki/Blast_injury

The question is extremely broad.
Electro Magnetic signals
Even this subquestion is very broad. Electro magnetic signals encompass a lot of phenomenon, some of them represent health risks, some of them don't. It is funny to wish to limit the health effect to brain in your question as to reduce the scope of the question given how variable are difference electro magnetic waves can have on matter overall.
Ionizing radiations
Ionizing radiations will obviously represent health risks. But even non-ionizing radiation can pose health risk.
Non Ionizing radiations
Microwave
You are probably aware that you should not put your cat in a microwave!
Retina damage
Intense light can cause photochemical damage to the retina. See here.
Intense infra-red
High intensity infra-red affect cells (see König et al. 1997)
Cell Phone
Overall, there is likely no impact of cell phone radiation on our health. If there were any, it would be minimal.
See this Veritasium video: Do Cell Phones Cause Brain Tumors?. You should also have a look at the skeptics.SE post Do mobile phones have anything to do with brain cancer?.
Cell phone towers
Likely has no health effect. See Do cellphone towers cause health issues?
Other electro magnetic signals
For more information, you should have a look at WHO > Electromagnetic fields and public health: radars and human health
Sound wave
Some sound can cause hearing loss. The frequency of this sound, the intensity and duration of exposure to the sound are all important in determining the degree of the hearing loss. Have a look at this article from the American Hearing Society for more information.

Please add about sound waves as OP is asking about it too.


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Identification of an unusual tree
Location : Lyon, France

I think it's one of the laziest trees I've ever seen XD

It looks like a cypress topiary. The form is most definitely not natural and trained to grow that way.

As Sudachi has commented it has been pruned, probably over many years, to take on this form. It is not natural shape.
I would say that it is not possible to identify the exact species of tree without a close up of the leaves. From zooming in it looks like it could be a Lawson Cypress (Chamaecyparis lawsoniana) although it could be a Leyland Cypress (x Cupressocyparis leylandii), or a number of other possibilities.
One way to investigate this further if you want to know for certain, apart from posting a close up of the foliage which may help, would be to find some specimens of cypresses that you can find the name of. Perhaps in a garden centre or an arboretum, then compare the smell of the foliage when you pinch and crush it between your fingers. Different species have a characteristic smell that is a useful method for identification.


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Difference between Classic Satellite DNA and Microsatellites/Minisatellites
I am very new to this community and have a basic question about repetitive DNA sequences.
How is different (classic) satellite DNA from microsatellites/minisatellites?
All textbooks give concrete examples of microsatellites and/or minisatellites like --(AC)2--- or ---TACA(TAG)3--TACA----.
Are Classic Satellite DNA just sharing the same properties (perfect, imperfect, compound, complex, di-nucleotides, tri-nucleotides, etc.) as STRs or Minisatellites but the only difference is Classic Satellite DNA are longer?


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Identifying Fossil
Few days ago I found this stone with fossil near 6 centimeters. Can anyone identifying it.
Location: Europe,Bulgaria, Elena


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ID of a pair of similar-looking birds in NT, Australia
I spotted these two birds in Yellow Water, Kakadu NP. They were not in each other's vicinity, so it's not a pair in the sense that they were mates (not that I can tell at least :-).
Their appearance is quite similar, so I'm expecting they are the same species of bird. They look like egrets to me, which are common water fowl in the wetlands of Kakadu. However, they may in fact be different species altogether. One has these speckles on the wings, the other one doesn't, by the looks of it.
Can anyone help me ID these birds?

Where: Yellow Water Region in Kakadu NP, Northern Territory, Australia;
Size: Not too big, my guess is about 20 to 40 cm from beak to tip of the tail (about a foot or so);
When: Southern hemisphere's spring, early September; the end of the dry season;
Time of day: afternoon.

I think these are most likely nankeen night heron (Nycticorax caledonicus). The only that does not fit is your size estimation. See the images (from here):

I think the first image shows a bird which still has parts of its juvenile feathers, which look pretty different (from here):

A lot of information about these birds can be found here and here.

How. On. Earth. Can. You. Manage. To. Do. This. So. FAST?  And so complete with the juvenile identified?! I've been searching for this for ages. :-)

The size estimate was rough. I gave a more proper range now.

@AliceD Magic. Seriously: I had luck being around when the question popped up and finding the right bird relatively fast :-)

@AliceD: what field guide do you use? The Slater field guide for Australia (http://www.publish.csiro.au/book/6145/) is very good, as is the  Australian Bird Guide (http://www.publish.csiro.au/book/6520/#author. Full disclaimer: my PhD supervisor is an author, but the plumage detail in ABG is stunning).


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What makes a rotator cuff tear symptomatic in humans?
The majority of   rotator cuff tears  is asymptomatic {1}. What makes a rotator cuff tear symptomatic or asymptomatic in humans?

References:

{1} Minagawa, Hiroshi, Nobuyuki Yamamoto, Hidekazu Abe, Masashi Fukuda, Nobutoshi Seki, Kazuma Kikuchi, Hiroaki Kijima, and Eiji Itoi. "Prevalence of symptomatic and asymptomatic rotator cuff tears in the general population: from mass-screening in one village." Journal of orthopaedics 10, no. 1 (2013): 8-12. https://scholar.google.com/scholar?cluster=6848408356619886538&hl=en&as_sdt=0,22 ; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768248/

In conclusion, our survey of 664 residents in one village demonstrated that the prevalence of rotator cuff tear was 22.1% in the general population, which increased with age. Asymptomatic tear was twice as common as symptomatic tear.
[…]
In this study, “asymptomatic” was defined as having neither pain nor
  any other symptoms related to the shoulder when the survey was
  conducted including the past history of shoulder pain, whereas
  “symptomatic” was defined as having pain or any other symptoms related
  to the shoulder when the survey was conducted.

Caption: Prevalence of symptomatic and asymptomatic tears.
  Asymptomatic tear accounted for 50% of all tears in the 50s. However,
  in the 60s and over, the percentage of asymptomatic tear was
  significantly greater than that of symptomatic tear.

The underlying reason is difference in the rate of firing of torned and intact muscle in movement of shoulder joint.

Asymptomatic patients had minimal pain (<3 on the visual analog scale and no loss of active range of motion compared with the contralateral side); symptomatic patients had pain greater than 3 on the visual analog scale and decreased range of motion compared with the contralateral side (>10 degrees of motion loss). Electromyographic activity from 12 muscles and kinematic data were collected simultaneously during 10 functional tasks. Both symptomatic and asymptomatic cuff subjects demonstrated a trend toward increased muscle activation during all tasks compared with normal subjects. During the internal rotation tasks, asymptomatic patients had significantly greater (P<.05) subscapularis activity than symptomatic patients (65% maximal voluntary contraction [MVC] vs 42% MVC). During the carrying task, asymptomatic patients demonstrated significantly less (P<.03) upper trapezius muscle activation than symptomatic patients (16% MVC vs 50% MVC). During shoulder elevation tasks, symptomatic patients had significantly greater supraspinatus (52% MVC vs 28% MVC, P<.03), infraspinatus (32% MVC vs 16% MVC, P<.05), and upper trapezius (39% MVC vs 20% MVC, P<.04) muscle activation compared with asymptomatic patients. During heavy elevation (8 lb), asymptomatic patients showed a trend toward increased activation (P<.06) of the subscapularis compared with symptomatic patients (34% MVC vs 21% MVC). Differential shoulder muscle firing patterns in patients with rotator cuff pathology may play a role in the presence or absence of symptoms. Asymptomatic subjects demonstrated increased firing of the intact subscapularis, whereas symptomatic subjects continued to rely on torn rotator cuff tendons and periscapular muscle substitution, resulting in compromised function.

Source: Kelly, Bryan T., Riley J. Williams, Frank A. Cordasco, Sherry I. Backus, James C. Otis, Daniel E. Weiland, David W. Altchek, Edward V. Craig, Thomas L. Wickiewicz, and Russell F. Warren. "Differential patterns of muscle activation in patients with symptomatic and asymptomatic rotator cuff tears." Journal of shoulder and elbow surgery 14, no. 2 (2005): 165-171. https://www.ncbi.nlm.nih.gov/pubmed/15789010


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Why does our face get red during anger?
My attempt: This site says that it is due to flight or fight mechanism, which results in more amount of blood being passed to face causing red face.
But isn't it wasteful for our body to send more blood to face than to our muscles for efficient action?
Also an answer to this question says quite opposite.
So, I think that first site maybe wrong.
So, what exactly is the reason for red face during rage(anger)?

Evidence for my claim:

Several physiological studies have demonstrated that human facial color also varies with emotional states. The face often flushes during anger, or pleasure, and sometimes goes pale when experiencing fear or fear mixed with anger.

Source:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5259783/

But does it get red? Do you have any reason to think this is not just a comic representation that does not match reality? You pointed to a post suggesting that our face gets pale when under stress, so it really feels like stating that our face turns red when angry is not evidence based.

Come on, Does this fact even need a proof? Have you ever seen an angry person?

I sure have already seen an angry person but I would not be able to tell whether their face turned red or not. We will see if other usage are happy about considering "faces turning red when angry" as common knowledge or whether they doubt about this claim. I might be the only one unsure of this to being true. If I may, a correct terminology would imply saying "Does this claim need evidence" rather than "Does this fact need proof".

Thanks for correcting my English. Please see my edited question.

Why voted to close?

I did when I I commented. You made an edit since. However, it seems to me that the edit rather argue that our face goes pale when experiencing fear or fear mixed with anger, which is right the opposite opposite from you claim and the site that sustain your claim. I think the first question is really "Does it turn red or pale?". The video in the first link explains why it would turn red while the article you link explains why it turns pale.

Let us continue this discussion in chat.

@JM97: I have seen many angry people, enough to know that there are individual differences in the way anger is expressed, and also different types of anger.  The red face is a stereotype, but by no means universal.

But do you agree that it happens in some? If yes then there must be a reason for that too. So what could be the reason. And why it's an opinion based question? Is the physiological reason behind it is opinion based??

The comments and answer so forth are mainly related to the visibility and possible social and evolutionary explanation of the 'red face'.
While not discussing the social or evolutionary factors, I can give an overview of the biochemistry involved.
Anger and associated feelings such as stress are part of the 'fight or flight' response. This response is regulated mainly by the release of epinephrine and norepinephrine (the same as adrenaline and noradrenaline) into the blood stream by the adrenal glands, and from neurons into the synapses.
Wiki:Fight or Flight response
(Hence, the signal is send out both in the whole organism, and locally between neurons).
These hormones/neurotransmitters have a number of physiological effects:

They trigger a combination of vasoconstriction and vasodillation  in different parts of the body, meaning that the blood vessels constricted and widened, respectively, in different tissues.
This allows for a more effective transfer of nutrients to the muscles and brain. Wiki: Epinephrine
They trigger the increase of blood sugar by breakdown of glycogen deposits. Again, the body is in a situation where it needs to use the available energy ressources.
The heart rate is increased. Again, this allows for more effective transportation.

As listed above, the hormones related to anger both trigger the constriction and dilation of blood vessels in different tissues. Thus, the routing of the blood through the system also changes.
However, the routing of the blood seems to differ, depending on the exact feeling, where blood sometimes are routed to the surfaces areas of the skin, and sometimes away from them (by means of vasoconsttriction and vasodillstion, respectively).
Intuitively, this is can be a way of controlling the body temperature, as the body can expose the warm blood to the surroundings to a lesser or greater extent.
I don't think it is entirely understood, what determines this, but a guess could be that in situations of anger, the body has to be able to effectively use the muscles and fight, and thus also needs to be cooled, in order for the systems to work properly.
In situations of fear you might to hide instead for a long time and preserve the body heat and energy (just speculations).
Besides, it also could have a social impact.
But when blood is transferred to the facial areas, including the brain which needs energy to think quickly, and the skin surface for cooling down, it can have an affect on the perceived color of the face.
As noted by others, the degree of visibility is highly personal, as it depends on several factors such as the degree of hormone release, hormone sensitivity, anatomical features of the face such as placement of blood vessels, skin color and so forth.

Welcome to Biology.SE and thank you for your answer. Could please give some references (preferably peer-reviewed articles or e.g. Wikipedia for common knowledge). Also consider taking the tour and look at what is considered a good answer on this site for further information. Thanks!

I don't think the answer to your question is known per se, and as some comments pointed out the claim "our face gets red during anger" itself needs examining.
I will provide one element to think on however, which is that with emotional responses in general there might not always be a simple physiological reason for all the physical manifestations of the emotion, and if there is it might not be the whole story. There can very plausibly be social reasons why our emotions are visible and hard to control. It's useful for communication, letting other people know how we feel; it could also be useful to get people to do what we want (if someone is visibly angry in a way they clearly can't control then there might be other things they can't control and any threat they make may be more credible because of that; someone who's visibly upset demonstrates that they care about an issue more effectively than just saying they care does).
In other words, it is quite plausible that there were adaptive reasons for us to develop visible emotions, and from there any physical manifestation of those emotions (such as getting red in the face) might well exist mainly because it makes the emotion visible, and not because that particular response has a specific use beyond that.


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How does alzheimer's affect an octopus, particularly relating to their multiple brains?
From what I have read, Octopus' have multiple brains rather than a single one like in humans. They are also affected by alzheimer's, and so an interesting question arises:
Do Octopus' get alzheimer's in one brain, or are all affected, and can they shut off a single brain if it gets the disease?

I have no idea. Was hoping someone knowledgable could give a full rundown but if not will have to research this sort of thing :-)

Welcome to Biology.SE. This is an interesting question. Could you please add a reference about Alzheimer's in Octopus?

Pathology due to Alzheimer's disease is primarily because of the loss of neurons which cannot be repaired. Many organisms can actually regenerate their brains because they have active adult neurogenesis (which is reduced to a few small regions of brain in most mammals).


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Why are the most heat tollerant organisms prokaryotic?
Prokaryotic organisms are able to grow at far higher temperatures than are
eukaryotes.
Archaea are known to group, among some mesophiles, the most extremophiles organisms (es. Pyrococcus furiosus), but also some bacteria can reach quite high-temperature habitats, such as Thermus aquaticus.
Eukaryotes instead are far less tolerant in terms of maximum growth temperature.
Also most of the hyperthermophiles are chemoorganotrophs or chemolithotrophs, being autotrophs (Cyanobacteria) far less heat tolerant.
My question is about the physical or chemical limitations that block eukaryotes from adapt at extreme habitats like prokaryotes do.

Isn't it true that champions of resistance to extreme environments (whether extreme hot, extreme cold, extreme salinity, extreme drought, ...) are often prokaryotes? I feel like it might not be specific to heat alone.

I think so, for what I know Archaea are the champions of resistance to extreme environments sensu lato, but I was concentrating on heat alone to pose a question that can be answered in a concise and specific manner.

The premise, that only Prokaryotes tolerate high temperatures, might not be true. For example, the Pompeii worm can tolerate high temperatures. Since Prokaryotes developed earlier, the diversity might be greater and examples of extremophiles more extended.


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The link between muscle mass and muscle strength and how to train for each
I'm getting into my fitness and am beginning to see an increase in muscle mass. However, I look at people like Bruce Lee, Elliott Hulse, Mohammad Ali and Wim Hof who are capable of incredible strength but do not look as "buff" as people like Arnold Swarzenegger. It is clear that an increase in muscle mass does not necessarily lead to an increase in strength.
How is training for strength different to training for mass?
To add a new angle to this question, is there a correlation between the two?

FYI Correlation between muscle size and absolute strength

I'm voting to close this question as off-topic because it is better suited for fitness.SE.

I think this is perfectly at home in the biology stack exchange considering it conscerns biological functions.

Also: How does muscle size relate to strength?


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Bonding in the primary structure of a protein
My textbook says:

The amino group of an amino acid reacts with the carbonyl group of another amino acid at the end of a polypeptide chain. This condensation reaction forms a peptide bond. ... The precise sequence of amino acids in a polypeptide chain is the primary structure of the protein.

Later, it states that

The primary structure of a protein is established by covalent bonds ...

Is the primary structure of a protein governed by covalent bonds or peptide bonds? Are peptide bonds a type of covalent bond?
Any help is greatly appreciated.

Peptide bonds (also called amide bonds) are definitely covalent bonds.
This is also mentioned in the first line of wikipedia entry: https://en.wikipedia.org/wiki/Peptide_bond

Yes. Lots of words for the same thing.
Covalent bonds are any bonds where electrons are shared. Polyamide bonds, peptide bond etc.


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Can anyone id this flower
I took this photo on Madeira, in a botanical garden.

This is Kleinia, a genus from Asteraceae family. It is a succulent  native to  Africa.
I found a number of possible candidates, there may be more:

Kleinia abyssinica

Kleinia fulgens
Kleinia stapeliiformis
Kleinia pendula

P.S. There's not much free information from authoritative sources online about this genus. There are similarities in the blossoms' colour across  the Genus and also differences within a single species so to do a species level ID more information about the plant is needed.


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Can anyone give me the common name of this flower/vine?

Photo taken in NYC in April 2017

I think this is Kerria japonica (L.) DC, in it's less common non-filled form.

I think this is Rosa foetida, the yellow rose. Unfortunately the leafs are not visible very well but the flower, together with the growth, is pretty characteristic. See this image (from here) for comparision:

The German Wikipedia also has a drawing of the plant (from here):


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Where are examples of Interspersed repeats?
Interspersed repeats are often defined as repetitive sequences dispersed throughout the genome.
However such definition (IMO) does not exclude Tandem Repeat Sequences.
So I started to search for examples of such sequences.
After checking many Bioinformatics and Genetics books, I found many examples of Microsatellites and Minisatellites. However, I couldn't find any examples of Interspersed Repetitive DNA out there, in any of its variants (LINEs: L1, L2, L3, SINEs, etc.).
So my conclusion is Interspersed Repeats DNA Sequence looks like any other type of repeat (such as STRs or Minisatellites), the only real difference is they are flanked by Open Reading Frames (ORFs 1 and 2 for LINEs) or specific tandem duplications (like GC for SINEs)
Do anyone have one or two examples of concrete Interspersed Repeat DNA Sequences?


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How are bubbles formed and how do they make dough rise in bread?
So we took in biology that carbohydrate is broken into $\ce{CO2}$ and ethanol. But all I see in my mind here is that since gas is inside the dough then the gases will try to get out expanding the dough and rising it and I know that ethanol will rise as it is baked. However I am not sure how and why are bubbles formed in the first place or how they're related to this at all and does the ethanol taste stay in bread or is it completely removed once rised?
I heard on another resource that;
"It is because air bubbles get stuck inside, and when the bread bakes, the holes appear."
How does bubble getting stuck inside lead to holes appearing? it is confusing me.

For a yeast bread, the yeast is consuming sugars in the dough and producing CO2.  Kneading the bread causes the gluten in wheat to link up and become elastic, sort of like rubber.  So the CO2 makes lots of tiny little balloons in the dough.  A similar process takes place with non-yeast breads (and cakes &c), except that the CO2 comes from baking powder or soda.  AFAIK the ethanol really isn't a big factor in rising.

So it is because of the immense collision of CO2 into the bread it breaks and goes up? If so how does that piece it collided with go away?

@jamesqf — Please follow the instructions in the comment box. Do not use comments to answer questions. This negates the model on which SE is based.

Anybody competent and/or interested in this matter will answer the question on finding it, until then you need to have some patience.

@David: If I was a food chemist, I would write an answer.  Since I am not one - just a person who bakes, and takes a reasonable interest in how the process works - my comment is simply directed at helping the OP find an answer elsewhere - something that is all too often  hindered by those poorly thought out instructions.

@jamesqf You don't need to be a food chemist! You could write your comment as an answer, I'd say

@jamesqf — The instructions are not poorly thought out. They are integral to the SE model, as you will see if you re-read the introductory tour. Their importance — and unfortunately frequent violation — is why they are emphasized in the comment box. One pays nothing to use this site, so one should abide by the rules or find a different one with a model that one prefers. Please try to help make the site better.

@David: Perhaps you (or whoever wrote those rules) might learn something from that frequent violation, which is that many people who participate here do so despite those rules, and the model they try to enforce.

What I have learned from users who answer questions in comments is that text injunctions are insufficient if others are seen to be ignoring the rules with impunity. Hence the need for human intervention. The SE model states that “moderation starts with the community itself”. I did not invent the rules, nor am I a moderator, but I understand their purpose, and I implicitly agreed to them when I joined SE. Those who wish to understand the SE model and why it differs from other models should watch this YouTube video presentation from the founder of SE: https://www.youtube.com/watch?v=LpGA2fmAHvM.


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Link between pornography abstinence and hormone levels
I have a question regarding abstinence from pornography, and also possibly celibacy, and how these two lifestyle choices affect hormone levels.
Trends such as No Fap have been emerging recently. An excerpt from their website states :

No Fap held you to sharply increase your testosterone levels.

Is this true? From my research, I see no evidence to suggest this. Links to any studies would be appreciated. It is clear that people participating in No Fap have experienced psychological changes, but whether these changes are present on a hormonal level is an interesting proposition. If there is no hormonal change, what does this infer about what has happened to the minds of participants?

My immediate response, although I have zero evidence to back this up, would be it's along similar lines to quitting eating chocolate. You're simply stopping a habit that you enjoy. It sucks at first but then you get used to it after a period of time. More likely to be to do with dopamine than anything else.

Thanks for your answer. Yes, after doing more research it would seem that a pornography addiction desensitises the dopamine receptors in the brain and hence affects the wellbeing of the person in other activities. I suppose this could have the same kind of effect as low testosterone or adrenaline does.

I've written this up for you as a proper answer, if this solves your query I'd appreciate it if you marked it as accepted

In the context of breaking a pleasure producing habit, such as masturbation (with or without pornography), testosterone plays very little part.
There are two factors at play here:

Habitualisation - the tendency for an orgasm to repeat behaviours that it has become accustomed to.
Addiction/Dopamine Response - it feels good so I'm going to carry on.

The first bullet point is obvious, if you've always done something, it's going to make you feel different if you stop. If generally in society it is perceived as being a bad thing (thus making you feel guilty for partaking, even subconsciously), stopping that habit will make you feel good. Especially once you've gotten over the relapse stage.
The second bullet point is more involved. Orgasms, along with the viewing of sexually stimulating material, release dopamine into the blood. Over time, the dopamine receptors in the brain become desensitised and require more and more dopamine to get the same buzz. This is exactly why drug addicts need bigger and bigger doses of their drug. Consequently, once one has stopped partaking in the dopamine producing behaviour the receptors gradually begin to return to normal levels of sensitivity. This results in a generally better mood and a potentially higher libido. To those that don't know the root cause, this increase in mood and libido may appear as though testosterone levels had increased, however, this is likely not the case.


text:
How far can a mosquito fly over the sea?
My question is: how far can a mosquito fly over the sea? I am interested to know, because from this, I could possibly deduce on which islands there either might not be mosquitoes or on which it would be achievable to eradicate all mosquitoes until somebody brings another larva.

That won't work because remote islands are known to have been populated by insects and spiders that have been blown by winds to quite high altitudes and then transported over thousands of kilometers. So, even spiders can be found on young volcanic Islands in the middle of the Pacific.You can find insects and spiders right until the edge of the troposphere at about 10 km altitude, the vast majority of them will end up dying, a few lucky ones may end up in some tropical paradise on the other side of the planet.

How much wood could a woodchuck chuck??

Also, mosquitoes can hitch rides on something else that floats or flies across the sea.

they are exhansted in under 5 miles, and they tend to shelter from wind, because it uses their energy until they find a host.

If we ignore the weather effects mentioned by Count Iblis we can do a fairly simple calculation.
The lifespan of a male mosquito is about 10 days whereas females live to about 50 days.
Their flying speed is generally about 1.2mph.
So if we assume that they can fly whilst asleep and maintain a constant velocity for their entire lifespan (obviously ridiculous because of the need to eat etc), their maximum ranges would be:
Male: 1.2 * 24 * 10 = 288 miles.
Female: 1.2 * 24 * 50 = 1440 miles.
It should be noted that these are absolute theoretical maximums. I would suspect real life values to be somewhere in the region of 10%-20% of these. However, once wind is taken into account they can easily spread globally.

Can a mosquito not land on the sea water to take a rest, or mate in the air, or find some blood to suck along the way?

Mosquitos are fragile. They don't like direct sun, it dehydrates them fast. they come out a lot at night and in humidity. they don't like spending energy uselessly, their only food source is blood, so they have limited reserves for flight life. I suspect that they can't fly more than 2-3 days continuously without exhaustion. freshwater mosquitos may struggle with sea mist and seawater landings, it may coat them with too much salt for them to preen and work effectively. Either way, they are not fast flyers and they have low energy reserves.

sorry, that answer is inaccurate, they can only fly 1-2 percent of the given figure, not 10-20%, 2.8 miles not 28. They are thought to travel globally by airplane much more often than from wind!

They fly maximum a few kilometers, normally about 2-3 kilometers, before being tired.
Mosquito species preferring to breed around the house, like the Asian Tiger Mosquito, have limited flight ranges of about 300 feet. Most species have flight ranges of 2-5 km. Certain large pool breeders in the Midwest are often found up to 10 km from known breeding spots. The undisputed champions, though, are the saltmarsh breeders - having been known to migrate up to 160 km in exceptional circumstances, although 30 to 50 km are much more common when hosts are scarce. When caught up in updrafts that direct them into winds high above the ground, mosquitoes can be carried great distances. When it's windy they tend to hide in forest leaves and in shelters because wind fatigues them, If you can feel the wind, then they probably can't navigate in it.
Time (h)        Speed (km/h)        Distance (km)       Glycogen (J)

WT  3.68 (±0.31)......      A   0.68 (±0.03)......  A       2.39 (±0.19)........        -A  2.75 (±0.10)... A
Here is a full study, you may find different figures, and even if some species can cly for 10-20 hours total, they would get less than 10-20km without favorable wind conditions.
Wind can sweep them kilometers high where they can travel 1000ds of kilometers, as long as they don't freeze, land in the sea, exhaust themselves, or land somewhere without food, it's a good tactic for them.
To measure their energy reserves of insects, they can do this:

The glycogen, sugar and lipid contents of individual adults of four mosquito species
(Armigeres subalbatus, Culex quinquefasciatus, Aedes aegypti and A. albopictus) were
estimated following standard methods (VAN HANDEL 1965, 1985a, 1985b). Dead and dried
mosquitoes were individually homogenized in 0.2 ml 2% sodium sulphate and a few drops
of methanol in a 15×155 mm glass tube. This solution was vortexed
vigorously, after which a mixture of methanol and chloroform (1:1) was added to it.
The
tissues were crushed and then stirred. The mixture was centrifuged (
MOHAN S. et al.: Energy reserves in for co-occurring mosquito species 53
USA) at 2000 RPM for 20 min. The supernatant was transferred into a 15×155 mm glass
test tube for the sugar assay, while the precipitate
was left for the glycogen and lipid assays. The test tubes containing sugar were heated to
evaporate the solution in it to 0.1-0.2 ml. Anthrone solution was added (up to the 5 ml
mark), stirred and heated in a water bath for 17 min. Following this the test tubes were
cooled in an ice box and then stirred.
The absorbance of the resultant solution was
measured at 625 nm in a spectrophotometer (SHIMADZU® UV-17000, India) and
compared with glucose standards.
To the precipitate left earlier, 0.5 ml chloroform and methanol were added and the
whole gently shaken. The mixture was centrifuged at 2000 RPM for 10 min using
a centrifuge, yielding a supernatant (containing glycogen) and
precipitate (lipid).
The supernatant containing glycogen was collected in separate test tubes
(15×155 mm, marked up to 10 ml, graduated at 0.1 ml) and then heated well to evaporate
the solution. Next, anthrone solution was added to it (up to the 5 ml mark), stirred and
heated in a water-bath for 17 min. It was then allowed to cool in an icebox and stirred. The
absorbance of the resultant solution was taken at 625 nm using spectrophotometer and compared with glucose standards.
For estimating the lipid content, the precipitate was dissolved in a mixture of methanol:
chloroform (1:1). The test tubes (15×155 mm, marked up to 10 ml, graduated at 0.1 ml)
were put in a water bath for evaporation and 0.2 ml concentrated sulphuric acid added.
Then they were cooled in an icebox and vanilin was added up to the 5 ml mark. The
solution was stirred and a reddish colour allowed to develop within 5 min. The absorbance
was measured at 525 nm using a spectrophotometer (SHIMADZU® UV-17000, India) and
compared with the lipid standard.
*
 All the standard curves for sugar, glycogen and lipids
were prepared with 10, 20, 30, 40, 50 ml concentrations of glucose and lipid solution
(mg/ml) using the same reagents, and the same treatment was applied to the mosquito
tissues. A schematic diagram of the experimental setup is shown in Fig. 1.*

... that's what they do in the lab!!! sugar, alcohol, it's only missing some fruit and spices.
Dragonfly and Locusts are long distance flight champions, they can cover 1000ds of miles overseas, some dragonflies can feed on the wing. Small animals generally have to feed very often to survive, mice, moths, run out of energy quickly.


text:
Which countries do not feature mosquitoes?
Please, I am so itchy, I need to know: which countries are free of mosquitoes?

Iceland is a good choice.

You'll get itchiness due to dry skin if you move to cold places where there are no mosquitoes.

Our school geography book told that there exist mosquito in Antarctica (don't know whether t/f but iceland remembered me that). Also in several  quiz-book and competitions I've seen previously that France donot have mosquito  (dont no it is t/f) and there is a Quora question also on that.

According to India.com, Chris is right and Iceland has been declared mosquito free.
The science behind this is quite interesting and there are various hypotheses regarding as to why Iceland doors are shut to mosquitoes. The most preferred hypothesis by scientists, according to New York Times is >>

When mosquitoes lay eggs in cold weather, the larvae emerge with a
  thaw, allowing them to breed and multiply. Iceland, however, typically
  has three major freezes and thaws a year, creating conditions that may
  be too unstable for the insect’s survival.


text:
What is the current consensus on the Loveheim Cube of Emotion
I recently encountered the Lovheim Cube of Emotion. I was wondering what level of supporting research there is to go with it and whether or not there is a concensus at this stage.
If I'm perfectly honest, I'm skeptical, the evidence that I've seen is uncompelling and the model over simplistic but maybe I've missed something.

What research have you done into this, and can you tell us what you found? Your link states, "While the validity of the model remains unverified ..." Thanks.

That's part of the problem, barring that wikipedia page I've struggled to find any scholarly resources discussing this in any depth. I tend to take wikipedia articles with a strong pinch of salt since they rarely represent active research very well.

@JamesHughes What about the resources cited on the wikipedia page, and all of their citing articles? This isn't my area of expertise within neuroscience, but from a very cursory overview it seems like it has gotten a lot more traction in models for artificial emotional systems rather than explaining actual biological emotion; I suspect this may be partly because there is no spatial component. The monoamines are not hormones in the nervous system, they are neuromodulators or neurotransmitters, so spatial components matter a lot. Simplifying it to a cube based on concentration ignores space.


text:
What is the name of this injured species?
Location: South India
Size: 2-3cm
looks like injured species, unable to stand.

It's a sort of scarab, though which will be hard to pinpoint. It's not injured, they're just clumsy.

Well, after a lot of research, I hardy believe that it is a Rhizotrogus aestivus. First of all, the size (2-3cm) you mentioned fits exactly. Secondly, the colour matches fair enough. Finally the antennas and the body shape, may not be seen very well in the picture but I assume that they match. The only thing that I am not sure is the "laziness" of that insect, beacause they are only lazy or clumsy and not active, only when they are about to die.
For more informations check here: https://inpn.mnhn.fr/espece/cd_nom/10907?lg=en


text:
Can DNA be considered as a fractal antenna?
I was reading about the consequences of using mobile phones and came across the statement that mobile phones are a potential source of cancers because DNA is a kind of a fractal antenna. The reason put forward for this was that it shares with mobile phone antennae the properties of self-similarity and electric conductivity.
The scientific paper which is the source of this statement appears to be: Blank and Goodman, “DNA is a fractal antenna in electromagnetic fields” Int J. Radiation Biology, 87:4, 409–415, DOI:10.3109/09553002.2011.538130. Is anyone able clarify this assertion and explain whether or not the arguments in the paper support it.

Where did you "meet" said statement?

@BenBolker why bogus? this is my question

@BenBolker See also this comment: http://www.tandfonline.com/doi/full/10.3109/09553002.2011.626490

I have revised the question so that it is clear that the main question is the validity or not of the arguments in the source paper, which is cited. If someone is able to argue in support them they no doubt will be able to explain what a fractal antenna is and how this could cause DNA damage. I for one would be interested to know.

See my associated question https://biology.stackexchange.com/questions/91078/what-is-the-antenna-gain-of-two-pieces-of-sars-cov-2-retrotranscribed-dna . It was deleted because I initially mentioned a disapproved reference that I later removed but the moderators did not undelete the question. I will post i Physics SE if it isn't unlocked.

I looked at the original paper, Blank and Goodman "DNA is a fractal antenna in electromagnetic fields" Int J Radiation Biology, 87:4, 409-415, DOI:10.3109/09553002.2011.538130.
To be honest I can't give concrete reasons to doubt it, but here are a few things that raise my suspicions:

it is a review article that relies heavily on self-citation (15/50 citations are authored or co-authored by the two authors of this paper, including most of the primary experimental references)
in my judgement "responding to many different frequencies" and "having structures on several different scales" (Table 1) is not particularly strong evidence to support the conjecture that DNA acts as a fractal antenna; I would be much more convinced by an analysis based on physics rather than analogy (this comment on the paper by Foster reviews the physics of fractal antennas and its application to DNA and concludes that "Loose and implausible conjectures about DNA as a fractal antenna do not substitute for careful discussion of these matters"; I don't find the authors' rebuttal particularly convincing)
the authors cite epidemiological evidence that non-ionizing/low-frequency radiation causes cancer: according to the US NIH's National Cancer Institute, this evidence is weak. (However, one of the authors of this paper is a contrarian on this subject and believes that the mainstream view is wrong, for a variety of reasons.) (See Are low-intensity radio-waves carcinogenic? for more discussion on Biology.SE.)
the paper uses very disparate lines of evidence (not necessarily a bad thing, but in this case it feels haphazard): in particular, the authors discuss both low-frequency and ionizing radiation (this is part of their "DNA is sensitive to many different frequencies" argument, but ionizing radiation operates in a very different way)
it is highly speculative in places (e.g. "EMF is believed to have been an important driving force in evolution", p. 413, no reference; the authors go on to attribute the faster evolution of eukaryotes to the fact that their DNA structures are more fractal)
at least one of the references cited (de Pomerai et al. Nature 2000) was retracted in 2006 (5 years before the current paper was published)

What I can say in favor of the authors is that exploring the mechanisms by which low-frequency electromagnetic fields/radiation (ELF) affect cellular biology is indeed interesting; many of the epidemiological studies, while finding very weak effects, have also downplayed risk because so little is known about mechanisms of operation. If we could come up with a rigorous mechanistic understanding of ELF effects, that would be scientifically worthwhile.

See also the comment on this article: http://www.tandfonline.com/doi/full/10.3109/09553002.2011.626490

thx, incorporated in my answer

Well done Ben for taking the time to handle a complex subject!

many thousands, perhaps millions of people have been incorporated into studies of cancer rate Vs mobile phone use since mobile phones started warming folk's ears in 1995, so the topic went a phase of intense study in the 2000's as folk were suspicious that phones could actually cause cell damage. Actually, the many studies surprising found that the cancer rates were inconcluseively low and non-detectable. Also the conductivity of DNA is not like an antenna, it is probably 100 times less, and that conductivity may serve to protect it anyway, by giving oxidative charge a path of escape.


text:
Text Book Recommendation: Cell & Molecular Biology + Organic Chemistry
I am studying undergraduate biology course and I have cell biology and molecular biology in my next semester. Our college recommends three books : Cooper, Lodish & Bruce Alberts. It would be really helpful if you give me your opinion on which of these (or your own recommended book) would be the best to learn these subjects properly. The only thing I need is the book to be easy to understand because it will most probably be totally self taught because our instructors are not always helpful in explaining stuff properly.
We also have an organic chemistry class and the recommended books are Solomon's&Fryhle & LG Wade. It would be helpful if you help me choose between these as well, my requirement stays the same. Book should be easy for self learning.
If you know about online video lectures about organic chemistry and molecular biology do let me know. MIT OCW doesnt really have good bio videos. I cant seem to find video lectures anywhere for gre preparation. Thank you

Cell & Molecular Biology belongs to Biology Stack exchange and Organic Chemistry to Chemsitry SE. Also your question needs a  bit more details, you have only covered the last criterion,level of study.

Along with Molecular Biology of the Gene, Alberts' Molecular Biology of the Cell is one of my favourite text books.

@Sanjukta Ghosh I do know that these two belong to different SE but I wanted opinions from biologists not from chemists because my o.chem course is not advanced one, also it would be helpful if you mention what details you are looking for in my question. I just want an easy to learn textbook and can't try them all because 1) These books are expensive 2) I wont have much time to experiment with different books. I need to pick one and stick to it

Basic books of any subject (here Organic Chemistry) would be the same from both Biologists' and Chemists' perspectives as they teach the basics which stand on the ABCDs of that subject which has nothing to do with the domain knowledge of other discipline(here biology),  so I woud suggest you asking them because it is off-topic in Biology. Besides from my experience no single book covers all the topics well (in any discipline) and multiple sources (books and often papers) are required to learn something clearly.

Your post is missing what topics you want it to cover, you have to be more specific (see the scond point in the prev. link). Your post may get closed due to two reasons-off-topic and too broad if the issues are not resolved.

Sorry but I'll have to disagree with what you said about basic books. This semester we had physical chemistry and I asked for book recommendation in chemistry se. They told me I should go for Atkins but it was a waste of money. Not because it is a bad book, I am sure it is a great one due to its strong reviews but for a bio student like me it was very difficult to deal with, thats why I did not want to repeat the same mistake once again. Ignoring chemistry if you can help me with molecular biology book like  canadianer and AlexDeLarge did it would be helpful. Thank you

Given your requirements I would go for the Alberts for molecular cell biology.
For organic chemistry, in my opinion, there is no better book then the Clayden. It is targeted at OC students but I - as a biologist - learned a lot from it and still sometimes love to browse through it even though my work is far away from organic chemistry.
In general, I would advise you to go to your local library and take a look at the different choices before getting one. Take your time to get a feel for the writing and teaching styles and pick the one you find most access to (and maybe give feedback as a comment/an own answer to your post which book you took and why, for future reference).

I got myself a copy of Bruce Alberts, lets see how it goes!

"The only thing I need is the book to be easy to understand because it will most probably be totally self taught because our instructors are not always helpful in explaining stuff properly."

I can understand the problem with the stream you are telling about; there is an outburst of information, but there is a severe shortage of correlating between different chapters. That is causing the difficulty in the streams.
For Organic chemistry:
I Have not read about L. G. Wade, so I could not comment,
but I bought a  Solomon and Fryhle's  organic chemistry , 10th Edition (by T. W. Graham Solomon and Craig B. Fryhle; published by Wiley) , and it is really amazing book. It worth buying a copy for home use. . If you are one who sticked with understanding how stuff works, then Solomon & Fryhle is a good option.

Publisher link: Willey link: 12th edition, 11th edition, Students' companion site
Google book link Ed-8, Ed-9 content Ed-10.
Amazon link: Ed-10.
This book, though not with title of bio-organic chemistry, it very well discuss about organic chemistry in biology. The book is also cover the role of stereochemistry in biology, such as the bias of a biological system to produce one-type of chiral molecule out of two. While telling about any functional-group or type-of compound, the book mentions its significance in nature. The book also
discuss about various types of biomolecules.
.........................................................
Organic Chemistry by I. L. Finar, Vol-2. can work like an alphabet of the structures found in biological molecules.  It also discusses well about the secondary metabolites.
Publisher link
.........................................................
Besides the organic chemistry, you will need some backup in bioinorganic chemistry, such as structures of various metalloproteins,
For the very basics of bioinorganic chemistry,  one chapter book I found very nice, but I can't assure whether this book is available worldwide.
in General and inorganic chemistry by Ramaprasad Sarkar; Volume -2 , the chapter about bioinorganic chemistry, it very well explains the basics, especially how different inorganic elements form the different types of chemical bonds in biomolecules. It also gave elaborate classifications of bioinorganic compounds.

Though the edition (I can't recall now) I've read from a library, contained some old theories about mechanism; however the chapter is written very much systematic way, with first a bird's eye view and then gradual details.
Publisher link: Vol-2 in New Central Book agency
......................................................
For Cell-biology
There is a very old edition of Biochemistry, by Albert L. Lehninger, with title "BIOCHEMISTRY- the molecular basis of cell structure and function" The book was published by Kalyani Publisher, Ludhiana.
(The book is much different from the modern version "Lehninger's biochemistry" edited by Nelson and Cox).
This is a very basic and easy-to-read textbook covering biological chemistry as well as cell-biology. You could consult your college library for the book.
.........................................
For all aspects of cell-biology; the best comprehensive book I've ever seen, is by Pollard et al. .
Cell biology, by Thomas Dean Pollard, William C. Earnshaw, Jennifer Lippincott-Schwartz, Graham T. Johnson
The beauty of this book is, beside detailed and elaborate explanations of structures and their functions, everything is arranged in very systematic way. For example, in the biosignaling pathways; each-type of components, such as ligand, receptor, second messengers etc. classified and given in tabular way. When I can't understand a topic from some-other book, I need to consult this-book.
Publisher Website: Elsevier
Google books preview: Ed-2, Ed-3.


text:
What does cell-to-cell variability means?
I'm reading an article where they claim that transcriptional bursting could play a role in cell-to-cell variability.

Cell-to-cell variability plays a critical role in cellular responses and decision-making in a population, and transcriptional bursting has been broadly studied by experimental and theoretical approaches as the potential source of cell-to-cell variability.

I was looking for a definition of Cell-to-cell variability and I found only the one of Single-cell variability

In cell biology, single-cell variability occurs when individual cells in an otherwise similar population differ in shape, size, position in the cell cycle, or molecular-level characteristics. Such differences can be detected using modern single-cell analysis techniques. Investigation of variability within a population of cells contributes to the understanding of developmental and pathological processes.

I won't ask a question that's related to an article before reading it completely! The answer was in the first paragraph.

Cell-to-cell variability defined as when genetically identical cells in an identical environment behave differently, leading to significant consequences in many biological processes from bacterial decision-making to mammalian development.


text:
How to evaluate broad-sense heritability of microbiome associated plant genotypes in R
I have a data containing 196 accessions of A. thaliana from which I studied leaf bacterial and fungal community and, therefore, sequenced and found several OTUs. Now, I want to evaluate broad-sense heritability of microbes across accessions of A. thaliana in R. Kindly reply and if needed, I'll provide the data table.

As a disclaimer i don't know how to do this, but a package exists in R for these calculations. The package contains datasets from Arabidopsis you can use to play around with the functions.

Can you explain what you mean by "evaluating the heritability"? Moreover, how to do something in R is not really on-topic here. The focus should be on the idea instead of the programming.


text:
Why is EcoRI supplied with a unique buffer when it is allegedly 100% active in universal buffers?
Thermo packages a unique buffer with EcoRI:

50 mM Tris-HCl (pH 7.5)
10 mM MgCl2
100 mM NaCl
0.02% Triton X-100
0.1 mg/mL BSA

However, they also list their EcoRI enzyme as 100% active in Buffer O with no indicated star activity:

50 mM Tris-HCl (pH 7.5 at 37°C)
10 mM MgCl2
100 mM NaCl
0.1 mg/ml BSA

The same is true of 2X Tango:

66 mM Tris-acetate (pH 7.9 at 37°C)
20 mM magnesium acetate
132 mM potassium acetate
0.2 mg/ml BSA

Is there a reason one would preferably use the unique buffer over a universal one? Given that buffer compatibility is a major selling point for restriction enzymes, why would they continue to supply a unique buffer?

I look forward to the explanation for why this is a homework question...

Me too. I think this is a legitimate question. And an interesting one, too.

Interestingly for the Fast Digest system an universal buffer (green) is recommended.

@Chris Thanks. Are the Fast Digest enzymes engineered? I know NEB offers two EcoRI enzymes: regular and high fidelity. The latter is engineered for high activity in universal buffers. For Thermo, their "regular" EcoRI is apparently active in multiple universal buffers and is actually supplied with the unique buffer and Tango universal.

The composition of the fast digest buffers is not disclosed...I found one paper, which links the presence of Triton X-100 to a lower star activity, but they use much higher concentration, see here.

I have a suspicion that the unique buffer might be technically the best but the enzyme is also almost fully active in the universal buffers and displays neglible star activity so they just list it as 100% active for simplicity's sake. I may write their technical support a short email to see if they can clarify.

If you do, please let us know when you get an answer that tells us anything (although I doubt it).

@Chris I will do.

I'd +1 your thought to ask their technical support; they probably have more technical data than most users would, most users are probably just going to say "oh yeah it worked fine for me in _____ buffer" without having a quantitative comparison to a dozen buffer compositions. I don't use restriction enzymes in my work but I'm guessing they might supply it with the Triton X to get it into solution when it could be adhered to the supplying vessel. The other buffers might work fine but with a little Triton X they are confident it will all be in solution and therefore results more reliable.

@canadianer I expect that you get 100% of the listed units as activity in all buffers, but that you can get more activity if you use the unique buffer. Who might need this? No clue...

@Chris In case you're interested, I contacted tech support and updated the answer below. Apparently it may show star activity in the universal buffers despite this not being listed.

@canadianer Cool thanks. I find this interesting, and the suspicion it might have to do with star activity is right.

Activity toward the desired substrate sequence is not the only concern in evaluating a restriction enzyme buffer system. In addition, you need to be concerned about so-called "star activity", or activity of the enzyme toward other, non-desired nucleotide sequences.
For example, NEB supplies an enzyme-specific buffer for it's standard EcoRI, even though it lists 100% activity in buffer #2 of NEB's standard buffer series. But at the very bottom of the page, there's this note: "May exhibit star activity in NEBuffer 2.1 or CutSmart Buffer."
Promega has a similar warning about it's "MULTI-CORE" buffer - even though EcoRI has 100% activity in that buffer. The MULTI-CORE buffer is not recommended due to star activity - cleavage at non-standard sites.
It's a little hidden on the product data sheet, but Thermo Scientific does have a mention of star activity in the standard "Tango" buffer, and mentions star activity with overdigestion in the standard "R" buffer. There's no warning about buffer "O", but given EcoRI's propensity toward star activity, I'm guessing this is part of why they recommend a unique buffer for routine usage. Given how frequently EcoRI is used in molecular biology, it's worth using a custom buffer to get the star activity as low as possible.

From canadianer: I contacted Thermo's technical support. Despite the fact that star activity is not listed as a concern for either 2X Tango or Buffer O in the product data for EcoRI, they say that it may actually show some star activity in these universal buffers which is why they continue to supply the unique buffer for this enzyme.

Thanks for your answer. I should've clarified in my question that Thermo does not indicate star activity for both Buffer O and 2X Tango. As I mentioned in the comments, I suspect you may be right that star activity is minimized in the unique buffer whereas there may be some higher degree (negligible?) in the universal buffers.


text:
Assumptions of Hardy-Weinberg rule
The post Solving Hardy Weinberg problems offers an easy explanation of Hardy-Weinberg rule. The current top answer explicitly does not talk about the assumptions of Hardy-Weinberg. A model makes sense only if one is able to tell its domain of definition and therefore it is critical to understand the assumptions underlying Hardy-Weinberg assumptions.
What are the assumptions of Hardy-Weinberg rule?

Here are the assumptions to the standard Hardy-Weinberg rule (HWr) formulation
$$p^2 + 2p(1-p) + (1-p)^2 = 1$$
See Solving Hardy Weinberg problems for more info about this formulation.
Assumptions
The locus of interest is bi-allelic
This is an obvious assumptions, however it is very easy to extrapole HWr to any number of loci.
Organisms are diploid
This is another obvious assumption that is very easy overcome. This also means that HWr does not hold for loci present on sexual chromosomes as those chromosomes do not display a simple diploid behaviour.
Only sexual reproduction occurs
If some individuals are able to undergo non-sexual reproduction, then the rule does not hold anymore. See also Panmixia as these two assumptions are related.
Panmixia
Panmixia is often called "random mating". Panmixia is the state where each individual is equally to mate with any other individual in the population (including itself). There is therefore no population structure and no mate choice.
Let $N$ be the number of individuals in the population, in absence of selection (see If selection, it must be on fecundity alone), the probability to mate with any given individual (including itself) is $\frac{1}{N}$. You will note that it requires that individuals are able to self (but not clone as reproduction must still be sexual).
If selection, it must be on fecundity alone
If selection occurs, then it must on fecundity (right before reproduction). If selection occurs on survival during the lifetime, then the selected genotypes will be in excess in comparison to Hardy-Weinberg expectations.
If migration, it must be right before reproduction only
For the same reason as above, if there is migration, then it must be right before fecundity. If migration occur during the lifetime, then it will have a very similar effect than selection. Selection would increase the frequency of selected genotypes above HR expectations. Migration would increase the frequency of incoming genotypes above HR expectations.
Non-overlapping generations
This means that everyone reproduce in the exact same time and die right afterward. Very few species would qualify for such assumptions.
Population of infinite size
If previous assumptions already seemed hard to meet in the real world, the assumption of infinite population is absolutely impossible to meet.
Deviation from this assumption will cause deviations from expectations. Such deviations are often tested via a Chi squared goodness-of-fit test.
Note by the way that if the population is of infini size, there is no mutation, no migration and no selection, then there is no evolution.
Other assumptions
Biology is a science of complex systems. There are always other assumption one might want to consider. For example I did not talk about sex-specific selection or sex-specific mutation rate. But I am hoping that with the above I went over the most important assumptions.
So what's the point of HWr?
All models are wrong but some are useful. There exist no real life example of a population that perfectly fit into HWr assumptions but it does not mean the model isn't useful. Actually most population approximate HW expectations quite well. You will note also that it is by understanding how a scenario lead to a specific observation that we can interpret how derivation from the expectations can be achieved.
So yes, HWr is one of the most basic and most important rule in population genetics. It is so basic, that I would hardly name it in any fancy way as it is just the simple application of basic probability theory. See Solving Hardy Weinberg problems for more info.

You missed that (i) generations are assumed to be discrete and without overlap and that (ii) allele frequencies are unbiased between sexes.

@AlexDeLarge Thanks. I added "Non-overlapping generations". When you say "allele frequencies are unbiased between sexes", is it any different from what I meant in his also means that HWr does not hold for loci present on sexual chromosomes as those chromosomes do not display a simple diploid behaviour.?

It just means that males and females do not differ in allele frequencies. If they did - and given the assumptions mentioned in your answer there is no obvious reason (you can construct it implicitly from the panmixia assumption, I guess, but this is too vague) why they would not -, the population would not be in HWE.

Yes... "males and females do not differ in allele frequencies" sounds more like a consequence of the violation of specific assumptions that we should make sure to include. I see the mention of this assumption in the wikipedia article. I would not know how to justify the addition of this assumption so I'll leave it out for the moment until someone can teach me more on it.

I don't like this Hardy-Weinberg formulation because it reduces to 1=1. Nevertheless, nice answer.

@canadianer: That's why I don't like Euler's identity. 0=0 ... come on.


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I'm trying to figure out what the name of this flower is
This is a flower that grows in my backyard. I really want to know the name so I can read about it and possibly get more.

Rose. (Rosa sp.)

can you give a location and time of year?

It has actually just started blooming again recently and I live In Ga. Let me know if you need more.

That is a rose. At least we have such flowers around my flat and we called them roses for 18 years. See: Rosa Gallica

Welcome to Bio.SE! Please add an image and give some description of the species and provide references to support that the ID is actually correct.


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Is there any strong factor against human edible plants being widespread and easy to gather?
While many habitats have plants, fruits, nuts and berries available for consumption by humans walking by, most places (if any?) seem to require significantly more effort than simply picking our food from trees and bushes in order to survive.
Borrowing @BryanKrause's words in a comment below:
"Why don't you find enough things like broccoli, green peppers, almonds, and wheat to support a human population when you are walking in the woods/natural fields?"

because except in the case of fruit plants don't benefit from being eaten so they have evolved a wide range of defenses. You might as well ask why gazelle just don't lie down and let lions eat them.

@John But gazelles graze grass, why haven't either we evolved to eat such abundant food or why haven't any plant species filled that niche? I guess this is a set of rather complex and unanswerable questions…

Because there are already many grazers in africa, and having evolved from omnivores our ancestors could not compete with them. Grass may be abundant but it it rather difficult to digest grazers need to be specialized.  Why haven't plants evolved to fill what niche?

I meant the niche of being easily available food for humans? @John I guess these questions really are unanswerable…

The questions are perfectly answerable if, asked clearly.

Is your question essentially: "why you don't find enough things like broccoli, green peppers, almonds, and wheat to support a human population when you are walking in the woods/natural fields?"

Yes, exactly, @BryanKrause! @John, does this help? Maybe I should add that very quote to my question.

to that the answer is becasue human don't live in those places, of have moved into them only recently. Evolution has no foresight, plants can not evolve for conditions that do not exist yet or have only existed for a few generations, not without a lot of intervention (artificial selection). Note also none of the plants Bryan listed actually benefit from humans eating them without farming.

Oh And I should mention that broccoli is not a naturally occurring plant it is entirely a human invention. even the other plants listed have been modified by humans to be easier for us to eat. A lot of features we prefer in plants make them horrible at surviving outside farming.

Define "easily available to human", lots of fruit are perfectly edible to humans. Human have only become widespread in the last few million years so there is not enough time to see things specialized in humans via natural selection. Especially since we  are both generalists and for most of the world completely new factors in the environment.
But there are plants that have evolved to be eaten by humans. Wheat, rice, and, maize have done amazingly well by having the right factors to be useful to humans, they are also some of the most common plants on earth now thanks to us.
Artificial selection is still evolution, it's just not natural selection. Humans are generalists and its hard for natural selection to push things to specialize in edible symbiosis with a generalist, especially in as short a time as humans have been around, but artificial selection can do it just fine becasue it is faster, provided the plant in question survives us long enough.
Being useful to humans is also a bit of a mixed bag sometimes it means we spread you over the whole world, such as wheat and dogs, but sometime is means harvesting to extinction like Silphium. Then you have things like avocado which almost went extinct becasue humans killed off their parter animals and almost nothing else could eat them, then we invented farming and decided we liked them and brought them back from the brink. Human intelligence and cultural information sharing means capabilities and technology change so much faster than the speeds natural selection tends to work at, most things just have not had the time to really adapt to how fast we changed the world,  unless we take an interest in forcing them to.

Humans prefer the very tenderest of plants as found in shops, which only grow abundantly when there is a lot of rain and warmth: salads, roots, tubers, fruit. Other animals are not so fussy, they have more stomachs and more grinding teeth. So plants that are palatable to humans have very few chemical and physical protections, and are good food for all herbivores. That's why the majority of plants have chemical and physical defenses, cellulose that makes them stringy, hair, tannins and so forth. plants favored by humans are favored by insects and mammals too. harsh habitats that favor slow growth have very few fast growing and low cellulose plants, i.e. mediterranean, where everything is strawy and has spines and strong resins. In cold habitats, juicy low cellulose plants can't grow fast enough to gain advantage by rapid low cellulose growth. In arid habitats, insects and animals covet juicy salad type plants, and they are eaten fast and also grow slower. Only in lush green habitats, i.e. tropics and in temperate climates can indigenous people go for a 10 minute walk and bring home malva, palms, thistle stems, reed roots, vine, and make a salad in a very fast time.


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What happens when you take a deciduous tree and place it in a climate controlled greenhouse?
The greenhouse would have stable level of light, (matched with day/night wavelength brightness changes like outside the greenhouse), humidity and temperature.
Do certain processes in the tree not trigger?
Does this harm the organism, and are there changes in life expectancy?

Transplantation success rates vary between species. Do you have a particular deciduous tree in mind? Or are you imagining creating a greenhouse around the tree?

Are you asking whether the tree would drop its leaves in the fall, or if it would just keep on growing as outdoor trees do in the summer?

I dont really know to what extent this has been researched/tried, but I want to know what happens to trees that have evolved to lose their leaves (and other adaptations ofc) when winter stops and the weather doesnt fluctuate annually.

It harms the trees, seasonal chemistry in the plant is reduced and weakened they have tried growing apples and decidious fruit trees at the equator and they have to treat them chemically to help them stay stronger:
http://www.actahort.org/books/49/49_14.htm
the tropics have seasonal queues, and in a greenhouse with no temp and light change, the plant would be very disoriented, the critical glucose and leaf cycling would be very degraded, because plants have most of their queues from temps, water and sun.
http://www.madsci.org/posts/archives/2001-02/981072513.Bt.r.html
more infos

My understanding (as a gardener) is that a lot of temperate-zone fruits actually require a certain number of chilling hours - that is, time spent below some temperature - to trigger fruit production the next season.  (Something similar applies to some bulb & seeds - they don't sprout unless they've experienced some chilling.)  I don't know whether that applies to things other than fruit production, though.

@jamesqf My understanding from living by the Mediterranean, where winters without any chilling night aren't uncommon but most European fruit trees grow and produce fruit, is that chilling days are not critical. Daytime length is probably more important as regulator.

@Pere Dec. The meditteranean evokes citrus grapes and almonds, I just checked this info for apples: Most apple varieties need 500 to 1,000 chill hours or temps below 45 degrees F.... some northern plants require some time in the freezer to sprout, and they do have deciduous biochemistry, where some seasonal change is essential.


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Can i grow bacteria on potato dextrose agar?
I was wondering if potato dextrose agar was a suitable environment for bacteria. Does it have all the requirements bacteria need or is it limited? Specifically:
Escherichia coli,
Staphylococcus aureus,
Enterococcus faecium,
Pseudomonas aeruginosa.

We need to know which bacteria you want to grow in order to answer you

Without knowing specifics about the bacteria I question this will be kept vague.
Generally speaking though, yes, some bacterias can be cultured using a PDA plate. The plate contains potato starch agar and dextrose. Sometimes Tartaric acid is added to stop unwanted bacterial colonies from forming, which again highlights how possible it is for them to form on the plate. The mechanism of action of the Tartaric acid is to lower the pH, out of the physiological range of most bacteria.


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How many allele for one gene are found inside our cell?
I know it depends on phase. So i am talking of -
1) in human (diploid organism) with cells before prophase (before replication, when 23 pair of homologous chromosomes are present ). I think answer is 2 if we not consider male XY sex chromosome because they are not homologous in which case the answer should be 1. But then i get confuse why genotype is shown like Tt (doesnt this means two alleles per chromosome).
2) in gamete cell. I think the answer should be 1.
Please tell if i'm correct.

In short. Yes.
Each diploid cell has 23 pairs of chromosomes (22 of which autosomal)
In relation to the genotype part of the question. The "Tt" refers to each allele on the chromosome and wether it is dominant or recessive. Take for instance, hair colour. On one chromosome, there would be an allele from one parent and on the other an allele from the other parent. This is why two letters are needed, to show the allele given by each parent.
You can think of dominant and recessive in terms of how powerful the copy of the gene(allele) is. An allele that is able to overpower and mask traits is called dominant, one that is not strong and cannot mask traits is called recessive. This is why you need two recessive alleles for recessive disorders, otherwise the dominant allele would cover it up.
As this is a homework question I have tried to explain this in simple terms which you should understand. Hope this helps.

Your use of the term sister chromatid is incorrect. I think you mean homologous chromosome.

Apologies. I deleted half of a paragraph before posting and joined the wrong sentences together.


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What flower is this?
I received this flower as a gift.

So far, I couldn't identify what flower it is. My family thinks it may be either some sort of Clematis or an Ipomoea purpurea.
The main reason I want to identify this flower is to know if it can live outside most of the year (I live in France).

my first impression was that it was mandevilla. We had this plant in a pot on the porch when I was growing up. The plant stayed outside until winter (temps typically below 0 C for 3 months) at which point we stored it inside. Mostly dies back each winter and we clipped it. Each summer, we put it back outside and it grew nice and big again.

The leaves are most similar to this Mandevilla
It may be a hybrid periwinkle, in France and UK there are blue ones in wild and there are pink ones i.e. in Madagascar. If it's a periwinkle you can tell by the fruit and veins of the leaves. It can be a variant of Vinca minor. It has evergreen type leaves, it may be tropical. It is also similar to the Oleander family. Clematis and Ipomea have new foliage every year.
Also see this.

@comprehensible is right: it's a Mandevilla, most likely the Mandevilla sanderi which is common in cultivation.
You can find further information on wikipedia, and of course on a lot of gardening sites.


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What will happen if there is high concentration of both calcitonin and PTH in blood?
What will happen if there were a high concentration of both calcitonin and PTH (parathyroid hormone) in the blood? In that case, will calcium resorption from bone occur, or absorption from intestine, or deposition of calcium in bones? Also, will blood calcium level rise or fall?

It depends on duration of PTH , whether its intermittent or chronic hyperparathyroidism, in different cases effects will be different.

Thanks @David for all your effort in improving this post. Your comments were flagged for deletion and the mods did so. However, they were quite helpful and if you feel they should stay in place, let me know. Cheers.

To OP, is this a homework question? You are required to show prior research effort. We're not here to spoonfeed the answers to your assignments.

@AliceD This aint homework. I was reading this in book and question spoofed in my mind. There was no where to research properly. The two hormones works on different osteocytes, I had no such idea,  to search anything relevant.

Short Answer: quite surprisingly, both will occur.
Long Answer: as is quite well known, calcitonin lowers blood Ca2+ levels. It performs this task by two methods:

it inhibits the activity of osteoclasts in the bones (Custoff, 2008)
it inhibits reabsorption of Ca2+ in renal tubular cells, allowing it to be excreted in urine (Potts et al, 2008)

However, the second mechanism is only minor. On the other hand, parathyroid hormone (PTH) performs just its opposite: it increases Ca2+ levels in the blood.
So, lets come to the main point: since calcitonin and PTH have opposing functions, what would happen if both were acting simultaneously?
It seems, funnily though, that both the functions will occur simultaneously. Wong et al, 1975, in their research, showed that the target cells of calcitonin and PTH are different i.e. calcitonin and PTH act on different osteoclasts. So, to put it simply, while activity of some osteoclasts would be decreased, that of some others would be increased. Overall, Ca2+ levels in the blood would remain pretty much constant.

Would be much better if this is also added, PTH is not always reabsorbing the bones, https://www.ncbi.nlm.nih.gov/pubmed/16563840


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Why sea water fish can't survive in Fresh water?
Why the sea water fish can't survive in fresh water?
What really happens to the fish if it get into fresh water from sea water.
What are the possible reason...

Does it really depends osmotic pressure on the cell of the fish?
It depends on the buoyancy of the fish?
The bacteria content in water?
The temperature of the water?

homework questions should be tagged as such. They should also show some effort on your part to find an answer.

Osmosis:
In case you didn't know, osmosis is the flow of solvent (here its water) across a semipermeable membrane from lower concentration of solutes to a higher concentration.
Freshwater fishes have their bodies with body fluids isotonic, or same concentration, with the surrounding freshwater body. If you throw such a fish into seawater, considering that seawater has a lot more solutes dissolved in it, water will flow from the fish into the seawater. The fish would get deprived of water and will most probably die.
Note: Certain fishes like Sockeye Salmon can survive both saltwater and freshwater. Sockeye in particular usually lives in marine habitats, but returns to freshwater for spawning (egg laying). This fish overcomes the osmotic problem, by staying in the intertidal zone for a while, thus adjusting it's body fluids to the intertidal zone, and then finally moves to the freshwater. Yet, some others have non-permeable membranes as skins, so that osmosis isn't a problem for them.


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What happens if the queen ant is removed and taken elsewhere?
Suppose I manually remove the queen ant from a colony, and take it to a completely different place (ant cannot visually travel back to its colony). Will it start a new colony in its new surroundings, similarly to the way in which it did after the nuptial flight? Or will it keep on looking for its old colony?

I didn't find any previous attempts of that artificial test, it depends a lot what kind of new habitat she is placed into. Ants use a lot of chemical queues, that tell them if they are in the right kind of habitat, humidity, rock, wood, to use as a burrow, and queens have an instinct to hide from light. There may be a question of time before the queen ant changes behavior, if she has no colony chemistry to react from, so it may take her 1 hour, 1 day, 3 days to return to solitary behavior. So she would search for her perfect scenario, as similar to a nest as she can find, and start a brood.


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Protein content in sprouted beans
I have checked on Wikipedia which says that sprouted mung beans has way less protein than normal one, while on web you will find articles saying sprouted beans are best, which is true, how do I eat unbaked mung bean anyway without any processing they are so hard. Does soaking moon beans overnight really reduce protein content drastically ?

Short answer:

Yes the legume seed protein content decrease when it germinates.

but still;

The sprouting seed is healthier.

Long answer:
Yes it is true that after germinating some of the protein decrease. It is mostly due to breakdown, transport and consumption of protein stored in seed. All fabaceae (former Leguminosae-sensu-stricto) members use a large amount of protein storage, such as Vicillins, Legumins, etc in their seed cotyledons . All edible true-pulses , including pea , mung, etc belong to fabaceae.  When the seed germinates, theses proteins breaks down into simple amino acids and small peptides, and get reallocated*.  In addition, a part of this work as food (respiratory substrate) through amino acid oxidation  **.

Fig-1

  Protein mobilization in seeds... simplified.
  Source... *
Fig-2
  .
  The cellular process of protein mobilization in Mung bean cotyledon.
  Source ... *

We are commonly advised to eat sprouting seeds not for their protein content (we get the major portion of protein from daily major foods like meat, fish, eggs, leafy vegetables, etc.); but it is for the vitamin content.
This paper says

" Mung bean sprout produces several kinds of hepatoprotective compounds such as flavonoid and chlorogenic acid."

There are also many papers related to sprouting mung bean; such as this but I do not have full access to them (sorry for that), such as this, this etc.

Reference

* Protein Storage and Utilization in Seeds; by Rod Casey, J.Derek Bewly and John S. Greenwood. Published as a chapter in a book, Plant Metabolism, Edited by Dennis, Turpin, Lefbvre, Lyzell. Second Edition.
** Amino Acid Catabolism in Plants; Tatjana M. Hildebrandt , Adriano Nunes Nesi, Wagner L. Araújo, Hans-Peter Braun (NCBI-PMC) (Full-text Free Open access link)


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Why has life evolved around oxygen?
Why has life evolved around oxygen? Many lifeforms require oxygen to breakdown bio-molecules and release energy. I think there are two possibilities:

Reactions with oxygen tend to release more energy, so it is profitable to use oxygen for metabolic activities.
It is chance that it got to be oxygen; it could have been anything.

Which is right? Or is there some other possibility?
Edit: Yes, it is true that there are organisms to which oxygen is toxic. But you can't ignore the large numbers of organisms to which it is absolutely necessary for living. Why could it not have been some other molecule? Which property of oxygen drives it to become the most useful in bio-processes?

Have you done any research before asking this question? If you have, we would like to see it (edit it into your question.) Thanks!

I think you need to consider that oxygen is toxic to large groups of microorganisms, because it poisons their electron transport chains.
Strict anaerobes does not tolerate the presence of oxygen at all and as such I would argue that life can survive and thrive without O2.
Also life on earth evolved under conditions were O2 levels were extremely low, in fact when some organisms started to release oxygen into the atmosphere it caused an extinction event (Great Oxygenation Event).
So I think you need to change your question to why did life adapt to the presence of oxygen?

The reason life adapted to the presence of oxygen is that if it hadn't, it would have died - and so we wouldn't be around to ask the question :-)  Just a larger version of why bacteria become resistant to antibiotics, plants develop resistance to herbicides, insects to insecticides, &c.

@jamesqf You cite the reason why organisms became adapted to the presence of oxygen. But why did oxygen become so vital to a large number of organisms? If it is because of the abundance of oxygen, aren't plants major contributors to stable oxygen levels during the oxygen cycle? So does it not mean that life also contributed to the abundance of oxygen and so it could not be the reason why life evolved around it?

@prlfak1: I think what I'm trying to say is that asking "why" really isn't all that meaningful in evolutionary terms.  Photosynthetic organisms hit on the trick of using light for energy, releasing oxygen.  Then other organisms evolved ways of using this energetic waste product for their metabolism, which allowed them to survive & reproduce.  Lots of photosynthesis eventually meant lots of O2, so lots of O2-using organisms.  But there are other ways, like chemosynthetic bacteria that react CO2 & H2S to produce carbohydrates & sulfur.  It's just that H2S isn't all that plentiful...

The main drive towards oxygen is it's efficiency. When you consider the order in which different energy generation pathways evolved you will see the improvement. Here are the main ones

Glycolysis - produces 2 NADH and 4 ATP. Plus you end up with two pyruvates ()
Pyruvate Decarboxylation - 3 NADH, 1 FADH2, and 1 GTP (equivalent to
12 ATP)
Electron Transport Chain (final electron acceptors other than O2) - 2-36 ATP equivalent. This number varies so much because bacteria have a whole range of different systems and their efficiency varies greatly. However efficiency mostly depends on the final acceptor redox potential which is highest for O2
Oxydative phosphorelation (ETC with O2 as final acceptor) - 10 NADH (equivalent to 30-36 ATP)

In addition to that 2.3 bya Great Oxygenation Event occured. What happened is that cyanobacteria was releasing a lot of oxygen as part of photosynthesis for a while but it was all instantly bound to Iron diluted in ocean waters (and other compounds). Then 2.3 bya, oxygen levels got saturated and atmospheric oxygen levels increased rapidly driving many obligate anaerobes to extinction.

Yes, oxygen is crucial for all of the processes mentioned above, where it is used as electron acceptor. The reason why oxygen was "chosen" over other electron acceptors, which are in fact better electron acceptors, was due to the abundance of water and therefore how easily accessible oxygen is. There are in fact certain organisms, such as lithotrophic bacteria, that instead of oxygen use sulfur.
You can also read up more about when the production of oxygen first occurred on Earth and which were the first organisms to use oxygen here: https://en.wikipedia.org/wiki/Great_Oxygenation_Event.

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