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Blahah

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Everything posted by Blahah

  1. OK, sorry I thought you were saying you had come up with a design. So, my previous comment still stands. Choose one variable property. Then you need to find a dataset for global fish abundance and another one which gives you your property (e.g. world ocean temperatures). I wouldn't bother with salinity - it doesn't change that much in open ocean. Oxygen content will be closely related to temperature. pH also won't change much in the open ocean. Temperature would be a sensible thing to look at. Edit: I didn't address the basic points of your assignment.... You might hypothesize that temperate oceans are more biologically productive than arctic oceans due to the effect of temperature. This leads to the predictions that: - there is a difference in temperature between oceans - there is a difference in biological productivity between oceans - with regards to fish abundance, a productive ocean should support a higher fish abundance, so there should be a greater fish abundance in the warmer ocean - fish abundance in general should be correlated with ocean temperature, where all other properties of water are equal And the method would involve finding datasets on the internet which tell you temperature of the ocean and fish abundance. They don't need to be from the same source. Then you just analyse whether your predictions are met by the data. Ideally you would compare sites where all the other properties of water which you identified are identical, with only temperature differing between the sites.
  2. Hi, Firstly you don't need to post twice. Secondly, you haven't given your experiment design, you only named the properties of water you looked at. Please describe the experiment you designed. If your lecturer has said you looked at two variables at once, then that's probably the problem. You say you looked at 4 properties of water. To do this you would have to make sure that in each run, 3 of those variables were kept constant and one was varied. Then you can explore the effect of changing that variable. So for example if you wanted to look at sites with varying salinity, you would choose sites where OC, temp and pH were the same between all sites. Then you can map fish abundance between those sites and graph it against salinity. If I were you, I'd think about what the primary difference is between temperate and arctic waters is. Is the the mean daily temperature? Is it the range of temperatures experienced over time (e.g. does the temp fluctuate more in temperate waters)? Is it salinity? Whatever you think characterises the difference between the two locations, look at that first.
  3. Deoxygenated blood is not blue, it's dark red. If you've ever given blood, you can see deoxygenated blood flowing along the tube as it is taken venously. It looks like red wine. Oxygenated blood is bright scarlet, so your answer could still be correct, in that because the scarlet colour of oxygenated blood contributes much of the hue of normal skin colour, when the blood is less oxygenated the skin is less bright red. Cyanosis is not people actually being blue, they just appear bluish due to the relative colour difference between normal skin tone and cyanosis. Here's a paper which attempts to explain why veins appear blue (PDF); the same principle applies to cyanosis.
  4. Remember that it's just a trend, there are many exceptions and the reasons are not necessarily obvious at all. Also, veterinary healthcare is nowhere near as advanced as human medicine. So an animal in captivity is not in similar circumstances of care to a human in the developed world. If you include humans in the scale it should be humans before modernisation - i.e. before 1700. The average lifespan at birth of a human in the Roman empire was 28 years. See this Wikipedia article for some other figures. The lifespan of the red deer is about 20 years, yes. There are slight variations between different animals, the point of the exercise is that endothermic animals tend towards the trend. It is unlikely that genetic diversity is a major factor in human survival, I would suggest that intelligence and social living are the main reasons why humans might live longer. But certainly different species have different abilities to counter the effects of aging. Consider that species which care for their young have a stronger evolutionary pressure to survive longer to ensure their offspring survive. Human babies are completely useless until the age of about four, and not really equipped to survive on their own until much older. Deer fawns on the other hand are fairly competent after just one year. Ectothermic (cold-blooded) animals may survive longer because when then allow their body temperature to fall, as sea turtles and giant tortoises frequently do, free radicals (and all other molecules) are less active.
  5. help button suggests these tags for LaTeX... [latex...] [latex]y = \sqrt{4x^2}[/latex] a thread gives these tags... [math...] [math]y = \sqrt{4x^2} [/math] edit: turns out both work
  6. This is not at all obvious, and there is no reason at all to suppose that it's true. Why must there be any deep undiscovered truths? Whether you find it hard to accept or not has no bearing on the subject. Do you have any evidence that there must be more to the world than meets the eye, other than a feeling? This surely belongs in speculation, or philosophy. It's certainly not quantum mechanics - whether consciousness is a quantum phenomenon is not established or even tested AFAIK.
  7. I don't care at all whether we have free will. The illusion of free will is functionally equivalent to having free will. However, you haven't given any logical sequence which leads to the conclusion that we have no free will. Your suggestion is no more likely than an infinite number of other possible explanations for consciousness. Do you have any scientific basis for your 'theory'? The closest we currently have to a scientific basis for an understanding of consciousness is that it is an emergent phenomenon of the complexity of interactions in the brain. It might be illusory, it might not, we have no evidence either way. Guessing about it really has nothing to do wth physics that I can see. edit: and there is no evidence for a mind/brain duality either. Progress in neurobiology brings us closer to the conclusion that the Cartesian duality is false, out of date.
  8. I always autoclave media with foil folded over the mouth of the container and secured with autoclave tape.
  9. This is a rather well publicised idea which stems from people's general perception of a correlation between body size and lifespan in endothermic ('warm blooded') animal species, and some research papers which compared metabolic rate with mass for some species. The entire concept is called the allometric scaling laws of biology. I'll try to tie the various ideas together in historical context... The first person to study it was Max Rubner in 1883. He compared the body mass and metabolic rates of 7 breeds of dog ranging from ~3kg to ~30kg, and found that plotting the data on logarithmic scales produced a straight line relationship (with gradient 2/3). He later worked this into a theory after doing more experiments, called the 'Rate of living' theory. It was widely thought that the reason that the relationship worked out to approx [math] metabolic\,rate \approx mass^{2/3}[/math] was because this same relationship holds for surface area to volume of a cube: [math]surface\,area = volume^{2/3}[/math] and the relationship is similar for surface area to volume of animals. This gave heat conservation as a reason for larger animals to live 'slower'. Metabolism produces heat, and as volume increases animals retain more heat and therefore larger animals must have a slower metabolic rate in order to avoid overheating. Biological systems in general start to operate less efficiently over about 37°C, a limitation caused by the denaturation of proteins. Max Kleiber also worked on this idea in the 1930s. He measured metabolic rate but did so for a range of species, and he produced a mathematical formulation of the relationship between metabolic rate and body weight: [math]q_0 \approx M^{\frac{3}{4}}[/math] where [math]q_0[/math] is metabolic rate and [math]M[/math] is mass. This formulation is very famous and is found in many biology textbooks. It's often referred to as Kleiber's Law. It shows a similar relationship to that described by Rubner, but with a power of 3/4 instead of 2/3. This confused people for a while - if the relationship is not governed by the temperature constraints, then what causes it? In 1997, Brown and Enquist published a paper in which they suggested that the efficiency of branching networks might be the reason for all the allometric scaling laws. For example, the circulatory sytem of mammals is a branching network. Another theory, suggested by Hung-hai, Ulf and Rajindar (1993), relates size with lifespan. They suggested that free radicals released by mitochondria during respiration cause cellular damage and create ageing. This would suggest that animals which respire faster would die faster because the rate of free radical production is increased. Since animals essentially respire as fast as they can given other constraints (such as the heat constraints, and the limitations of their circulatory system) and these restrictions increase with size, smaller animals might indeed tend to have much shorter lifespans than longer animals. Faster metabolism would have to be supported by faster heartrate to provide oxygen and fuel for respiration, whilst slower metabolism so there MAY be a general similarity in total hearbeats per lifetime between endothermic mammals. There have been some studies which specifically correlate heart rate and life expectancy, such as Levine's 1997 paper. This just goes to support the idea that living fast often means dying young. There's a good book about the whole topic of allometric scaling in animals, by the famous animal physiologist Knut Schmidt-Nielson, called Scaling, why is animal size so important? And if you have access to journals, this paper by West, Woodruff and Brown (2002) ties together all the various scaling laws across all sizes of life.
  10. I can't actually find the ATCC definition, I just remember it from lectures. However, you are right, it's almost certainly 16SrRNA. I wasn't even aware of DDH until I read your reply (before my time!). It seems the traditional DDH threshold was 70%: Richter, Michael, and Ramon Rosselló-Móra. 2009. Shifting the genomic gold standard for the prokaryotic species definition. Proceedings of the National Academy of Sciences.doi:10.1073/pnas.0906412106. confusingly, whilst trying to learn about DDH, I came across this paper which doesn't seem to distinguish between hybridisation and 16S: de la Cruz, Fernando, and Julian Davies. 2000. Horizontal gene transfer and the origin of species: lessons from bacteria. Trends in Microbiology 8, no. 3 (March 1): 128-133. doi:10.1016/S0966-842X(00)01703-0.
  11. I'm a new member, and one of my first actions was to check the help pages to see what BBcode was allowed. I was particularly interested to see whether I could post in LaTeX. I did eventually find the answer in a post, but I think it should be mentioned in the Posting section of the Help pages. That's the natural place to look for the information.
  12. Moontanman they look similar in shape and colour, but I would be surprised if they are the same. If you look at the raised parts of the cap in the OP's second picture, you can see they are quite a regular shape with straightish edges. Compare it to Amanita muscaria var. formosa where the white raised areas of the cap look like they have torn edges. Regular shaped raised bumps like in the OP's second picture are characteristic of the genus Lepiota and are called scales. Powdery/torn bumps like A. muscaria are called 'volval remnants' and are left over from when Amanita species cap bursts out of the volva (a cup like structure) as they first emerge. It is conceivable that they are the same, and this could just be an unusual specimen - it's the star shaped ring which is confusing. In either case, Moontanman is definitely correct that you shouldn't eat them. If you want to eat wild mushrooms, stick to the extremely obvious ones which can't be confused with poisonous species. Roger's Mushrooms is an excellent site for both identifying wild mushrooms and learning how to recognise common poisonous ones. I have his book, Mushrooms, and it is very clear and useful.
  13. Whoops sorry - Shadow's right, I didn't notice that yours was log base 20. However, I think my solution is still correct as well. eidt: ugh, I also formatted the text wrongly in my answer. Corrected now. Maybe I should wait until I'm better at maths before advising others!
  14. I believe the American Type Culture Collection defines species delimitation at 97% similarity. SGM uses the same definition. It's just a working definition though, in practice the species concept is false for prokaryotes. It is useful, which is why it's kept around, but I think it would be better to have (and expect a move towards) a new taxonomic nomenclature for prokaryotes, more similar to that used for viruses which actually accounts for the unique properties of the systematics of the clade.
  15. Blahah

    Growing wood

    GM is a much more likely source of future refinements to wood production. If we want to strengthen wood by enforcing less variability in cell length, higher lignin content etc. then engineering new or existing tree species is the way to achieve that. Growing wood bacterially is not feasible. Mainly because wood derives its structure from cells - it is the very fact of multicellularity that allows wood to exist. However, growing meat substitutes via microorganisms is entirely feasible and being actively researched. We already have a major food product produced in this way: Quorn. It's mycoprotein grown in continuous culture fermentation of the fungus Fusarium venenatum. In answer to Mr Skeptic's question about where the energy and nutrients come from, a basic input of water, heat and simple sugars plus a mineral mixture is required - the fungus then synthesizes the other required components itself.
  16. The zebrafish is an ideal model organism because is it seethrough - allowing very easy study of organ development in living organisms. You can't just decide on a new model organism yourself, and there's certainly no point in keeping it secret. For it to be model, many groups must be working on it. CharonY's criteria are spot on.
  17. Blahah

    Plant Questions

    Node is correct, but I don't think he's asking about root hairs. "absorb water & minerals from the host plant" makes it sound like you're talking about a parasitic plant, in which case the haustorium is the organ you are talking about. http://en.wikipedia.org/wiki/Haustorium
  18. I'm sorry but both of those identifications are definitely wrong. @Truth: Both the fungal species you suggested are brackets: Daedalea quercina looks like this: It is only found growing directly on the surfaces of wood, especially Oaks (hence the quercina in the name). while Laxitextum bicolor looks like this: It is also only found growing on the surfaces of rotting wood. @antwann: I can't identify the first species from that picture but if it's still growing you can pick it, turn it upside down and take a picture which shows the gills. If you could also take a picture with a ruler next to the mushroom I can probably identify it from that. The second one is not an Amanita, their ring develops by falling down from the cap as it opens. Since that one has a closed cap but the ring is clearly visible, I don't think it's an Amanita I would guess that it's a very young Lepiota of some sort, or from the star-shaped ring it might be an earthstar. I don't know of any earthstar species with a scaly bulb like that though. If you can go back the spot and find it again it should have opened out more, then you can take pictures of the gills. Also please incude the size.
  19. Yes you would expect some variation depending on the species and the growth conditions. What species are you working with? What's the growth medium?
  20. This is unlikely to be a fungus. Pi Lo Chun tea is prized for the attractive white hairs on the leaves, so it is more likely that you're just seeing is the wispy hairs of the leaves themselves. This is what it should look like: http://upload.wikime...ing_2007%29.jpg It is possible to get leaves which are contaminated with fungal pathogens harvested and included in a product on the shelf, but the likelihood that a dangerous quantity of mycotoxins would be found in them is extremely small. If nothing else, many others would likely have died before you and you'd be able to easily locate a report on the internet. If you're still interested in doing some experiments with your tea leaves, you can put a pinch of them in a petri dish with enough warm water to rehydrate the leaves. After a few hours take a drop of the liquid, or cut a thin section of tea leaf, and look at it under a microscope with the 100x objective and an oil droplet. You'll probably see lots of filamentous bacteria swimming around, and some spirochaetes too perhaps. Fun to watch. Tea leaves, despite their antimicrobials, actually contain very high microbial load (all harmless bacteria and some harmless fungal species). If you still think it's a fungus after comparing with the photo above, post the best pictures you can produce of your tea leaves and I'll get it identified by our mycologists (I work at Royal Botanical Gardens Kew, we have a very good mycology dept).
  21. The gamma subunit and the attached c subunit of ATP synthase rotate in between the alpha and beta subunits. In the diagram below, gamma is yellow, c is red and the alpha and beta subunits are the greenish parts at the top. The whole yellow and red part rotates driven by the flow of protons down the gradient. You can see the path of protons in the diagram. edit: source of diagram is here... http://www.life.illinois.edu/crofts/bioph354/lect10.html you can read more detail about ATP synthase at that site.
  22. Hi kyky. I hope a teacher didn't set you this as an essay question! Firstly because GMO (genetically modified organisms) are not made by injecting DNA. The two most used methods in transformation of plants are using Agrobacterium tumefaciens as a vector, and biolistic techniques in which small lumps of gold (or similar metal) are coated in the DNA to be inserted, then fired at a porous plate above the target plant cells. Fragments of the metal carrying DNA enter the cells and if you're lucky, something gets into the nucleus and if you're even luckier, something gets incorporated. For bacteria, electroporation is the most common method of transformation. Read more about the methods here: http://en.wikipedia.org/wiki/Genetic_engineering#Transformation The major GM crops in the world are herbicide resistant. Then a smaller, but significant group of other crops are pest resistant. A much smaller group of crops are biofortified, having the engineered ability to synthesize vitamins. The GM foods industry is really strong in the USA and China. Much less so in the UK and Europe. In the UK, there is strong public opinion against foods containing GM ingredients, and also strong opposition to the growing of GM crops. Most of this public opinion stems from a deliberate campaign by Greenpeace to convince the British public not to support GM. The entire campaign relies on misinformation and lying about the science, and I spend a painfully large portion of my time correcting people about the scientific basis of GM. The Wikipedia page which zapatos linked to gives an overview of the current state of GM foods. Do you have any more specific questions?
  23. No, this step is incorrect. you have 36.65=20n first put the unknown on the left: 20n = 36.65 to get rid of the exponent you can take the log of 20n. Make sure you do the same to both sides. n log20 = log36.65 then you should be able to find n.
  24. It is usually standard, at least in the biosciences, to use a CI of 95% (a= 0.05). However, you should consider the test you are using. I will give an example with ANOVA. Does your data violate any of the assumptions of the test? ANOVA assumes homogeneity of variance and normally distributed data. Let's say your data is not normally distributed (but only a bit off). You can make your ANOVA more reliable choosing a CI of 99% (a = 0.01) to reduce the possibility of an error due to violation of the test assumptions. So, usually you would just go for 95% CI, but if you have a reason to think the test might not be ideal (assumptions slightly violated for example) then you could use a higher CI to make your test more trustworthy.
  25. Hi all, biology undergrad here, specialising in plant biology and microbiology. I hope to bring my chem, maths and physics up to scratch whilst sharing my bio knowledge in return. I've been reading the forums and it looks like a great community. Peace
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