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Friday, November 13, 2009

What would happen if you lit a match in space?


What would happen if you lit a match in space?

A flame goes upwards because of convection. The hot gas created by the flame rises. As you say, there's no up or down in space so the gas just forms a sphere around where it's burning and you just get a sort of circular flame. But actually stuff doesn't really burn very well in space. This is because the process of the gas going upwards (as happens on Earth) gets rid of the carbon dioxide formed in the burning process and sucks in more oxygen to keep the flame stoked. This keeps everything burning quickly. As there's no upward movement of gas in space, you don't have much oxygen getting into the flame and it's quite a poor flame that is formed. So essentially it chokes itself in its own waste products and just goes out


Why do pictures fade in paintings and books? Is it a chemical reaction?


Why do pictures fade in paintings and books? Is it a chemical reaction?

The colours in pictures are made out of chemicals. They tend to be chemicals that interact with light quite well because they have a colour, meaning that they absorb some colours and reflect others. If they are exposed to too much light, especially ultraviolet light from the sun, they break, become damaged and stop being coloured. It depends what dyes you're using. Inorganic dyes that include metals tend to survive a lot better in sunlight than organic ones, but basically the chemicals get damaged and bleached. If the molecule is broken by absorbing lots of UV light, then its absorbency changes. The same thing happens with human hair in summer. You can make the process happen a little bit quicker if you put some lemon juice on. On a similar point, the reason why bleaches work is that dye molecules are sensitive and quite easily damaged. A bleach is something which oxidises something, and goes round and damages things at random. The things that get damaged first tend to be the colour molecules and so things tend to go white.


Why is it that bubbles are always round?


Why is it that bubbles are always round?

You may have heard of surface tension this is due to water molecules pulling together and trying to minimize the number of them on the surface and not surrounded by other water molecules, it can hold up pond skaters and float pins etc. Now the water in the soap film is trying to minimize it's area too, and as there is a fixed amount of air trapped within the bubble and the shape with the least surface area for its volume is a sphere, bubbles are spherical.

Why is the sun so hot?


Why is the sun so hot?

The sun is so hot because the sun is a giant nuclear reactor in the sky. It's mixing on hydrogen with another hydrogen to make another light gas called helium. You can find helium in the funky balloons that float. When you mix the two hydrogens together, you get a lot of heat energy, and so the sun on its surface is at least six thousand degrees centigrade. That's what keeps us warm.

Thursday, November 12, 2009

Does the nicotine vaccine stop the cravings to smoke?


Does the nicotine vaccine stop the cravings to smoke?

Probably not. The mechanism works by stopping the effects, and so might actually increase the cravings. The vaccine is probably best used in combination with something that helps with the withdrawal symptoms. However, by stopping the effects, it also helps to break the cycle of reinforcement. Eventually this may lead to people stopping people smoking because it does nothing to help the cravings.


Why don't I ever dream?


Why don't I ever dream?

Surveys have shown that about 6% of the population say that they absolutely never dream. There doesn't seem to that much difference between them and the rest of the population, but what has also been done is take some of these people and wake them up in sleep lab when they're in REM sleep. Every 90 minutes or so during your sleep the majority of people go into REM sleep, so you put these people in the lab, wire them up, and what happens is that you can wake people up during these periods of sleep when they ought to be dreaming. With most people you've got about an 80% chance of a dream being reported if you wake them up like this. Now if you're a non-reporter of dreams, that is one of the 6%, what's been found is that 0.6% of these absolutely never report a dream even if you wake them up during REM sleep, so in your case Betty, it is quite possible that you are having dreams and you just don't remember them.

What ingredients go into antibiotics, and how do they work ?


What ingredients go into antibiotics, and how do they work ?

Tablets taken by mouth contain a lot of the actual antibiotic. They also contain lots of other substances which enable the manufacturer to produce a tablet that can be kept in packets and are easy to swallow. For example, the smooth outer coatings of some tablets are often made out of vegetable products. Once the tablet is in your stomach, the active bits distribute around the body through the bloodstream, reach the site(s) of infection, and kill the offending bacteria. There are three different ways antibiotics kill bacteria. Some stop bacteria from growing by stopping their protein production; others stop them from making chromosomes; and the third type stop bacteria from making cell walls. Without a proper cell wall, the bacteria explode and die.


Is it safe to swallow chewing gum ?


Is it safe to swallow chewing gum ?

Chewing gum used to be from a rubber plant, but is now artificial. It sticks to the road because it contains long oily polymer chains which are chemically similar to some of the constituents of the road surface. It's very hard wearing stuff and doesn't get digested when you swallow it. It can cling onto the sides of your intestines and distort the gut, are occasionally trigger a dangerous disorder called intussusception where the gut telescopes inside itself, although this is rare in adults. It would be better for the environment if people could swallow it. Until then, it would be good to develop a family of chewing gum-consuming bacteria that could eat it off the pavement !

Do fish ever get thirsty, and do they sweat?


Do fish ever get thirsty, and do they sweat?

Bony fish that live in the sea have blood that is less concentrated (in terms of salt) than the water they live in. By a process called osmosis, these fish will lose lots of water into the sea. To stop them from dehydrating, bony fish drink lots of water. Although drinking salt water is never a good idea if you're a thirsty human, fish have special mechanism on their gills that enables them to excrete the excess salt they are drinking. By pumping the salts back out again, they are able to drink water without become even more dehydrated. In contrast, sharks make their bodies as concentrated as the water around them. They do this by building up levels of urea in their blood. This is why dead sharks smell like urine. Having highly concentrated blood also means that sharks won't do very well if put into freshwater - water will rush into the shark by osmosis and it might even explode! Sweating is a process designed to help organisms cool down. On land, sweat on the skin evaporates and takes heat away from the body, making you feel cooler. In the sea, water can't evaporate off the fish because they are already in water! So no, fish don't sweat.

Wednesday, November 11, 2009

what is the difference between a freckle and a mole ?


what is the difference between a freckle and a mole ?

A freckle is a collection of the skin pigment melanin in the skin, but in a concentration. Some people who are very freckly, have very pale skin in-between their freckles, so they have little patches of skin which makes the pigment not many cells which make the pigment outside that patch. A mole is the cells in the skin which make the pigment but more them in a lumpy patch.


Why are some Animals Born with their Eyes Closed?


Why are some Animals Born with their Eyes Closed?

There are lots of examples of animals that are born with their eyes close - rabbits are just one example. It's all to do with whether animals need to be able to see when they are first born. Some animals, like horses or deer, are born with their eyes open because they have to be independent from birth. In the wild they have to be alert so that they can escape from predators or others dangers. But rabbits don't have to be able to see because they can rely on their parents looking after them until they are old enough to survive on their own. And since they are born in dark burrows anyway, there wouldn't be much point in them being able to see. Baby rabbits don't open their eyes for about a week after they're born. Kittens don't open their eyes for a week or so, and they can't see as well as a fully grown cat until they are several months old. Hares, though, are born with all their fur, and their eyes open !


Why can you smell some gases, but not others ?


Why can you smell some gases, but not others ?

Actually, methane doesn't smell either, but you probably thought it did because it is often found with hydrogen sulphide which is very stinky and smells just like rotten eggs. Gases get into our noses to excite our olfactory (or smelling nerves) which are connected to our brains to allow us to smell. How a gas smells depends on it's size and shape, and how it can fit into our smell receptors in the nose. It also depends of course on how easily a gas evaporates. Gases which evaporate more easily smell stronger because more vapour manages to get into the nose. Gases which smell tend to be the ones which are heavier, and more than 15 times the weight of hydrogen which is the smallest atom, so methane and carbon monoxide (CO) don't smell but hydrogen sulphide (H2S), and chlorine (Cl2) do. Why does it smell when we break wind? This is because the your gut contains lots of bacteria and enzymes to digest your food and in this process gases like hydrogen sulphide (H2S) are produced. Interesting fact - we break wind on average 14 times a day. However a word of warning, if the concentration of hydrogen sulphide increases too much, your olfactory, or smelling, nerves are paralysed and you lose the ability to smell it. Other gases which don't smell are Oxygen, Nitrogen, and steam. Gases which do smell include chlorine, bromine, iodine and sulphur dioxide.


What makes glue sticky ?


What makes glue sticky ?

Glues like the ones used at school are made up of long chains called polymers, which are a bit like spaghetti strands. When you glue 2 pieces of paper together the polymers get into all the microscopic cracks and crevices in the paper, (a bit like ink soaking into the porous surface of paper). As it dries and the water evaporates the polymer molecules are left in the cracks to hold the paper together. But not all glues work like this. Sometimes the glue contains a substance that temporarily melts the 2 surfaces you're trying to stick together, effectively welding them together when the glue dries. Superglue contains cyanoacrylate. When this substance comes into contact with water it forms chains which bond to the ends of the 2 things you're trying to stick together. As the glue dries the chains harden until they can't move.

Why do animals have to die ?


Why do animals have to die ?

Dying actually serves a useful purpose because it is one way to eliminate weaker individuals, and the genes that they carry, from the population. If you inherit a bad gene which makes you less healthy and causes you to die at a young age, there is a lower chance of passing that faulty gene on to your future offspring, removing the gene from the population so that it cannot harm any of your descendents. But for most people the simple answer to why we die is because of the process of ageing. But if you ask why do we age, the simple answer is we don't know. It would appear that our bodies do not repair themselves adequately to the extent that we slowly accumulate damage to our cells and our DNA which eventually claims our lives. What we do know about ageing and longevity is that the process is heavily influenced by the genes that you inherit from your parents - in other words, if members of your family tend to live a long time, then you will too. One way to increase you life expectancy is to eat a diet which contains just enough calories to provide for your daily needs. Experiments on flies, monkeys and even people consistently show that low calorie diets like this can significantly increase your life expectancy, possibly by as much as 30%

Where does the rainbow end ?


Where does the rainbow end?

The rainbow doesn't touch the ground and there is no end to it. Light from the sun looks white, but it is actually made of lots of different colours. Normally they are all mixed together. Arainbow is formed when light from the sun meets raindrops in the air and the raindrops separate out all these different colours. Because rainbows are made in the sky they don't touch the ground. So if you're on the ground, however far you walk, the end of the rainbow will always look as if it were on the edge of the horizon. But what people don't realise is that rainbows are actually complete circles, and obviously a circle has no end. You never see the whole circle because the earth's horizon gets in the way. Apparently if you see a rainbow from a plane it should be almost a complete circle. Another interesting fact about rainbows - have you ever noticed that you'll only ever see a rainbow if the sun is behind you? You can also sometimes see miniature rainbows in your garden if you're watering your plants with the sun behind you.

I bleached my hair recently, does bleach affect the scalp?


I bleached my hair recently, does bleach affect the scalp?

Hair bleach is hydrogen peroxide - it's an irritant, so it can make your skin itch, and feel a bit dry and tight for a while afterwards, but there shouldn't be any long term consequences.

why do we get wrinkly in old age ?


why do we get wrinkly in old age ?

We all get wrinkly as we age - they come because our skin gets less elastic as we get older. If you get look at a child's skin it has plenty of stretch and twang, but an older person's skin doesn't have this. As you get older your skin gets saggy, and loses its elasticity, causing wrinkles. Creams on the market can help with the really small wrinkles, but the deep ones, of the sort you can see a couple of feet away, I'm afraid, creams won't do anything for those. Things that you can do of course, are not go out in the sun, particularly when you're young, and not smoke. If you look at smokers, particularly women, they can be incredibly wrinkled. It's not known quite how that happens, but it is thought that it may be a chemical reaction in the skin and may also be a genetic predisposition in some people.

Sunday, November 8, 2009

How does photosynthesis work underwater?


How does photosynthesis work underwater?

fundamentally photosynthesis actually began in the oceans — in underwater, because that’s where plants and algae first evolved. They then moved onto land. So light definitely gets into the upper layers of the ocean and that’s where the process of photosynthesis traps that light and converts it into energy — into carbohydrates really, that the rest of the food chain relies on. So it’s really the idea is that you have to maintain plant life, algae has to maintain itself in the upper layers of the ocean because once you get further down into the depths of the ocean, first of all red light gets absorbed which is why the oceans look blue and green-y colours. Light does get down there but it has to maintain itself up in the high levels. So if you look, for example, at coral reefs and they have plants living inside their tissues or algae and those types of coral have to maintain themselves by growing on big reefs, depositing calcium carbonate in great big layers that build up and build up and as sea levels rise, they have to keep up their pace to keep themselves in that lovely, sunny, gorgeous bit of tropical oceans where we all love to go snorkelling and diving. But as you go deeper down, they tend to peter out, and there are some types of corals actually that don’t have photosynthetic algae in their tissues; they actually rely on catching their food like other animals. They catch it from the water, and those are the ones that live deeper down. So you do see this zonation. You see similar things on the beach with different types of seaweed using different types of pigments to harness light both in the open areas where there’s lots of light and then lower down where light start to get absorbed.

Are snakes susceptible to their own venoms?


Are snakes susceptible to their own venoms?

There’s two things to consider. That is they aren’t susceptible to their own venom in their own fangs because they don’t kill themselves every time they make some venom. That’s pretty cool but also quite easy to understand. We also have poisonous chemicals inside our bodies that don’t kill us. They’re kept in certain areas, for example, our pancreas contains a deadly cocktail of enzymes. If your pancreas bursts and they all come out then that can really spell a big problem for you and you start digesting yourself from the inside. Because it’s kept in certain organs that are lined with cells that aren’t susceptible to those enzymes then you’re okay. Once it gets into your digestive tract then you’re okay.

This is also why if a snake happens to swallow some of its own venom it will be ok ay because the venom is made of protein. The enzyme, which is a type of protein, will denature when it gets into the strong acids in your stomach and break down the structure of those enzymes and stop them from working, stop them from being so deadly.

The other question is what if a snake accidentally bit itself or if another snake bit it? The answer seems to be yes, they are susceptible to their own venom. If it’s injected into their system they can be susceptible to it but some scientists have also found anti-venom inside snakes. They can develop their own anti-venoms to their own venom but we don’t quite yet know how that happens. It could be that they have a low level of exposure. Accidentally biting themselves occasionally, as you do?

You can imagine there’s some selective pressure for a snake to evolve, maybe not from itself, but perhaps from its mate or something.


Do Fish Sleep?


Do Fish Sleep?

yes, they can but it also depends on how you define what sleep is because in humans the transition into sleep involves changes in the patterns of brainwaves in an area of our brain called the neocortex and fish don’t really have the same development in their neocortical region as mammals, really.

So it’s kind of difficult to say in the same way what sleep really means for fish but they do. If you count up things like a reduced metabolic rate and slowing down activity then they do seem to sleep and Zebra fish, which are fresh water fish, have been studied in the laboratory. If you watch them, and I think this is rather sweet idea that. You can watch them during the day and they will actually sort of doze and their tails droop down and they stop moving around at certain times of the day and they do seem to sleep.

That’s one thing and in Antarctica, actually only last year they discovered the first hibernating fish and apart from mudfish that aestivate and keep themselves alive when things dry out. In Antarctica they actually slow down and stop feeding and their heart rate slows down. They used heart rate monitors on these fish to see what was going on and we think that it was probably because it gets darker in the winter in Antarctica. In fact it gets completely dark because there’s no sun and they find it hard tracking down their prey because this prey is still out there but they are visual hunters and without the light around they find it very difficult to find their food so they sort of stop.

Do viruses have a metabolism?


Do viruses have a metabolism?

This is interesting in terms of biomimetics because people are talking about using viruses and their ability to infect cells and inject their DNA and RNA into cells for gene therapy so it’s an important question. And the answer is no. Viruses are not alive they don’t have a metabolism, they’re nothing more than an infectious bag of genes which is able to put those genes into a cell and make the cell produce all the viral products to make more viruses. That’s all they do.