Science Mole

ilovebacteria.com New science website for kids and big kids! Contains answers to strange science questions, DIY experiments you can try at home or school, info about microbes and much more.

We’ve moved - see this experiment and lots of others at: http://ilovebacteria.com/testenzymes.htm 

Enzymes are involved in a huge number of processes in the human body- every job has an enzyme to do it. You can easily see enzymes at work using fresh pineapple and gelatin.

What do you need?

1. Fresh pineapple
2. Jelly (if you are American, you will need Jello, not the stuff that you stick on toast and call jelly)

Recipe:

• Make some jelly/jello according to packet instructions and allow to set in two glass bowls. (Get someone to help you with the boiling water if you’re likely to burn yourself).
• Cut up the pineapple into rings (Don’t cut any fingers off with the knife) and add a ring to one of the jellys.
• Leave the jelly for a bit and check back every now and then to see what happens.
• Eat the second jelly that hasn’t been ruined by putting pineapple in it.
• The clever thing about enzymes is that they don’t get used up in a reaction- they come out at the end exactly the same as they went in. This means that the pineapple will still be pineapple at the end of this experiment and you can fish it out of the jelly and eat it too.

Why does this work?

When I was younger, I was convinced that pineapple and kiwis removed the top surface of my tongue as I was left in considerable pain when I ate large amounts of these fruits. At the time, my parents just laughed and said “Yes dear, of course dear”, but I now know that I was in fact right. This is because these fruits contain large amounts of protease enzymes that act to break down long polypeptides into their constituent amino acids. In other words, the fruit was breaking down the proteins making up my tongue. Nice.

It would be interesting to find out how much pineapple is required to break down an entire human tongue, but so far I’ve found no one willing to part with their tongue. Oh well, today’s experiment makes do with Jelly- this contains proteins called gelatins. The pineapple enzyme is called bromelain and it breaks down gelatins. This is why jelly manufacturers warn you against putting pineapple and kiwi into jellys!

For the more blood thirsty among you, you can show another enzyme at work using some calf’s liver and hydrogen peroxide. Drop a little bit of liver into 20% hydrogen peroxide and you will be able to see the oxygen bubbles released as the catalase enzyme in the liver breaks down the hydrogen peroxide (try and find out why catalase is a really important enzyme in the body for extra points).You can even try boiling the liver first too and looking at what effect this has. Hydrogen peroxide is really dangerous though, so if you’re interested in testing out this experiment, ask your parents or teacher to get everything ready for you and then you won’t risk burning your hands off with the hydrogen peroxide.

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Formula 1 has found itself a new hero in the form of British Lewis Hamilton. Never before has a rookie driver led the world championship after consecutive podium finishes in all of his races. British fans finally have a great British sportsman to back, and international Motorsport lovers have a new, exciting driver to cheer on as he battles with the other F1 greats vying for the top spot, Fernando Alonso, Felipe Massa, and Kimi Raikkonen.

Profile Designs has introduced a new line of car-themed products for the F1 enthusiast. The stylish art work, available on a range of products from t-shirts to hats to stickers and badges, will appeal to anyone looking for simple and elegant designs.

Whether you are a Jenson Button, Scott Speed or Nick Heidfeld fan, you can show your support with an F1 design featuring the national flag of your driver. All the current drivers and manufacturers, from Ferrari to McLaren-Mercedes, BMW to Honda, are catered for, as well as some of the past greats, Michael Schumacher, Aryton Senna and Damon Hill to name a few.

Visit Profile Designs to see more products and check out their other original designs featuring classic cars, sports cars and more.
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We’ve moved - see this experiment and lots more at: http://ilovebacteria.com/rocket.htm  

What do you need?

1. Rocket fuel - an Alka Seltzer tablet (or if you can’t get any, bicarbonate of soda and vinegar will work ok)
2. Some warm water
3. 35mm film canister
4. Thin A4 card and sticky tape
5. Safety goggles

Recipe:

• Make a tube out of some of the card by wrapping around the film canister. You need to be able to get to the lid of the container, so make sure it opens at the bottom of the rocket
• Make a cone out of some card and use as the nose of your rocket. Make some rocket fins too, and stick them on to make it look pretty
• When you’re ready to launch, put 1/2 of an Alka Seltzer tablet into the container and fill 1/3 full with warm water
• Snap the lid on as fast as you can (or it won’t work) and turn upside down
• Stand back and watch the rocket launch (don’t touch till the reaction has stopped)
• Try varying the amount of water, amount of tablet and temperature of the water
• If you want to use vinegar and bicarbonate of soda instead, you’ll need to dissolve the bicarbonate of soda in around 1/4 container of water and add an equal volume of vinegar to start the reaction

Why does this work?

When an acid (low pH - like lemon juice or vinegar) and a base (pH over 7 - bleach, bicarbonate of soda are examples) are mixed together, they react to produce a salt and a gas.

If you carry out this reaction inside a closed container, the gas generated will have no where to go and the pressure will build up, till either the lid is forced off, or the whole thing explodes. Containing a reaction that rapidly produces gas is pretty much the principle behind most bombs but on a much bigger scale than simple acid base reactions. This is also why if you hold a firework, like a firecracker, on the palm of your hands you’ll get burnt but if you close your fist around it, your whole hand will be blown off.

Any way, back to the rocket. You may be wondering what acids and bases have to do with Alka Seltzer - well, the tablets are in fact made from sodium bicarbonate and dehydrated citric acid, this makes them fizz when you drop them in water. This is why you can replace the tablet with vinegar (or lemon juice) and baking powder in the experiment. The reaction produces CO2 gas and it is this than launches the rocket. The reaction is faster if you use warm water and this will make the rocket go higher.

The same principle of an acid/base reaction producing CO2 can be used to blow up a balloon if you stick it over the mouth of a bottle containing the reaction ingredients.

More DIY experiments here

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The mind sees and the mind hears. The rest is blind and deaf.

(Epicharmus, 450 BC)

Can you always trust what you see? What happens when our minds wrongly interpret the information from the eyes leading to our perception of something being different from the reality? This is what is happening in my favourite optical illusion: the horizon moon.

Ever wondered why the moon looks so much bigger as it appears over the horizon than when its at its highest point in the sky? There are varying theories for why this happens; some are extremely complicated and none fully explain the phenomenon. But here is a rough summary of what could be happening.

Firstly, the moon’s 27.3 day orbit around the Earth is ecliptical (oval), and this results in its distance from the Earth varying between 363,300 and 405,500 km. This does mean that the moon will appear 11% larger in the sky when it is at its closest (perigee) than at its furthest away (apogee). But remember, the moon’s changing position in the sky over the course of a night isn’t caused by the moon rotating round the Earth, but the rotation of the Earth on its axis. This means that the distance of the moon from the Earth is constant throughout the night and it doesn’t explain the difference in apparent size of the moon when it is over the horizon.

So could it be due to the way that the light reflected from the moon travels through the atmosphere on its way to our eyes? After all, when its near the horizon, the light has to travel further through the atmosphere than when its directly above us. It turns out that refraction (bending) of light does alter how we see the moon, but not to make it appear larger at the horizon, although it will make it appear sort of squashed when it is low in the sky.

But if we have ruled out the possible physical causes of this phenomena, what is left? Could it be all in our mind?

First of all, lets prove that the image of the moon projected on our retinas doesn’t vary during one rotation of the Earth. If you were to hold a coin at arm’s length and compare it to the horizon moon and the moon at its highest point in the sky, you’d see that it doesn’t actually change. Also, if you were to photograph it, the moon would be the same size in the picture regardless of how it looked to the naked eye.

It could have something to do with size constancy. Imagine you are walking towards an elephant. The actual image of the elephant will fill up more and more of your visual field as you get closer. But you don’t perceive the elephant to be growing in size as you approach. This is because our brains take into account how far away the elephant is to tell us it is huge even when its hundreds of metres away despite it looking tiny in comparison with, for example, our own hand. You can test this out by staring at a light bulb or a bright circle of paper and then staring at a white wall. The image burnt onto your retina is of fixed size but the circle will look much bigger if you look at a distant wall than if you look at a piece of paper right in front of you.

Judging how far away something is depends largely on the surroundings. When the moon is on the horizon, you are seeing it surrounded by reference objects such as trees, buildings and the contours of the land. Try this: next time you see the massive horizon moon, try looking at it through a cardboard tube – the size illusion should disappear. Many people take this as evidence that the reason the moon looks so large at the horizon is because we are comparing it to smaller objects, such as trees and buildings, making it appear larger in comparison.

But it isn’t only the surroundings that cause the moon illusion, the way our brain judges distances plays a big role. Visualise the sky as a dome over the top of us as if we’re trapped in a snow globe. Our brains don’t judge distances exactly right and we don’t actually tend to imagine the sky as a perfect dome but instead underestimate vertical distances compared with horizontal distances and our mind sees the sky as a sort of flattened bowl. This all means that when you see the moon directly overhead, you think it is closer than when it is at the horizon. And, just like the light bulb demonstration above, thinking that the moon is far away makes the mind tell you that it is bigger than when its above you in the sky. If you fancy a bit of yoga, you could try bending over and looking at the horizon moon through your legs. Does it still look so large? Being upside-down confuses your brain and makes it harder to judge distances and use other objects as a size reference.

But this still doesn’t make complete sense. Most people would say the horizon moon is closer than the moon directly overhead. How can our subconscious mind be thinking it is further away and must therefore be bigger, while our conscious brain is telling us that its closer? Is it our brain trying to rationalise something that doesn’t make sense? Our knowledge tells us that the moon isn’t growing so could we be trying to understand the tricks our mind are playing on us by thinking that it is closer? Its not just how your brain perceives something, but how you then try to understand it based on what you have learnt. Past experience and how we expect something to look probably plays a bigger part than you would expect.  It makes my head hurt just thinking about it.

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We’ve moved - see this page and lots more at: http://ilovebacteria.com/humor.htm  

I know plenty of humans who can’t manage to muster a sense of humour, so I think this skill is probably a little above our canine friends. Jokes aside, there are plenty of crazy dog people out there who swear that their pets find stuff funny and laugh in their own little way. In my opinion, this is people insisting on putting human emotions on their pets because there are unable to except that their beloved companions are not human. There is no denying that dogs do feel unhappiness and joy, so perhaps Rover is associating the laughter of his owner with happiness, and acting as if he is excited too in order to please us.

Humour appears to be a largely human trait, although some higher primates show some form of sense of humour. This could be because humour is largely language based (eg: Patient: “Doctor, I’ve got a strawberry stuck up my bum.” Doctor: “I’ve got some cream for that.”) so its hard to tell if other animals can find things funny. There is a fair amount of research into why humans have evolved to have a sense of humour. For this trait to be selected for by evolution, it must have provided our ancestors with some advantage in finding a mate and passing on their humorous genes to the next generation.

There is no denying that humour is an important part of human life. It helps us to deal with stress, lets us communicate ideas, feelings and opinions, has a positive effect on the immune system and is considered a defining trait of being human. So what does humour do for us? Firstly, when you smile and laugh, you appear unthreatening to others and it acts to include others in your social group. Smiling itself is a way of showing that you are a friend, not a foe, and showing submission to another person. Humour could be acting to help bonding between humans and to reinforce relationships. Today, many of us find someone with a sense of humour far more attractive than those without, as laughter can be contagious and makes us happy.

The fact that we find someone who has a sense of humour more attractive than someone who doesn’t get a joke supports one of the theories for why we evolved to have a sense of humour. Much of humour is based on things that go against the norm and defy logic. For example, when someone throws a cake in their friend’s face we laugh because it is unexpected. To understand jokes we often need to be able to make links between things that are normally separate- the ability of humans to take knowledge learned from one experience and use it in a different situation is part of what makes us so special. So humour requires a certain degree of intelligence and may have evolved as an indicator to a prospective mate that we are smart and therefore carry good genes. Laughing at a joke is our way of broadcasting how great our sense of humour is to everyone around us.

But is this all? I’ve read some articles that have suggested humour has its roots in learning. Laughter is fun, so it positively reinforces the recognition of something that goes against what we see as normal. It can also help us accept situations where we are wrong to cushion us against the emotional anxiety that can accompany this. Because humans don’t like to be wrong, its sometimes difficult to accept new ideas that go against our beliefs so we could be using humour to get around this problem and effectively enjoy getting things wrong.

Another explanation could be the superiority theory which assumes that we laugh at others misfortune. Apparently, humans are in constant competition with each other, always looking for shortcomings in our fellow humans. Laughter is the realisation that we are better than someone else.

The incongruity theory is one of the most influential theories of humour and laughter. The idea is that humour is based on the resolution of incongruity. This theory states that something is funny when it is different from what is expected and the understanding of this incongruity is what makes something humorous. Again, it requires intelligence to understand an incongruity and our laughter tells the guys or gals that we are clever and would therefore be a good parent for their babies.

Two hunters are out in the woods when one of them collapses. He doesn’t seem to be breathing and his eyes are glazed. The other guy whips out his phone and calls the emergency services. He gasps: “My friend is dead! What can I do?” The operator says: “Calm down, I can help. First, let’s make sure he’s dead.” There is a silence, then a shot is heard. Back on the phone, the guy says: “OK, now what?”

He, he.

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We’ve moved - see this page and lots more at: http://ilovebacteria.com/papercut.htm   

In the next few paragraphs I am going to be answering one of the greatest questions ever known to mankind: Why is it that paper cuts hurt more than pretty much anything else?

Lets start off by thinking about pain. What is the point of it? Surely we would all be better off without this unpleasant sensation? Well this isn’t actually the case. As nasty as it is, pain is on the whole a really good thing. It is our body’s way of forcing us away from danger and making us rest until any injury or illness has had a chance to heal. Evolution has kept selecting for our ability to feel pain as those who can’t are more likely to get themselves killed before they can reproduce and their genes get wiped out of the gene pool.

The major importance of pain to our bodies is illustrated if we think about the millions of touch receptors in our skin. In every square centimetre there is 1 receptor for warmth, 6 for cold, 15 for pressure and a huge 200 for pain. Pain is felt when these pain receptors are stimulated and the nerves send a message at around 180 miles per hour to the brain that tells us we are hurting.

Back to papercuts. The problem is that they usually occur on our fingers, and it just so happens that our hands have more nerve endings than any part of the body. Other areas where you really don’t want to get a paper cut are your palms, lips, nipples and genitals (ouch), as these areas all have a particular type of touch receptor that allows them to respond to light touching, making them extra sensitive.

A paper cut is generally not a serious injury despite how it feels, and only irritates the nerve endings in our hands rather than destroying them like a really bad injury would. This unfortunately means that all the nerves work just fine as they send their message to the brain. In the case of a serious injury, it might not hurt too much to start with as the damaged nerves have to repair them before they can contact the brain.

What else? Well, paper cuts aren’t the same as razor cuts- the edge of the paper is pretty blunt and serrated so it rips and tears our flesh, leaving little bits of paper in the wound. Our body doesn’t like it much when foreign objects end up imbedded in our skin and it tells us about it by making it hurt.

So, knowing all of this, I’m afraid isn’t going to make a paper cut hurt any less but at least you know what is causing all the pain now. If it all gets too much you can always try hitting the cut with a hammer to destroy some of the nerve endings and maybe it will hurt a bit less.

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 We’ve moved! - See this article and more at: http://ilovebacteria.com/parasiteallergy.htm

Science fiction? Unfortunately, this one is firmly based in fact. Various studies have suggested that a parasite commonly found in cats may be affecting human behaviour to such as extent that it leads to mass cultural change.

Toxoplasma gondii is a parasite that starts its life in kitty poo as eggs, which are then accidentally eaten by another warm-blooded animal, such as a rat. Cleverly, the presence of the parasite in the infected rat somehow leads to the animal becoming less cautious. In fact, some of the infected rats actively seek out cat-urine-marked areas. And a less careful rat is more likely to get itself eaten, allowing the parasite to start its lifecycle all over again. How it manages to alter the rat’s mind is unknown, although it does appear to raise the levels of a brain chemical called dopamine.

Toxoplasma gondii can also infect humans, although this represents a dead end for the parasite, unless you happen to be unlucky enough to die and be eaten by your pet cats. In some countries, most adults are infected, with factors such as poor hygiene, eating undercooked meat and having pet cats playing a part in your risk of infection. For example, France has a high proportion of infected people due to their love of partially raw meat. As in rats and cats, the parasite lives in the brain or in other tissues and is not associated with disease, except in unborn children who lack their own immune systems.

So this got people thinking: Does the parasite have a similar affect on the human mind as it does on that of the rat? The answer to this happens to be yes. Infected individuals appear to exhibit increased risk taking behaviour and have slower reactions. This has been used to explain the observation that infected people have an increased risk of having a car accident. On top of this, personality changes are though to resuts from infection. Infected women may tend to be more open hearted and men can become less interested in seeking novelty. In addition, it is thought that you are more likely to have feelings of insecurity, self-doubt and neuroticism if the parasite has made its home in your brain. For anyone who doesn’t frequent those irritating “Know yourself better” personality tests, neuroticism is one of the Big Five personality traits, characterised by feelings of anxiety, anger, or depression, and exaggerated reactions to emotional events.

While these individual changes in personality have been known for some time, a more recent study chose to look at cultural change influenced by Toxoplasma gondii. Little is known about the causes of cultural change, although there are undeniable differences between different human populations when considering ego, money, material possessions, work and rules. The researchers involved in the new study found that in countries where most people are infected, they see much higher levels of neuroticism across the entire population. The author of the recent paper states, “Toxoplasmosis is one of many factors that may influence personality and culture, which may also include the effects of other infectious diseases, genetics, environment and history. Efforts to control this infectious pathogen could bring about cultural changes.”

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Ancient tracks discovered at the bottom of what was once a huge lake suggest that dinosaurs could swim.

The footprints are around 125 million years old and were likely caused by a large meat-eating dino clawing at the sediment on the lake floor as it swam in around 10 feet of water. They are very different from the tracks left on land, as you cannot see the shape of the foot. The ripple marks surrounding the scratches make scientists think that the animal was swimming against the current.

According to one scientist involved in the discovery:

“The dinosaur swam with alternating movements of the two hind limbs: a pelvic paddle swimming motion,”

“It is a swimming style of amplified walking with movements similar to those used by modern bipeds, including aquatic birds.”

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