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Author Topic: Question of the Week - Old Version  (Read 179127 times)

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #50 on: 07/10/2003 02:16:53 »
ANSWER TO "WHY DO PEOPLE HAVE DIFFERENT COLOURED SKINS ?"
 
Itís all down to a substance called melanin, the stuff that suntans are made of. The body produces melanin, which is a dark brown colour, to protect us from the sun because melanin stops harmful ultraviolet rays that can cause sunburn and skin cancer. People with dark skins naturally make much more melanin than fair-skinned people and thatís why their skin is browner. Most of these people have ancestors from hot countries where there is a lot of strong sun and so they have their own natural sun-block. Scientists think that our ancient ancestors came from Africa and all had dark skins to protect them from the sun. But, over thousands of years as they migrated out of Africa to inhabit colder countries, it was no longer an advantage to have a dark skin because there was less sunlight, so people lost their natural sun-protection and became fair skinned.
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #51 on: 07/10/2003 02:18:17 »
This week's question of the week was suggested by Tom (Nilmot)

WHY CAN YOU SOMETIMES SEE THE SUN AND MOON IN THE SKY TOGETHER ?

Have a go below...answer next week.

TNS
 

Offline Donnah

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Re: Question of the Week - Old Version
« Reply #52 on: 07/10/2003 23:26:48 »
Why wouldn't you be able to see them both?  The sun emits light and the moon reflects that light.  It just depends on where they are relative to the observer's field of vision.
 

Offline chris

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Re: Question of the Week - Old Version
« Reply #53 on: 08/10/2003 01:00:06 »
Quick comment to Bezoar in relation to her remark about melanocytes - yes you are definitely right. The melanocyte density is equivalent in black and white people. However, the expression of melanin and the cellular environment differs to make black people produce more melanin overall.

Chris

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Offline Qing

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Re: Question of the Week - Old Version
« Reply #54 on: 08/10/2003 09:52:43 »
usually,when we see the sun and the moon appear in the sky together will either be break or dawn except when there is a solar or lunar eclipse,so what I am thinking is that it depends on the angle the earth "lays"and the orbital it is "running" aroud the sun and also how the moon orbiting around the earth.besides this,I guess there must be something to do with at which latitude you are standing and observing from. I vaguely remember when I was in school I was taught that the orbital of the earth travelling around the sun is not horizontal,it's kind of oblique,a few degrees to the horizontal.
These just pure guesses,and don't know how to explain it clearly:(hope you can all understand me.

Qing
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #55 on: 17/10/2003 13:37:49 »
HERE'S THE ANSWER TO LAST WEEK'S "QUESTION OF THE WEEK", SUBMITTED BY NILMOT (Tom Lin)

The appearence of the moon in the sky depends upon the position of its orbit. There is no reason why the moon and sun should not appear together in the sky since they are totally independent of each other. The moon orbits the earth and the earth orbits the sun. Therefore sometimes the moon coincide on its orbit with the rising of he sun and hence the two will appear in the sky together.

This is precisely how an eclipse occurs, only on this occcasion the path of the moon crosses the path of the sun. But the two bodies are still in the sky at the same time.

I think most people seemed to get that one right. Good question though. By an amazing co-incidence a lady phoned the radio show a few weeks ago with the same question !
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #56 on: 17/10/2003 13:41:08 »
THIS WEEK'S QUESTION OF THE WEEK

"HOW DO WE KNOW HOW HOT THE SUN IS SINCE WE CAN'T GO AND MEASURE IT ?"

TNS
 

Offline Ians Daddy

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Re: Question of the Week - Old Version
« Reply #57 on: 17/10/2003 15:01:01 »
Guessing....will take a better stab at it later after some thought.
Guess: Temp. x Distance

I know that's probably wrong, but I'll build on it.
 

Offline Quantumcat

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Re: Question of the Week - Old Version
« Reply #58 on: 17/10/2003 22:19:43 »
colours - the material of anything burns at different colours depending on the temperature and what the materials are

we know what the materials are from the spectrum

Am I dead? Am I alive? I'm both!
 

Offline cuso4

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Re: Question of the Week - Old Version
« Reply #59 on: 22/10/2003 17:17:30 »
Is this called the BLACK BODY RADIATION? Never mind me if I'm talking rubbish.

Angel
 

Offline tweener

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Re: Question of the Week - Old Version
« Reply #60 on: 23/10/2003 04:49:35 »
quote:
Originally posted by cuso4

Is this called the BLACK BODY RADIATION? Never mind me if I'm talking rubbish.

Angel



Black Body Radiation is correct.  The spectrum of the radiation given by any body that has a temperature above absolute zero has a certain shape and the location of the peak and the distribution change with temperature.  So, it doesn't matter what the body is made of, you can measure its temperature by measuring the radiation it emits.

The universe is emitting radiation in the microwave range (wavelength of several cm) which gives it a temp of about 3 degrees Kelvin.  Red hot steel is emitting in the red end of visible light (wavelength about 700 nm), and the Sun emits in the visible and higher (wavelength around 500 nm) with a surface temperature of 5800 K.  The core is about 15 million degrees K.

To find out what it is made of, again measure the radition, but look for other things.  Each element and molecule will emit or absorb radiation strongly at certain wavelengths.  Looking at the spectrum, these appear as bright or dark lines.  The selectivity is caused by the quantum nature of the electrons in the outer part of the atom or molecule and how the electrons can behave in their orbits. Each element and molecule is very distinct.  Because they are all bunched together, the lines are spread out because of all the collsions the particles are undergoing.

Another book, but this is fun!

John

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No words of wisdom here.
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #61 on: 27/10/2003 22:45:51 »
Since John explained it so beautifully, there is virtually nothing I can add to the answer to last week's question "How do we know how hot the sun is?". The answer is indeed by spectroscopy - the colour of the sun indicates its surface temperature. Some experienced steel workers can predict, to within 1 degree accuracy, the temperature of their steel, just by looking at its colour.

Well done everyone.

TNS
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #62 on: 27/10/2003 22:47:30 »
Here is this week's Question of the Week :

"HOW DO BACTERIA BECOME RESISTANT TO THE EFFECTS OF ANTIBIOTICS?"

Have a stab below...

TNS
 

Offline Ians Daddy

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Re: Question of the Week - Old Version
« Reply #63 on: 27/10/2003 23:11:16 »
I know it's layman and probably sounds silly, but my guess is like a military strategy. Like keeping your friends close and your enemies closer. They bond to the antibiotic and learn all they can of it's make up. They record a memory of it and restructure to accomidate it. At that point, they are immune because they are somewhat related. Just like snake venom used as the anti-venom. I really don't know, I just thought I'd take a guess. I figure I've got 50/50 odds of being right or wrong.

Just a thought.
 

Offline bezoar

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Re: Question of the Week - Old Version
« Reply #64 on: 28/10/2003 04:44:00 »
Sounds like a layman's description of mutation to me.  Pretty astute. Then too, bacteria like to exchange DNA when they sit together side by side.  I hear it's only a matter of time before we get a Vancomycin resistance staph strain, from exchanging DNA with the Vancomycin resistant enterococcus.  Heard of a couple of scares recently, but no confirmations.  What was thought to be Vancomycin resistant did respond, but only after lengthy treatment.  If anyone has ever read the book The Coming Plague, it'll give you a good scare, but a fascinating book.
« Last Edit: 28/10/2003 04:47:37 by bezoar »
 

Offline nilmot

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Re: Question of the Week - Old Version
« Reply #65 on: 01/11/2003 16:51:02 »
Change their antigens?

Have caspules so they're hard to engulf?

Just some guesses....

Tom
 

Offline Donnah

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Re: Question of the Week - Old Version
« Reply #66 on: 02/11/2003 00:59:13 »
I'm guessing that if we don't finish the course of any antibiotics we take, or if the course is not effective in killing the bacteria then the bacteria learn to recognize the antibiotics (as Ron said) and it's like the bacteria have been vaccinated against the antibiotics.
 

Offline cuso4

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Re: Question of the Week - Old Version
« Reply #67 on: 03/11/2003 08:31:38 »
Each generation of bacteria produces quite fast, so there are always some bacteria survive under the presence of antibiotic. These bacteria then reproduce and create the next generation. This will eventually lead to a mutation in the genes of bateria.

Angel
 

Offline MarkH10178

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Re: Question of the Week - Old Version
« Reply #68 on: 05/11/2003 07:02:14 »
I was just looking into this one. Those little bacteria are so damn smart - but I forget exactly how they do it. Transposons, something like that. They actually develop the ability to degrade the antibiotic that was meant to knock them off, by producing an enzyme that breaks it up. "Penicillinases" - something like that.

May I suggest a famous question? A while back somebody ran around the Harvard graduation ceremony with a videocam asking these supposedly smartest of all smart kids the question: "Why are there seasons?" - they had the worst time trying to get it right!
 

Offline Qing

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Re: Question of the Week - Old Version
« Reply #69 on: 07/11/2003 09:50:48 »
Is the resistance temporary or permanent?Would you feel that if you start using the same antibiotics after quiting for a long time,it becomes effective again? Does that mean the bacteria are not resistant to the antibiotics any more?

Qing
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #70 on: 09/11/2003 22:01:23 »
ANSWER TO THIS WEEK'S "QUESTION OF THE WEEK"

HOW DO BACTERIA BECOME RESISTANT TO ANTIBIOTICS ?

You've all pretty much got the answer right. The mechanism of bacterial anti-microbial resistance comes down to them making a fortuitous mistake when they are copying their DNA.

Because bacteria grow so rapidly they need to copy their DNA rapidly. Occasionally this leads to an error creeping into the genetic code. Most of the time bugs which inherit these errors are at a growth disadvantage because all of the other bugs grow much better than them and hence they are out-competed and disappear.

But if the genetic mistake changes a bacterial protein so that an antibiotic can no long bind on to it, or another enzyme made by the bacterium gains the ability to chew up antibiotics molecules (as well as doing what it did before), now the mutant bacterium has a significant growth advantage whenever that antibiotic is around. All the non-resistant bugs are killed, leaving the resistant bacterium to father a new population of resistant mutants. With all of the competing bugs gone the new mutants enjoy life without any competition - rather like the shrimp fishing in forrest gump !

So the long and the short of it is, the more antibiotics you use, the more resistance you will see. It is a fortuituous mistake on the part of the bacteria. It comes down to the principles of Darwinian natural selection.

TNS
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #71 on: 09/11/2003 22:02:35 »
We liked MarkH's suggestion, so this week's question is :

WHY ARE THERE SEASONS ?

Happy debating,

TNS
 

Offline cuso4

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Re: Question of the Week - Old Version
« Reply #72 on: 10/11/2003 13:40:59 »
The Earth spins on its vertical axis at an angle (I forgot the exact value). As a result, different part of the planet receive different amount(strength) of sunlight creating seasons. This really needs a good diagram to explain properly.

In the summer of a location, the place is slightly closer to the sun and so receive slightly stronger sunlight. In the winter, the place is slightly away from the sunlight so receive slightly weaker sunlight. This also explains why places near the poles have longer daylight in the summer than those near the equator.

As to the changes in the way plants and animals behave also depend on seasons . For example, the hibernation in bears (don't know whether this apply to other hibernating animals or not) is triggered by the change in length of daylight. And people seem to be happier in summer is because seratonine is only produce in sunlight (providing you're not taking anything). This is the substance that stimulates the productiion of noradrenaline.

Angel

"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
 

Offline george

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Re: Question of the Week - Old Version
« Reply #73 on: 10/11/2003 18:45:54 »
I take on board what you've said Angel, about the planet being at an angle as it spins, but what makes the seasons change then ? How does the earth alter its degree of tilt; first it tilts one way, closer to the sun for one hemisphere, then the other. How does that happen ?
 

Offline UScaV

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Re: Question of the Week - Old Version
« Reply #74 on: 11/11/2003 00:10:08 »
The earth is always tilted at the same angle, which is 23.5 degrees.  The tilt of the earth is always the same and doesn't change.  So as the earth rotates around the sun, the angle changes depending on where the earth is.  That's why it happens at the same time of year each year.  There are 2 equinoxs and 2 solstices a year, and on the winter solstice, the Northern hemisphere is tilted as far away as it possibly can be, and during the summer as close as it possible can be.  Also, twice a year, the the angle to the sun of both hemispheres is the same, and the amount of light and length of day are pretty much equal all over the earth(equinox).

And I don't think winter and summer have to do with the amount of time light is hitting the earth, but rather the distance is has to travel, either fighting it's way through a longer distance and more atmosphere, or a shorter distance and a smaller amount of atmosphere.

« Last Edit: 11/11/2003 00:20:45 by UScaV »
 

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Re: Question of the Week - Old Version
« Reply #74 on: 11/11/2003 00:10:08 »

 

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