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Author Topic: Question of the Week - Old Version  (Read 179183 times)

Offline Ians Daddy

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Re: Question of the Week - Old Version
« Reply #25 on: 18/09/2003 05:47:16 »
I'm going to stray a bit, because this is where I am. Does anyone know what happened to "Nilmot" / Tom / "The Riddler"? Haven't seen him in quite awhile.
 

Offline Qing

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Re: Question of the Week - Old Version
« Reply #26 on: 18/09/2003 09:31:22 »
quote:
Originally posted by cuso4

Now I got another theory.

May be cells of penguins feet are surrounded with networks of cappilaries and this enables oxygen to be transported to the cells in the feet. So that energy can be generated by respiration to keep their feet warm.

Angel


I came up with this idea as well, but this might not be enough.i mean, penguins feet are in direct contact with freezing enviornment,and the tempearture is really low. so there might be other adaptations e.g. like Donnah said,"they cover their feet with their pot bellies when they are not moving". just a thought.

Qing
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #27 on: 19/09/2003 01:24:10 »
ANSWER TO : WHY DONíT PENGUINS FEET FREEZE ?
Part of the reason is that penguins are birds and are warm blooded so they keep their feet from freezing by pumping warm blood from their body into them. But thatís only half the story because penguins live in such a cold environment that they would very quickly lose all of their body heat if they continuously pumped hot blood around their feet. Instead they have hit upon an ingenious solution which saves heat and keeps their feet just above freezing. In the penguinís legs the arteries, which carry hot blood from the body, are wrapped around the veins bringing cold blood back from the feet. The cold blood in the veins removes most of the heat from the arteries, warming up as it does so, so that the blood entering the feet is just above freezing, but the blood in the veins, by the time it reaches the body, is back up to body temperature. So the penguins feet receive blood just warm enough to keep them from freezing, but are not so hot that the penguin melts into the ice.
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #28 on: 19/09/2003 01:25:54 »
HERE'S THIS WEEK'S "QUESTION OF THE WEEK" :

"HOW, AND WHY, DO CHAMELEONS CHANGE COLOUR ?"

Fire away.

TNS
 

Offline Qing

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Re: Question of the Week - Old Version
« Reply #29 on: 19/09/2003 15:51:13 »
that's an interesting question. i know that chameleons change colour to protect themselves. their colour changes according to the environment. but how do they change it.

Qing
 

Offline Ians Daddy

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Re: Question of the Week - Old Version
« Reply #30 on: 20/09/2003 02:47:33 »
Surely it's chemical. Maybe it detects the light rays emmiting from a surface and can balance itself to that. It's probably automatic, the same way that I turn so red when embarrassed or angry. When frightened, they "balance" themselves with their surroundings. [?]
 

Offline Exodus

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Re: Question of the Week - Old Version
« Reply #31 on: 20/09/2003 09:45:04 »
I've always considered myself to have chameleon properties... If i drink too much i turn green too, what help that does i dont know, when your in that state you want to be found, not blend in with the grass! LOL

As for th answer, i don't really know, well i have an idea...

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Offline cuso4

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Re: Question of the Week - Old Version
« Reply #32 on: 24/09/2003 09:05:13 »
quote:
Originally posted by NakedScientist

ANSWER TO : WHY DONíT PENGUINS FEET FREEZE ?
Part of the reason is that penguins are birds and are warm blooded so they keep their feet from freezing by pumping warm blood from their body into them. But thatís only half the story because penguins live in such a cold environment that they would very quickly lose all of their body heat if they continuously pumped hot blood around their feet. Instead they have hit upon an ingenious solution which saves heat and keeps their feet just above freezing. In the penguinís legs the arteries, which carry hot blood from the body, are wrapped around the veins bringing cold blood back from the feet. The cold blood in the veins removes most of the heat from the arteries, warming up as it does so, so that the blood entering the feet is just above freezing, but the blood in the veins, by the time it reaches the body, is back up to body temperature. So the penguins feet receive blood just warm enough to keep them from freezing, but are not so hot that the penguin melts into the ice.




Just found out that human (and other mammals) keep their hands and feet from freezing the same way as penguins. Because we are all HOMEOTHERMS.

Angel
 

Offline cuso4

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Re: Question of the Week - Old Version
« Reply #33 on: 24/09/2003 09:11:53 »
quote:
Originally posted by NakedScientist

HERE'S THIS WEEK'S "QUESTION OF THE WEEK" :

"HOW, AND WHY, DO CHAMELEONS CHANGE COLOUR ?"

Fire away.

TNS



Here's the answer. This is not purely my knowledge because I did a bit of research.

Under a chameleon°Įs outer skin are special skin cells with colour (or pigment) in them. These cells are called chromatophores. The top layer of chromatophores have red or yellow pigment. The lower layers have blue or white pigment. A chameleon changes colour when its brain sends a message to the cells. The message tells the cells to grow bigger or to shrink. When this happens, the cell pigments mix and the chameleon°Įs colour changes.

Temperature affects the chameleon°Įs colour too°™if it°Įs cold, darker skin allows the chameleon to absorb more heat from the Sun. And, light from the Sun can signal a chameleon to change to a lighter shade, to reflect the sunlight.

Angel
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #34 on: 29/09/2003 19:05:51 »
ANSWER TO "HOW DO CHAMELEONS CHANGE COLOUR ?"


If youíre not sure what a chameleon is, itís a kind of lizard that lives in trees, usually in Africa or Madagascar. Most people have heard of chameleons because of their amazing ability to change the colour of their entire body within seconds. But itís a myth that  chameleons change their colour to blend in with their surroundings. In fact the main reason that they change colour is so that they can communicate with each other. For example a calm chameleon is a pale green colour, an angry chameleon turns bright yellow and a chameleon who spots another chameleon it would like to mate with usually displays an explosion of different colours including reds, greens, browns, whites and blues. So how do they actually change colour. The answer lies in special cells buried in their skin called chromatophores. These cells are all wired up to the chameleonís brain and contain different coloured pigments. When the chameleon wants to change colour, signals from the brain tell the skin cells to release their coloured pigment which spreads out in the cell and changes its colour, rather like giving the cell a coat of paint. The chameleon can make a range of different colours by switching on different coloured pigment cells at the same time, a bit like mixing red and yellow paint together to make orange.

WELL DONE ANGEL - HIT THE NAIL ON THE HEAD !
 

Offline NakedScientist

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Re: Question of the Week - Old Version
« Reply #35 on: 29/09/2003 19:07:53 »
HERE IS THIS WEEK'S "QUESTION OF THE WEEK" :

"WHY DO PEOPLE HAVE DIFFERENT COLOURED SKINS ?"

Have a go, answer next week.

TNS
 

Offline Ians Daddy

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Re: Question of the Week - Old Version
« Reply #36 on: 30/09/2003 00:18:14 »
Different levels of melanin?
 

Offline cuso4

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Re: Question of the Week - Old Version
« Reply #37 on: 30/09/2003 09:27:53 »
Yes Ronnie, I believe so.

I think different levels of melanin are due to human's adaptation to the environment. The pigment melanin can absorb UV radiation to prevent the damage to skin cells.

For example, people live in Africa are constantly exposed to strong sunlight during day time, so their ancester had evolved (not sure it's the right word to use) to have a dark skin to suit the environment.

However, people live in places like UK or Canada where the weather is colder and experience less sunlight had not adapted for exposure to sunlight but for the reduction of heat lost. Although pale colour absorb less heat they also radiate less heat.

Finally, people live in Asia especially with sub-tropical weather are adapted for medium level of sun exposure. This accounts for their tan-ish coloured skin.

Angel
 

Offline Quantumcat

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Re: Question of the Week - Old Version
« Reply #38 on: 30/09/2003 09:57:03 »
darn it cuso4, that's my kind of question!![:(!] I was too late:( lol only kidding I'm not mad !!:)

I can add a little bit.

When humans have little or no pigment, that is, albanism, it's because there is a mutation in the gene for tyrosinase which is an enzyme that changes tyrosine into melanin in the melanocytes.

People with darker skin have extra genes (I think, correct me if I'm wrong!!!) that increase tyrosinase production so more melanin is converted from tyrosine in the melanocytes, then let out and distributed around the skin...

When the skin is exposed to UV light, tyrosinase production is stepped up so more melanin is made. This is an emergency response designed to protect the skin from further damage from the UV light (because UV radiation can change genes, therefore cause cancer)

Tyrosinase is being made all the time, melanin isn't permanent and if you get a tan then stay is a dark room for a while you'll see that the tan wears off in a month or so.

When people get freckles it's because the melanocytes are spaced far from each other and aren't very efficent at delivering the melanin into the surrounding skin (also correct me of I'm wrong there not so sure)

Anyway I didn't copy and paste that, I wrote it from my own head ... probably why some of it is probably wrong ... lol

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Offline cuso4

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Re: Question of the Week - Old Version
« Reply #39 on: 30/09/2003 13:33:12 »
Sorry Quantum [|)], but my bit is quite simple and can be worked out logically whereas your bit is....very scientific (good on you :D!) and thanks for the extra info as I didn't know melanin was made from tyrosine.

And...I'm certain that the bit about freckles is correct. People who get tan because they got even distribution of melanocytes.

Angel
 

Offline Ians Daddy

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Re: Question of the Week - Old Version
« Reply #40 on: 30/09/2003 13:35:30 »
How long does the "evolution" take to adapt to the amount of sun? ie.. transplanted people from different regions. I know that a tan would fade, but how does and how long for the melocytes to alter?

Why do freckles fade with age in some people? ie... kids with freckles on their noses.[:o)]

Why do I turn deep red [:(!](not a burn)[V] as opposed to brown when I'm in the sun alot?

Just some thoughts.
« Last Edit: 30/09/2003 13:37:43 by Ians Daddy »
 

Offline cuso4

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Re: Question of the Week - Old Version
« Reply #41 on: 01/10/2003 08:42:10 »
May be you don't have enough melocytes to produce a tan. Instead, the capillaries near the surface of your skin expand allowing more blood flow, you therefore lose heat through radiation and convection. This is vasodilation.

Angel
 

Offline Qing

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Re: Question of the Week - Old Version
« Reply #42 on: 01/10/2003 08:57:45 »
why do people get headache [xx(] after being exposed to bright sunlight for a long time perticularly if you skin colour is light?

Qing
 

Offline cuso4

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Re: Question of the Week - Old Version
« Reply #43 on: 01/10/2003 13:57:19 »
Don't people get overheated and the enzymes in the body start malfunctioning?

Angel
 

Offline Donnah

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Re: Question of the Week - Old Version
« Reply #44 on: 01/10/2003 22:43:26 »
Ronnie, maybe you turn red due to your Indian heritage.  

As for the geographic effect of the sun over the course of generations, why are Eskimo and Inuit people, who live in the far north, dark skinned?
 

Offline Ians Daddy

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Re: Question of the Week - Old Version
« Reply #45 on: 01/10/2003 23:35:36 »
Maybe the elevation. Or, the reflective affect of the snow and sun. Actually, maybe the evolutionary adaptation period is very slow and these people are decendants from a southern race. It's fascinating to see that Eskimo, Somoan, Polinesian, Mexican, Native American Indian and Asian people have very present similarities in skin tone and features. So, maybe our "family tree" is more narrow than we thought.
 

Offline Quantumcat

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Re: Question of the Week - Old Version
« Reply #46 on: 02/10/2003 09:44:41 »
Snow reflects more light than soil, a lot more. Either that or they haven't lived in the far north for very long.

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Offline Donnah

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Re: Question of the Week - Old Version
« Reply #47 on: 03/10/2003 01:34:09 »
There's also the issue of constant daylight in northern summers, and constant dark in winter.
 

Offline bezoar

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Re: Question of the Week - Old Version
« Reply #48 on: 03/10/2003 06:02:47 »
I seem to remember, way back in high school, being taught that it isn't the number of melanocytes, but the size of the granules of melanin that makes for the differences in skin color.  Any feedback on that?

Bezoar
 

Offline Quantumcat

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Re: Question of the Week - Old Version
« Reply #49 on: 03/10/2003 09:45:53 »
Oh, yes!! That's it. In summer their nights would be like one hour long. But, their days in winter would be like one hour long too, so it doesn't work. Bugger.

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Re: Question of the Week - Old Version
« Reply #49 on: 03/10/2003 09:45:53 »

 

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