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Biology

¨  How does bacteria manage to grow in mascara?
¨  Why does a cut stop bleeding when we apply pressure?
¨  What is the role of vitamin D and folic acid in the evolution of skin color?
¨  My preschoolers would like to know why a spider dies after laying eggs.
¨  Where can I find information about spider monkeys?
¨  How do I stop fish tank snails from multiplying?
¨  Why would only one side of a persons head have gray hair?
¨  Why do children like sweet food, but not so much when they get older?
¨  Do some molecules in the body remain with us for the whole of our lives?

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QUESTION:
How does bacteria manage to grow in mascara, out of all cosmetics, the most?  Does mascara act as a nutrient source?

ANSWER from Imagiverse on 21 October 2006:
The mascara bacteria mystery can be solved by focusing on the way that mascara is applied.  Every time you pull the mascara wand out and then put it back in you are creating a pumping motion that can increase the liklihood that bacteria will grow.  What the pumping of the mascara wand is actually doing is pushing bacteria from the air around you or even from your own eyelashes into the bottom of the tube.  The bottom of the tube is the wettest and darkest area of the mascara tube.  Bacterias thrive in this kind of environment.

For some tips on how to prolong the shelf life of mascara and decrease bacteria growth as well as more information on why bacteria grows on cosmetics visit the following website: http://www.ivillage.co.uk/print/0,,183872,00.html

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QUESTION:
Why does a cut stop bleeding when we apply pressure?

ANSWER from Imagiverse on 26 June 2006:
When you apply pressure on a cut you slow the flow of blood allowing it time to coagulate.  When you apply pressure on a larger wound or artery, you prevent blood from escaping until the patient gets medical attention.

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QUESTION:
What is the role of vitamin D and folic acid in the evolution of skin color?

ANSWER from Stephanie Wong on 3 May 2006:
I read a few Internet sources and have found this information.  Please do some more research to verify what I found.

The differences in skin colour of humans can only partially be explained due to latitude.  In general, peoples originating near the equator (i.e. Africa) have darker skin tones since their skin evolved to produce more melanin (the dark pigment) to protect them from the sun.  UV light from the sun damages folic acid producers so that's why the skin needs to be dark in those regions.

What must also be considered is Vitamin D.  Humans need Vitamin D which the body can produce from sunlight.  However, too much melanin blocks out too much of the sun.  This can explain some of the regional discrepancies of the above model.  For example, why are the Inuit of the Far North so dark-skinned?

One final issue that I will mention is genetics.  The latitude model would predict that the peoples of South America should be as dark as African peoples.  One theory is that in traversing northern areas from Eurasia through the land-ice bridge and down into South America, they lost the gene to produce a very dark skin.  So, when they returned to an equatorial climate, they were unable to do so.

Please be aware that the skin colour issue is not a fully-resolved scientific problem.  I hope my bit of research wasn't redundant.

Sources:
http://www.backintyme.com/Essay021215.htm
http://en.wikipedia.org/wiki/Human_skin_color

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QUESTION:
My preschoolers would like to know why a spider dies after laying eggs?

ANSWER from Michelle Mock on 21 March 2006:
This is a great question from some very smart preschoolers!  Did you watch the movie or read the book Charlotte's Web?  I really liked that story but it was sad when Charlotte died.

I guess you could say that the spider dies of "old age".  It has reached the end of its life.  The life cycle of the spider is four stages: egg, larva, young spider and adult spider.  The spider lays eggs at the end of its life cycle and then dies.  The larva is the newborn baby spider.  The mama spider lays her eggs and encloses them in a sac that later serves as food for the hatching spiders.

Did you know that not all spiders die after they lay their eggs?  Some spiders actually carry the egg sac around and protect the spiderlings after they hatch.

Thank you for your wonderful question. I hope this answer helps! We look forward to more questions!

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QUESTION:
I need any information on spider monkeys.  I would really appreciate all the help you can give.

ANSWER from Jenny Alvarez on 31 January 2006:
There is so much information about Spider Monkeys out there on the web.  For example, did you know that the scientific name of spider monkeys is Ateles geoffroyi geoffroyi or that in its natual habitat the spider monkey rarely comes down from the trees to the jungle floor?  I found those facts on this site: http://www.honoluluzoo.org/spider_monkey.htm

If you try a search engine, like Google.com, type Spider Monkeys into the search bar, press enter and collect all the information you could ever need.

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QUESTION:
Last month I bought my son a couple of fish for a small tank.  The man who got them out of the tank at the store did not realize there was a snail in the bag with the fish.  A few weeks later, I noticed at least six more snails.  I just looked again today, and there are at least nine.  I do not want to flush them down the toilet, but I do not need hundreds of snails!  Do I need to put each snail in a separate container?  Thank you for at least reading my question.

ANSWER from Imagiverse on 21 January 2006:
There are many website (and books) with information on aquariums and snails.  We found several by using google.com and searching for "aquarium snails".  Some snails do reproduce rapidly and it requires that you get rid of them.  You may have to flush them.  You can also get fish that eat snails and can help control the population.  Snails can be very good in your fish tank... in moderation.

Here are some of the links we found.  I hope these help:
http://www.petfish.net/articles/Invertebrates/snails.php
http://naturalaquariums.com/inverts/snails.html
http://www.thetropicaltank.co.uk/snails.htm
http://www.fishpondinfo.com/snail2.htm

There are plenty more sites!  Good luck with your fish and your snails!

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QUESTION:
Why would only one side of a person's head have gray hair?

ANSWER from Jenny Alvarez on 2 November 2005:
Melanin is what causes the pigmentation of your hair.  For more information, here is a really great website:
http://kidshealth.org/kid/grownup/getting_older/gray_hair.html

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QUESTION:
How come children find lots of sweets to be tasty, but by the time they become adults, they find the foods too sweet?  Is it some psychological reaction, or does something change in their tastebuds?

ANSWER from Danielle R. Reed on 14 September 2005:
You are correct in your facts: children are born liking the taste of sugar and prefer more concentrated sweetness early in life compared with adults.  The decline of sweet preference with age is a reliable change which occurs for boys and girls and across cultures, and is also seen in mammals other than humans, e.g., laboratory rats.

What developmental changes accompany this decline in preference is not known, but it is probably not due to cultural learning or social expectations, but has a biological cause.  One speculation is that slowing growth signals the decline in sweet preference but more research is needed to resolve this point.  Susan Coldwell and her co-workers at the University of Washington are pursuing this hypothesis.

Danielle R Reed
Associate Member
Monell Chemical Senses Center
Philadelphia, PA, USA

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QUESTION:
From the moment of our birth to our death, is it possible to prove if any molecules remain with us all our life?

ANSWER from Eric Chudler on 21 August 2005:
Neurons (nerve cells) are some cells that are present from birth until death.

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2 July 2007
 

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