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Plant Sciences, Zoology & Evolution / Why are plant cells often square?

« on: 17/01/2014 17:52:03 »

It seems like even with the cell wall they could be circular, triangular, etc.  Why do they usually look square under the microscope?

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Cells, Microbes & Viruses / Re: What is the difference between cytokinesis and mitosis?

« on: 01/05/2012 15:20:41 »

What cells are supposed to do this?   Mitosis is the division of the nucleus, home to DNA, while cytokinesis is the division of the actual cell and dividing up its contents.   So if this happened you'd have a cell with  two nuclei, and therefore twice the DNA it's supposed to have.   I wouldn't think this could happen.

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Plant Sciences, Zoology & Evolution / Re: Why Does A Sea Sponge Have No Brain And No Nervous System ?

« on: 01/05/2012 15:10:08 »

I think the basic point is that the brain didn't evolve yet.   Sponges were probably the first animals to evolve.  The brain came along later, maybe encouraged by the evolution of bilateral symmetry, meaning animals like worms are right-left mirror images and therfore store have a head region.   Sponges don't have a head and rear; they are circular.   The evolution of a head would allow all the sensory organs and nerves to concentrate in one area, leading to a brain.

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Plant Sciences, Zoology & Evolution / Re: What are the purpose of flies and ants and mosquitoes?

« on: 01/05/2012 14:59:43 »

Ants also allow air to circulate in the soil by digging tunnels.   Plant roots need oxygen, just like us.   So ants help your garden grow.   I'm not sure how big the effect really is, but I try this argument to keep my husband from killing all the ants in our yard.   Fireants, though, he can kill.  No purpose for them!

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Plant Sciences, Zoology & Evolution / Re: Are herbicide resistant plants a good idea?

« on: 01/05/2012 14:49:15 »

The only positive spin is that herbicide-resistant crops cut down on erosion; when you dig up the weeds you loosen up the soil.   But on the other hand, there are a ton of studies out there suggesting various environmental issues caused by herbicides.

It's interesting that you seldom hear anything about health effects of herbicides.   Pesticides we hear about all the time.   I guess there are more established risks with pesticides, while herbicides are maybe less studied?

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Physiology & Medicine / Do your bowels know the time?

« on: 16/03/2011 13:57:31 »

It seems possible to "train" your bowels to empty at the same time every day.  How do they know what time it is?

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Plant Sciences, Zoology & Evolution / Why don't chickens urinate?

« on: 16/11/2010 03:30:25 »

Chickens and other birds and reptiles concentrate their nitrogen wastes into uric acid instead of urine.  This takes more energy, but conserves water. 

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Physiology & Medicine / Moderate drinking is better for you than not drinking?

« on: 05/11/2010 16:43:58 »

http://www.forbes.com/forbes/2009/0216/026.html

Moderate drinkers also make more money!  They come to the same conclusion in the article as BoredChemist; the cause and effect is probably the other way around.  (If you are successful you are probably in social situations where drinking happens.)

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General Science / Examples that "Correlation does not imply causation"?

« on: 05/11/2010 15:27:05 »

The idea that correlation does not imply causation is sometimes hard to get across.  Has anyone read any interesting studies that suggested a link that ended up not being a direct cause and effect realtionship?

I've used the example before about the study that suggests Diet drinks "cause" you to gain weight.

http://www.foxnews.com/story/0,2933,159579,00.html 

But there could be a cause and effect relationship there if diet drinks cause you to crave sugar, so perhaps it's not the best example.

Any other ideas?

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Physiology & Medicine / Why am I immune to motion sickness?

« on: 05/11/2010 00:51:14 »

I would classify myself as motion-sick prone because I get really sick sometimes on planes with a lot of turbulance or on twisty roads. But never on boats, even once when it was really swaying & lots of people were sick.  Do you think this is just chance or is seasickness different somehow?

The blind question is interesting. Ive shut my eyes before and it didn't help!

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Radio Show & Podcast Feedback / Ask the NS podcast on iTunes?

« on: 04/11/2010 21:30:40 »

Has anyone else had trouble downloading Ask the NS from iTunes?  I see no new shows since Sept.  Need my fix

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Plant Sciences, Zoology & Evolution / Some Random Animal and Plant Facts.

« on: 01/11/2010 03:01:51 »

The corpse flower smells like rotting flesh, attracting beetles and flies to pollinate it.

http://en.wikipedia.org/wiki/Titan_arum

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Technology / How safe are hydrogen fuel cells in vehicles?

« on: 31/10/2010 03:21:24 »

Hydrogen gas is so explosive that I'm wondering how they can engineer a hydrogen fuel cell powered car to be safe.  Am I misunderstanding that there is actually a tank full of hydrogen in these cars? 

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Cells, Microbes & Viruses / Re: Why are there multiple alleles for each gene?

« on: 31/10/2010 02:59:31 »

There is only one "sense" strand on the chromosome.  The other strand is not the other allele, it is the sequence of letters that is the complete opposite of the actual gene, basically "nonsense".  The other allele is on the homologous chromosome, as you've said.  It might vary by just one or two letters from the other allele.

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Physiology & Medicine / Why do children's hearts beat faster?

« on: 31/10/2010 02:43:20 »

The heartrate of a child is much faster than an adult, and small animals have very rapid heartbeats.  Why is that so?

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Question of the Week / Re: QotW - 10.10.30 - What's worse, the air industry, or a volcano?

« on: 26/10/2010 16:15:00 »

The ash in the air would decrease the sun's rays warming the earth, so it might actually have slight cooling effect that would outweigh the small amounts of greenhouse gasses released.

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Plant Sciences, Zoology & Evolution / Did dinosaurs and humans coexist as creationists say they did?

« on: 09/10/2010 02:36:02 »

The creation museum in Kentucky does have an exhibit with dinosaurs coexisting along with humans.  I think the strain of creationists that are literalists think that the Earth and all creatures were created in 6 days, so that includes the dinosaurs. 

All of this basically throws the fossil record out the window.  Fossils are "a test from god" according to some evangelicals. The idea of a god that is trying to trick you and asks you to put reason aside is kind of disturbing to me personally!   

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Physiology & Medicine / Are \

« on: 06/10/2010 16:44:55 »

I think it's a combination.  You might tend to be one way and then train your body and set your internal clock to reinforce the habit.   

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Physiology & Medicine / What makes you feel weak when you're sick?

« on: 01/10/2010 03:46:45 »

Does the inflammatory process somehow make you feel weak when you're fighting off a virus?  Or are you just running out of energy reserves?  Where does this weak feeling come from?

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Cells, Microbes & Viruses / What's the advantage of many, linear chromosomes?

« on: 01/10/2010 03:39:13 »

Early life probably resembled today's prokaryotic cells, meaning the DNA was in a chromosome that was large and circular.  But today many forms of life have divided up their DNA into many linear chromosomes.  Linear chromosomes introduce a problem of "losing" ends in the replication process, and I can't think of an advantage. 

Was this just random chance that so many cells now have their DNA in many, linear chromosomes, or is there some advantage over a circular chromosome?