30 12 / 2013

dietcrush:

did you know soap doesn’t really clean your hands it just makes the water molecules smaller so the water can go into smaller crevices in your skin isn’t that the weirdest shit you’ve read today

No no no no no no no no no nonononononono

OK, let’s go through the different ways in which this is obviously not true even without any knowledge of molecules or how they work.

  1. How big is a molecule of water. Who cares but, like, really freaking tiny, right? So tiny that it’s already plenty small to fit into any crevice your skin happens to have.
  2. When you get bacon grease on your skin, it doesn’t wash off, it just spreads around…it’s clearly on the surface of your skin, not hiding in a bunch of crevices. How do we envision “shrinking water molecules” helps solve this problem?
  3. If the water molecules are smaller and thus getting into the crevices like the post says, why does soap not “really clean your hands.” I mean, my hands are cleaner after I use soap…I can see that with my own eyes. How does something get reblogged 90,000 times that can be absolutely, unequivocally refuted by looking at the results of an activity which, I assume, we all do multiple times per day?

So, now that we know this is false, let’s talk about reality!

  1. Water molecules cannot be shrunk. They are the size they are due to the size of the atoms that make them and the size of an atom cannot be changed without taking away electrons. 
  2. Water is really good at dissolving molecules that, like water, have partial charges. But water is bad at dissolving stuff that doesn’t have any charge. Oil, of course, being a really good example of a “non-polar” molecule. The molecules that make up soap have one side that’s really good at dissolving polar molecules (like water) and another side that’s really good at dissolving non-polar molecules (like butter). The non-polar side dissolves the non-polar stuff, while the polar side dissolves in the water, allowing the whole mess to get washed away.
  3. Soap also often contains stuff that’s specifically designed to kill bacteria. This works by creating an environment that pretty much blows them up…it cuts their cell membranes and their insides spill out. And then all of it gets WASHED AWAY! 
  4. By normal, regular-sized molecules.

29 12 / 2013

Anonymous asked: Why does the sun appear a yellowish color meanwhile other stars appear a shade of blue, red or orange?

fishingboatproceeds:

I think you have mistaken me for my brother Hank.

The sun is actually very nearly white when viewed from outer space. But our atmosphere scatters blue light (you may have noticed our beautiful blue sky) and so the sun generally appears as white with a bit of blue taken out or…yellow. 

26 12 / 2013

wordfulwonderlous asked: Dear Hank, how do genes become 'dominant' or 'recessive'? When I ask my teacher this, she just says that she needs to go to a meeting. Thank you!

It isn’t the gene that’s dominant or recessive, it’s the trait. In biology, we call traits “alleles”. Things like “I have blue eyes” or “my blood cells do not function properly” are traits. Traits are caused by genes. 

Traits that only require one copy of the same gene to show up are called “dominant” while traits that require two copies of the same gene are called “recessive.”

Real world example:

Red-headedness is a trait that is linked to a gene for the production of a protein being a little bit busted. If you have one functional copy of this protein, then the trait doesn’t show up because at least one gene is doing its job and making normal pigment. But if both of those genes have the “red hair” mutation then neither of them are producing the pigment properly and the allele “I’m a ginger” shows up. 

In short, both genes are being expressed, but the expression of one (the dominant one) over-rides the expression of the other.

Of course, genetics is usually much more complicated than this and there aren’t actually very many traits that are pure recessive or pure dominant, but that’s often an entry point that we use when teaching biology.

26 12 / 2013

Anonymous asked: probably a really stupid question, but how come fish that live in the really deep sea dont get squished by the weight of the water? cuz there must be a lot of pressure on them, and i know that if you put stuff at the bottom of the ocean-like say a toy or something-it'll get completely flattened, why doesnt this happen to fish? do they have really strong bone structures? if so, shouldnt we be modeling stuff after fish skeletons cuz they must be really strong

They aren’t super strong, they just have internal pressures equal to external pressure of the water. So, if you take a deep-sea fish to higher sea levels, it will literally EXPLODE because it’s internal pressure is designed to push back against all of that pressure. 

The trickier problem to solve is how do sperm whales survive at lots of different water pressures without exploding or being crushed. This is especially important in mammals as they have lungs which contain air which is particularly susceptible to alternations by pressure. You can read all about how sperm whales deal with this here.

It’s fascinating…their lungs actually COLLAPSE at depth, preventing any kind of gas exchange at all. The oxygen they need for these deep dives is stored in massive quantities of blood with massive quantities of hemoglobin and also in special oxygen-storage proteins in their muscles.

SO COOL!

25 12 / 2013

bbeckyboots asked: Hey Hank, I have a science question! Is there any truth in the saying "Beer before liquor, never been sicker"?

Well…kinda. The idea is that if you start with beer and move to liquor, you’re already a little drunk and thus it’s hard to meter your alcohol intake. Because it’s so easy to drink a LOT of alcohol when drinking hard liquor, this can be super dangerous. 

But if you have some liquor and then switch to beer, there’s just a lot more volume of beer per unit of alcohol, so it’s harder to drink as much alcohol as quickly. Of course, you can still make yourself extremely ill, even fatally ill with beer, so you’re never really “in the clear.”

DON’T BINGE DRINK!

24 12 / 2013

wingsofwriting asked: So this is a science adjacent questions that I don't know where to find the answer to and thought you might know. But can organ recipients (from organ donations) be organ donors? And if so, what happens to the organ they received from another person?

OOO! Fascinating question! Just did some research…it turns out that, yes, indeed, there has been one organ (at least) that was in three different people…he said, casually avoiding the obvious dirty joke. The original donor, a young man to whom the new organ didn’t take, and a third recipient. 

The kidney was only in the first recipient for a couple of weeks before it had to be removed, though. Often, when people get new organs it’s because there’s something wrong with their body that places stress on the organ (the most common example is diabetes, which is terrible on your kidneys.) So, usually, the organ will be degraded by the time the recipient is…done with it. But apparently there’s nothing medically preventing an organ from being…re-gifted.

Interestingly, however, as soon as the organ is placed in the new person’s body, it becomes their choice whether they want to donate the organ or not, they get the same rights over that organ that they have over all of their other organs so, if they die in a car accident and are not signed up as an organ donor, they get buried with it.

In the case I cited above, the young man couldn’t keep the organ, but he still got to choose whether it was thrown out or placed in another person who needed it. Of course he chose to donate the organ, but it’s just kinda cool to me that it was /his/ choice, not just a default “This didn’t work for you so we’re taking it back.” It became his property the moment the put it in his body cavity.

24 12 / 2013

tyrantlizardrampage asked: Earlier you answered a question about bats, and stated that they make up roughly 20% of known mammalian species. Then it got me to thinking; what mammalian genus makes up the most by weight? like, if you got all the mammals together in a pile of mammal-flesh, which genus would make up the most of the pile?

Well I doubt that any one genus would make up “most” of the pile…but I wouldn’t be surprised if humans made up the largest piece. There are a lot of us…and we’re pretty big. We’re certainly the most populous species in our weight class. Probably if you lumped all rodents together they would weigh more than all humans…but I’m guessing completely blindly, and I don’t know if there’s any way to even get a reasonable estimate. 

I would be SUPER interested if anyone had ever legitimately tried to answer this question.

24 12 / 2013

groglog asked: I have seen the term "_____ is found on all continents except Antarctica" on a number of occasions. Are there any species that can literally be found on all continents? Thanks and keep up the good work.

Two come to mind. Arctic terns migrate from the north pole to the south pole and I’m pretty sure they stop over in every continent. There are probably some other birds as well, but the only non-bird (I’m pretty sure) is the human.

24 12 / 2013

nativetohere asked: I have a question. It's kind of just bats?!? Powered aerial locomotion in a mammal?!? I mean duh evolution, but how did it happen? How are they the only mammal specie to do this?

There are actually over 1,200 species of bats. About 20% of known mammal species are bats. They’re found on every continent except Antarctica and range in size from 1 inches long to a flying fox with a wingspan of over five feet. About 70% of bats use echolocation. The majority of others are fruit bats which requires significantly less aerial acrobatic skill…so they just use their eyes.

As for how it happened…you can read all about bat evolution on their wikipedia page!

24 12 / 2013

letsgetgreidy asked: Hi Hank! I have a science question. Today about 30 minutes before sunset, my sister and I saw an awesome light phenomenon that we could not explain. (I put a picture of it on my tumblr.) It looked like 2 rainbows shooting straight out of the ground, evenly spaced on either side of the sun. I'm wondering if you have any idea what it might be. Thanks! Merry Christmas Eve Eve!

That was a sun dog! They’re caused by ice crystals in the air reflecting the sun’s light back at different angles. Wikipedia article here.