What is the most common symbiotic relationship in the plant kingdom, involving over 80% of plant species?Posted on December 2nd, 2010 No comments
Tweet your answer to http://twitter.com/ScienceTrivia. I’ll post the answer tomorrow afternoon EST.
Why are peanut allergies suddenly becoming more common in North America than elsewhere in the world?Posted on December 1st, 2010 No comments
Nobody gave the answer I was looking for. The answer from @jchaager is probably at least partly correct: “Parents are raising their kids in a bubble and preventing early exposure to allergens that would build up their immunity.”
The “overprotective parents” hypothesis (or “hygiene hypothesis”) of increase of allergies is probably at least partly true, but doesn’t lend itself to experimental verification. What parent would agree to raise their child in “dirty” conditions for experimental purposes? Nevertheless, there is some anecdotal support of the idea. On the other hand, there is also experimental support of the idea that exposing a child to an allergen too early may trigger an allergy rather than boost their tolerance.
Anyway, there is a biochemical and cultural cause that is hypothesized as a reason for increased peanut allergies in North America. In North America, most peanuts are roasted, rather than boiled. Boiling, as done in most of the rest of the world, neutralizes some allergens in peanuts.
One of the main allergens in peanuts is “Ara h2,” which inhibits protein digestion. Roasting peanuts makes this protein more effective at blocking protein digestion. Thus, once a person with peanut sensitivity ingests Ara h2, other undigested proteins in the peanuts cause further allergic reactions. Boiled or raw peanuts have less effective Ara h2, so are far less likely to trigger allergic reactions than roasted peanuts.
More specifically, Ara h2 inhibits the action of the enzyme trypsin in the digestive system, which normally breaks down the peptide chains in proteins, liberating the component amino acids. These undigested peptides are thought to be a contributor to the abdominal symptoms of peanut allergies.
More about peanut allergies: http://en.wikipedia.org/wiki/Peanut#Allergies
Posted on November 26th, 2010 No comments
One last Thanksgiving-related question, since Friday is still a holiday for some of us.
There are two correct answers to this, but only one was mentioned by Twitter correspondents. The first correct answer was from @little_mavis: The guinea pig is a species domesticated in the New World but given an Old World name.
Guinea pigs (Cavia porcellus) are called “pigs” (commonly and scientifically) because of their pig-like build and the pig-like sounds they make. They were first domesticated in mountainous regions of northwestern South America. Why they are called “guinea” pigs is a matter of conjecture, and may be a combination of several factors. One hypothesis is that “guinea” is a corruption of Guiana, though they’re not originally from there, either. Another guess is that “guinea” pigs may have been imported to Europe via Guinea (West Africa) and so been named for the wrong place.
The misnaming of the “guinea” pig may simply be similar to the misnaming of the turkey. It may have been intentionally named for an exotic-sounding place, even though that place is not where the animal actually came from.
A third species first domesticated in the New World and given a misplaced name is the muscovy duck (Cairina moschata). It’s not from Muscovy, but from northern South America and possibly Central America.
The muscovy duck is the only breed of domestic duck not descended from the mallard (Anas platyrhynchos). Most domestic ducks are descended entirely from the mallard, but a few from hybrids of mallard and other Anas species. In fact, transgeneric hybrids of muscovy ducks and mallard-derived ducks can be bred, but the hybrids can not reproduce. They are often raised for meat because they grow quickly, like mallard-descended domestic ducks, but grow to be larger, like the slower-growing muscovy duck.
The muscovy duck may have derived its name from incorrect association with Muscovy (the duchy that includes Moscow), or from their musky odor. The scientific name Cairina moschata means “musky one from Cairo,” but the muscovy duck is not from Cairo, either.
More about New world domesticates with Old World names:
Posted on November 24th, 2010 No comments
First correct answer was from @mlv: Pellagra is a niacin deficiency disease caused by rapid spread of corn-based diet.
Pellagra, a niacin deficiency, was caused by the rapid spread of a corn-based diet and by improper preparation of the corn. Traditional preparation of corn included soaking in alkali. This released the niacin and prevented pellagra. When Europeans spread corn from the Americas to other parts of the world, and it became a staple of many impoverished populations, they failed to spread the cultural traditions that made the corn a properly nutritious staple food.
Note that pellagra is not caused by corn in the diet, but is not prevented by a nearly exclusive diet of corn. It’s a matter of balance. Anyone can certainly eat corn without fear of niacin deficiency, but if their diet includes no other significant source of niacin, they may be in trouble.
Modern strains of corn have been selected to make niacin more accesible to digestion without alkali processing.
Pellagra is still a problem in some refugee populations where corn is provided as an unfamiliar new staple food.
More about pellagra: http://en.wikipedia.org/wiki/Pellagra
Posted on November 23rd, 2010 No comments
First correct answer was from @arachne182: The fleshy protuberance above a turkey’s beak is called the snood.
Many galliformes (grouse/quail/pheasant family) have elaborate head decorations, but the snood is probably unique to the turkeys. Both male and female turkeys have snoods and other head decorations (wattles and caruncles), but all of these decorations are larger and more colorful in the males.
Turkeys can raise and lower the snood at will, but it serves no function other than display.
More about turkeys: http://en.wikipedia.org/wiki/Turkey_(bird)
Posted on November 22nd, 2010 No comments
First correct answer was from @ilrokery: The cranberry is a traditional Thanksgiving food that was named for a bird (originally “crane berry”).
The cranberry was so named for the resemblance of its flowers to a crane’s courtship display. The cranberry’s petals curve far backward, exposing the anthers and stigma, like the outstretched neck and backard-pointing wings of a courting crane.
The cranberry is native throughout high latitudes of the Norhtern Hemisphere, but was first used as food in the Americas. As a food introduced to the English by the Indians, cranberries (usually as sauce) became part of the traditional Thanksgiving Day feast. After the Indians introduced them to cranberries, Europeans began harvesting them in the Old World as well.
More about cranberries: http://en.wikipedia.org/wiki/Cranberry#Etymology_and_history
Plane takes off, reaches mach 1.3, flies 1K miles, accelerates to mach 2.1, flies 100 mi. How many sonic booms?Posted on November 19th, 2010 No comments
First correct and complete answer was from @jchaager: A plane flying at mach 1 or faster produces one continuous sonic boom which “follows” the plane. At least two people said a supersonic plane makes 1 sonic boom without specifying that it was continuous. Not sure they got it or not.
An airplane, or any other object traveling at the speed of sound or faster produces a sonic boom continually until it decelerates below mach 1. There is a common misconception that a plane produces a singular sonic boom when it “breaks the sound barrier.” Not true. There is an almost equally common misconception that a plane produces another sonic boom at each whole multiple of speed of sound, as it “breaks the second sound barrier” at mach 2, and so on. Not true.
An object moving faster than the speed of sound produces a shock wave which is perceived by an observer as a “sonic boom” as it passes. An observer hears a sonic boom after the airplane passes, even though the plane may have “broken the sound barrier” hundreds of miles away.
One would have hoped that the famous “double sonic boom” of a Space Shuttle on final approach would cure the “sonic boom/sound barrier” myth. The double sonic boom of the Space Shuttle is caused by its curving approach. The shuttle passes the observers twice while still supersonic.
Here in Middle Georgia, sonic booms from U.S. Air Force fighters are a weekly occurrence, but I have a couple of noteable personal experiences with sonic booms.
One day (many years ago) while hunting, I heard sharp “crack” in the trees overhead. About two seconds later, I heard gunshot on next hill. A moment later, this was repeated: A “crack” overhead followed by a distant gunshot two seconds later. What was happening here was that another hunter a mile or so away was shooting at something (and missing), and the bullets were passing my position. Each bullet arrived at my location before the sound of the shot that fired it. As the supersonic bullet passed me, I heard its tiny sonic boom. I didn’t hear the gunshot until that sound had time to travel the mile or so from the shooter’s position to mine.
Now, these bullets “broke the sound barrier” within the barrel of the gun about a mile away from me. But I heard the sonic boom as the bullet passed me. It took a total of about five seconds for the sound of the gunshot – and any sound the bullet may have made by “breaking the sound barrier” – to reach me, but I heard the sonic boom from the bullet 20 feet over my head long before the sound of the gunshot reached me.
There is a very odd phenomenon that may be observed after a sonic boom if the airplane making it passed very close by. I observed this once when a U.S. Navy F-14 “buzzed” my ship while supersonic at mast-top level. The plane had approached from the port side while I was on the starboard side, so I never saw it coming. After the hellaceous blast of the sonic boom, I saw the plane departing very rapidly off the starboard side, and I heard the sound of its departing engines following it. But I also noticed what sounded like another plane’s engines departing rapidly off the port side of the ship, in the direction from which the F-14 had come.
What was happening here was that the sounds made by the plane were “catching up” to my position in reverse order. Sounds made 10 seconds before the plane passed us were arriving at the ship after the sounds made 9 seconds before the plane passed, and so on. This is a perfectly straightforward consequence of the supersonic flight of the plane, but it produces a very disconcerting effect. The observer hears the sounds of the departing plane in “normal” fashion, but the sounds the plane made as it approached are “played in reverse” as earlier sounds catch up to later sounds. It sounds like an invisible airplane flying away.
Ever since that day, whenever I see an airplane approaching but I can’t hear it, I plug my ears and cringe. I have never again heard a sonic boom from mast-top level, but I really, really don’t want to.
More about sonic booms: http://www.sciencetriviatweets.com/?p=1008
Posted on November 18th, 2010 No comments
No correct answers to this one. The floors of polar craters, where the Sun never shines, are the coldest places on Mercury.
It was long thought that Mercury is tidally locked to the Sun, as the Moon is to Earth, keeping one side always facing the Sun. There was once a hypothesis that the “dark side” of Mercury was among the coldest places in the Solar System. Now we know this is false.
In 1965, careful observations revealed that Mercury does indeed rotate with respect to the Sun. It has no “dark side.” All longitudes of Mercury are lit by the Sun at various times. Only the deep craters near the poles of Mercury are permanently shaded, and these are thought to contain vast quantities of water ice.
Mercury happens to have the smallest axial tilt of any planet in the Solar system. This ensures that the Sun never lights the polar craters. A crater at or near the poles of Earth, for example, would be lit by the Sun during that hemisphere’s summer, when that pole is tilted toward the Sun. Mercury’s tilt is so small that its polar craters are permanently in shadow.
More about Mercury: http://en.wikipedia.org/wiki/Mercury_(planet)
Posted on November 17th, 2010 No comments
First correct answer was from @KessCat: The giant river otter (Pteronura brasiliensis) it the largest member of the weasel family by length.
The sea otter (Enhydra lutris) is often named among the largest mustelids. Individuals vary greatly, and the species overlap in size (i.e. the longest sea otter is longer than smallest giant river otter), but the giant river otter takes the record as the longest mustelid. The longest giant river otters measure about 5.9 feet. Sea otters reach just about 5 feet. By weight, the sea otter and giant river otter reach about the same size: 100 lb. or so at the most.
Many people mentioned the wolverine. The wolverine (Gulo gulo) is the largest land-dwelling mustelid, but only about 4 ft long and 55 lb. at the largest.
More about the biggest weasels:
Posted on November 16th, 2010 No comments
First correct answer was from @paulsmoffett: The Ganges Delta is the largest delta on Earth.
The Ganges Delta is formed by confluence of the Ganges, Brahmaputra, and Meghna rivers, and some smaller streams. Depending on how you look at it, the Ganges and Hooghly might look like one river, and the Brahmaputra and Meghna as one other river. The Meghna River is actually a combination of a major distributary of the Ganges and a major distributary of the Brahmaputra. It’s all tangled. The Ganges and Brahmaputra have clearly separate headwaters, but as they approach the Bay of Bengal, they seem to turn into one huge braided river with many different names. And they all empty into the denser braids of the Ganges Delta.
One reason the Ganges Delta is so large is that so many rivers contribute to it. Another is that each river has a heavy silt load compared to most rivers on Earth. Most of the rivers feeding the Ganges Delta drain large areas of the rapidly eroding Himalayas, providing rich silt to the delta.
The Ganges Delta encompasses huge wilderness areas, including the largest mangrove swamp in the world, the Sundarbans. It also supports nearly 150 million people with its rich soil and fisheries.
The Ganges Delta comprises much of the nation of Bangladesh, and much of the state of West Bengal, India.
The Ganges Delta is subject to frequent flooding due to the hydrology of the wide, shallow Bay of Bengal directing typhoons to it. Even lesser storms on the Bay of Bengal can cause serious flooding. Flooding in the Ganges Delta is likely to become much worse in the future. Not only is the sea rising due to global warming, the land around the Ganges Delta is subsiding as a result of the continuing tectonic collision of the Indian Subcontinent with Asia.
More about the Ganges Delta: http://en.wikipedia.org/wiki/Ganges_Delta