Term for perennial plants which produce above-ground parts only in spring, then die back to underground parts.Posted on November 12th, 2010 No comments
No correct answers to this one: Perennial plants that produce above-ground parts only in spring are called “spring ephemerals.”
The strategy of spring ephemerals is to leaf and flower in early spring, when trees and other taller (mostly woody) plants have no leaves. They use the energy they stored last season to produce their leaves and flowers very early in the season, then store energy underground for next season. Spring ephemerals include many woodland flowers which can be seen before trees shade them, then disappear in summer.
Spring ephemerals are different from annual or “weedy” ephemerals in that they have perennial bulbs, roots, or rhizomes. The “weedy” ephemerals survive their non-growing seasons in the form of seeds, while spring ephemerals survive underground.
Trillium species are often cited as examples of spring ephemerals, but many of them do persist above ground through summer and fall. I have observed Trillium erectum, T. grandiflorum, and T. undulatum in leaf and in fruit well into fall.
More about spring ephemerals: http://en.wikipedia.org/wiki/Ephemeral_plant#Spring_ephemerals
What does it mean when a scientific study of a new species calls it “incertae sedis” or “inc. sed.”?Posted on November 10th, 2010 No comments
Didn’t get to Twitter yesterday. Here is the discussion of Wedensday’s question.
1st correct answer was from @mlv “Incertae sedis” defines a taxonomic group whose relationships to other groups is not (yet) known.
The Latin term “incertae sedis” is used when the relationship of one species or larger group has not yet been determined for sure. It means “of uncertain placement,” meaning that it is not known how this species relates to others. It is most often used in descriptions of newly discovered species or genera, but it may be applied in other cases. When taxonomists disagree about the relations among groups, they may move disputed species or genera to “inc. sed.” temporarily.
When a species is called “inc. sed.” it is known to some extent, but not fully. e.g. we know its order, but not family.
More about “Inc. Sed.” http://en.wikipedia.org/wiki/Incertae_sedis
Posted on November 9th, 2010 No comments
There were several correct answers to yesterday’s question, but not all were as clear or complete as others. The first “complete” answer was from @jpwarren: Going to orbit of Mercury requires more fuel than leaving Solar System because must slow down. Quoting @jpwarren: “because you’re going deeper into the Sun’s gravity well and have to slow down.” Earlier correct but less clear/complete answers included:
- @jchaager: Entering orbit around mercury requires traveling faster than exiting the solar system due to the high gravity.
- @rozberk: I would say that it would take more power to fight increased gravitation forces than to exit from it.
And @rozberk had another answer about orbiting Mercury: “Because you’d just “have” to visit Vulcan while you’re there. :)”
As a spacecraft travels downsun, it gains kinetic energy (speed). To match Mercury’s orbital velocity, it must slow down tremendously. Thus, entering into orbit of Mercury with a starting point on Earth requires more rocket fuel than exiting the Solar System completely.
“Rocket fuel” is not necessarily the right term. The BepiColombo mission to Mercury will use solar ion drive to slow it down. This does not involve “rocket fuel” per se, but the spacecraft will still require a huge amount of propulsion to slow it down to match Mercury’s orbital velocity. The ion drive will do the job, but it will require a very long time to do so.
The current MESSENGER mission to Mercury uses conventional chemical thrusters, but it also makes extensive use of gravitational adjustments from planetary flybys to help it slow down to Mercury’s speed. That is why MESSENGER has already made three flybys of Earth since it was launched. Earth is helping to slow the spacecraft down (as are Venus, Mercury, and the Earth’s Moon).
BepiColombo is also making use of gravity assists from Earth, Venus, and Mercury to supplement the braking provided by its ion drive.
More about Mercury exploration: http://en.wikipedia.org/wiki/Exploration_of_Mercury and http://en.wikipedia.org/wiki/BepiColombo
What is the most widespread _wild_ freshwater fish in the world? (Spread mostly by human agency, of course.)Posted on November 8th, 2010 No comments
(This is the question I intended to ask on Friday, but “goldfish” was the correct answer to that question as originally worded. Now, what is the most widespread non-domesticated freshwater fish?)
There were no correct answers to this one. The western mosquitofish (Gambusia affinis) is probably the most widespread freshwater fish in the world.
There was a small clue in yesterday’s discussion of goldfish, but mosquitofish are even more tolerant of marginal habitats than goldfish. Mosquitofish can tolerate a wide variety of habitats, and they feed on larval mosquitos. They have been introduced for mosquito control, even more frequently than goldfish have been. Mosquitofish can live in salt water, so once introduced, they spread to nearby rivers and soon permeate whole watersheds.
Although often effective at controling mosquitos, the introduction of mosquitofish often harms native fish and other aquatic species.
The mosquitofish introduced and causing environmental havoc near Brisbane, Australia, is not the western mosquitofish (Gambusia affinis), but the closely related eastern mosquitofish (G. holbrooki).
More about mosquitofish: http://en.wikipedia.org/wiki/Gambusia_affinis
What is the most widespread freshwater fish in the world? (Spread mostly by human agency, of course.)Posted on November 5th, 2010 No comments
First correct answer was from @mlv: The goldfish is the most widespread freshwater fish in the world. Honorable mention to @KessCat for suggesting carp. The carp family (Cyprinidae) includes goldfish and many other widespread species.
Goldfish (Carassius auratus auratus) are the earliest fish to be domesticated, and are probably the most commonly kept aquarium fish. Besides being widely kept in captivity, there are wild-living populations of goldfish on every continent except Antarctica.
Like many domestic animals, goldfish readily revert to a wild state, and return to their ancestral appearance within 3 generations. Wild-living goldfish can breed among themselves, or crossbreed with related carp species. Goldfish are sometimes introduced to the wild for mosquito control due to their tolerance for stagnant water and wide range of temps. Like any introduced species, goldfish can harm ecosystems by outcompeting native species.
More about goldfish: http://en.wikipedia.org/wiki/Goldfish
What is the term for a lab test to determine whether a bacterial infection is resistant to antibiotics?Posted on November 4th, 2010 No comments
First correct answer was from @cakTo: The test to determine whether a bacterial infection is resistant to antibiotics is a “disc diffusion test.”
The test is a disc diffusion test. The result is called an “antibiogram.”
To perform a disc diffusion test, first a culture of the infecting bacteria is grown in a Perti dish. Discs of paper containing various antibiotics are placed on top of the culture to see which ones kill the bacteria and which don’t. The degree of sensitivity of bacteria to the antiobiotic diffusing from the discs is measured by how far from the disc the bacterial die.
An image of the results of the diffusion test is called an antibiogram. It is used to plan treatment for the infection. Whichever antibiotic is most effective against the bacteria in this particular infection is used to treat the infection.
Disc diffusion tests take time, as it takes time to grow the culture, then more time to allow the various antibiotics in the test to take their effect on the culture. Therefore, doctors will first begin treating the infection with the “best guess” antibiotic for the infection, then switch to another antibiotic as indicated by the antibiogram.
Generally, an infection picked up “in the wild” will be treated with general-purpose antibiotics and no disc diffusion test will be performed. Ironically enough, an infection aquired in a hospital is more likely to be resistant to common antibiotics, and so a disc diffusion test will be ordered. If a hospital is experiencing an outbreak of an antibiotic-resistant infection among its patients, the doctor will begin treatment with whatever antibiotic was indicated in tests of earlier patients rather than beginning with general-purpose antibiotics.
Of course, if an infection does not respond to general antibiotics will be followed up with a disc diffusion test, regardless of where it was aquired.
More about disc diffusion test: http://en.wikipedia.org/wiki/Antibiogram
Posted on November 3rd, 2010 No comments
First correct answer was from @rozberk: Forsythia is one of very few plants which produce lactose (milk sugar) in their nectar.
The most common sugars in nectar are more typical “plant” sugars, like sucrose and fructose, or even glucose. Forsythia produces lactose, the main sugar in the milk of mammals. Few plants produce lactose.
Forsythia is a genus of striking shrubs that produce a profusion of bright yellow flowers before the leaves in early spring. (Their common name is the same as their genus name, forsythia.) Forsythia is native to East Asia, and one species, F. europaea, is native to the Balkans. Many species, cultivars, and hybrids are commonly cultivated throughout the world, and naturalized in many places.
How do larvae of monarch and related butterflies avoid getting their jaws gummed up by the sap of milkweed plants?Posted on November 2nd, 2010 No comments
No correct answers to this one. Monarch butterfly caterpillars (and relatives) cut the veins of leaves before feeding to avoid gummy sap.
When very small, the caterpillars simply feed on the surface of the leaf, then move to a different spot when the sap begins to flow. Sometimes they do get their jaws stuck in the latex-rich sap, and caterpillars often starve as a result.
When they grow large enough, the caterpillars cut a vein near the base of the leaf, then eat the part that has been cut off from sap. All the latex that the plant exudes to try to repel the attack leaks out through the cut vein, and the caterpillar can feed in safety. This technique allows monarch and related caterpillars to feed on milkweed leaves despite their sticky, gummy sap.
Besides coping with sap that would glue their jaws shut, monarch caterpillars must also tolerate toxins within milkweed leaves. They do this successfully, and even incorporate the toxins into their own tissue, rendering the caterpillar and the butterfly that develops from it toxic to predators.
More about monarch butterfly caterpillars: http://en.wikipedia.org/wiki/Monarch_(butterfly)
Posted on November 1st, 2010 No comments
First correct answer was from @rozberk: Many types of cat litter contain microscopic fossil diatoms.
Clumping cat litter usually contains diatomaceous earth, comprised of fossil shells of diatoms, a type of alga with a silica shell. Diatomaceous earth is frequently used in fine filters. It is also used as a fine abrasive, and for absobent materials, such as cat litter. Some diatomaceous earth is used as a supplement to livestock feed due to its deworming capabilities.
The shells of diatoms, settling as sedimentary rock, result in a highly porous form of silica which allows water to pass but traps particles. The diatomaceous earth used in cat litter is usually from freshwater sources, but the more common type is from the sea.
Picturess of diatoms, thanks to @rozberk for the link: http://www.google.com/images?q=diatom At least one image is labeled as a “typical diatom.” A quick scan of the other images will reveal that there’s no such thing as a “typical diatom.”
More about diatoms in cat litter: http://en.wikipedia.org/wiki/Cat_litter#Clumping_litter and http://en.wikipedia.org/wiki/Diatomaceous_earth
What fish produces a neurotoxin which some researchers claim to be part of the process of creating zombies?Posted on October 29th, 2010 No comments
First correct answer was from @jrechs: Blowfish (or pufferfish) produce a neurotoxin which hypothetically creates zombies.
Tetrodotoxin (TTX) is a powerful and frequently fatal neurotoxin found in the flesh of the pufferfish (order Tetraodontidae).
There is a hypothesis proposed by Dr. Wade Davis of Harvard University, an idea that is not universally accepted, that Haitian Vodou practitioners create “real zombies” using TTX and other toxins. According to this hypothesis, the victim enters a near-death state, is buried, then reanimated as a slave of the zombie-maker. Part of this hypothesis is that the “reanimated” victim is psychologically predisposed to behave as a zombie due to cultural beliefs.
Many victims of accidental TTX poisoning, mostly in Japan where pufferfish is sometimes eaten, report that they remained fully aware of what was going on around them, able to hear, and sometimes even to see, when they were thought to be in a deep coma or near death. This is consistent with the reports of some Haitian “zombies,’ saying that they were aware of who was at their funerals, they remember being buried, and that the vodou practitioner later exhumed and revived them to be slaves.
Some critics claim that Davis might be a bit too gullible in taking the “zombies'” claims too seriously.
More about pufferfish and zombies: http://en.wikipedia.org/wiki/Zombie#Zombies_in_Voodoo