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1500 questions
16
votes
3 answers
What happens to dextrorotatory amino acids in humans?
As indicated by this question, most of the amino acids in the human body have the L-chirality. As enzymes also have handedness, what happens to the D-amino acids that end up within the human body? Are they simply excreted? Are there enzymes (perhaps…
LanceLafontaine
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16
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1 answer
Can you identify this bird?
Can somebody please identify this bird for me?
I spotted this in July 2012 while birding in Ranganthittu Bird Sanctuary.
Manu Manjunath
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16
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2 answers
How does a woodpecker not give itself concussions?
How does a woodpecker go about smacking it's head into a tree without killing itself?
Sciiiiience
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16
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Why does the oxygen produced in the photosynthesis come from water and not carbon dioxide?
In the photosynthesis equation:
$$\ce{6CO2 + 6H2O ->[sunlight] C6H12O6 + 6O2}$$
The only place where we have 6 molecules of $\ce{O2}$ is in $\ce{6CO2}$. Then it reacts with $\ce{6H2O}$ to form $\ce{C6H12O6}$ and $\ce{6O2}$ that apparently comes from…
Yuran Pereira
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16
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2 answers
How does an axon "know" it's not connecting to its own neuron?
I recently read about an experiment where they removed the dendrites and axons from rat neurons and placed them on a grid. After a while they started reconnecting and were able to learn things.
Since I'm trying to create a model simulating this, I'd…
Lennart_96
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16
votes
2 answers
Seeing strange things in light
I have noticed that if you look directly at tubelight (I have only white ones in my home) and close your eyes little, you see little random shaped colourless things sometimes with slow speed and sometimes with falling down.
They are shaped like…
evil999man
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16
votes
4 answers
Was the mitochondrion or chloroplast first?
I still don't know if the mitochondrion or chloroplast was first? I've looked for it on the internet and in various books but haven't found anything. Does anyone have the answer and a theory which backs up this answer?
user114141
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16
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2 answers
How are viruses weakened to be suitable for vaccination?
I understand there are two kinds of active vaccination
Injecting complete viruses that are weakened to not cause the disease being vaccinated against
Injecting only antigen particles of viruses that the body creates antibodies for. So the disease…
Johannes Schaub - litb
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16
votes
3 answers
How does the human body metabolize gasoline?
A Chinese man has been drinking gasoline to relieve his pain for 25 years. How does the human body metabolize gasoline? Also, what are the side-affects to gasoline?
Dale
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16
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2 answers
Can humans transdermally absorb minerals from ocean water, and if so how much?
According to several studies quoted here, chemicals can be absorbed by the skin transdermally, at least under certain conditions.
When it comes to elements in seawater like sodium, magnesium, potassium and iodine, is it possible for a human to…
user3362
16
votes
1 answer
At which step should I apply a detection filter when preprocessing microarray data? (Before/After normalization, batch effects removal)
What is the best practice when preprocessing microarray data using a detection filter (on scanner p-value)?
Suppose I have a microarray dataset that I have to normalize with Loess and correct with ComBat. When should I apply a detection filter,…
gc5
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1 answer
This looks like it was somebody’s home - but who?
Found this near the edge of a forest in upstate New York. It looks like the remnant of a cocoon of some kind. I would appreciate any help in identifying its original maker / occupant.
I hope my fingers give a reasonable indication of scale -…
Floris
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16
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3 answers
Do insects with compound eyes have depth perception?
Do insects with compound eyes have depth perception? They fly as if they do, but their eyes are so close together it seems like the image would be 2 dimensional.
J. Musser
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16
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1 answer
How many mice are on the Earth?
We are 7 billion human beings on the Earth. But how many mice are there? How would you estimate such a number?
Gianpaolo R
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16
votes
4 answers
Why do we have no enzyme to digest cellulose?
As we know, cellulose is the most abundant polysaccharide in nature. Why don't we have an enzyme to digest cellulose?
Sagar
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