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Sharpen Your General Knowledge
Shamim Ansary:
Why Do Evergreen Trees Not Lose Their Leaves In the Fall?
Evergreen trees do not keep their leaves indefinitely, but rather may grow new ones before the old ones fall, or keep some and drop others over a period of time.
As any southern gardener can tell you, some broadleaf evergreens, like Magnolia grandiflora, drop their heavy leaves in a staggered cycle over the course of the year.
Some, like the live oak, may show a heavy leaf loss in early spring, but retain a few old leaves while the new ones develop.
There is also seasonal needle loss with evergreen species of conifers, like pine, spruce, and fir trees. The leaf drop is a normal process, not a disease. The older,
Shamim Ansary:
Can Your Hair Change Color Overnight?
Your hair can and will change color when you are old, but this does not happen overnight.
Different hair colors, from blonde to black, are determined by the melanin, the coloring matter, in your hair cells. This melanin becomes part of your hair cells as they form in the roots. Gray hair starts to appear in older people when less melanin is deposited in the new hair cells as they form. Without this coloring matter, the hair becomes gray and then white.
Certain diseases can cause the body to stop or slow down the production of melanin. So might worry, shock, or deep sorrow.
Shamim Ansary:
Why Are Black Eyes Black and Why Does a Bruise Change Color When It Heals?
Blood released from capillaries and trapped under the skin and breakdown products of hemoglobin in the blood are chiefly responsible for the coloration of black eyes and other bruises.
In the case of black eyes, old blood is never really black, but dark purple and green.
The color of the pooled blood is magnified by the loose and transparent skin around the eyes, making a bruise there darker than it is on other parts of the body.
The chemicals mainly responsible for the changing colors of bruises are a series of products of the breakdown of hemoglobin, the oxygen-carrying compound in red blood cells.
An important one is biliverdin, which is green. There may also be bilirubin, which is yellow-brown.
The timing of the breakdown and the mixing of colors are not fully predictable, but at first bruises are usually dark blue, purple or crimson.
The color gradually changes to violet, green, dark yellow and pale yellow and finally disappears.
In one study pathologists found that they could conclude only that a yellow bruise was more than eighteen hours old.
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