My Science School

The sky is blue because air molecules in our atmosphere filter blue light out of the colour spectrum. A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light.  When we look towards the sun at sunset, we see red and orange colours because the blue light has been scattered out and away from the line of sight. The white light from the sun is a mixture of all colours of the rainbow.  This was demonstrated by Isaac Newton, who used a prism to separate the different colours and so form a spectrum.  The colours of light are distinguished by their different wavelengths.  The visible part of the spectrum ranges from red light with a wavelength of about 720 nm, to violet with a wavelength of about 380 nm, with orange, yellow, green, blue and indigo between.  The three different types of colour receptors in the retina of the human eye respond most strongly to red, green and blue wavelengths, giving us our colour vision.

 

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Everyone’s blood contains the same basic stuff, but mixed in with that stuff are ‘’antigens’’. These special proteins act like an ID tag for a person’s own and not a foreign invader. Antigen combinations make different blood types – eight in all – which are passed along from parent to child just like eye color and other genetic traits. If you get in an accident and lose a lot of blood (or get sick and need a fresh supply), you’ll have to go to the hospital to get a ‘’transfusion’’ of someone else’s red stuff. Transfusions are simple procedures and the most common type of hospital procedure but they always start with the doctor determining the patient’s blood type. If you get a transfusion of the wrong type, your immune system will think it’s an infection and go on the attack!

 

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Remove all your bones – along with the joints and muscles pinned to them – and you’d end up a shapeless, motionless bag of blood and organs. Your skull and spinal vertebrae, made of tough deposits of calcium and other minerals, are like armor for your brain  and nervous system. Special bone marrow in your vertebrae  and elsewhere is your body’s blood factory. Your muscles and joints, meanwhile, set your human machine in motion.

 

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A mix of special cells and liquid ‘’plasma,’’ blood delivers all the good stuff (oxygen vitamins, minerals, and chemicals called hormones) to the cell in your body and carries away all the bad stuff (carbon dioxide and other waste) for disposal. Red blood cells transport oxygen, while white blood cells fight infection. Special cells called platelets seal the leak when blood vessels break – a process called clotting. An oxygen-carrying protein called hemoglobin is what gives blood its red color.

 

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You can’t always guess a child’s appearance just by looking at his or her parents. The study of genes – called genetics – is achieving breakthroughs all the time, but much about heredity remains mysterious. Combinations of genes can affect other genes, leading to unpredictable characteristics or features that lurk in the genetic background for several generations. Our genes are riddled with so-called junk DNA that doesn’t seem to express itself in any noticeable way. Environment and diet also play a large role in shaping a person’s weight, skin tone, and other physical characteristics.

 

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While you admire your good looks in the mirror, don’t forget to thank your parents. Genes come in pairs: one from Mom and other from Dad. It’s the combination of genes that bring about – or ‘’express’’ – various physical traits (in a process called heredity). Some genes are more influential on your appearance than others. The genes for dark hair are dominant over the genes for red and blond hair, making dark hair more common.

 

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