A Cockroach Can Live without Its Head!

Cockroaches can live without their heads. Entomologist Christopher Tipping at Delaware Valley College in Doylestown, Pa., has actually decapitated American cockroaches (Periplaneta americana) very carefully under microscopes. He sealed the wound with dental wax, to prevent them from drying out. A couple lasted for several weeks in a jar. And it is not just the body that can survive decapitation; the lonely head can thrive, too, waving its antennae back and forth for several hours until it runs out of steam.

To understand why cockroaches—and many other insects—can survive decapitation, it helps to understand why humans cannot, explains physiologist and biochemist Joseph Kunkel at the University of Massachusetts Amherst, who studies cockroach development.

Why Humans Can't Survive Decapitation?	Why Cockroaches Can Survive Decapitation?
Decapitation in humans results in blood loss and a drop in blood pressure hampering transport of oxygen and nutrition to vital tissues.	Cockroaches have open circulatory system with low blood pressure. They don't have a huge network of blood vessels like that of humans, or tiny capillaries. After you cut their heads off, very often their necks would seal off just by clotting. There's no uncontrolled bleeding.
A drop in blood pressure hampering transport of oxygen and nutrition to vital tissues.	Insect blood does not carry oxygen. The spiracles carry air directly to tissues through tracheae.
Humans breathe through their mouth or nose.	Cockroaches breathe through spiracles, located in each body segment.
The brain controls that breathing, so breathing would stop.	Their brain does not control this breathing. Insects have ganglia distributed within each body segment capable of performing the basic nervous functions responsible for reflexes.
The human body cannot eat without the head, ensuring a swift death from starvation should it survive the other ill effects of head loss.	Cockroaches are also poikilotherms, or cold-blooded, meaning they need much less food than humans do. An insect can survive for weeks on a meal they had one day.

Source: Scientific American

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Why is sucrase called invertase?

Sucrase 
Sucrase (systematic name: beta-fructofuranosidase) is an intestinal enzyme that hydrolyzes sucrose.
C12H22O11   +   H2O   →   C6H12O6    +   C6H12O6
 (sucrose)        (water)         (glucose)          (fructose) 
Sucrase Secretion 
It is not present in newborn animals so that they are unable to digest sucrose and feeding of the sugar will cause severe, osmotic diarrhea. Sucrase activity in the intestine increases as the need for, and secretion of, lactase decreases with age.
Why is it called invertase? 
Sucrase is also known as invertase or saccharase. It catalyzes the hydrolysis (breakdown) of sucrose (table sugar) to fructose and glucose, usually in the form of inverted sugar syrup. Invert sugar is the mixture of glucose and fructose produced by hydrolysis of sucrose, 1.3 times sweeter than sucrose. It is called invert sugar because the optical activity is reversed in the process.
The method of measuring the concentration of sugar syrup 
The concentration of sugar syrup is measured using a polarimeter. Plane-polarized light, when passed through a sample of pure sucrose solution, is rotated to the right (optical rotation). As the solution is converted to a mixture of sucrose, fructose and glucose, the amount of rotation is reduced until (in a fully converted solution) the direction of rotation has changed (inverted) from right to left.