The reason why veins ( and hence the blood flowing inside them ) appear blue has to do with different colours and their respective wavelengths . Red with higher wavelength can penetrate deeper into skin surface unlike blue . Since veins are at such depths that allow only red colour to penetrate while the blue gets reflected , veins appear blue in colour .
How does water rise to great heights in trees like coconut and redwood ?
The long distance transport of water in a plant takes place in the xylem of vascular bundles or in the wood . The conducting elements are called vessels ( tracheae , tracheids ); they have the dimensions of capillaries . They form long capillary tubes with uninterrupted pathways for water transport . The uninterrupted columns of water in the vessels are characterised by large tensile strength . This characteristic is due to the cohesion of water molecules by intermolecular hydrogen bonds . The tensile strength of water threads in vessels has limits that are species specific . The adhesion of water to the vessel walls is so strong that even under strong suction ( hydrostatic tension ) the capillary water threads do not collapse . The stiffened vessel walls are able to withstand strong suction within the vessels . This makes possible the rise of water to greater heights in plants .
SCIENCE FACTS
WINSPIRE : Empowering youth | January , 2017
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How does eel produce electricity ?
Each animal that hunts for its food depends upon definite cues in the search . For this they develop special adaptations which help to increase biotic potential . Although almost any individual kind of animal demonstrates such adaptations in sensory mechanisms related to food acquisition , some are sufficiently spectacular to earn special mention . One such is the sensory adaptations found in certain members of Teleost fishes , which have independently developed organs , which produce electricity . These are used for defense , the capture of prey and perhaps as direction finders . The best-known is the so called Electric `eel ’ ( Electrophorus ) — a blind , superficially eel-like fish which grows to a length of about eight feet , and is almost as thick as a man ’ s thigh and lives in shallow muddy parts of the Amazon and other South American rivers . On land Electrophorus can discharge about 500 volts . In water the charge is partly short circuited and the shock is about 250 volts , but still sufficiently strong to cause great discomfort to man or to activate an electric buzzer . The electric organ consists of some seventy columns , each of which contain a series of about 600 disc-shaped syncytial electroplaxes ( Electroplate cells ). The cells are probably formed from striated muscle-cells and together constitute a jelly like mass located in the postero-ventral four-fifth of the body and tail .
Each electroplate is innervated and shocks are normally transmitted only when the fish is molested or when it comes within the range of its prey , which is stunned and then swallowed whole . These fishes that can generate high voltages have protective insulation around their own nervous system , shielding them from damage .