Category Science

What makes coconut oil freeze during winter?

            Oils are liquid fats. Fats are esters of carboxylic acids which are either saturated (do not contain double bond) or unsaturated (contain one or two double bond). These esters are derived from a single alcohol called glycerol and are called glycerides. Usually fats with greater percentage of un-saturation tend to be in liquid state and fats with greater percentage of saturation tend to be in solid state at room temperature.

            Vegetable fats are all liquid fats since they belong to esters of long chain fatty acids with one or more double bonds while most of the animal fats are solid in nature since they are all esters of long chain fatty acids which do not contain double bond.

            Coconut oil unlike other vegetable oils contains nearly 91 per cent of saturated fatty acids. Even though it has greater percentage of saturation it remains as liquid fat instead of solid fat.

            Its liquid nature is due to the presence of more number of short chains (C12 and C14) saturated fatty acids (only fats with long chain saturated fatty acids remains as solid fats). Because of the greater percentage of saturation coconut oil can easily be solidified at low temperature and becomes solid during winter when the temperature falls below 20 degree centigrade.

            Oils which contain unsaturated fatty acids can also be solidified if their double bonds are broken by hydrogenation at very high temperature. Vegetable ghee and vanaspathi are made in this way. This process is called hardening. In the case of coconut oil this hardening occurs not because of hydrogenation but because of low temperature.

Can anyone throw some light on Bermuda Triangle?

 Bermuda Triangle is a section of the Western Atlantic, off the southeast coast of the U.S, forming a triangle extending from Bermuda in the north to southern Florida and then east to a point through the Bahamas past Puerto Rico to about 40 degrees west longitude and then back again to Bermuda.

       In this mysterious place, a large number of planes and ships have vanished into thin air, of them since 1945. Interestingly, of the thousands of lives lost in the past not a single body or pieces of wreckage from the vanishing planes and ships have been found.

            Many varied and imaginative explanations have been offered and seriously considered to account for the continuing disappearances and assumed (because no bodies have been recovered) fatalities.

            These include sudden tidal waves caused by earthquake, fireballs which explode the planes, attacks by sea monsters, and a time-space warp leading to another dimension, electromagnetic or gravitational vortices which cause planes to crash and ships to lose themselves at sea, capture and kidnapping by flying or submarine UFOs (Unidentified Flying Objects) manned by entities from surviving cultures of antiquity, outer space, or the future looking for specimen of currently existing earth inhabitants.

            One single common thread which unites them is the fact ships and planes have completely vanished or that the ships have been found without their crews and passengers. While isolated mysteries of this nature could be explained by unusual circumstances or coincidences of weather and human error, so many of the Bermuda Triangle incidents have happened in clear weather, near to port, shore or landing base, that they seem unexplainable according to presently held concepts.

How do spiders manage without getting caught in their own web?

A thin coating of oil on the surface of the spider’s legs prevents them from sticking to their own web.

Spiders have 3 pairs of spinnerets (silk spinning apparatus) located beneath the hind tip of their abdomen. Silk, made up of proteins, secreted by the silk glands, and are made into fibres as thin as a thousandth of a millimetre. The threads we see are actually a bundle of these fibres. The proteins are water soluble when secreted, but when made into a fibre, some Physical and chemical changes take place, and so, after a while the fibre becomes tough and does not dissolve in water. In fact, it becomes stronger than a steel wire of the same thickness. Hence, the spider silk is also used to make bullet proof vests.

To construct a web, the spider first lays the radical threads. These resemble the spokes on a wheel and they radiate from the centre or hub of the web. The radial fibres are then connected by spiraling threads. There may be 10-60 turns in a web. To capture the insects, spiders scatter small glue droplets throughout. The glue droplets remain sticky by absorbing moisture from the air. They also increase the capacity of the web to resist wind forces.

While some spiders do not place glue droplets around the central area of their web so that they can wait there for the prey, a few others attach a separate ‘signal thread’ from the web’s centre to a nearby place (not on the web) where it can conveniently relax. When the insects get stuck to web, spiders sense the vibrations and leap on the prey.

To help avoid being caught in their own webs, the spiders secrete oil and coat it on their toes. One can test this by dipping a spider’s legs in ether, an organic solvent, which dissolves the oil. If the spider is returned to the web after the dip, it will be caught in its own web.

Why do snakes move in a zigzag manner?

The snakes are the only vertebrates which have efficiently overcome the handicap of absence of limbs making them survive with relatively long, slender body and a cosmopolitan habitat bestowed on them by nature. This achievement was basically by adapting different modes of locomotion fulfilling the need of the environment (terrestrial, water and arboreal) in which the animals lives.

The most common mode of progression which is generally employed by all species and is characteristic to them is the ‘serpentine type of locomotion’ better named as ‘undulatory motion’ in which the animal forms a zigzag track.

The basic necessity and attribute of this motion is some form of maximum provided by any projections or depressions on the substratum like rocks, branches, twigs, dust, sand or pebbles. This roughness in real sense resists the long, slender body to move on a straight line owing to which the body assumes a position of a series of s-shaped horizontal loops or curves.

 Each loop or curve which faces some resistance in turn delivers an equal and opposite thrust against the resistance leading to the formation of a series of  lateral or horizontal waves produced by a flow of muscular  contraction and relaxation passing from head to tail, resulting in the , propulsion of the  body in the forward direction.

 This kind of a zigzag motion is undergone only when the surface is rough enough to offer maximum resistance. It is of no use when they move on a really smooth surface, where they are offered least resistance. 

 

Why does the light of firefly twinkle while that of glow-worm remains constant?

            Fireflies are not really flies and glow worms are not really worms. Fireflies are soft bodied beetles in the family of Lampyridae and glow worms are actually young fireflies (larvae).

            Although the luminescent molecule in many organisms is yet undetermined, in most organisms the light producing reaction is mediate by the action of a class of enzymes called luciferases on their substrate called luciferins.

            Some organisms do not make use of luciferases but instead use calcium activated photo proteins in their bioluminescent reaction involves the oxidative decarboxylation of luciferins in the site of special cells called photocytes present on their lower abdomen segments to attract mates. It appears that male fireflies flashing patterns are mating signals and females seem to prefer the most rapidly flashing males.

            Since glow worms do not mate, no one knows exactly why they glow. But glow worms are carnivorous and probably use the light to lure or locate its prey.

            There are over 2000 species of fireflies inhabiting the tropical and temperate regions. Fireflies of the same species recognize each other by number of flashes used the frequency of flashes and colour of the light. Fireflies’ eggs are also reported to glow.

How do ants go in a line?

     Ants are social insects. Many ant species go out of their nests in groups in search of food. Initially, a few worker ants, called scouts, go out of the nest in search of food. Once an abundant source of food is found to the nest, it presses its abdomen to the ground and at frequent intervals extrudes its sting, the tip of which is drawn lightly over the ground surface, much like a pen drawing a thin line.

            As the sting touches the surface, a volatile chemical (trail pheromone), flows out of a gland (Dufour’s gland), associated with the sting. In this way the worker draws an invisible chemical line from the source of food to the nest. As soon as it returns to the nest, it contacts a couple of workers, antennates them and makes quick looping movements on the line for short distances. This excited movement attracts the attention of more workers and they start following the scout, which leads, initially, to the food. These workers return to the nest with more samples, and reinforce the chemical line while returning.

            This results in recruitment of more and more workers and soon one will find a never ending line of ants moving up and down the line bringing back food. Since the chemical is highly volatile, the trait remains only for a short time. Hence, all the worker ants constantly draw the line over and over again.