General Science GK Questions with Answers – Page 87

The correct answer is D, castor, which is the host of the eri silkworm and has nothing to do with lac culture.

The correct answer is A, Kerria lacca, earlier named Laccifer lacca, a tiny scale insect whose female settles on the twigs of a host tree, sucks its sap and secretes the resin we call lac.

The correct answer is A, Karl von Frisch, who decoded the dance language of bees: a round dance for a source near the hive and a waggle or tail-wagging dance for a distant one, in which the angle of the straight run shows the direction of the food relative to…

The queen can lay both fertilised and unfertilised eggs; the unfertilised ones develop into haploid males called drones, a form of parthenogenesis, while fertilised eggs give rise to diploid females.

The correct answer is C, Apis dorsata, the rock bee, the largest of the Indian honey bees, which builds a single huge comb on cliffs and tall buildings and yields the most honey per colony, yet is fierce and cannot be kept in hives.

The eri silkworm, Samia ricini, feeds on castor leaves, and its silk is called ahimsa silk because the moth is allowed to emerge before the cocoon is used, leaving a broken fibre that is spun like cotton instead of being reeled.

Muga silk comes from Antheraea assamensis, reared on Som and Soalu trees of the Brahmaputra valley, and Assam's muga carries a Geographical Indication tag.

The correct answer is B, Bombyx mori, the mulberry silkworm, the only fully domesticated insect of the silk group and the source of most of the world's raw silk.

Wool is the fleece of sheep and other animals and is made of the protein keratin, so it is a protein fibre; silk, which is the protein fibroin, is the other natural fibre of this kind, and both come from animals.

Bakelite is a phenol-formaldehyde resin, prepared by condensing phenol with formaldehyde; on curing the chains cross-link into a rigid network, giving a hard, heat-resistant and electrically insulating solid used for switches, plug tops, pan handles and distributor caps.

Thermocol is polystyrene expanded with a blowing agent so that the solid becomes a rigid foam of tiny closed cells.

Buna-S, also called styrene-butadiene rubber, is made by copolymerising 1,3-butadiene with styrene; the S in the name stands for styrene.

Rayon is made by dissolving the cellulose of wood pulp, forcing the solution through fine holes and regenerating the cellulose as a thread.

Polyvinyl chloride has linear chains held to one another only by weak forces, so it softens when heated and hardens when cooled and can be melted and moulded again and again; that reversibility is what makes a plastic thermoplastic, and it is also what allows such plastics to be recycled…

Vulcanisation is the heating of raw rubber with sulphur, which forms short cross-links between the long isoprene chains. Raw rubber is soft, sticky when warm and brittle when cold; the vulcanised product is strong, far more elastic and stable over a wide range of temperature.

Nylon-6,6 is a polyamide formed when hexamethylenediamine condenses with adipic acid, with a molecule of water eliminated at each linkage; the name records that each monomer contributes a chain of six carbon atoms.

Teflon is polytetrafluoroethene, made by the addition polymerisation of tetrafluoroethene. The fluorine atoms shield the carbon chain so completely that the surface is chemically inert, water repellent and almost frictionless, and it holds its properties to high temperature, which is why it coats frying pans and is used for gaskets…

Bakelite is made by condensing phenol with formaldehyde, and on moulding its chains join to one another by strong covalent cross-links into a single rigid network.

Polythene, also written polyethene, is formed by the addition polymerisation of ethene, in which the double bond of each molecule opens and the units join into a long chain with nothing eliminated.

Silk is the protein fibroin, spun by the silkworm, so it is a polymer made by a living organism and is therefore natural, like cellulose, starch, wool and natural rubber.