General Science Mixed Quiz: Set 199

The English physicist James Prescott Joule showed around 1841 that when a current flows through a conductor, the heat produced is proportional to the square of the current, the resistance of the conductor and the time for which the current flows.

Anthropology, from the Greek 'anthropos' (human) and 'logos' (study), is the science of human beings: how societies and cultures began, how they changed and how people live today.

. A Fischer projection draws a molecule as a cross: the horizontal bonds point towards the viewer and the vertical bonds point away.

A lever is a rigid bar turning about a fulcrum, and by the principle of moments the load multiplied by the load arm equals the effort multiplied by the effort arm, so a long effort arm lets a small effort balance a large load; this is the simplest way of…

Cardiac muscle, found only in the wall of the heart, is made of cylindrical cells that branch and join with one another, and each cell usually has one central nucleus.

In an ion exchange plant the water passes through a cation resin, which takes up the calcium and magnesium ions, and then through an anion resin, which takes up the sulphate, chloride and bicarbonate ions; because the hardness-causing ions are actually taken out of the water, the hardness can be…

Helicobacter pylori is a spiral-shaped bacterium that lives in the lining of the stomach. It survives the strong acid by producing the enzyme urease, which makes ammonia around it, and it inflames and weakens the protective mucus layer, so acid can damage the wall and cause a peptic ulcer.

The iris is the coloured ring in front of the lens, formed by the front part of the choroid, and the muscles in it widen or narrow the pupil so that the right amount of light reaches the retina; in dim light the pupil opens wide and in bright light…

A galvanometer detects whether a small electric current is flowing in a circuit and shows its direction. A moving-coil galvanometer has a coil placed between the poles of a magnet.

The working rule for charging a storage battery is that the charging current should be about one-tenth of the ampere-hour capacity of the battery, which is called the C by 10 rate.

Centrifugation separates very fine insoluble particles that are too small to settle on their own. The mixture is spun at high speed in a centrifuge.

Indian food standards divide preservatives into two classes. Class I preservatives are the natural ones that cooks have always used, and no limit is placed on the quantity: common salt, sugar, dextrose, spices, vinegar or acetic acid, honey and edible vegetable oils.

By Archimedes' principle, the upward force, called buoyancy or upthrust, equals the weight of the fluid displaced by the body.

The silkworm's silk gland secretes a protein called fibroin, and over it a second protein, sericin, which acts as a gum and hardens the cocoon; boiling the cocoon softens the sericin so the filament can be reeled, and removing it afterwards is called degumming, which gives silk its lustre and…

Tiny gas molecules in the air scatter short wavelengths far more strongly than long ones. This is Rayleigh scattering: the amount of scattering varies inversely with the fourth power of the wavelength.

Egg white is mostly water and protein, and heat denatures these proteins so that they set into an opaque white solid.

The word fission is used in two sciences: in biology for splitting of a single-celled organism, and in physics for splitting of a heavy nucleus.

Biogas is mostly methane, usually about 50 to 75 per cent, and methane is the part that burns. Biogas is made when bacteria break down cattle dung, crop waste, kitchen waste or sewage in the absence of oxygen, a process called anaerobic digestion, inside a closed digester.

All rose plants of one kind belong to a single species, the basic unit of classification. A species is a group of individuals that are alike in their main features and can interbreed in nature to produce fertile offspring.

Planaria is a free-living flatworm, while the other three are parasites that live inside a host. Planaria belongs to the phylum Platyhelminthes and lives in freshwater ponds and streams, gliding under stones and feeding on small animals.