General Science Mixed Quiz: Set 25

The sensation of a sound persists in the human brain for roughly one tenth of a second, so a reflected sound must arrive at least that much after the original to be heard as a separate echo.

A ligament is the connective tissue that joins one bone to another at a joint. It is very elastic and strong, and it holds the bones in place so that a joint can move without the bones slipping apart.

Tungsten has the highest melting point of all metals, well above three thousand degrees Celsius, so a thin tungsten wire can be heated until it glows white without melting.

The BCG vaccine takes its name from Albert Calmette and Camille Guerin, the two French scientists who developed it from a weakened strain of Mycobacterium bovis.

The alkali metals are lithium, sodium, potassium, rubidium, caesium and francium. Each has a single electron in its outermost shell, loses it readily to form a positive ion, and therefore stands in group 1 of the modern periodic table.

Bacteria are grouped by shape, and bacilli are the rod-shaped ones; the Latin word bacillus itself means a small rod or stick.

A tissue is a group of cells that come from the same source, look alike and work together at one job.

Guava is the classic jam fruit because it is rich in both pectin and acid, the two things a jam needs to set into a firm gel.

The small intestine is the longest part of the human alimentary canal, about 6 to 7 metres in an adult, which is why it is called the longest organ of the digestive system.

In a suspension the particles of the solute are large enough to be seen and do not dissolve; they stay spread through the liquid only while it is stirred and settle to the bottom when it is left standing.

Human beings are ureotelic, which means the main nitrogen waste they pass out is urea. When the body breaks down extra amino acids, ammonia is produced, and ammonia is highly poisonous even in small amounts.

Silk comes from the cocoon spun by the caterpillar of a moth. The common silk moth is Bombyx mori, and rearing it is called sericulture.

Bos mutus is the scientific name of the wild yak, the long haired bovine of the high cold plateaus of Ladakh, Tibet and the Karakoram, which grazes above four thousand metres and is listed as Vulnerable on the IUCN Red List.

The fusion of a male gamete with a female gamete is called fertilisation, and the single cell it produces is the zygote.

Abscisic acid is the one plant hormone in this list that slows growth instead of speeding it up, which is why it is often called the stress hormone of plants.

Sulphur dioxide dissolves in water to give sulphurous acid, a weak acid with the formula H2SO3, by the reaction SO2 + H2O to H2SO3.

Hold the conductor in your right hand with the thumb stretched along the direction of the conventional current; the way your fingers curl round the wire is the direction of the concentric magnetic field lines.

Electronegativity is the tendency of an atom to attract a shared pair of electrons towards itself. It increases from left to right across a period, as nuclear charge grows, and decreases down a group, as each new shell puts the outer electrons further from the nucleus.

The left atrium is the chamber that receives oxygen-rich blood coming back from the lungs through the pulmonary veins. From there the blood passes the bicuspid or mitral valve into the left ventricle, which pumps it out through the aorta to the whole body.

In Fleming's left hand rule the forefinger, the middle finger and the thumb of the left hand are held at right angles to one another: the forefinger points along the magnetic field, the middle finger along the current, and the thumb then gives the direction of the force.