General Science Mixed Quiz: Set 194

Starlight is bent again and again as it passes through layers of air whose temperature and density keep changing, so the star seems to flicker in brightness and position.

He noticed that a mould of the genus Penicillium growing by accident on a culture plate had stopped the growth of Staphylococcus around it, and Howard Florey and Ernst Chain later turned that observation into a usable drug, the three sharing the Nobel Prize.

Potential difference is the work done per unit charge, so V = W/Q = 24 J ÷ 2 C = 12 V. The potential difference between two points is the work needed to move one coulomb of charge from one point to the other.

Quinine is an alkaloid extracted from the bark of trees of the genus Cinchona, native to South America and grown in India in the Nilgiris and in Darjeeling, and it was the standard treatment for malaria before synthetic drugs appeared.

Mass by mass percentage is the mass of solute divided by the mass of the whole solution: 20 ÷ (20 + 180) × 100 = 10%.

His study of the characteristic X-rays of the elements showed that the nuclear charge, the atomic number, is the quantity that rises regularly from element to element, and the modern periodic law therefore states that properties are a periodic function of atomic number.

The eye lens focuses light on the retina, the light-sensitive layer at the back of the eye, where a real and inverted image is formed.

Besides its normal roots, Cycas bears small branched roots that grow upward near the surface and look like coral; these coralloid roots hold cyanobacteria such as Anabaena and Nostoc, which fix atmospheric nitrogen and supply it to the plant.

Cattle, buffaloes, goats and sheep are ruminants, and a ruminant's stomach has four chambers. The four chambers are the rumen, the reticulum, the omasum and the abomasum.

It is called laughing gas because it produces a feeling of elation when inhaled in small quantities, and it is used as a mild anaesthetic in dentistry and minor surgery and as the propellant in whipped cream; it is also a greenhouse gas.

Cytokinins are the plant hormones whose main job is to promote cell division, or cytokinesis, which gives them their name.

Tooth enamel is made mainly of calcium phosphate in the form of a hard crystal called hydroxyapatite. Enamel is the hardest substance in the human body, harder even than bone.

The English engineer Thomas Savery patented a steam pump in 1698 and called it the Miner's Friend, as it was meant to pump water out of flooded mines.

Neem is Azadirachta indica, a tree valued in Indian medicine for its leaves, bark and oil, and it is remembered in current affairs as well because a European patent on a neem based fungicide was revoked after India challenged it.

The force exerted by light depends on how much light falls on the surface, so with the same intensity, half the area receives half the light and feels half the force.

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.

The cornea is a clear layer made of cells and proteins, chiefly collagen fibres laid out in a regular pattern that keeps it transparent.

For a photon, energy equals momentum multiplied by the speed of light, E = pc, so a momentum of 10 MeV/c gives an energy of exactly 10 MeV.

Osmosis is the passage of water from where water is more concentrated (a dilute solution) to where it is less concentrated, across a membrane that lets water through but holds back solutes.

In it nitrogen from the air and hydrogen from natural gas combine directly over a finely divided iron catalyst at high pressure and a temperature of about 450 to 500 degrees Celsius; the ammonia produced is then reacted with carbon dioxide to make urea.