General Science Mixed Quiz: Set 166

Wire B has half the resistance of wire A, and at the same voltage power is V²/R, so B dissipates twice the power: P₁ = 2P, which means P = P₁/2.

Palaeontology is the study of fossils, the preserved remains or traces of organisms of past geological ages, and it supplies the evidence on which the history of life and the theory of evolution rest.

The element with atomic number 11 is sodium, and with one electron in its outermost shell its valency is 1.

A fathometer, also called an echo sounder, sends a pulse of sound from the hull of a ship to the sea floor and times the returning echo; since the speed of sound in sea water is known, the time gives the depth.

When magnesium burns, magnesium loses electrons and is oxidised, while oxygen gains them and is reduced, so oxidation and reduction happen together.

Melting means breaking the particles free of the forces holding them in a fixed lattice, so a higher melting point means stronger forces of attraction.

Silver bromide is the light-sensitive compound coated on black and white photographic film and paper, because light breaks it down into tiny grains of silver metal.

By Archimedes' principle the upthrust on a body equals the weight of the fluid it displaces, and that weight is the volume of the body actually immersed multiplied by the density of the fluid and by the acceleration due to gravity.

Ribosomes make proteins, a job every living cell must do, so they are present in both prokaryotic and eukaryotic cells.

Both absorb neutrons strongly, so pushing the rods into the core removes neutrons and slows the chain reaction, while withdrawing them allows the reaction to build up; this is how the power of a reactor is controlled and how it is shut down.

A pollen grain lands on the stigma, grows a pollen tube that travels down through the style, and enters the ovary to reach an ovule, where fertilisation takes place.

They are called universal gates because either one of them, used repeatedly, can build every other logic gate, including NOT, AND, OR, XOR and XNOR.

Soap in water forms a lyotropic liquid crystal, a phase whose ordered structure appears because of the amount of solvent mixed in, not because of temperature alone.

In froth flotation the powdered ore is agitated with water, a frothing agent such as pine oil and a collector.

For an astronomical telescope in normal adjustment the magnifying power equals the focal length of the objective divided by that of the eyepiece, so the eyepiece focal length is 50 ÷ 25 = 2 cm.

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

Autotrophs take carbon dioxide from their surroundings and build their own organic food from it, so CO₂ is their main source of carbon.

Several groups of ants, above all the leafcutter ants of the Americas, grow fungus as their food, a form of farming that began millions of years before human agriculture.

Without oxygen, yeast carries out alcoholic fermentation, breaking glucose into ethanol and carbon dioxide and gaining a little ATP. Glucose is first split into two molecules of pyruvate by glycolysis, which yields a net gain of two ATP.

B cells and T cells are lymphocytes, the white blood cells of the adaptive immune system that recognise and fight specific bacteria, viruses and other pathogens.