General Science GK Questions with Answers – Page 78

Transfer RNA picks up a specific amino acid and brings it to the ribosome, where it is added to the growing protein chain.

Cerium oxide (CeO2) strongly absorbs ultraviolet rays while letting visible light through, so it is added to glass to make it UV-protective.

Methanol (CH3OH) is called wood spirit or wood alcohol because it was first obtained by the destructive distillation of wood.

Where oil meets water, the unequal pull of their molecules sets up a surface (interfacial) tension that keeps the two liquids as separate layers.

Violet light has the shortest wavelength among the visible colours, so the medium bends it the most. The splitting of white light into its colours is called dispersion.

Mitochondria carry their own circular DNA and their own ribosomes, so they can make some of their own proteins. Mitochondria are the sites of aerobic respiration, where ATP is produced, which is why they are called the powerhouse of the cell.

Photosynthesis absorbs energy from sunlight to build glucose, so it is an endothermic process. An endothermic process takes in heat or light from its surroundings, while an exothermic one gives energy out.

The de Broglie wavelength depends only on momentum, so equal wavelengths mean equal momenta. In 1924 Louis de Broglie proposed that every moving particle has a wave linked to it, with wavelength λ = h/p, where h is Planck's constant and p is the linear momentum.

The product forms a coating that shuts the acid out. Calcium reacts with dilute sulphuric acid to give calcium sulphate and hydrogen gas: Ca + H2SO4 gives CaSO4 + H2.

The atomic number (Z) is defined as the number of protons in the nucleus of an atom. Every atom of an element has the same number of protons, so the atomic number identifies the element: hydrogen has 1, carbon 6 and oxygen 8.

X-rays are electromagnetic waves with no electric charge, so electric fields cannot deflect them. X-rays were discovered by Wilhelm Röntgen in 1895, who won the first Nobel Prize in Physics in 1901 for it.

This is a double displacement (precipitation) reaction, in which no element gains oxygen or loses electrons. When the two solutions are mixed, the ions swap partners: BaCl2 + Na2SO4 → BaSO4 + 2NaCl.

The sound travels to the cliff and back in 5 s, so it covers 340 × 5 = 1,700 m in all, and the cliff is half of that, 850 m away.

Slaked lime is calcium hydroxide applied as a watery solution, and it takes up carbon dioxide gas from the air to form solid calcium carbonate and water.

Dissolved salts make sea water less compressible, so sound travels faster in it, about 1,530 m/s at 25 °C, than in pure or drinking water.

The pulmonary veins bring oxygen-rich blood from the lungs straight into the left atrium. The human heart has four chambers and works as two pumps.

HIV spreads through body fluids such as blood, so a transfusion of infected blood passes the virus directly into the bloodstream.

Argon is an inert gas, so it does not react with the white-hot tungsten filament and slows its evaporation, which makes the bulb last longer.

Magnesium is above hydrogen in the reactivity series, so it displaces hydrogen from the acid: Mg + 2HCl → MgCl2 + H2.

Pitch is how high or low a sound seems to the ear, and it depends on the frequency of vibration: the higher the frequency, the higher the pitch.