General Science Previous Year Questions (PYQ) with Answers – Page 42

Iron is a micronutrient, needed by plants only in very small amounts, and calcium is a macronutrient, needed in large amounts.

The lysosome is a small sac bound by a single membrane that is filled with digestive enzymes, so it breaks down food particles taken into the cell and clears out worn out parts of the cell itself.

These are the weak attractions that appear when the electron cloud of an atom becomes momentarily lopsided, creating a temporary dipole which then induces a matching dipole in a neighbouring atom.

Permanent tissues are made of cells that have stopped dividing and have taken on a fixed shape, size and function, and in simple permanent tissues such as parenchyma the loosely packed cells leave clear intercellular spaces through which gases can move.

Both are tiny algae grown in tanks and sold as protein rich food supplements, and both have been studied as food for astronauts.

Gamma rays sit at the far end of the electromagnetic spectrum, with the shortest wavelength and therefore the highest frequency and energy.

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

This pair is wrong, because tomato contains oxalic acid, along with some citric and malic acid. Formic acid, or methanoic acid, is the acid of an ant sting and a bee sting, and its name comes from the Latin word for ant.

Urea is made industrially by reacting ammonia with carbon dioxide under high pressure. The process runs in two steps: ammonia and carbon dioxide first form ammonium carbamate, which then loses a water molecule to give urea.

Pneumonia is an infection of the lungs in which the alveoli, the tiny air sacs where oxygen passes into the blood, fill with fluid or pus.

Among the allotropes of carbon, graphite has the lowest standard enthalpy of formation, which is taken as zero, so it is the reference state and the most stable form under ordinary conditions of temperature and pressure.

A conservative force is one whose work depends only on the starting and the finishing point, not on the path taken, and whose work around any closed path is zero.

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.

CH3CH2OH, also written C2H5OH, is ethanol or ethyl alcohol, the second member of the alcohol family. The -OH group attached to the carbon chain is the functional group that makes it an alcohol.

By Ohm's law the resistance equals the potential difference divided by the current. Here the current must first be converted into the base unit: two milliampere is 0.002 ampere.

A magnet cannot be cut into a single north pole and a single south pole.

Loudness and frequency are two different properties of sound. Loudness depends on the amplitude of the vibration, that is how far the vibrating part moves from its rest position, while frequency is the number of vibrations made in one second and is measured in hertz.

Convert the units first: 1 kilohertz is 1000 hertz and 50 centimetres is 0.5 metre. The speed is frequency multiplied by wavelength, that is 1000 multiplied by 0.5, which gives 500 metres per second.

Plants respire day and night, breaking glucose down to release energy, and carbon dioxide is the waste product of that process.

The same magnet moves at the same speed in both cases, so the rate of change of magnetic flux through the coil is equal and the induced potential difference has the same magnitude.