General Science Previous Year Questions (PYQ) with Answers – Page 33

The cochlea of the inner ear changes the pressure variations of sound into electrical (nerve) signals, which the auditory nerve then carries to the brain.

The speed of sound in air increases, not decreases, as temperature rises, so statement B is the incorrect one. Sound in a gas travels faster when the gas is warmer, because its molecules move faster and pass the vibration on more quickly.

SONAR sends out ultrasonic pulses and times their echo from underwater objects. SONAR stands for Sound Navigation and Ranging.

A solar cell turns the energy of sunlight directly into electricity through the photovoltaic effect. A solar cell is a large p-n junction, usually made of silicon.

The time period of a simple pendulum depends on its length but not on the mass of the bob, so halving the length divides the period by √2.

The packet’s density is 800 g divided by 1,000 cm³, which is 0.8 g/cm³, less than the density of both liquids.

Refractive index is the ratio of the speed of light in air to its speed in the medium, so the speed in glass is c divided by 3/2, which is (2/3)c. The absolute refractive index of a medium is n = c/v, where c is the speed of light in…

For lenses in contact the powers simply add, and here they are +2 D and +4 D. The power of a lens is the reciprocal of its focal length in metres, P = 1/f, and its unit is the dioptre.

Covaxin is an inactivated virus vaccine and Sputnik V is a viral vector vaccine, but Covishield is a viral vector vaccine, not an mRNA vaccine.

By Newton's law of gravitation, the acceleration due to gravity at the surface is g = GM/R², where G is the universal gravitational constant, M is the mass of the Earth and R is its radius.

In simple harmonic motion the velocity is given by omega times the square root of A squared minus x squared.

After fertilisation the ovary of the flower grows into the fruit, and each ovule inside it develops into a seed.

Lysosomes are small sacs bound by a membrane that are filled with digestive enzymes able to break down almost any material in the cell.

The gastric glands in the stomach wall secrete pepsin, which begins the digestion of proteins into smaller peptides. The chief cells of the gastric glands release pepsin in an inactive form, pepsinogen.

Varignon theorem states that the moment of a force about any point equals the algebraic sum of the moments of its components about the same point; it speaks of the moments themselves, not of their squares, so statement S1 is false as written.

Sulphur vapour turns straight into solid sulphur on the cooler rocks without first becoming a liquid, and a direct change from gas to solid is called deposition.

At about 6 to 7 metres in an adult, the small intestine is by far the longest part of the alimentary canal.

This is the fluid mosaic model of the cell membrane given by Singer and Nicolson in 1972. Each phospholipid has a water-loving (hydrophilic) phosphate head and two water-fearing (hydrophobic) fatty acid tails.

Vegetable oils are hardened into margarine and vanaspati ghee by hydrogenation. Liquid vegetable oils are unsaturated: their fatty-acid chains contain carbon-carbon double bonds.

A honeybee sting injects methanoic acid, also called formic acid (HCOOH), which causes the burning pain and irritation.