General Science Previous Year Questions (PYQ) with Answers – Page 3

In an apple, the fleshy part we eat develops from the thalamus, the swollen tip of the flower stalk, and not from the ovary, which is why it is called a false fruit.

A ring of muscle at the lower end of the stomach, the pyloric sphincter, opens and closes to let food pass into the small intestine a little at a time.

A Carnot engine is an ideal reversible engine, not an irreversible one, and its efficiency is 1 − T2/T1 with temperatures in kelvin.

Clay is a plastic material: it deforms permanently under even a small force, so its stress is not proportional to its strain.

When only conservative forces do work on a system, the sum of its kinetic and potential energy stays the same; this is the principle of conservation of mechanical energy.

In uniform circular motion the speed stays the same but the direction keeps turning, and that change needs an acceleration pointing to the centre.

Inside a long, narrow solenoid the field lines run straight and parallel and are evenly spaced, which is the picture of a uniform field.

The primary spermatocyte is the diploid cell that enters meiosis I and splits into two haploid secondary spermatocytes. Spermatogenesis takes place in the seminiferous tubules of the testes.

In parallel the equivalent resistance is always smaller than the smallest single resistor, so here it falls below 1 Ω. For resistors in parallel, 1/R = 1/R1 + 1/R2 + 1/R3 = 1/1 + 1/2 + 1/3 = 11/6, so R = 6/11 Ω, about 0.55 Ω. Each extra parallel…

SONAR sends out pulses of high-frequency sound, above 20 kHz, which travel well through water and bounce back from objects.

When calcium carbide reacts with water it gives acetylene (ethyne) gas and calcium hydroxide, not hydrogen. The reaction CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂ is the old method of making acetylene, once burnt in miners' lamps and still used for welding and for ripening fruit illegally.

Petroleum ether is a solvent and petroleum jelly is spread on metal surfaces as a protective coating, while the uses given for petroleum wax and white spirit have been swapped around.

Mature sclerenchyma cells have thick walls hardened with lignin and lose their living contents, so they are dead cells that give the plant strength.

Only statement II is correct: a small amount of gypsum is added to cement to slow down its setting. Portland cement is made by heating limestone and clay to form clinker, which is then ground with about 2 to 3 per cent gypsum (calcium sulphate dihydrate).

Monkeys are primates, and female primates have a menstrual cycle, not an oestrus cycle.

. Oppositely charged ions in an ionic crystal pull on each other strongly from every side, so a great deal of heat is needed to break the lattice apart.

Both statements swap the two scales: octane number rates petrol, cetane number rates diesel, and their reference fuels are the other way round.

EDTA is a hexadentate ligand: one EDTA ion binds a metal ion through six donor atoms, so it forms complexes with coordination number 6.

When water is short, leaves make more abscisic acid (ABA), which makes the guard cells lose water and close the stomata, so the plant loses less water through transpiration.

Every biological molecule, from sugars and fats to proteins and DNA, is built on a skeleton of carbon atoms, which is why carbon is called the basic building block of life.