General Science Previous Year Questions (PYQ) with Answers – Page 34

Adipose tissue is a loose connective tissue whose cells, called adipocytes, are built to store fat. Each cell holds a large droplet of fat that pushes the nucleus and cytoplasm to one side.

Potassium permanganate, KMnO₄, forms dark purple crystals that contain no water of crystallization; its formula has no attached water molecules.

Bronze is made by mixing copper (Cu) with tin (Sn), usually about nine parts copper to one part tin. Adding tin makes the metal harder, stronger and more resistant to corrosion than pure copper, which is why bronze was used for tools, weapons, bells, coins and statues.

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.

Speed tells only how fast a body moves, while velocity also tells the direction of motion, and a quantity with both magnitude and direction is a vector.

A freely pivoted magnetic needle turns to line up with any magnetic field around it, so its deflection shows that a field is present and which way it points.

Railway tracks are joined by the thermite process, in which aluminium powder reduces iron oxide to molten iron. The reaction is Fe₂O₃ + 2Al → 2Fe + Al₂O₃.

Liquid nitrogen boils at about −196 °C, cold enough to stop almost all biological activity, and it is cheap, inert and safe to handle.

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.

A generator, whether AC or DC, produces electricity because a coil rotating in a magnetic field has a changing magnetic flux through it, and Faraday's laws say that a changing flux induces an electromotive force.

Pressure is force divided by the area in contact: the weight is 2 kg × 10 m/s² = 20 N and the face touching the table is 0.30 m × 0.10 m = 0.03 m², so the pressure is 20 ÷ 0.03 ≈ 666.6 N/m².

Electric charge equals current multiplied by time, Q = I × t, with time in seconds: 0.6 A × 600 s = 360 coulombs.

Using the lens formula with sign conventions, the object is found to be 10 cm from the lens, and the magnification v/u comes to 0.5.

Since both wires have the same material and thickness, resistance is proportional to length, so R2 = 2R1, and the parallel combination works out to R = 2R1/3.

With uniform acceleration, velocity changes by the same amount in every equal interval of time, so the velocity-time graph is a straight line whose slope equals the acceleration.

Fleming's right-hand rule is used for electromagnetic induction, as in a generator, and its middle finger gives the direction of the current induced in the conductor.

Buoyancy, also called upthrust, is the upward force that a liquid or gas exerts on any object placed in it.

Lipids, including steroids and the phospholipids of membranes, are made by the smooth endoplasmic reticulum, so a defect there would stop lipid synthesis.

Papaya bears unisexual flowers: a flower has either stamens or a pistil, and male and female flowers usually grow on separate plants.

. Oral contraceptive pills prevent pregnancy mainly by stopping the ovary from releasing an egg.