General Science GK Questions with Answers – Page 34

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

The egg is fertilised to form the zygote, the zygote grows into the embryo, and the ovule carrying the embryo becomes the seed.

The vehicle goes 100 m east and 200√2 m south, and the straight-line distance between start and finish is √(100² + (200√2)²) = 300 m. Each leg starts from rest, so the distance covered is s = ½at².

When light of a suitable frequency falls on a metal and knocks electrons out of it, the process is called photoelectric emission.

Carbon monoxide binds to the haemoglobin of red blood cells to form carboxyhaemoglobin, so the blood can no longer carry oxygen to the tissues.

. Thyroxine sets the body's basal metabolic rate, that is, how fast cells use oxygen and food to release energy.

The refrigerator uses 5 kW × 10 h × 30 days = 1,500 kWh, and at ₹ 4 per kWh that costs ₹ 6,000.

. When quicklime reacts with water a large amount of heat is released, so the reaction is exothermic.

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

Pollen grains are formed by meiosis, the division that halves the chromosome number and DNA content of the parent cell.

In free fall all the potential energy turns into kinetic energy, so 625 J = ½ × 0.32 kg × v², which gives v = 62.5 m/s. First change the mass into kilograms: 320 g = 0.32 kg.

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.

ACE2 is the receptor through which the coronavirus SARS-CoV-2, the cause of COVID-19, enters human cells. ACE2 stands for angiotensin-converting enzyme 2, a protein on the surface of cells in the lungs, heart, blood vessels, kidneys and gut, where it normally helps control blood pressure.

Statements 1 and 3 describe real differences; statement 2 gets the life span backwards. A sodium vapour lamp is a glowing tube that sends light out in all directions, through 360 degrees, so reflectors are needed to push the light down onto the road and some light is wasted.

Statement 1 has both genomes wrong, while statement 2 is a correct fact. Adenoviruses carry a double-stranded DNA genome.

When a wire is stretched its volume stays the same, so the length must grow in the same ratio as the cross-sectional area shrinks.

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.

Both beams carry conventional current in the same direction, north to south, and parallel currents in the same direction attract each other.