General Science Mixed Quiz: Set 167

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.

Sericulture is the rearing of silkworms for the production of raw silk, and it includes the growing of mulberry, on whose leaves the mulberry silkworm feeds; India produces mulberry silk as well as the wild varieties tasar, eri and muga, the last being special to Assam.

Magnesium oxide melts at about 2,850 °C, far higher than the other three, because its small Mg2+ and O2− ions carry double charges and hold each other with a very strong ionic lattice.

The rounded head of the humerus sits in the socket of the shoulder blade and the head of the femur sits in the socket of the hip bone, which lets the limb move forwards, backwards, sideways and in rotation; these are synovial joints with a fluid-filled cavity.

Cardiac muscle is a muscular tissue, not a connective tissue; it is the striated, branched, involuntary muscle that makes up the wall of the heart and contracts rhythmically for life.

After ovulation the ruptured Graafian follicle turns into the yellow body called the corpus luteum, which secretes large amounts of progesterone to thicken and maintain the endometrium for implantation.

When ice melts it only changes from solid to liquid; the substance is still water, so it is a physical change.

Genetic engineering uses recombinant DNA, cloning and gene transfer, and restriction enzymes cut DNA at specific sites; but they do not unzip DNA into two strands, so statement 3 is wrong.

Plant growth regulators, or plant hormones, are small molecules that control growth even in tiny amounts, and each main group comes from a different chemical family.

It is produced when a plant faces drought, salinity or extreme temperature; it closes the stomata so that water is not lost, for which reason it is called an antitranspirant, and it induces dormancy in seeds and buds so that growth waits for better conditions.

The 2015 film 'The Man Who Knew Infinity' tells the life of the Indian mathematician Srinivasa Ramanujan and is based on Robert Kanigel's 1991 biography of the same name.

Thomson. Working with cathode rays in a discharge tube in 1897, he showed that the rays were a stream of negatively charged particles far lighter than any atom, and he measured their charge to mass ratio, which established the electron as the first known subatomic particle.

In bryophytes the main, independent plant body is the haploid gametophyte, while the diploid sporophyte stays attached to it and depends on it for food.

Bryophytes such as Marchantia, Riccia, Funaria and Sphagnum grow on soil, rocks and tree trunks, but their male gametes are flagellate and must swim through a film of water to reach the egg, so fertilisation cannot take place in dry conditions.

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

The sino-atrial node is a small patch of specialised muscle tissue in the wall of the right atrium near the opening of the superior vena cava, and it generates the impulse that sets the rate of each heartbeat without any outside stimulus, which is why it is called the pacemaker.

Electromagnetic waves need no medium, so they travel through vacuum, and they consist of electric and magnetic fields that oscillate at right angles to each other and to the direction of travel.

A typical flower has four whorls arranged on the thalamus: sepals on the outside, then petals, then stamens, and carpels at the centre.

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

Boyle's law, established in 1662, says that for a fixed mass of gas at constant temperature the product of pressure and volume stays constant, so doubling the pressure halves the volume.