General Science GK Questions with Answers – Page 70

The apple's gravitational potential energy first becomes kinetic energy as it falls, some is lost as heat to the air on the way, and at impact the rest goes into heating the ground and apple and into sound.

Diamond and graphite are allotropes of the same element, carbon, so their chemical properties are the same; only their physical properties differ.

In the electrolytic refining of copper, a solution of copper sulphate made acidic with a little dilute sulphuric acid carries the copper ions between the electrodes.

Two ammonium ions, each with a charge of +1, are needed to balance one carbonate ion with a charge of -2.

Putting a soft iron bar inside a solenoid makes the magnetic field much stronger, so the claim that the field stays the same is not correct.

Magnesium combines with oxygen to form a new substance, magnesium oxide, so a chemical reaction takes place. When a magnesium ribbon is heated, it burns with a dazzling white flame and leaves a white powder: 2Mg + O₂ → 2MgO.

The nitride ion, N³⁻, carries a charge of minus three, so its valency is -3. Nitrogen has five electrons in its outer shell.

A telescope's objective must gather as much light as possible from a distant object and form a large image, so it is both wide and of long focal length.

At a fixed temperature, changing the pressure of an ideal gas does not change the speed of sound in it, so x and y are equal.

A small piece of tissue called an explant is placed in a sterile nutrient medium with growth regulators, it forms an unorganised mass called a callus and then whole plantlets, because a plant cell is totipotent, that is, able to give rise to a complete plant; the plants so raised…

The system comes from a defence mechanism of bacteria against viruses: a guide RNA takes the Cas9 protein to a chosen sequence in the DNA, Cas9 cuts both strands there, and the cell's own repair machinery then changes the sequence, so a gene can be switched off or corrected in…

This committee works under the Ministry of Environment, Forest and Climate Change and appraises proposals for the large scale use and the environmental release of genetically engineered organisms and products, so no transgenic crop may be grown commercially without its clearance.

The deficiency of adenosine deaminase destroys the immune system because the enzyme is needed for the normal working of lymphocytes, and in 1990 lymphocytes of a girl with this disorder were grown outside the body, given a functional gene and returned to her blood; since those cells are not permanent…

In 1983 the American company Eli Lilly put the DNA sequences of the A and B chains of human insulin into Escherichia coli, produced the two chains separately and joined them by disulphide bonds to make a hormone identical to the human one; it was sold as Humulin, the first…

The British geneticist Alec Jeffreys developed DNA fingerprinting in 1984 by studying short repeated sequences that vary in number from person to person, and the method is now used in criminal investigation, in disputes about parentage and in identifying victims of accidents and disasters.

Dolly was a sheep produced at the Roslin Institute in Scotland in 1996 by the technique of somatic cell nuclear transfer, in which the nucleus of an udder cell of one sheep was placed in an egg whose own nucleus had been removed, so the lamb carried the genes of…

The polymerase chain reaction repeats three steps, denaturation at a high temperature, annealing of short primers and extension of the new strand, so the enzyme must survive near boiling water; Taq polymerase, obtained from the bacterium Thermus aquaticus of hot springs, does exactly that and lets a single DNA segment…

Golden Rice carries genes that let the grain make beta carotene, the orange pigment that the human body converts into vitamin A, and the colour of the grain gives the variety its name; the aim is to reduce night blindness and childhood blindness in populations whose diet is mainly rice.

The genes called cry genes are taken from Bacillus thuringiensis, a bacterium of the soil that forms protein crystals during its spore stage.

This soil bacterium naturally transfers a part of its tumour inducing plasmid, called the Ti plasmid, into the cells of a dicotyledonous plant and causes crown gall disease; genetic engineers disarm the plasmid, insert the gene they want and use the bacterium as a vector, which is why it is…