General Science Mixed Quiz: Set 211

A rainbow forms when raindrops split white sunlight into its seven colours. When sunlight enters a raindrop, it is refracted, and because each colour bends by a different amount, the colours spread apart.

The urinary bladder is a hollow muscular sac made of smooth muscle and a stretchable lining; it has no cartilage.

The peacock is a bird and the camel is a mammal, and these are the only two groups of animals that are warm-blooded.

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

Penicillin stops bacteria from building their peptidoglycan cell wall, so the weakened cells burst and die. Penicillin binds to and blocks the transpeptidase enzymes, also called penicillin-binding proteins, that cross-link the peptidoglycan chains of the wall.

These are the organs in which lymphocytes are produced and in which they mature into cells able to tell self from non-self; the B cells complete this training in the bone marrow and the T cells in the thymus, a gland behind the breastbone that shrinks with age.

Both statements describe how nucleases are used as tools of recombinant DNA technology. Nucleases are enzymes that break the phosphodiester bonds of DNA.

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.

A constellation is a group of stars that appears to form a shape when seen from the earth, but its stars usually lie at very different distances from us.

Cytokinins promote cytokinesis, that is cell division; kinetin was the first of them to be identified, from the degraded DNA of herring sperm, and zeatin, the natural form, was obtained from maize grains.

The British physicist said these words in a lecture in January 2016, using his own work on black holes as a message of hope for people facing depression.

All three follow from Einstein's General Theory of Relativity, published in 1915. General relativity explains gravity not as a force but as the curving of space-time by mass and energy; in John Wheeler's words, matter tells space-time how to curve, and space-time tells matter how to move.

It is very cold, chemically inert and cheap, which makes it the standard coolant for preserving cells and tissues. Liquid nitrogen boils at about −196 °C. At such low temperatures the chemical and enzyme activity inside cells almost stops, so tissues can be kept unchanged for years.

Sphagnum is a bog moss, a bryophyte, whose dead cells hold many times their own weight of water; in waterlogged and acidic bogs its remains decay only partly and pile up as peat, which is cut, dried and burnt as fuel and is also used in nurseries to keep soil…

Only a pressure greater than the osmotic pressure of seawater can push pure water backwards through the membrane. In ordinary osmosis, water moves through a semipermeable membrane from the dilute side to the concentrated side.

In the Haber process nitrogen from the air and hydrogen are combined under high pressure at a few hundred degrees Celsius over a catalyst of finely divided iron, and the ammonia so made is the starting point of nitrogenous fertilisers such as urea and of nitric acid.

In an ideal gas the molecules move with a whole range of speeds, so this statement is false. The kinetic theory treats an ideal gas as a large number of tiny molecules in random motion that collide elastically with one another and with the walls.

Phloem carries the sugars made in the leaves to every part of the plant that needs food. Phloem is a complex permanent tissue made of four kinds of cells: sieve tubes, companion cells, phloem parenchyma and phloem fibres.

Both stress and pressure are force per unit area, so both are measured in newton per square metre, or pascal (Pa).

Nitrogen gas is the element itself in a very stable form, and plants cannot take it up directly from the soil or the air, so it is not used as a fertilizer.