General Science GK Questions with Answers – Page 81

After 3 minutes 45 seconds the boy has completed seven and a half rounds, so he stands at the point exactly opposite his starting point.

Bile has no digestive enzymes at all; it only prepares fats for digestion by other enzymes. Bile is made by the liver, stored and concentrated in the gall bladder, and poured into the duodenum through the bile duct.

The reaction centre of a photosystem is a special chlorophyll a molecule, not a carotenoid. In photosynthesis, pigments are grouped into photosystems.

Transcription is the step in which the genetic message of a gene is copied from one strand of DNA into a strand of RNA.

The balanced equation is Fe2O3 + 3CO → 2Fe + 3CO2, which has equal numbers of every atom on both sides.

The lower the pH, the stronger the acid, and pH 0 lies at the most acidic end of the common scale.

In household wiring the wire with green insulation is the earth wire, not the live wire, so this statement is not correct.

In an isotonic solution the concentration outside the cell equals that inside, so there is no net movement of water.

All three symbols come from the Latin names of these metals: aurum, stannum and plumbum. Many metals known since ancient times take their symbols from Latin rather than English.

Xerophytes live where water is scarce, so they have few stomata to cut down water loss. Xerophytes are plants of deserts and dry habitats, such as cacti, Opuntia, Calotropis and Acacia.

Many white blood cells destroy germs by swallowing them, and that digestion needs a large number of lysosomes. Lysosomes are small membrane-bound sacs packed with hydrolytic enzymes that break down proteins, fats, carbohydrates and nucleic acids.

The correct answer is A, Aspergillus niger, a fungus grown on a sugar medium to make most of the world's citric acid, which is used in soft drinks, food and medicines.

The short, sharp heating kills the disease-causing and most spoilage microbes while leaving the taste and most of the food value of the milk unchanged, which is exactly what boiling does not do.

A virus has heredity and mutates like a living thing, yet it has no cell, no metabolism and no means of reproduction of its own; outside a host it is an inert particle that can even be crystallised, as W. M. Stanley showed with the tobacco mosaic virus in 1935…

It spreads through droplets in the air, chiefly attacks the lungs, and is treated with a long and uninterrupted course of several antibiotics.

The yeast Saccharomyces cerevisiae ferments the sugars of the dough into ethanol and carbon dioxide, and the gas, trapped in the gluten, makes the dough rise and leaves the bread spongy; the alcohol evaporates during baking.

Fungi are eukaryotes with a true nucleus, and their wall is built of chitin, the same tough polysaccharide that forms the exoskeleton of insects and crustaceans.

It lives in a symbiotic relationship inside the nodules on the roots of gram, pea, groundnut and other legumes, converting atmospheric nitrogen into compounds the plant can absorb while drawing its food from the plant.

The correct answer is B, measles, a viral disease spread by droplets, which is why it is prevented by vaccination and not treated with antibiotics.

It is the target of penicillin, which blocks its formation, and the amount of it in the wall is what makes a bacterium stain Gram-positive or Gram-negative.