Writing topic sentences
Write the topic sentences for each of the following paragraphs.
Firstly, they live in or on a host, and do it harm. The depth to which they penetrate the host varies, as indeed does the damage. Fleas, leeches and lice live on the surface and cause superficial injury. Athlete's foot is a skin disease caused by a fungus living in the surface layers of the foot. The parasite of sleeping sickness is found in the host's blood wriggling between blood corpuscles. Secondly, parasites show some simplification of body structures when compared with free-living relatives. Sacculina (a relative of the crab) shows loss of limbs and is reduced to a mass of reproductive tissue within the abdomen of its crustacean host. Dodder, a plant parasite, lacks leaves, roots and chlorophyll. Thirdly, although all organisms show adaptations to their way of life, in the case of parasites they are often associated with a complex physiological response, e.g. the ability to survive in regions almost devoid of available oxygen, such as adult liver flukes, or the hooks and suckers of adult tapeworm. Lastly, parasites exhibit a complex and efficient reproduction, usually associated in some way with the physiology of the host, e.g. rabbit fleas are stimulated by the level of sex hormone in their host.
(J. Hard, (1975). Biology, p. 57)
In 1920 an average of 2.75 pounds of waste were produced each day by each individual in the United States. Today the quantity of waste produced is 53 pounds per person, and by 1980 it is estimated that this will rise to 8 pounds per person. One year's rubbish from 10,000 people covers an acre of ground to the depth of 10 feet. In one year Americans throw away 48 thousand million cans, 26 thousand million bottles, 430 million tons of paper, 4 million tons of plastic and 100 million tyres which weigh almost a million tons.
(John W Klotz, (1972). Ecology crisis, p. 197)
That it might be experienced in any other way seems unnatural and strange, a feeling which is rarely modified even when we begin to discover how really differently it is handled by some other people. Within the West itself certain cultures rank time much lower in over-all importance than we do. In Latin America, for example, where time is treated rather cavalierly, one commonly hears the expression, "Our time or your time?" "Hora americana, hora mejicana?"
(Edward Hall, (1973), The silent language, p. 6)
From the late 1870s onwards, cheap American corn began to arrive in the country in large quantities, along with refrigerated meat and fruit from Australia and New Zealand, and in a period when both farmers and businessmen were complaining of depression, standards of living rose higher than they had ever done. The change began each day, as Victorian writers frequently pointed out, with the food on the breakfast table - with eggs and bacon as staple fare for the middle classes - and went on through tea, high or low, to multi-course dinners or fish-and-chip suppers. The poor were eating better as well as the rich. The annual per capita consumption of sugar, which had increased from 18 lb. to 35 lb. between the Queen's accession and 1860, rose to 54 lb. in 1870-99 and 85 lb. in 1900-10; that of tea, which along with beer had now become a national drink, went up from 1½ lb, first to 4¼ lb and then to 6 lb.
(Asa Briggs, (1983). A social history of England, p. 246)
The first is the way in which living cells develop an energy currency. This, like ordinary money, can be used to exchange one vital commodity for another. The second is the use of substances called enzymes as go-betweens to reduce the amount of energy needed to make many chemical reactions essential to life take place fast enough.
(The sciences: Michael Beazley Encyclopaedias (1980), p. 136)
At first it was little more than a trickle. For a long time the Norman conquerors did not mix much with their Saxon subjects. There are plenty of indications of this; for the languages, too, moved side by side in parallel channels. The custom of having one name for a live beast grazing in the field and another for the same beast, when it is killed and cooked, is often supposed to be due to our English squeamishness and hypocrisy. Whether or not the survival of this custom through ten centuries is due to the national characteristics in question it would be hard to say, but they have certainly nothing to do with its origin. That is a much more blame-less affair. For the Saxon neatherd who had spent a hard day tending his oxen, sheep, calves and swine, probably saw little enough of the beef, mutton, veal, pork and bacon, which were gobbled at night by his Norman masters. There is something a little pathetic, too, in the thought that the homely old word, stool, could be used to express any kind of seat, however magnificent, until it was, so to speak, hustled into the kitchen by the smart French chair. Even the polite, however, continued to use the old word in the idiom to fall between two stools.
Owen Barfield: History in English Words (Faber, 1954)
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