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minimumdrawnNew Zealand SeaweedCall us not weeds; we are flowers of the a.Section ASeaweed is a particularly nutritious food, which absorbs and concentrates traces of a wide variety of minerals necessary to the body去头屑的方法’html5培训s health. Many elements may occur in aweed—aluminium, barium, calcium, chlorine, copper, iodine and iron, to name but a few—traces normally produced by erosion and carried to the aweed beds by river and a currents. Seaweeds are also rich in vitamins: indeed, Eskimos obtain a high proportion of their bodily requirements of vitamin C from the aweeds they eat.The nutritive value of aweed has long been recognized. For instance, there is a remarkably low incidence of goiter amongst the Japane, and for that matter, amongst our own Maori people, who have always eaten aweeds, and this may well be attributed to the high iodine content of this food. Rearch into old Maori eating customs shows that jellies were made using aweeds, fresh fruit and nuts, fuchsia and tutu berries, cape gooberries, and many other fruits which either grew h
ere naturally or were sown from eds brought by ttlers and explorers.Section BNew Zealand lays claim to approximately 700 species of aweed, some of which have no reprentation outside this country. Of veral species grown worldwide, New Zealand also has a particularly large share. For example, it is estimated that New Zealand has some 30 species of Gigartina, a clo relative of carrageen or Irish moss. The are often referred to as the New Zealand carrageens. The gel-forming substance called agar which can be extracted from this species gives them great commercial application in ameal, from which ameal custard is made, and in cough mixtures, confectionery, cosmetics, the canning, paint and leather industries, the manufacture of duplicating pads, and in toothpastes. In fact, during World War II, New Zealand Gigartina were nt to Australia to be ud in toothpaste.Section CYet although New Zealand has so much of the commercially profitable red aweeds, veral of which are a source of agar(Pterocladia, Gelidium, Chondrus, Gigartina), before 1940 relatively little u was made of them. New Zealand ud to import the Northern Hemisphere Irish moss(Chondrus crispus)from England and ready-made agar from Japan. Although distrib
ution of the Gigartina is confined to certain areas according to species, it is only on the east coast of the North Island that its occurrence is rare. And even then, the east coast, and the area around Hokiangna, have a considerable supply of the two species of Pterocladia from which agar is also available. Happily, New Zealand-made agar is now obtainable in health food shops. Section D Seaweeds are divided into three class determined by colour—red, brown and green—and each tends to live in a specific location. However, except for the unmistakable a lettuce(Ulva), few are totally one colour; and especially when dry, some species can change colour quite significantly—a brown one may turn quite black, or a red one appear black, brown, pink or purple. Identification is nevertheless facilitated by the fact that the factors which determine where a aweed will grow are quite preci, and they tend therefore to occur in very well-defined zones. Although there are exceptions, the green aweeds are mainly shallow-water algae; the browns belong to medium depths, and the reds are plants of the deeper water. Flat rock surfaces near mid-level tides are the most usual habitat of a-bombs, Venus’ necklace and most brown aweeds. This is also the location of the purple laver o
r Maori karengo, which looks rather like a reddish-purple lettuce. Deep-water rocks on open coasts, expod only at very low tide, are usually the site of bull kelp, strapweeds and similar tough specimens. Tho species able to resist long periods of exposure to sun and air are usually found on the upper shore, while tho less able to stand such exposure occur nearer to or below the low-water mark. Radiation from the sun, the temperature level, and the length of time immerd all play a part in the zoning of aweeds.Section EPropagation of aweeds occurs by spores, or by fertilization of egg cells. None have roots in the usual n; few have leaves, and none have flowers, fruits or eds. The plants absorb their nourishment through their fronds when they are surrounded by water: the ba or “英语说课稿格式holdfast”alder of aweeds is purely an attaching organ, not an absorbing one.Section FSome of the large aweeds maintain buoyancy with air-filled floats; others, such as bull kep, have large cells filled with air. Some, which spend a good part of their time expod to the air, often reduce dehydration either by having swollen stems that contain water, or they may(like Venus’ necklace)have swollen nodules, or they may have distinctive shape like a a-bomb. Others, like the a cactus, are filled with sli
tzdmy fluid or have coating of mucilage on the surface. In some of the larger kelps, this coating is not only to keep the plant moist but also to protect it from the violent action of waves. You should spend about 20 minutes on Questions 1-13 which are bad on Reading Passage 1 on the following page.Questions 1-6Reading passage 1 has six ctions A-F.Choo the correct heading for each ction from the list of headings below.Write the correct number i-x in boxes 1-6 on your answer sheet.List of Headingsi Locations and features of different aweedsii Various products of aweedsiii U of aweeds in Japaniv Seaweed species around the globev Nutritious value of aweedsvi Why it doesn’t dry or sinkvii Where to find red aweedviii Under-u of native speciesix Mystery solvedx How aweeds reproduce and grow
