amoeba-4 - lining and causes a severe form of diarrhoea....

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Amoeba 4 Protozoa Amoeba is classed as a protozoan or ‘single-celled animal’; this is because it feeds like an animal by taking in solid food and digesting it internally. Amoeba proteus is the ‘textbook’ amoeba. It has the advantage that it is comparatively large and uncomplicated compared with other protozoa in the same group but is not a typical member of that group. Its pseudopodia are blunt, unlike most of the other representatives, many of which have internal or external ‘skeletons’. Two of these are illustrated here. Arcella is a fresh water protozoan. It has blunt pseudopodia but also a shell. Arcella (x500) Polystomella, a marine protozoan , has an internal skeleton and filamentous pseudopodia. The cytoplasm can be seen streaming in the pseudopodia which pick up and ingest food particles. Polystomella (x30) Many amoebae live in the soil and some live in the human intestine. Entamoeba coli lives harmlessly in the colon, feeding on bacteria, but Entamoeba histolytica attacks the intestinal
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Unformatted text preview: lining and causes a severe form of diarrhoea. Cryptosporidium occurs in water that has not been treated to make it fit for drinking. Cryptosporidium causes cryptosporidiosis - a short-lived diarrhoeal disease. Multicellular animals carry out their living processes by means of speed organs and tissues; the digestive system, nervous system, muscular system etc. The cells in these organs are speed for a particular function. Muscle cells can contract, nerve cells conduct impulses, gland cells secrete enzymes or hormones. These speed cells cannot survive on their own. They need other cells or systems to supply them with food and oxygen and to remove their waste products. The single-celled animals can carry out all these vital functions. They grow, feed, breathe, reproduce, excrete all within the cell though certain parts of the cytoplasm may be speed to carry out special functions; the contractile vacuole for example. D.G. Mackean pseudopodia pseudopodia...
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